Mountain, Plain
and Garden >vf
The Magazine of Denver Botanic Gardens ■ Spring/Summer 1990
Published by:
Denver Botanic Gardens, Inc.
909 York Street
Denver, Colorado 80206
Rob Proctor, Editor
Andrew Pierce, Acting Executive Director
Beatrice Taplin, President
Sent to all members of Denver Botanic Gardens. Mem¬
bership fees are as follows: Student $18, Individual
Senior Citizen $18, Senior Couple $25, Individual $25,
Family/Dual $35, Contributing $50, Supporting $100,
Patron $500, Benefactor $1000.
By becoming a member of Denver Botanic Gardens,
Inc., you will receiveMountain, Plain and Garden and
the monthly Green Thumb News. You will also have
year-round admission to the gardens and unlimited
access to the use of the books in the Helen K. Fowler
Library, located in Boettcher Memorial Center at 1005
York Street.
For further information, write to Membership Chair¬
man, Botanic Gardens House, 909 York Street, Denver,
Colorado 80206, or call 331-4000.
Denver Botanic Gardens, Inc. , maintains a collection of
living plants, both native and exotic, for the purpose of
acquiring, advancing and spreading botanical and hor¬
ticultural knowledge.
This is a non-profit organization supported by munici¬
pal and private funds.
Copyright 1990 by Denver Botanic Gardens, Inc.
Cover and Back cover photographs of Annual
Plant Sale: by Robert Heapes
Design: Graphic Impressions, Denver
Color Separations: T & R Engraving, Inc, Denver
Printing: The Pressworks, Denver
Mountain, Plain
and Garden W'
The Magazine of Denver Botanic Gardens
Volume 47 Number 1 Spring /Summer 1990
Contents
Introduction
Emerson R. Birchfield . 1
Selecting and Growing Annuals
Joedy Arnold, with sections by
Jeanne Ruggles, Katy Dickson
and Rosemary Laughlin . 4
Fruitful Harvest
Kenneth Roberts . 6
Ancient Herbs in the Modern Garden
Diane Ipsen . 7
Colorado Style: A Perennial Perspective
Rob Proctor . 9
Plant Donations: Sharing the Best
Marilyn Moore . 10
Alpines for Colorado
Panayoti Kelaidis . 11
The Versatile Rose
Betty Lou Roberts . 12
Bulbs for Summer Color
Janet Sickafuse . 14
Classic Trees and Shrubs
Diane Ipsen, with Alan Rollinger . 15
A Vegetable Sampler
Knobby Brown . 17
Water Gardening in Colorado
Len Freestone . 18
Selected Listing
of Plants and Cultural Tables
Annuals . 19
Berry Basket . 25
Herbs . 26
Perennials . 28
Rock Alpine/Ground Covers . 33
Summer Bulbs . 40
Trees and Shrubs . 41
Vegetables . 43
Water Gardening . 44
Introduction
by Emerson R. Birchfield
“The Flowering of Denver” is the Denver Botanic
Gardens’ Annual Plant and Used Book Sale on
May 10 and 11. The name, of course, implies
more, since the purpose of the event is to expand
the avenues of horticultural possibilities for re¬
gional gardens. Its educational aspect is very im¬
portant.
This inaugural edition oiMountain, Plain and
Garden is a flowering, in a sense, as well. This
magazine, known since 1944 as The Green
Thumb, has been updated with a new name, new
look, and new format. Mountain, Plain and Gar¬
den continues The Green Thumb and will be pub¬
lished semiannually.
We are pleased that this first issue is a special
one for “The Flowering of Denver.” It evolves
from the so-called “Emerson’s Handbook” from
the 1989 sale. The handbook was so popular we
decided to try our hand at hybridizing: this special
edition is the result. It chronicles Rocky Mountain
horticulture in the year 1990. The plants offered at
the sale, listed within these pages with cultural
information, are indicative of the wide variety of
plants suitable for our climate and the diverse
interests of area gardeners.
It is appropriate, too, that many of the plants are
old-fashioned ones. The unique climate of the
Denver metropolitan area lends itself to ex¬
perimentation. While the range of plants grown
here has greatly expanded over the years, we look
back at dozens of plants that have been peren¬
nially popular and have truly made our city
bloom. The reason that many of the old-fashioned
flowers, shrubs, trees, and vegetables are still
available is a testimony to their adaptability and
hardy nature. They have become the classics of
our gardens.
Although there are changes each year at the
plant and book sale, the tables enable us to grasp
the enormous scope of plants grown outdoors in
Colorado. The lists are not entirely definitive as
there are always small quantities of special vari¬
eties that are not listed. Each division contains an
introduction by an experienced amateur or pro¬
fessional horticulturalist with practical tips and
observations. Collectively, among these keen
gardeners are literally hundreds of years of ex¬
perience. Their cumulative experience has made
this guidebook possible, although it should be
considered only as a guide. Remember that most
plants are as adaptable as those who tend them,
and they often thrive under less-than-optimum
conditions. Gardeners will discover microcli¬
mates within their own gardens.
Know what you grow. For accuracy, we list Latin
as well as common names. Please don’t be intimi¬
dated. When consulting expert nurserymen or
the books in the Helen Fowler Library at DBG, it is
always helpful to know the exact species consi¬
dered.
With this first issue of Mountain, Plain and
Garden our focus is on outdoor gardening, al¬
though our house plant and bonsai divisions are
equally outstanding. We trust “The Flowering of
Denver” special edition will serve as a source
book not only for the plant sale but as a useful
cultural guide for common and unusual plants
grown in this area. Please keep this issue for
future reference. We plan to update it with sup¬
plements every few years.
“The Flowering of Denver” has grown to be a
Front Range spring celebration. I approach it with
great anticipation, not only for the abundance of
exciting plants offered for sale, but for the beauti¬
ful results that follow later in the summer in
gardens everywhere. Our purchases benefit a
very special place — Denver Botanic Gardens.
1
Rob Proctor Denver Botanic Gardens
Pot marigold (< Calendula officinalis )
has been grown in herb gardens since
medieval days.
Petunia ‘Summer Madness’ and white
Gomphrena globosa are effective
companions in containers or beds.
The pretty white flowers of highbush cranberry ( Viburnum trilobum )
are followed by striking autumn fruit.
The blossoms of ‘Azure Pearls’ petunia and ‘Irish Eyes’ rudbeckia
smother the plants in midsummer.
Peach-leaf bellflower ( Campanula
persicifolia) lends old-world charm to
a garden.
Fragrant and hardy trumpet lilies, sold
in the summer bulbs division, grace a
garden in July.
Rock cress ( Aubretia deltoidea) is a
charmer for rock gardens or perennial
plantings.
Basket-of-gold is an indispensable feature of Colorado gardens.
Euonymus alatus ‘Compactus’ is a dwarf form of the classic burning
bush.
w
Selecting and Growing Annuals
by Joedy Arnold, Co-chairman: with sections by Jeanne Ruggles,
Katy Dickson, and Rosemary Laughlin. Sheila Stephens, Co-chairman
It would takd a gardener many years to sample
every ajYnual that can be grown successfully in
Colorado. Either that, or it would require an
enormous garden. Those who rely on perennials
alone are missing a fascinating class of plants.
Various annuals grow from several inches to
many feet in height. They are valued for colorful
blooms or foliage throughout the growing sea¬
son.
Annuals did not become an important feature
of gardens until the nineteenth century, although
nasturtiums, amaranths, poppies, sweet Williams,
and hollyhocks were grown several hundred
years earlier. During the Victorian era, many new
annuals flooded into the western world from
tropical lands. The new technology of iron and
glass that had made the construction of green¬
houses possible, also allowed the seeds of many
annuals to be started in early spring and bedded
out later. Seed companies hastened the spread of
new species throughout the United States. Many
of the old favorites are still grown. Heliotrope,
flowering tobacco, forget-me-nots, coleus, cos¬
mos, and snapdragons are as important in our
gardens as they were in our grandparents’.
The varied shapes and forms, as well as modest
expense, make annuals a rewarding choice for
the beginner and a source of almost endless vari¬
ety for the experienced gardener.
Annuals are planted alone or among bulbs to
cover unsightly fading foilage; among perennials
to unite and provide season-long color; among
shrubs to add color and interest. They adapt well
to border plantings and containers. Annuals are
often grown for cutting, and some are perfect as
ground covers.
Three factors determine the adaptability of an¬
nuals to your garden: tolerance for sun or shade,
preference for a warm or cool growing season,
and the length of time plants need to reach matur¬
ity from planting to full bloom.
When selecting annuals, remember the impor¬
tance of planting the right plant at the right time in
the right location. Planting tender annuals, such
as impatiens, zinnias, coleus, and begonias,
should be delayed until late May. Nights below
40°F will stunt their growth. Water requirements
vary. Effective irrigation means a good soaking to
ten inches. Well-prepared soil not only is essen¬
tial for good plant growth but also for proper
water retention. Generous amounts of organic
matter added to create enriched soil for some
plants will hold more water than a sandy soil with
fast drainage required by other plants. Wind, loca¬
tion of planting, sun or shade, and the soil condi¬
tions must all be considered when determining
the amount and frequency of water applied. Cul¬
tural information is available when purchasing
plants, and the tables will prove helpful in plant¬
ing and care.
In addition to true annuals, some biennials and
perennials are also included. Technically, these
plants are not annuals. They are used as such
because they develop good color in the length of
time most annuals do when started from seed
Examples are hollyhocks and foxgloves, which
bloom the first year.
In books, seed catalogs, and even at nurseries,
annuals are often listed by their common names,
which can vary from area to area. Our listing is by
the Latin scientific name, followed by the com¬
mon name. Latin names need not be intimidat¬
ing— after all, petunia, ageratum, cosmos, be¬
gonia, lobelia, salvia, and zinnia are all Latin
names. The terms ‘cultivar’ or ‘variety’ are now
used interchangeably. The term ‘cultivar’ should
be used only for plants that are vegetatively prop¬
agated. Since annuals are usually propagated
from seed, there is variation in plants although
uniformity is remarkable. The term ‘variety’ is
commonly used; for example Calendula of¬
ficinalis variety ‘Indian Song.’
After purchasing plants, the next step is the
hardening-off process. Find a protected area and
place the plants there. Gradually introduce more
light each day. After being fully exposed, they
should be transplanted into the already prepared
beds. The tables suggest the necessary spacing
between plants to allow for proper development
and avoid potential disease and insect problems
brought about by overcrowding. Due to our rela¬
tively short growing season, those spacings are
reduced somewhat from those recommended by
most catalogs and garden books.
Some authorities advise gardeners to grow an¬
nuals in poor soil to encourage bloom. Although
most flowers don’t need the high level of plant
nutrients as vegetables, they do require enough
to produce healthy vegetation to sustain bloom¬
ing. Complete fertilizers for garden flowers are
readily available. Be sure to read the label care¬
fully, and follow the directions for proper applica¬
tion.
After all the planning and planting, weeding
and dead-heading become an on-going process.
Dead-heading is simply removing faded flowers
to promote more flowering. Sometimes seed
heads add interest to the overall effect of the
garden and should be left. Poppies and love-in-
a-mist (Nigella damascena) have attractive seed
pods that can be used for dried arrangements.
In addition to favorite annual flowers in our
gardens, annual grasses give us the opportunity to
relieve this dependency on typical bedding plants
and add new interest and dimension to our plant¬
ings. Ornamental grasses are not necessarily
grown for their foliage, but for their endless vari¬
ety of flowers and seeds. They add an element of
surprise to the garden and can be gathered and
dried for winter bouquets as well. As a general
rule, they need full sun and average soil condi¬
tions.
The Children’s Garden division encourages
children to explore a fascinating world and de¬
velop a life-long friendship with plants. This sec¬
tion is almost a mini-plant sale in itself. Its charm
is in the wonderful varieties of plants chosen
especially for young gardeners. Gardening is
about discovery, and we offer fun and unusual
vegetables, and easy flowers for budding horticul-
turalists.
Children learn how to plant a seedling and how
to tend their own gardens. They also learn which
plants attract birds and butterflies. There are even
gardening projects for rainy days, like making
wreaths and working with dried flowers. Stone¬
ware and porcelain cache-pots can be planted by
eager young gardeners to make a cherished
Mother’s Day gift. Many children have a special
fascination with flowers and plants— -it might be
said they go hand-in-hand.
Colorful hanging baskets for the patio suit a
variety of sun requirements. We must stress,
however, that during the heat of the summer most
of the baskets need to be watered every day,
sometimes twice daily, expecially if they contain
fuchsias. Fertilize the baskets regularly, according
to the manufacturer’s directions— the reward will
be a beautiful show of color all summer long.
Baskets of portulacas, verbenas, nasturtiums,
and petunias will thrive in a hot, sunny loca-
tion.The nasturtiums have been grown without
chemicals so they are edible. The lovely Califor¬
nia Euryops daisy should bloom until the first
frost if it is watered regularly. The ‘Balcon’ ivy
geranium is a beautiful lacy plant that is full, lush,
and is not susceptible to budworm. It also makes a
beautiful ground cover.
Begonias and impatiens can stand morning
sun, but prefer shade in the heat of the day. Fil¬
tered light under trees is ideal. Ivy geraniums and
pansies will also do well with a little shade during
the day. Pansies need to stay moist for constant
bloom. Fuchsias really sulk in heat, and need full
or filtered shade, and their foliage should be
misted during the heat of summer.
In Terrace Baskets and Statuary, wicker baskets,
wooden or clay planters overflowing with color¬
ful annuals will add a decorative touch to a patio,
spa, or windowsill. Many are one-of-a-kind crea¬
tions and some baskets are planted for shaded
areas.
To complement a terrace or garden, consider
cast statuary, and terra cotta ornaments and pots.
These, and the planted baskets, are displayed
throughout the patio and annuals division. Potted
plants often look best grouped together rather
than space randomly. A splashy note can be made
with five or more containers of various sizes clus¬
tered together, with combinations of annuals
spilling lushly over the sides.
5
Fruitful Harvest
by Kenneth Roberts, Chairman
Nothing is quite so delightful on a summer even¬
ing as wandering through a garden and sampling
fragrant, succulent fruits and berries. Contrary to
what may people think, a spacious yard is not
necessary to have a mini-orchard. A small garden
can include a surprising variety of these produc¬
tive trees, vines and shrubs in a traditional land¬
scape. Dwarf and semi-dwarf trees can be used to
define property lines, and raspberries can fill in
that empty corner in the back yard. Mix colorful
‘Red Lake’ currants or one of the many varieties of
dessert gooseberries in with spring flowering
shrubs, or blueberries with the evergreens — if
the soil is on the acidic side. Strawberries make a
wonderful ground cover and an apple, pear or
plum tree can be espaliered behind a garage or
along a fence. And, what garden doesn’t have
room for an arbor filled with delicious grapes?
Plant fruits, vines and berries where they get
the maximum sun. There are some varieties
which will tolerate some shade but, in general,
the more sun the better. Prepare the soil well. Dig
an ample hole; the rule of thumb is twice the
width and depth of the root ball. Enrich the soil
with about 1/3 peat moss. The peat moss is par¬
ticularly important in the Denver area because of
our alkaline soil. Most fruits prefer a slightly
acidic soil with a pH between 5 3 and 6.5, and peat
moss is a wonderful natural acidifier. Ensure that
the soil is well drained. Do not plant fruit in low
areas which have a tendency to collect water.
Plant a standard fruit tree with the graft just
below the soil level. Do not bury the graft of a
dwarf fruit tree as roots may generate above the
graft and the tree will grow to full size. Fill the
hole carefully with the soil/peat moss mixture
being careful to avoid air pockets. It is helpful to
fill the hole about halfway, fill the hole with water
and then finish filling. Build a slight rim around
the hole to hold water, and mulch to help retain
moisture.
Give the tree or bush an initial pruning. The
trees offered at the plant sale have been pruned
properly. However, branches broken in handling
should be cut back. Also, trim off unwanted
branches to improve the shape. Sweet and sour
cherries can be pruned harder to stimulate faster
growth.
Fruit trees require ample moisture but will not
tolerate standing in water. Periodically soak the
soil well to the depth of the roots. Feed two to
three times from the early spring through early
summer with a 5-10-5 fertilzer, and control in¬
sects by spraying every week to two weeks from
petal drop to harvest.
Once established many fruit trees become too
productive to produce quality fruit. Limbs may
actually break under the load of small, gnarled,
unattractive apples, peaches or pears. Don’t be
afraid to thin out the surplus. Some years it may
be required to thin more than half of the develop
ing fruit. It takes courage but the reward will be an
abundance of large well-formed produce.
The table lists fruiting perennials, shrubs, trees
and vines for Colorado gardens.
Ancient Herbs in the Modem Garden
by Diane Ipsen
A perusal of the history of gardens and garden
design reveals that the cultivation of herbs is in¬
deed an ancient practice. Schools of herbal
medicine, apothecaries, monasteries and tem¬
ples, universities and botanical gardens in both
the New and Old Worlds record gardens of herbs,
some dating back centuries. Herbs graced the
cottage dooryard and kitchen gardens of the early
American settlers because such plants were in¬
dispensable to the smooth maintenance of any
household.
The herbs of yesteryear still captivate today’s
gardener. The current enthusiasm for cultivating
herbs perhaps derives as much from the fascinat¬
ing herbal lore and the magical significance these
plants had in people’s lives as from their current
uses. For example, curious legends embellish the
past of Rosmarinus officinalis about which
Shakespeare wrote, “There’s Rosemary, that’s for
Remembrance.” Greek scholars wore garlands of
the herb to stimulate their minds and assist mem¬
ory; rosemary wine was a remedial tonic of great
renown. Today’s herb gardener uses sprigs of
rosemary in the cooking of meats — or may bring
the entire plant indoors to decorate as a small
evergreen tree at Christmas. Similarly, Lady’s
mantle ( Alchemilla mollis) was the medieval al¬
chemist’s herb, for the diamond-like dew which
collects on the leaves was thought to have magical
properties. Lady’s mantle is grown today for its
exquisite foliage and chartreuse flowers that
make a lovely border or planting above a stone
retaining wall.
In fact, herbs are rarely grown for their flowers
alone, though their textural variety and foliage
coloration can lend exquisite beauty to a well-
designed bed. Rather than contributing a mere
seasonal splash, herbs give pleasure throughout
the year with fragrance, flavor and cosmetic uses.
A range of homemade products such as pot¬
pourri, lavendar sachets, herbal vinegars or jars of
dried herbs are perfect for gift-giving.
The gardener considering herbs may imagine a
formal ‘knot garden’ or other intricately laid-out
patterns with clipped borders and symmetrical
paths. Such a well-ordered garden dedicated to
herbs gives pleasure with its form and arrange¬
ment, but many herbs can be effectively mixed
with less formal, more natural plantings to add a
new visual quality to the garden. Simple, old-
fashioned flowers look best with herbs, rather
than those bred for extravagant blooms. Massed
as ground covers, sweeping over steps or soften¬
ing a wall, herbs can assume a more contempo¬
rary role in home landscaping.
As a group, herbs are generally thought of as
plants with uses and their great functional ver¬
satility in the garden is certainly one way to
employ them. Hyssop (Hyssopus officinalis) is an
old medicinal herb, but serves as a fine edging
plant that can be clipped like boxwood. It blooms
from July until frost. Fuzzy lamb’s ears (Stachys
byzantina) is an effective ground cover and a
lovely silver-gray foil for hot colors or lush greens
in the garden. Sweet woodruff ( Galium
odoratum), the flavoring of the German May
wine, is one of the most charming ground covers
for shady spots, delighting with it mass of dainty
white flowers shortly after May Day. Perilla
( Perillafrutescens ‘Crispa)) lends a rich burgundy
to the cutting garden and is handsome and long-
lasting incorporated in flower bouquets. The
many varieties of thyme may carpet the ground
around other plantings or soften steppingstones,
but how nice to pluck for the soup pot as well (or
enjoy the fragrance if it is trod upon). Numerous
herbs like the artemesias provide striking accent
in the rock garden.
Colonial Americans were well-versed in practi¬
cal herbal applications. The pungent leaves of
tansy (Tanacetum vulgare) were often strewn on
floors or along foundations as a deterrant to ants,
or leaves of costmary (Chrysanthemum bal-
samita) were pressed in drawers to repel moths.
Teas and infusions treated a variety of ailments,
and it can be fun to revive the custom of
chamomile, spearmint or applemint steeped
fresh from the garden to comfort and soothe.
Even to the unadventurous, simply using fresh
herbs in cooking is perhaps the most delightful
reason for growing them. A cluster of chives to
snip for cottage cheese, a mass of fragrant basil for
fresh pesto, parsley for the antipasto, and a border
of chervil for garden tomatoes are essential to al
fresco feasts. Dill, mint, and marjoram will have a
thousand uses upon your table and be remem¬
bered long after the snows fall. With fresh herbs at
one’s fingertips, our gardens are not just pretty
palettes of display, but, being integrated into our
patterns of living, become a means of connecting
our daily lives to the tradition of the past.
Happily, herbs are easy to grow and do not
require soils or complex horticultural skills.
Moreover, they seem especially well-suited to our
continental climate along the Front Range. Many
herbs are indigenous to the Mediterranean area
and thrive in our dry sunny region, provided they
are kept out of heavy clay soil. Gardening in a
half-shaded situation can include any of the mints,
chervil, lovage, sweet woodruff, parsley, angelica,
bergamot, pennyroyal, or even tarragon if the soil
is not too moist. The table provides cultural in¬
structions.
After the first frost, enjoy the pleasure of fresh
herbs growing on a kitchen windowsill. Try pots
of lemon verbena, parsley, marjoram, Greek
oregano, chives, rosemary, lemongrass and basil
for a winter herb garden. This should keep the
gardener supplied until the garden is again lush
with flavors and fragrances.
8
“ Here’s your sweet lavender, sixteen sprigs a penny,
Which you’ll find my ladies, will smell as sweet as any”
— street cry of nineteenth century London lavender sellers
Colorado Style:
A Perennial Perspective
by Rob Proctor
John Reber, Chairman
Gardening in Colorado presents unique chal¬
lenges as well as tremendous opportunities. Our
abundant sunshine, dry winters, and low humid¬
ity save us from so much grief about disease and
pests. On the other hand, we must cope with
drying winds, high summer heat, and unpredict¬
able frosts and storms. Local gardeners are a re¬
sourceful lot, and have found that this climate
allows us to grow many traditional perennials, as
well as an exciting range of native plants.
Garden design is a matter of personal taste, and
there are many schools of thought about the best
approach for our area. Most of them have merit,
and design must take many variables into account.
Shaded gardens of the inner city have a distinct
character, as do foothill gardens and those on the
plains. Considering the site and choosing adapta¬
ble perennials ensure success.
The perennial border is considered the ideal
by many, but there are many other options.
Naturalistic gardens, formal gardens, and in¬
terpretations of cottage gardens can all be suc¬
cessful. Low-water plantings can be as lovely and
colorful as traditional ones. Native plants and or¬
namental grasses contribute to a uniquely-
Colorado style with an exciting interplay of form
and texture. Using plants from around the world
from similar climates further increases the palette
of the garden artist. Perennial plantings are en¬
hanced by a well-chosen selection of shrubs,
bulbs, herbs, annuals, and even vegetables. The
true Colorado style incorporates many influences
and evolves to new glories each year.
Gardens in partly-shaded areas rely on many
old-fashioned flowers that have been grown for
generations, and they are especially appropriate
for plantings around Victorian homes. Jacob’s
ladder (Polemonium caeruleum ), Allegheny
foam flower (Tiarella wherryi), globeflower
( Trollius ledebouri), and bleeding heart are often
found in vintage gardens. The dark, heart-shaped
leaves of Ligularia dentata are effective accents.
Ivory spires (Cimicifuga racemosa), meadow rue
(Thalictrum spj, and monkshood ( Aconitum
napellus) add height and grace. The many var¬
ieties of hosta have lovely leaves and underrated
fragrant flowers, as do the hybrids of leatherleaf
( Bergenia cor difolia).
Sunnier gardens often feature phlox, bellflow¬
ers, peonies, daylilies, columbines, and cranes-
bills. These favorites from the cottage and
dooryard gardens of the past still deserve a valued
place in contemporary designs. Heirloom flowers
may even be incorporated in dryland plantings.
Indian blanket ( Gaillardia aristata), purple cone-
flowers (Echinacea purpurea) and (E. pallida),
blue flax, lamb’s ears, and iris were favorites a
century ago and are even more popular today
because of their hardiness and ease of culture.
They associate beautifully with the grasses, pen-
stemons, and sages of our rich native flora.
Perhaps the one weakness of our Colorado
style is the result of our own enthusiasm each
spring. We tend to shop and plant early, concen¬
trating on blossoms of spring and summer. Gar¬
dens too often peak early and lack interest in
autumn and winter. Anemone X hybrida ‘Hon-
orine Jobert’ and Prinz Heinrich’ bloom at the
first hint of the coming fall. Asters and chrysan¬
themums provide a wide spectrum of colors late
in the season. Flowers such as Coreopsis ‘Moon¬
beam’ and Baby Sun,’ and Maltese cross bloom
over a long period. Blackberry lily ( Belamcanda
chinensis) blooms in summer and displays shiny
“blackberries” later. Silver lace vine, if given
room enough to ramble, cloaks a fence with white
frosting late in the season, Others, such as um¬
brella plant (Peltiphyllum peltatum), plume
poppy (Macleaya cor data), and soldiers and
sailors ( Pulmonaria saccarata) have handsome
leaves that add a special impact even when the
plants are not in bloom.
Plant Donations: Sharing the Best
by Marilyn Moore, Co-chairman
Elinor Newmarker, Co-chairman
The Plant Donations division features an espe¬
cially varied and exciting selection of herbaceous
perennials and ground covers, as well as a limited
number of fruits, vegetables, herbs, trees, and
shrubs.
As areas of the Denver Botanic Gardens are
redesigned and replanted, many choice plants
that aren’t included in new designs are divided
and potted up for sale in Plant Donations. Gar¬
deners looking for unusual or rare plants will be
delighted to find poppy mallow ( Callirhoe in-
volucrata), Dianthus turkestanicus, giant sea
holly (Eryngium giganteum), and Ligularia den-
tata as well as many other outstanding flowers
from the perennial border. The many varieties of
chrysanthemums growing at DBG have been
carefully evaluated, and the very best of these are
divided for gardeners seeking dependable fall
color for a sunny spot in their gardens.
Ground covers on sale in quantity this year will
include the beautiful blue Turkish veronica (Ver¬
onica liwanensis) and border jewel ( Polygonum
affine), which is so frequently recommended for
low water use plantings. Many other drought-
tolerant plants suitable for dryland gardens (or
just a dry corner of the garden) are available,
including rabbitbrush and Euonymus fortunei
‘Coloratus,’ as well as several varieties of orna¬
mental grasses.
In addition to plants from DGB, this division
offers a wonderful selection of plants donated by
some of metropolitan Denver’s finest gardeners.
All these plants are proven to grow, thrive, and
10 multiply in regional gardens — and because they
are homegrown, prices in the Plant Donations
division are extremely reasonable. There is no
table of information for this division, because it is
impossible to reliably predict what gardeners will
share. Check the perennial table, in particular, for
cultural requirements.
Please be aware that because many of these
plants have been recently dug and divided, they
may require a little extra attention to watering and
some protection from wind and sun until their
roots are reestablished.
Alpines for Colorado
by Panayoti Kelaidis
Lynda Goldstein and Kathy Borgen, Chairmen
As cities grow, and gardens shrink, the value of
small plants correspondingly increases. Small
plants permit variety in small places, thereby
creating a longer season of bloom and interest,
but groundcovers and small perennials provide a
greater sense of scale and spaciousness in inti¬
mate settings. Alpines are nature’s quintessential
miniatures: dwarfed by climate and heredity, over
the last century an immense assortment of wild
flowers from the world’s high places have been
tamed and brought into horticulture. Garden al-
pines may look very much like their wild breth¬
ren, only they often germinate more quickly and
mature much faster, growing in gardens with
much greater ease.
The first European alpines appear to have been
cultivated in the late Rennaissance by the first
enthusiastic collectors of ornamental plants such
as Parkinson and Gerard in England. Often asso¬
ciated with herbalism and utilitarian plants, both
great English garden writers grew a variety of
high mountain plants from the Alps which have
always been primarily of asethetic import. The
bear’s ear primrose of gardens is often called
auricula, although that wild primrose (Primula
auricula) is invariably yellow in color, and gar¬
den hybrids represent centuries of selections
among a handful of species in this section. Few
primroses can compare with the auriculas for
tenacity, delicate bloom and subtle fragrance. Au¬
riculas are ideally suited to growing in shady rock
gardens in the Denver area and surrounding
mountains, needing only shade, gritty soil, cool
roots and water during prolonged droughts.
Most beginning gardeners associate rock gar¬
dens with sedums and sempervivums, and many a
wag has pointed out that most gardeners begin
and end their horticultural careers among these
accommodating succulents. Hundreds of hybrids
have been produced among the houseleeks,
some of which have dazzling red or yellow-green
rosettes, but none will exceed the grace and
beauty of the common spiderweb houseleek
(Sempervivum arachnoideum) . Each rosette has a
dense webbing of hairs twined from leaf tip to leaf
tip to exactly resemble a miniature spiderweb.
This astonishing feat should be enough for any
self-respecting plant, but this one goes on to pro¬
duce a cluster of showy, six-petaled flowers of
dusky rose. A pure white form has been intro¬
duced recently.
Most gardeners have the misfortune of starting
their sedum careers with S. album orS. sexangu-
lare, two delightful and utterly demoralizing
weeds, since even the tiniest rootlet or fallen leaf
quickly form a veritable horde of progeny. There
are several notable sections to this genus which
consist of tap-rooted clumpformers that barely
spread at all without human interference. The
best of these for rock gardens is Sedum sieboldii, a
very showy trailing ground cover with highly suc¬
culent blue leaves and glowing pink flowers in
late summer.
Perhaps the most famous triplets among rock
garden plants are three indestructible plants in
the mustard family: Aubrieta deltoidea, Iberis
sempervirens and Aurinia saxatile (syn. Alyssum
saxatile). All three are sold universally by garden 1 1
centers in the state, and planted by the acre every
year. Aubrieta usually has deep purple flowers
that smother the plant as effectively as snow for
much of April and May. It seems to do best on a
shady bank in Colorado, although it will with¬
stand full sun with reliable soil preparation and
mulching.
Basket-of-gold is one of those perennials that
will persist indefinitely in local gardens no matter
what sort of treatment it is given. The coarse,
bristly gray rosettes are evergreen and are com¬
pletely obscured during April and May with in¬
numerable little yellow stars. It should have a
place in every Colorado garden.
The Versatile Rose
by Betty Lou Roberts, Chairman
Throughout history no flower has been more
cherished, revered, or steeped in tradition as the
rose. In the landscape this timeless favorite offers
permanance, and rewards the gardener year after
year with fresh, fragrant blooms. Roses can be
used as a foundation planting, as a border, in pots
on a patio, climbing a trellis or fence, and, of
course, in a rose bed. Roses are a traditional
symbol of love and repay the gardener’s devotion
with their beauty.
Every garden has room for at least one rose. In
a shrub border, try mixing old-fashioned roses
with spring-blooming plants like forsythia and
lilac to extend the spring color well into summer.
Perennials and roses are a classic combination.
Roses provide a constant display while various
perennials have peaks of bloom. Climbers and
ramblers are excellent camouflage for unsightly
buildings, fences and walls. Rose-covered arbors
evoke a nostalgic feeling. Some roses sprawl over
the ground and act as a colorful ground cover.
Roses grown in containers are popular for small
city gardens and balconies. A rose hedge will add
elegence to a garden: use one basic color and
size, and plant closely to ensure dense growth.
12 HYBRID TEA: The “tea rose” we know originated
Rock cress (Arabis caucasica) is not planted
nearly as often as it deserves. Originally from the
Caucasus of the Soviet Union, this sturdy peren¬
nial seems to thrive in almost any soil, exposure
or watering regime it is subjected to in Colorado.
The mounds of neat, dark gray-green rosettes are
decorative at all times of the year, and the froth of
white or pink blossoms in spring is always wel¬
come.
These old-fashioned rock garden plants need
not be planted only in rock gardens. They can be
used as edgings or even in mass plantings as
ground cover. They have proved their mettle over
the years in gardens around the world.
in France in 1867 and is constantly being im¬
proved. Elegant, high-centered blooms on
long stems are often fragrant. Plants are grafted
onto vigorous shrub rootstock and bloom con¬
tinuously.
POLYANTHA: These also originated in France
about the same time as hybrid teas. They are
derived mainly from Rosa multiflora, crossed
with tea and China roses. Low-growing,
continuous-blooming plants produce large
clusters of small flowers.
FLOR1BUNDA: This is a cross between the classic
hybrid tea and the polyantha. Blooms resem¬
ble hybrid tea in form and color but are borne
in clusters. Most plants are disease-resistant,
hardy and low-growing.
GRANDIFLORA: These varieties came into being
about 25 years ago as an American classifica¬
tion to designate roses that are intermediate in
habit between hybrid teas and floribundas.
From the hybrid tea, grandifloras inherit
flower form and long cutting stems. From the
floribunda, they receive hardiness and con¬
tinuous clusters of blooms. Plants are gener¬
ally taller than hybrid teas.
MINIATURE: This type of rose is a tiny reproduc-
tion of a full size rose, with flowers, leaves and
stems in proportionate size. Plants range from
3 to 4 inches high to 18 to 24 inches tall. Most
bloom continously but few have fragrance.
CLIMBERS and RAMBLERS: This category con¬
tains tall-growing (6 to 20 feet) plants of any
one of the other rose types but none are true
climbers since they have no tendrils and must
be tied to a support. They may be everbloom-
ing or bloom in one wild flush in the spring.
OLD GARDEN ROSES: These are any roses exist¬
ing before 1867. These roses stand on their
own virtues: hardiness, fragrance, and low
maintenance. Few plants are as tough and tol¬
erant of neglect and poor growing conditions
as shrub roses. They vary in height from low-
growing ground covers to taller types used in
hedges.
The variety selected will depend on its use. For
a container, look for a compact and floriferous
variety, and remember that it will need special
protection in winter. A miniature or a polyantha
will best suit a small container while a large con¬
tainer will accomodate one floribunda. Miniature
roses are perfect for low edgings, and shrub roses
work well for a large screen. Climbers are suita¬
ble for arbors, trellises, fences and walls. Flower-
arranging enthusiasts should consider planting
fragrant hybrid teas or gradifloras.
Roses need a minimum of six hours of sun a
day. Morning sun is essential, and partial after¬
noon shade is acceptable, but full sun is ideal.
Plant roses at least 15 feet away from the spread of
large trees. Miniatures and climbers will be happy
with a little less sun. Soil preparation is critical:
soil should be light and rich. Improve it with
organic matter such as peat moss, leaf mold or
compost.
You can’t give a rose too much water, but a rose
will not tolerate wet feet. Normally a rose should
receive the equivalent of one inch of rainfall per
week starting in early spring and continuing
through fall. Hot and dry weather may call for
watering every three or four days. Soak the soil to
a depth of eight or ten inches each watering.
Roses are heavy feeders, so regular applica¬
tions of fertilizer are required for optimum
bloom. Begin to fertilize newly planted bushes
after the plants become established, about three
or four weeks after planting. The rate, frequency
and kind of fertilizer depend on the type of soil.
Roses should be fed at least three times a year
with a rose fertilizer spread over the root area. Do
not fertilize after August, or soft, weak growth will
invite winter kill. Insect and disease prevention
begins when leaves begin to emerge in early
spring. Spray or dust with a multi-purpose rose
spray once a week or so until cold weather. In
Colorado most roses need winter protection;
shrub, old garden, and miniatures are relatively
hardy and need little protection. The best protec¬
tion is to mound soil over the canes to a height of
at least 12 inches. This is then removed when
growth starts in spring.
Bulbs for Summer Color
by Janet Sickafuse, Chairman
Bulbs were a very important part of gardens of the
past, and they remain as favorites today. Whether
a garden has a nostalgic look or totally modern
outlook (the differences are not always clear)
bulbous plants may provide important focal
points. Many of these flowers are used for ar¬
rangements, and may be grown in a mixed plant¬
ing of annuals and perennials, or in a separate
cutting garden.
Among the most stately of bulbs are the elegant
and often very fragrant lilies. Asiatic hybrids are
the shortest of the lilies, the easiest to grow, and
the earliest to bloom. Their vivid rainbow hues
are effective in the garden for cutting. Trumpet, or
Aurelian, hybrids are taller and save their impres¬
sive flowers until mid-summer. Stems can grow to
five feet or more, and the sweet fragrance per¬
vades the evening air. Oriental hybrids, including
the Rubrums, bloom in late summer or early fall,
and rival orchids in beauty; they also carry a de¬
lightful scent. Hybrids of the old-fashioned tiger
lily, Lilium tigrinum, range in color from the
familiar orange with black spots to pink, lemon,
buff and cream. Their down-facing flowers with
recurved petals have made them favorites for
generations. They are very hardy and can be
planted in their own groupings or in a mixed bed.
Lilies can be left in the ground all year, topped
with mulch, and they will continue to bloom and
increase. They may also be planted in the fall.
They will rarely attain their full height the first
year.
Winter-hardy gladiolus and liatris are also pe¬
rennial in Colorado. The gladiolus are smaller
than most of the garden hybrids, but have a
charming appeal. Liatris are the most drought-
tolerant of bulbs, and the feathery spikes are pret¬
ty in sunny beds.
Dahlias and cannas are impressive accents in
any planting. The brightly-colored dahlias grow
14 as tall as five feet and are excellent for arranging if
the stems are seared with a match and quickly
plunged into cold water immediately after cut¬
ting. Cannas carry bold foilage topped with clus¬
ters of exotic flowers. The leaves provide an un¬
expected tropical effect in a planting. They often
look best planted at the back of a bed in clumps of
three or five, and are complemented by flowers of
a finer texture in front, such as yarrow, coreopsis,
cosmos, or rudbeckias.
Abyssian gladiolus ( Acidanthera bicolor
’Murielae)) have beautiful, sweet-scented, white
flowers with maroon markings at the base of the
petals. Old-fashioned montbretias have a similar
look, and the gold and orange flowers are great
for cutting. Their leaves resemble those of iris.
Tuberoses, shell flowers (Tigridia pavonia), and
stars of Bethlehem (Omithagalum) all make ex¬
citing additions to flower beds and bouquets.
The garden gladiolas, dahlias, cannas, Abyssi¬
nian gladiolas, tuberose, tigridias, and stars of
Bethlehem need to be dug in autumn, dried, and
stored in a cool, dry place until replanting in
spring. Montbretias can be treated in this manner,
although they often prove to be hardy in shel¬
tered gardens.
Full sun to partial shade is appropriate for all of
these, with slight variations. All benefit from
planting in well-drained soil supplemented with
humus. Oriental lilies need a more acidic soil, so
the soil should be liberally amended with peat
moss. Watering for summer bulbs is average —
slightly less than a typical lawn — except for can¬
nas, which prefer more water. All summer bulbs
benefit from a mulch to keep the roots cool and
help retain moisture. Shallow-rooted ground
covers or annuals provide the same protection.
Because most summer bulbs are more effective
planted in groups of three or more, suggested
groupings for each variety are indicated in the
table.
Classic Trees and Shrubs
by Diane Ipsen with Alan Rollinger
Eva Littlefield, Chairman
Before designing and planting your flower gar¬
dens, it is wise to create “the garden” in the larger
sense. One dated concept is the linear and boring
foundation planting — the “parsley garnishing the
turkey” that has restricted residential design. For
an aesthetically-pleasing outdoor living area,
spaces should be created, and the overall struc¬
ture planned intelligently. In order to create the
skeletal structure of the garden, establish a
backdrop for more detailed plantings, to screen
and to give privacy, and to create a feeling of
enclosure. A well-chosen variety of shrubs and
trees will evoke the sense that the space around a
home is a special place.
Shrubs and trees, while giving structure to a
garden, have color, texture, and fragrance as
specimens in their own right. The seasonal
dynamism that the woody plants will add —
flower, foliage, fruit, and winter form — may be
the most important landscaping aspect to con¬
sider. Additionally, shrubs can attract butterflies
and birds, or contribute to an edible landscape.
We all love the old familiar favorites. Imagine
blazing mounds of golden forsythia, snowy
spireas, the crimson glory of a highbush cran¬
berry in autumn or the red stems of dogwood
against a new-fallen snow. But if you are weary of
incessant pruning of shrubs over-scaled for your
garden and disappointed by frozen flower
buds — take heart. Many improved selections of
these heirloom shrubs are now available in com¬
pact forms or show much-improved hardiness for
our late freezes. They are bred for the smaller
urban yard, for ease of maintenance, and for
overall beauty.
Forsythia x intermidia Northern Sun’ is an im¬
proved variety which blooms reliably. New selec¬
tions of our native redosier dogwood ( Comus
sericea) display specific traits: ‘Baileyi’ produces
superior red stems (always enhanced by proper
renewal pruning) and ‘Isanti’ is more compact
than the sizeable species, with maximum height
at 6 feet. Don’t forget the 24 inch dwarf ‘Kelsey’
dogwood, whose stems get redder in the winter.
Some of the more delicate stems die back, so
prune this one to the ground in spring. Quince
(Chaenomeles japonica) is a monstrous shrub but
the many dwarf forms, ‘Texas Scarlet’ or ‘Jet Trails’
for example, can provide that appreciated April
bloom where a 4 foot shrub is more suitable.
Anyone who has grown ‘Vanhouttei’ spireas
knows what space-dominating plants they are.
Inevitably, this graceful shrub suffers hacking and
chopping by the homeowner trying to make a
smaller shrub of it, thereby destroying its form as
well as next year’s flower buds. Similar form and
flower can be obtained by using the smaller
three-lobe spirea (Spiraea trilobata) or the more
exploding ‘Snowmound’/S. nipponica). The pink
summer-blooming spireas, like the old-fashioned
favorite S. bumalda ‘Anthony Waterer,’ are only
2-1/2 feet tall. Even smaller are the many wonder¬
ful dwarf varieties like S. bumalda ‘Limemound,’
S. japonica ‘Little Princess,’ and S. x ‘Goldmound’.
The compact form of burning bush (Euonymus
alatus ‘Compactus’J has been with us since 1926
and offers that marvelous autumn red and in¬
teresting bark in a 5 foot rather than 15 foot shrub.
A dwarf version of the big familiar ninebark is
Physocarpus opulifolius ‘nana,’ a 4 to 5 foot shrub
with arching branches which produce masses of
pinkish-white flowers in June. Butterfly bush
(Buddleia alternifolia) is another heirloom
shrub often seen in Denver parks, for it is a big 20
foot specimen. The smaller butterfly bush, B.
davidii, is available in countless hybrids for a late
summer display. Ever wonder what that large
hibiscus-like flower is that blooms around town
in September? Rose of Sharon (Hibiscus syriacus)
is an old-time shrub that can be counted on for
blue, white or pink flowers when little else is
showy.
15
Michael Dirr writes that “a garden without a
viburnum is akin to life without art or music.” For
small gardens, the highbush cranberry (Vibur¬
num trilobatum ‘Compactum^) is a neat 4 feet.
Wayfaring tree/V. lantana ), which is insect- and
disease-free, is actually a large shrub. It with¬
stands shade and is excellent for screening.
Early-blooming Viburnum x ‘Juddii’ is intensely
fragrant and its coarse light green leaves contrast
well with more finely-textured plants. All have
remarkable red fall color.
For a hedge that needs a minimum of mainte¬
nance, consider using alpine currant (Ribes al-
pinum) a tidy 3 to 4 foot shrub which has been
grown for generations in our area. It doesn’t need
shearing. Tired of trying to keep a hedge of com¬
mon privet, which grows to 12 feet, at a 3 foot
height? For that old-fashioned tailored look,
Ligustrum vulgare ‘Lodense’ is a new and excel¬
lent substitute that has a more sensible height of 3
feet. It is semi-evergreen and tolerates heavy
shade.
Finally, we should not overlook the most tried
and true heirloom shrubs we have: the natives.
The early settlers dug specimens out of the moun¬
tains and creek beds for their fledgling gardens,
bringing back potentillas, currants, wild rose and
cherry. ‘Abbotswood,’ and improved selection of
potentilla, sports larger white flowers which
combine well with the more familiar yellow
forms. While potentilla is not very drought-
tolerant, many natives are, such as rabbitbush
(Chrysothamnus nauseosus) — available in dwarf
form, gambel oak (Quercus gambeli), fernbush
(Chamaebatiaria millefolium), and cliffrose
(Cowania mexicana). Non-natives with drought
tolerances include lavender-flowered Russian
sage (Perovskia atriplicifolia) and dwarf fragrant
sumac (Rhus aromatica ‘Gro-Low’/, an excellent
2-1/2 foot shrub for dryland plantings.
Trees, too, can be drought tolerant. Everyone is
familiar with the long-beaned catalpa (Catalpa
speciosa) that perfumes the air in June with its
blossoms. Less well-known may be the Kentucky
coffee tree ( Gymnocladus dioicus), though it has
been planted in Denver for almost one hundred
years. Consider both of these trees, along with
tree-formed serviceberry (Amelanchier alnifolia)
or Russian hawthorn (Crataegus ambigua), if
planting for low water usage. The table provides
more information on height, spread, and water
requirements.
■ 2
K
v N
f\
<
16
\a
<r
vK ,
*4
7^
by Knobby Brown, Chairman
A Vegetables Sampler
Nothing can compare with the sense of pride and
achievement of harvesting homegrown vegeta¬
bles. Presenting them to family and friends is
gratifying. The advantages of growing them your¬
self are many. They can be harvested at the peak of
perfection and ripeness. Chemical sprays can be
limited or eliminated entirely. Varieties for the
home gardener are almost always more delicious,
as they are chosen for taste, not for their shipping
qualities. The table offers a complete listing of
vegetables.
The varieties in this division are tried-and-true
and have been tested for success in Colorado.
Many varieties are space-saving bush types rather
than vining varieties. These plants are early
maturing, prolific producers, disease-resistant
and decorative, not to mention delicious.
The best site for a vegetable garden is a sunny
one and the soil should be fertile and free-
draining. Adding humus, in the form of peat moss,
compost, or well-rotted manure, will improve
growth and ensure better production. Colorado
gardeners have found that mulching is the pri¬
mary aid in saving water and in keeping weeds
between rows to a minimum. Thin layers of grass
clippings, straw, sawdust and wood shavings, and
half-rotted leaves are effective mulches.
Since these plants are greenhouse grown, they
should be hardened-off before being set out in
the garden. Find a protected outdoor area, espe¬
cially from the wind, and gradually move the
plants to a sunnier spot each day; after being
exposed fully for a few days, plants may be trans¬
planted into a prepared bed.
There are certain vegetable varieties which
have stood the test of time and would qualify as
Colorado classics. My five personal favorites in¬
clude ‘Celebrity’ tomato, with first-rate flavor,
color, and texture, as well as disease resistance;
‘Green Duke’ broccoli, which produces a central
head early in the season and an abundance of
smaller heads on the lateral branches until late
fall; and ‘Dusky’ eggplant, an early-maturing, very
productive variety with medium-sized glossy
purple fruits. ‘New Ace’ pepper produces a good
crop of medium-sized peppers on short sturdy
plants. They may be picked while green, or al¬
lowed to mature to bright red. ‘Sweet Success’
cucumber is a vigorous producer of long, uni¬
form, dark-green fruit with very few seeds. The
flavor is delicious, without a trace of bitterness,
and slices can be eaten skin and all.
There are some new introductions that appear
to have a promising future in our area. ‘Bushkin’
pumpkin is a triple-purpose bush variety for
cooking, canning, and seed snacks. Par-cel is a
plant that looks like a large-leaf parsley but has the
flavor and aroma of celery. The leaves can be used
in salads, for flavoring soups, or for garnish that
won’t be left on the plate. ‘Oriole’ pepper is a
sweet bell pepper that ripens from green to a
glowing orange. These may well be the future
classics of the Colorado vegetable garden.
17
I
Water Gardening in Colorado
by Len Freestone, Chairman
Water lilies are easy to grow and require very little
attention during the growing season. By selecting
healthy rhizomes and following a few simple
planting instructions, lilies will bloom from June
through September, depending on altitude and
weather conditions. The higher the altitude, the
shorter the growing season: for example, at 7,000
feet, they will bloom from late June through late
August. Most hardy lilies require at least four to
six hours of full sun, but some varieties will pro¬
duce blooms in as little as three hours of sun¬
shine. The table outlines additional information.
The larger the container, the better the results.
Use at least a 10 to 12 inch diameter pot, or better
yet, a shallow rectangular pan 12 x 16 x 5 inches.
Fill the container half-full with good garden soil
(some clay is helpful, but do not use potting soil)
but do not cover the crown. If the pool gets only
four hours of full sun the water depth should not
be more than six inches. Fertilize monthly, May
through September, with tablets or granular fer¬
tilizer. Tablets should be pushed into a depth of
about four inches, or granules may be wrapped in
a piece of newspaper and inserted to about the
same depth.
The soil requirements for bog plants are the
same as for water lilies, except that only half the
fertilizer should be used, and containers should
be suited to the size of the plant. Many bog plants
will grow either in very wet soil or in a pool.
Tropical bog plants will not survive Colorado
winters oudoors but plants such as papyrus,
canna, and umbrella palm may be used as house
plants if the container is placed in water up to the
level of the soil surface.
18 A properly balanced pool needs both plants
and fish to ensure clear, healthy water. Potted
plants such as water lilies and bog plants, floating
plants, and water moss should occupy approxi¬
mately one-half of the water surface. Plants re¬
duce algae by competing with the algae for nu¬
trients. They also provide both oxygen and hiding
places for the fish.
In most parts of the country, 20 inches is a good
depth for a pool, however, in Colorado, consider
a water depth of 24 to 30 inches to store hardy
water lilies over winter. Other methods can be
used, but the basic requirements are the same:
lilies must be allowed to go dormant, and should
be kept moist in a cool location (50° F maximum)
where their roots will not freeze. The method
involving the least amount of work requires a
pond at least two feet deep. After the first frost,
remove all leaves and stems from the plant and
lower the pot to the bottom of the pond. If the
pond contains fish, it must not be allowed to
freeze over completely. There must be a hole in
the ice to allow gases to escape. A submersible
pump with the outlet pointing toward the surface
will create enough surface movement to prevent
complete freezing. In a pool without a pump, use
hot water to make a hole in the ice, them remove
enough water to lower the water level by about
one to six inches and fill the hole with rags to slow
down freezing. Check the pond regularly to make
sure the hole has not re-sealed. Do not make a
hole in the ice with a hammer. Hammering will
harm the fish. If the pond is not deep enough or
must be drained for the winter, remove the pots,
prune dead leaves and stems, place pots in plastic
bags to retain moisture, and store them in a cool
basement.
Table 1, Annuals.
Joedy Arnold, and Sheila Stephens, Chairmen.
[HT (height): in inches (Vn= vine); SP (Spread): in inches (spacing); TYP (type): B = Bedding, C = Cutting, D = Drying,
F= Fragrant; SL (soil): 1 = acid peat, 9 = alkaline clay; SN (sun): 1 = full shade, 9 = full sun; WT (water): 1 = wet, 9 = dry]
LATIN NAME
COMMON NAME
COLOR
HT
SP
TYP
S
SI WT
Achillea millefolium 'Summer Pastels'
Yarrow
Mix
15
10
B,C,D
9
5
4
Ageratum houstonianum 'Pink'
Floss Flower
Pink
8
8
B
5
5
5
Ageratum houstonianum 'Blue Danube'
Floss Flower
Blue
6
8
B
5
5
5
Ageratum houstonianum 'Blue Horizon'
Floss Flower
Blue
30
22
B,C
5
5
5
Ageratum houstonianum 'Blue Puffs'
Floss Flower
Blue
5
9
B
5
5
5
Ageratum houstonianum 'Capri'
Floss Flower
Blue
12
10
B,C
5
5
5
Ageratum houstonianum 'Cut Wonder'
Floss Flower
Blue
18
12
B,C
5
5
5
Ageratum houstonianum 'Snow Ball'
Floss Flower
White
8
8
B
5
5
5
Ageratum houstonianum 'Southern Cross'
Floss Flower
Wt/Bl
8
8
B
5
5
5
Agrostemma githago 'Milas'
Corn Cockle
Pink
24
12
B,C,D
9
5
5
Agrostemma githago 'Purple Queen'
Corn Cockle
Purple
24
12
B,C,D
9
5
5
Agrostis nebulosa
Cloud Grass
Grass
18
10
B,C,D
7
5
7
Alonsoa warscewiczii
Mask Flower
Orange
18
16
B,C
7
5
5
Althaea rosea 'Pinafore'
Hollyhocks
Mix
36
14
B
9
5
5
Althaea rosea 'Powderpuff
Hollyhocks
Mix
36
14
B
9
5
5
Amaranthus tri-color 'Early Splendor'
Joseph's Coat
Rd/Choc 30
24
B
9
5
5
Ammi majus
False Q. Anne's Lace
White
30
24
B,C
7
5
5
Ammobium alatum
Winged Everlasting
Silver
20
12
B,C,D
9
5
5
Anethum graveolens 'Vierling'
Flowering Dill
Gn\Wht
30
24
B,C
7
5
5
Antirrhinum majus 'Floral Shower'
Snapdragon
Mix
6
10
B
7
5
5
Antirrhinum majus 'Madame Butterfly'
Snapdragon
Mix
26
12
B,C
7
5
5
Antirrhinum majus 'Rocket Tahiti Pink'
Snapdragon
Pink
7
10
B
7
5
5
Antirrhinum majus 'Sonnet Series'
Snapdragon
Mix
18
12
B,C
7
5
5
Antirrhinum majus 'Tahiti Mix'
Snapdragon
Mix
7
7
B
7
5
5
Antirrhinum majus 'Wedding Bells'
Snapdragon
Mix
26
12
B,C
7
5
5
Antirrhinum majus 'Rocket Mix'
Snapdragon
Mix
24
12
B,C
7
5
5
Antirrhinum majus 'Rocket White'
Snapdragon
White
24
12
B,C
7
5
5
Antirrhinum majus 'Rocket Yellow'
Snapdragon
Yellow
24
12
B,C
7
5
5
Antirrhinum majus 'Sweet Heart'
Double Snapdragon
Mix
10
10
B,C
7
5
5
Arctotis stoechadifolia
African Daisy
Mix
24
24
B
9
5
7
Asparagus densiflorus 'Sprengeri'
Asparagas Fern
Green
14
14
B
7
5
3
Begonia x semperflorens 'Clips'
Wax Begonia
Assort.
8
8
B
6
5
3
Begonia x semperflorens 'F.R. Dwarf
Wax Begonia
Mix
6
6
B
7
5
3
Begonia x semperflorens 'Happy End'
Wax Begonia
Mix
8
6
B
6
5
3
Bougainvillea x
Bougainvillea
Pk, Org
VN
—
—
7
5
3
Brachycome iberifolia
Swan River Daisy
Purple
10
12
B
5
5
5
Brassica oleracea acephala
Flowering Kale
Multi.
12
10
B
9
5
5
Brassica oleracea capitata
Flowering Cabbage
Multi.
10
12
B
9
5
5
Briza maxima
Big Quaking Grass
Grass
24
12
B,C,D
7
5
7
Briza minor
Little Quaking Grass
Grass
12
10
B,C,D
7
5
7
Bromus lanceolaUts
Brome Grass
Grass
24
18
B,C,D
7
5
7
Browallia speciosa 'Jingle Bells'
Sapphire Flower
Mix
9
12
B
7
5
5
Browallia speciosa 'Marine Bells'
Sapphire Flower
Blue
9
12
B
7
5
5
Browallia speciosa 'Silver Bells'
Sapphire Flower
White
9
12
B
7
5
5
Bupleumm routundifolium 'Griffittii'
Bupleurum
Green
12
12
B
9
5
5
Calendula officinalis 'Bon Bon Orange'
Pot Marigold
Orange
8
8
B
9
5
5
Calendula officinalis 'Fiesta Gitana’
Pot Marigold
Mix
12
10
B
9
5
5
20
Table 1. Annuals, continued.,
LATIN NAME
COMMON NAME
COLOR
HT
SP
TYP
S
SI WT
Calendula officinalis 'Indian Song'
Pot Marigold
Yellow
20
12
B,C
9
5
5
Callistephus chinensis 'Dwarf Mix'
Aster
Mix
8
6
B
9
5
5
Callistephus chinensis 'Early Ostrich Plume'
Aster
Mix
18
9
B,C
9
5
5
Callistephus chinensis 'Pinnochio'
Aster
Mix
6
8
B
9
5
5
Callistephus chinensis 'Pot + Patio'
Aster
Mix
6
9
B
9
5
5
Callistephus chinensis 'Tall Mix'
Aster
Mix
24
12
B,C
9
5
5
Calonyction aculeatum
Moon Vine
White
VN
—
F
7
5
4
Carthamus tinctorius ’Goldtuft'
Golden Safflower
Gld org
30
14
B,C,D
9
5
5
Catharanthus roseus 'Carpet'
Vinca
Mix
3
24
B
5
5
8
Catharantlius roseus 'Little Cooler Series'
Vinca
Mix
8
8
B
5
5
8
Catharanthus roseus 'Little Series'
Vinca
Wh,Rs,Pk 8
8
B
5
5
8
Catharanthus roseus 'Sahara Madness'
Vinca
Pink
10
8
B
5
5
8
Celosia cristata 'Century Mix'
Celosia
Mix
22
12
B,C,D
9
5
5
Celosia cristata 'Coral Garden'
Cockscomb
Mix
10
10
B,C,D
9
5
5
Celosia cristata 'Forest Fire'
Celosia
Red
18
12
B,C,D
9
5
5
Celosia cristata 'New Look'
Celosia
Scarlet
10
10
b,c,d
9
5
5
Celosia cristata 'Pink Castle'
Celosia
Pink
20
10
B,C,D
9
5
5
Celosia cristata 'Yellow Castle’
Celosia
Yellow
10
10
B,C,D
9
5
5
Centaurea cyanus 'Blue Boy'
Bachelor's Button
Blue
30
20
C,D
9
5
5
Centaurea cyanus 'Polka Dot'
Bachelor’s Button
Mix
15
12
C,D,F
9
5
5
Centaurea moschata
Sweet Sultan
Mix
24
2
B
9
5
5
Centaurea moschata 'The Bride'
Sweet Sultan
White
16
18
C
9
5
5
Chrysanthemum carinatum 'Court Jester'
Annual Mum
Multi
18
12
B,C
9
5
7
Chrysanthemum carinatum 'Rainbow'
Annual Mum
Multi
24
16
B,C
9
5
7
Chrysanthemum coronarium 'Primrose Gem'
Garland Mum
Lt. Yel
12
16
B,C
9
5
5
Chrysanthemum fnitescens
Marguerite Daisy
Yel, Wht
18
12
B
9
5
5
Chrysanthemum multicaule
Annual Mum
Yellow
4
10
B
9
5
5
Chrysanthemum paludosum
Annual Mum
White
4
10
B
9
5
5
Chrysanthemum parthenium ’Bridal Robe’
Feverfew
White
24
14
B,C
9
5
5
Clarkia amoena 'Dwarf Mix'
Dwarf Godetia
Mix
12
8
B,C
5
7
3
Clarkia amoena ’Tall Mix’
Godetia
Mix
24
10
B,C
5
7
3
Cleome hasslerana ’Cherry Queen'
Spider Flower
Pink
48
20
B,C
9
5
5
Cleome hasslerana 'Queen Mix'
Spider Flower
Mix
48
20
B,C
9
5
5
Cleome hasslerana 'White Queen'
Spider Flower
White
48
18
B,C
9
5
5
Coleus x 'Verigated'
Coleus
Verig.
12
10
B
4
5
4
Coleus x 'Black Tali'
Coleus
Drk Mix
10
8
B
4
5
4
Collinsia heterophylla
Chinese Houses
Lavender
18
20
B
5
5
3
Collomia cavanillessi 'Neon'
Collomia
Scarlet
20
10
B,C
9
5
5
Consolida ambigua 'Blue Cloud'
Field Larkspur
Blue
30
18
C,D
7
5
5
Consolida ambigua 'Dwarf Hyacinth'
Rocket Larkspur
Pk/Vio
12
8
C,D
7
5
5
Consolida ambigua 'Giant Imperial Mix’
Field Larkspur
Mix
36
18
C,D
7
5
5
Consolida ambigua 'Imperial White King'
Field Larkspur
White
36
18
C,D
7
5
5
Convolvulus tricolor ’Variegated’
Bush Dwarf Morning Glory
Mix
5
8
B
9
5
5
Coreopsis tinctoria
Coreopsis, Tickseed
Yel/Mahg24
10
B
7
5
5
Cosmos bipinnatus ’SeashelT
Cosmos
Mix
48
18
B,C
9
5
7
Cosmos bipinnatus 'Sensation'
Cosmos
Mix
48
18
B,C
9
5
5
Cosmos sulphureus 'Bright Lights'
Cosmos
Gld/Rd
30
16
B,C
9
5
5
Cosmos sulphureus 'Diablo'
Cosmos
Scrl/Org
40
24
B,C
9
5
5
Cosmos sulphureus 'Lemon Twist'
Cosmos
Yellow
26
68
B,C
9
5
5
Cosmos sulphureus 'Sunny Gold'
Cosmos
Gold
12
10
B,C
9
5
5
Cosmos sulphureus 'Sunny Mix'
Cosmos
Mix
12
10
B,C
9
5
5
Table 1. Annuals, continued...
LATIN NAME
COMMON NAME
COLOR
HT
SP
TYP
S
SI WT
Cosmos sulphureus 'Sunny Red'
Cosmos
Red
12
10
B,C
9
5
5
Crepis rubra
Hawk's Beard
Pink
15
16
B,C
9
5
5
Crepis rubra 'Snowplume'
Hawk's Beard
White
8
14
B,C
9
5
5
Cuphea ignea
Cigar Plant
Orange
12
10
B
9
5
3
Cynoglossum amabile
Chinese Forget-me-not
Turq
18
14
B,F
7
5
5
Dahlia x 'Opera Dwarf Mix'
Dahlia
Mix
10
8
B
9
3
3
Dahlia x 'Redskin'
Dahlia
Mix
15
10
B
9
3
3
Delphinium 'Magic Fountain'
Dwarf Delphinium
Mix
30
18
B,C
7
5
5
Dianthus barbatus 'Wee Willie'
Sweet William
Mix
6
6
B,F
7
5
5
Dianthus caryophyllus
Carnation
Mix
12
10
B,C
7
5
5
Dianthus chinensis 'Frosty Mix'
Pinks
Bicolor
12
12
B.C.F
7
5
5
Dianthus chinensis 'Princess'
Sweet William
Mix
8
12
B,F
7
5
5
Dianthus chinensis 'Snow Carpet'
Sweet William
White
8
8
B,F
7
5
5
Dianthus chinensis 'Telestar Picotee'
Sweet William
Red
10
10
B,F
7
5
5
Diascia barberae
Twinspur
Pink
10
8
B
7
5
6
Dracaena
Spike Dracena
—
36
24
B
7
5
5
Dyssodiaenuiloba 'Golden Fleece'
Dahlberg Daisy
Yellow
8
8
B
9
5
5
Emilia jauanica 'Scarlet Magic'
T assel Flower
Scarlet
18
6
B,C,D
8
5
5
Eragrostis elegans
Love Grass
Grass
36
24
B,C,D,F
7
5
7
Eschschozia califomica 'California Mix'
California Poppy
Mix
9
9
B
9
5
8
Eschschozia califomica 'California Orange’
Poppy, California
Orange
18
12
B
9
5
8
Euphorbia marginata
Snow-on-the-Mountain
White
36
24
B
9
5
5
Europs
Yellow Daisy
Yellow
10
20
B
8
5
3
Eustoma grandiflorum 'Lion Mix'
Prairie Gentian
Mix
14
8
B,C
9
5
6
Eustoma grandiflorum 'Yodel Mix’
Prairie Gentian
Mix
14
8
B,C
9
5
6
Fuchsia x hybrida
Upright Fuchsia
Assort.
18
12
B
2
4
2
Fuchsia x hybrida
Trailing Fuchsia
Assort.
12
12
B
2
4
2
Gazania ringens 'Chansonette'
Gazania
Mix
6
6
B
9
5
7
Gomphrena globosa 'Buddy'
Globe Amaranth
Magenta
6
6
B,C,D
7
5
7
Gomphrena globosa 'Strawberry Fields'
Globe Amaranth
Red
18
20
B,C,D
7
5
7
Gomphrena globosa 'Woodcreek Mix'
Globe Amaranth
Mix
14
10
B,C,D
7
5
7
Gypsophila elegans
Annual Baby's Breath
Mix
18
12
B,C,D
8
5
4
Gypsophila elegans 'Covent Garden
Annual Baby's Breath
White
18
12
B,C,D
8
5
4
Helianathus annuus 'Color Fashion Mix'
Sunflower
Yel/Brzn
72
36
B,C
9
5
5
Helianathus annuus 'Italian White'
Sunflower
Cream
48
36
B,C
9
5
5
Helianathus annuus 'Luna'
Sunflower
Lt Yel
60
42
B,C
9
5
5
Helichrysum bracteatum 'King Mix'
Strawflower
Mix
36
24
b,c,d
8
5
5
Helichrysum bracteatum 'Monstrosum'
Strawflower
Mix
24
12
B,C,D
7
5
5
Heliotropium arborescens 'Arbore'
Heliotrope
Violet
15
10
b,c,f
5
5
5
Heliotropium arborescens 'Marine'
Heliotrope
Violet
15
10
b,c,f
5
5
5
Hibiscus moscheutos 'Disco Belle White'
Rose Mallow
White
24
28
B
9
5
3
Iberis amara 'Iceberg'
Candytuft
White
8
10
b,c,f
7
5
5
Iberis umbellata Dwarf Fairy'
Candytuft
Mix
8
10
b,c,f
7
5
5
Impatiens balsamina
Balsam
Mix
9
6
B
7
5
5
Impatiens x 'Accent'
Impatiens
Mix
15
20
B
3
3
5
Impatiens x 'Blitz'
Impatiens
Mix
15
20
B
3
3
5
Impatiens x 'Cascade Beauty'
Impatiens
Mix
15
20
B
3
3
5
Impatiens x 'Dazzle'
Impatiens
Cranberry 18
20
B
3
3
5
Impatiens x 'Novette Stars'
Impatiens
Mix
10
12
B
3
3
5
Impatiens x 'Super Elfin Blue Pearl'
Impatiens
Lavender
10
12
B
3
3
5
Impatiens x 'Super Elfin Lipstick'
Impatiens
Red
10
12
B
3
3
5
22
Table 1. Annuals, continued.,
LATIN NAME
COMMON NAME
COLOR
HT
SP
TYP
S
SI
WT
Impatiens x 'Super Elfin Parfait’
Impatiens
Magenta
10
12
B
3
3
5
bnpatiens x 'Super Elfin Pearl'
\
Impatiens
Lilac
10
12
B
3
3
5
Impatiens x 'Super Elfin Pink'
Impatiens
Pink
10
12
B
3
3
5
Impatiens x 'Super Elfin Red Velvet'
Impatiens
Red
10
12
B
3
3
5
Impatiens x 'Super Elfin Salmon Blush'
Impatiens
Salmon
10
12
B
3
3
5
Impatiens x 'Super Elfin Star Mix'
Impatiens
Mix
12
12
B
3
3
5
Impatiens x 'Super Elfin Twilight'
Impatiens
White
10
12
B
3
3
5
Impatiens x 'Super Elfin Violet'
Impatiens
Violet
10
12
B
3
3
5
Impatiens x 'Super Elfin White'
Impatiens
White
10
12
B
3
3
5
Ipomoea purpurea 'Early Call'
Morning Glory
Mix
VN
—
B
9
5
5
Ipomoea purpurea 'Heavenly Blue'
Morning Glory
Blue
VN
—
B
9
5
5
Ipomoea purpurea 'Scarlet O'Hara’
Morning Glory
Red
VN
—
B
9
5
5
Ipomoea purpurea 'Spice Island'
Morning Glory
Mix
VN
—
B
9
5
5
Ipomoea quamoclit 'Relli- Valley'
Cypress Vine
Mix
VN
--
B
5
5
3
Kochia scoparia trichophylla
Summer Cypress
—
36
12
B
9
6
6
Lasthenia glabrata
Goldfields
Yellow
9
16
B
6
5
5
Lathyrus odoratus 'Mamoth Series'
Sweet Pea
Mix
VN
6'
B,C,F
7
5
5
Latliyrus odoratus 'Old Spice'
Sweet Pea
Mix
VN
6'
B,C,F
7
5
5
Lathyrus odoratus 'Painted Lady'
Sweet Pea
Mix
VN
6*
b,c,f
7
5
5
Lathyrus odoratus 'Patio'
Sweet Pea
Mix
9
6
B.C.F
7
5
5
Lavatera trimestris 'Mont Blanc'
Lavatera, Tree Mallow
White
18
12
B
9
5
5
Lavatera trimestris 'Silver Cup'
Lavatera, Tree Mallow
Pink
18
12
B
9
5
5
Limnanthes douglasii
Fried Eggs
Gold
6
9
B
9
5
5
Limonium bellidifolium
Statice
Lavender
36
24
B,C,D
8
2
7
Limonium sinuatum 'Art Shade'
Statice
Mix
24
12
B.C.D
9
2
7
Limonium sinuatum 'Petite Bouquet'
Statice
Mix
12
8
B.C.D
8
2
7
Limonium sinuatum 'Soiree'
Statice
Mix
24
12
B,C,D
9
2
7
Limonium suworowii
Statice
Pink
18
12
B,C,D
9
2
7
Linaria reticulata 'Crown Jewels'
Toadflax
Assort.
6
9
B,C
7
5
5
Linum grandiflorum 'Bright Eyes'
Annual Flax
White
14
12
B
9
5
5
Linum grandiflonun 'Scarlet'
Annual Flax
Red
16
12
B
9
5
5
Lobelia erinus 'Blue Moon'
Edging Lobelia
D Violet
4
4
B
7
5
4
Lobelia erinus 'Color Cascade'
Trailing Lobelia
Mix
4
15
B
7
5
5
Lobelia erinus ’Crystal Palace’
Edging Lobelia
Dp Blue
4
4
B
7
5
5
Lobelia erinus ’Fountain Mix'
Trailing Lobelia
Mix
4
4
B
7
5
5
Lobelia erinus 'Royal Mix'
Edging Lobelia
Mix
4
4
B
7
5
5
Lobelia erinus 'Sapphire'
Trailing Lobelia
Dp Blue
4
15
B
7
5
5
Lobelia erinus 'White Lady'
Edging Lobelia
White
4
4
B
7
5
5
Lobelia erinus 'White Trailing'
Trailing Lobelia
White
4
15
B
7
5
5
Lobularia maritima 'Easter Bonnet'
Sweet Allysum
Mix
3
8
B
7
5
5
Lobularia maritima 'Wonderland Rose'
Sweet Allysum
Rose
3
8
B
7
5
5
Lobularia maritima 'Wonderland White'
Sweet Allysum
White
3
8
B
7
5
5
Lonas annua
Lupinus 'Galaxy'
Lonas, Yellow Ageratum
Lupine
Gld-yel
10
8
b,c,d
7
5
5
Lupinus texensis
Texas Bluebonnet
Blue
10
10
B
9
5
5
Malope trifida
Mallow
Wt/Prp
26
12
B,C
9
5
5
Matliiola incana bicomis
Night Scented Stock
Lilac
10
8
b,c,f
7
5
5
Mathiola incana 'Midget Series'
Dwarf Dbl Stock
Mix
10
8
b,c,f
7
5
5
Mathiola incana 'Trysomic 7 Week'
Dwarf Dbl Stock
Mix
8
4
B,C,F
7
5
5
Melampodium paludosum
Melamopodium
Yellow
18
10
B
9
5
8
Mesembryanthemum criniflomm 'Livingston'
Annual Ice Plant
Pink
3
12
B
9
8
8
Table 1. Annuals, continued...
LATIN NAME
COMMON NAME
COLOR
HT
SP
TYP
S
SI WT
Mesembryanthemum criniflorum 'Lunette'
Annual Ice Plant
Yel/Red
2
12
B
9
8
8
Mimulus x 'Calypso'
Monkey Flower
Mix
10
8
B
7
5
5
Mirabilis jalapa
Four-O'clock
Mix
24
20
b,c,f
7
5
5
Moluccella laevis
Bells-of-Ireland
Green
30
12
B,C,D
7
5
5
Myosotis sylvatica
Forget-me-not
Blue
10
6
B
5
5
4
Nemesia stmmosa 'Carnival'
Nemesia
Mix
12
6
B,C
7
5
3
Nemesia strumosa 'Mello'
Nemesia
Rd/Wt
12
6
B,C
7
5
3
Nicotian a a lata
Tall Flowering Tobacco
White
48
15
B
7
5
5
Nicotiana alata 'Domino Purple'
Flowering Tobacco
Purple
12
10
B
7
5
5
Nicotiana alata 'Domino White'
Flowering Tobacco
White
12
10
B
7
5
5
Nicotiana alata 'Nicki Lime Green'
Flowering Tobacco
Lm Grn
24
12
B
7
5
5
Nicotiana alata 'Nicki Pink'
Flowering Tobacco
Pink
12
10
B
7
5
5
Nicotiana alata 'Nicki Red’
Flowering Tobacco
Red
12
10
B
7
5
5
Nicotiana alata 'Nicki White'
Flowering Tobacco
White
12
10
B
7
5
5
Nicotiana sylvestris
Candelabra Flwr Tobacco
White
48
18
B,F
7
5
5
Nierembergia hippomanica 'Purple Robe'
Cup Flower
Purple
8
8
B
7
5
5
Nigella damascena 'Mulberry Rose'
Love-in-a-Mist
Rose
14
10
B,C,D
7
5
7
Nigella damascena 'Persian Jewel1
Love-in-a-Mist
Mv/Lav
14
10
b,c,d
7
5
7
No l ana paradoxa
Nolana
Blue
6
10
B
9
7
8
Osteospemium jacundum
Dimorphotecha
Mix
12
12
B
9
5
7
Osteospermum hyoseroides 'Gaiety'
Tripteris
Orange
18
16
B
9
5
7
Osteospermum jacundum 'Star Shine'
African Daisy
Rd/Wht
12
12
B
9
5
7
Papaver rhoeas 'Flanders'
Flanders Poppy
Red
18
9
B,C
9
5
5
Papaver rhoeas 'Shirley Mix'
Shirley Poppy
Mix
18
12
B
8
5
5
Pelargonium peltatum
Ivy Geranium
Assort.
6
18
B
7
5
3
Pelargonium peltatum 'Balcon'
Ivy Geranium
Assort.
6
18
B
7
5
3
Pelargonium peltatum 'Decora'
Ivy Geranium
Assort.
6
18
B
7
5
3
Pelargonium peltatum 'Summer Showers'
Ivy Geranium
Assort.
6
18
B
7
5
3
Pelargonium x hortomm 'Multibloom Pink'
Geranium
Pink
8
6
B
8
5
5
Pelargonium x hortomm 'Multibloom Salmon'
Geranium
Salmon
8
6
B
8
5
5
Pelargonium x hortomm 'Multib. Scarlet Eye'
Geranium
Wt/Scar
8
6
B
8
5
5
Pelargonium x hortomm 'Multibloom Scarlet'
Geranium
Scarlet
8
6
B
8
5
5
Pelargonium x hortomm 'Multibloom White'
Geranium
White
8
6
B
7
5
5
Pelargonium x hortomm 'Orbit Hot Pink'
Geranium
Pink
14
10
B
8
5
5
Pelargonium x hortomm 'Orbit Red'
Geranium
Red
14
10
B
8
5
5
Pelargonium x hortomm 'Ogilvie'
Geranium
Red
10
6
B
8
5
5
Pelargonium x hortomm 'Zonal'
Geranium
Assort.
16
10
B
8
5
5
Pennisetum mppelii
Fountain Grass
Grass
48
30
B,C,D
7
5
7
Pennisetum villosum
Dwarf Feather Top Grass
Grass
24
12
B,C,D
7
5
7
Pentzia 'Gold Button'
Pentzia
Yellow
24
18
B,C,D
7
5
7
Petunia x 'Azure Pearls'
Petunia
Blue
8
12
B
8
5
5
Petunia x 'Bicolor Mix'
Petunia
Mix
8
12
B
8
5
5
Petunia x 'Bridal Bouquet'
Petunia
White
8
12
B
8
5
5
Petunia x 'Bride's Maid'
Petunia
Dk. Purple8
12
B
8
5
5
Petunia x 'Can Can Mix'
Petunia
Mix
8
12
B
8
5
5
Petunia x 'Cascading Salmon'
Petunia
Salmon
8
12
B
8
5
5
Petunia x 'Cascading White'
Petunia
White
8
12
B
8
5
5
Petunia x 'Fluf Ruf Mix'
Petunia
Mix
8
12
B
8
5
5
Petunia x 'Laser Series'
Petunia
Assort.
8
12
B
8
5
5
Petunia x 'Pearls'
Petunia
Assort.
8
12
B
8
5
5
Petunia x 'Polo Burgundy Star'
Petunia
Burgundy 8
12
B
8
5
5
23
24
Table 1. Annuals, continued..
LATIN NAME
COMMON NAME
COLOR
HT
SP
TYP
S
SI WT
Petunia x 'Strawberry'
Petunia
Red
8
12
B
8
5
5
Petunia x 'Summer Madness'
Petunia
Pink
8
12
B
8
5
5
Petunia x 'Tahitian Sails'
Petunia
Salmon
8
12
B
8
5
5
Petunia x 'Yellow Magic'
Petunia
Yellow
8
12
B
8
5
5
Phacelia campanularia
California Bluebell
Blue
9
9
B,F
5
7
5
Phalaris canariensis
Canary Grass
Grass
18
12
B,C,D
7
5
7
Phaseolus coccineus
Scarlet Runner Bean
Red
VN
—
B
9
4
3
Phlox drummondii 'Cecily'
Drummond's Phlox
Mix
6
6
B,C
9
5
5
Phlox dmmmondii 'Petticoat'
Drummond's Phlox
Mix
4
6
B,C
9
5
5
Polypogon monspeliensii
Rabit's Foot Grass
Grass
25
18
B,C,D
7
5
7
Portidaca grandiflora 'Sundial'
Moss Rose
Mix
6
8
B
9
5
7
Portulaca grandiflora 'Swan Lake'
Moss Rose
White
6
8
B
9
5
7
Portulaca grandiflora 'Wildfire'
Moss Rose
Mix
6
14
B
9
5
7
Primula x polyanthus
Primrose
Assort.
8
6
B
4
5
3
Primula malacoides
Primrose
Assort.
8
6
B
4
5
3
Reseda odorata 'Grandiflora'
Mignonette
Cream
24
12
C,F
7
5
5
Reseda odorata 'Machet'
Mignonette
Red
12
10
C,F
7
5
5
Rhodochiton atrosanguineum
Purple Bells
Maroon
VN
—
B
7
5
5
Ricinus communis 'Impala'
Castor Bean
Yellow
60
40
B
7
5
5
Rudbeckia hirta 'Goldilocks'
Gloriosa Daisy
Yellow
20
18
B,C
9
5
5
Rudbeckia hirta 'Irish Eyes'
Gloriosa Daisy
Yl/Gn
28
20
B,C
9
5
5
Ryhnchecetrum repens
Ruby Grass
Grn/Rose 18
16
B,C
7
5
5
Salpiglossis sinuata 'Casino'
Painted Tongue
Mix
10
8
B,C
5
5
3
Salpiglossis sinuata 'Splash'
Painted Tongue
Mix
22
18
B,C
5
5
3
Salvia farinacea 'Argent'
Mealycup Sage
White
18
12
C
7
5
5
Salvia farinacea 'Blue Bedder'
Mealycup Sage
Blue
18
12
c
7
5
5
Salvia farinacea 'Victoria'
Mealycup Sage
Blue
24
12
b,c,d
9
5
5
Salvia splendens 'Caribiniere Purple'
Salvia
Purple
10
8
B
9
5
5
Salvia splendens 'Caribiniere Scarlet King'
Salvia
Red
10
8
B
9
5
5
Salvia splendens 'Caribiniere White'
Salvia
White
10
8
B
9
5
5
Salvia splendens 'Rhea'
Salvia
White
12
8
B
9
5
5
Salvia splendens 'Stripes'
Salvia
Wt/Rd
16
10
B
9
5
5
Salvia splendens 'White'
Salvia
White
14
8
B
9
5
5
Sanvitalia procumbens 'Gold Braid'
Creeping Zinnia
Gold
6
9
B
9
5
5
Scabiosa atropurpurea 'Giant Imperial'
Pincushion Flower
Lt Blue
24
18
b,c,d
9
5
8
Scabiosa stellata' Ping Pong'
Pincushion Flower
White
18
14
B,C,D
9
5
8
Schizanthus wisetonensis 'Angel Wings'
Butterfly Flower
Bl/Pk
18
14
B,C
9
5
5
Senecio maritima 'Cirrus'
Dusty Miller
Silver
8
10
B
7
5
7
Senecio maritima 'New Look'
Dusty Miller
Silver
9
12
B,C,D
7
5
7
Senecio maritima 'Silver Feather'
Dusty Miller
Silver
12
10
B
7
5
7
Senecio maritima 'Silver Queen'
Dusty Miller
Silver
8
6
B
7
5
7
Setaria macrochaeta
Weeping Bristle Grass
Grass
48
30
B,C,D
7
5
7
Silene oculata 'Royal Angel'
Catch Fly
Blue
10
10
B,C
7
5
5
Sorghum bicolor
Black Millet
Grass
60
12
b,c,d
7
5
7
Tagetes erecta 'Crackerjack'
Marigold
Assort.
24
16
B,C
9
5
5
Tagetes erecta 'Primrose Lady'
Marigold
Lt. Yellow
16
10
B,C
9
5
5
Tagetes erecta 'Snowbird'
Marigold
White
16
10
B,C
9
5
5
Tagetes tenuifolia pumila 'Discovery Yellow'
Marigold
Yellow
10
10
B
9
5
5
Tagetes tenuifolia pumila 'Golden Gem '
Marigold
Gold
8
10
B
9
5
5
Tagetes tenuifolia pumila 'Lemon Gem'
Marigold
Lemon
8
10
B
9
5
5
Tagetes tenuifolia pumila 'Ginger'
Marigold
Gold
10
10
B
9
5
5
Table 1. Annuals, continued...
LATIN NAME
COMMON NAME
COLOR
HT
SP
TYP
S
SI
WT
Tagetes tenuifolia pumila 'Golden Gate'
Marigold
Gold/Rd
14
12
B
9
5
5
Tagetes tenuifolia pumila 'Saffron'
Marigold
Yellow
10
8
B
9
5
5
Tagetes tenuifolia pumila 'Star Fire'
Marigold
Mix
6
8
B
9
5
5
Tagetes tenuifolia pumila 'Tiger Eyes'
Marigold
Scarlet
12
12
B
9
5
5
Talinum crassifolium
Jewels of Opar
Dp Pink
20
12
B,C
7
5
5
Thunbergia alata
Black-Eyed Susan Vine
Mix
VN
—
B
7
5
5
Tithonia rotundifolia 'Torch'
Mexican Sunflower
Orange
26
24
B,C
7
5
5
Torenia foumieri
Wishbone Flower
Blue
8
8
B
3
5
3
Torenia foumieri 'Clown Mix'
Wishbone Flower
Mix
8
8
B
3
5
3
Trachymene caenilea
Blue Lace Flower
Lt Blue
24
12
C,D
7
5
5
Triticum turgidum 'Wakooma'
Bearded Wheat Grass
Grass
48
30
B,C,D
7,57
Tropaeolum majus 'Fragrant Giants'
Trailing Nasturtium
Org/Scrl
VN
—
B
9
5
7
Tropaeolum majus 'Jewel Mix'
Nasturtium
Mix
12
8
B,C,F
9
7
5
Tropaeolum majus 'Whirlybird Cherry Rose'
Trailing Nasturtium
Red
12
8
b,c,f
9
7
5
Tropaeolum majus 'Whirlybird Gold'
Nasturtium
Gold
12
8
B,C,F
9
7
5
Tropaeolum majus 'Whirlybird Mahogany'
Nasturtium
Mahogany 12
8
B,C,F
9
7
5
Tropaeolum majus 'Whirlybird Scarlet'
Nasturtium
Red
12
8
b,c,f
9
7
5
Tropaeolum majus 'Whirlybird Tangerine'
Nasturtium
Orange
12
8
b,c,f
9
7
5
Tropaeolum peregrinum 'Canary Bird'
Canary Creeper
Yellow
VN
-
B,C,F
9
7
5
Venidium fastuosum
Monarch of the Veldt
Org/Prp
24
20
B,C
9
5
5
Verbena bonariensis
Verbena
Lavender
40
20
B,C
9
5
5
Verbena hortensis 'French Blue'
Verbena
Blue
10
8
B,C
9
5
5
Verbena hortensis 'Novalis Series'
Verbena
Assort.
10
8
B,C
9
5
5
Verbena hortensis 'Sandy White'
Verbena
White
10
8
B,C
9
5
5
Verbena rigida
Verbena
Purple
12
10
b,c,f
9
5
7
Vinca major variegata
Trailing Vinca
—
VN
—
B
7
5
5
Viola wittrockiana 'Black Devil'
Pansy
Black
6
8
B
5
5
5
Viola wittrockiana 'Color Festival'
Pansy
Mix
8
8
B
5
5
5
Viola wittrockiana 'Giant Mix'
Pansy
Mix
8
8
B
5
5
5
Viola wittrockiana 'Joker Light Blue'
Pansy
Blue
8
6
B
5
5
5
Viola wittrockiana 'Jolly Joker'
Pansy
Org/Purp 8
6
B
5
5
5
Viola wittrockiana 'Masterpiece'
Pansy
Mix
8
6
B
5
5
5
Viola wittrockiana 'Rococo'
Pansy
Mix
7
5
B
5
5
5
Xeranthemum annuum
Immortelle
Wt/Lil
24
14
B,C,D
9
5
7
Zinnia angustifolia 'Orange Star'
Classic Zinnia
Orange
10
12
B,C
9
5
7
Zinnia elegans 'Canary Yellow'
Zinnia
Yellow
12
10
B,C
8
5
7
Zinnia elegans 'Chippendale Mahogany'
Zinnia
Mahogny
14
10
B,C
8
5
7
Zinnia elegans 'Envy'
Zinnia
Green
18
12
B,C
8
5
7
Zinnia elegans 'Peppermint'
Zinnia
Striped
22
10
B,C
8
5
7
Zinnia elegans 'Ruffled Pink'
Zinnia
Pink
26
18
B,C
8
5
7
Zinnia elegans 'Scabiosiflora'
Zinna Scabiosa Flw
Mix
15
10
B,C
8
5
7
Zinnia elegans 'Sombrero'
Zinnia
Yel/Red
15
10
B,C
8
5
7
Zinnia elegans 'Splendor Hybrid'
Zinnia
Red
22
18
B,C
8
5
7
Zinnia elegans 'Swirls'
Zinnia
Striped
24
12
B,C
8
5
7
Zinnia haageana 'Old Mexico'
Zinnia, Double
Yel/Rd
18
12
B,C
8
5
7
Table 2, Berry Basket.
Ken Roberts, Chairman
Strawberry ( Fragaria sp.) 'Fort Laramie' is an everbearing variety particularly suited to the cold winters of the Rocky
Mountain region. Plant 12 to 18 inches apart in well prepared soil. Mulch well to control weeds and retain
moisture.
Table 2. Berry Basket, continued...
Raspberry ( Rubus idaeus ) 'Heritage', 'Fall Gold' are red raspberries that are productive and ever-bearing. An early
summer crop appears on last years canes and a mid-summer-to-frost crop on this years canes. Plant in well
prepared, fertile soil about 18 inches apart, 3 to 5 feet between rows. In early spring clear out weeds, loosen
soil and dress with well rotted manure.
Gooseberry ( Ribes hirtellum ) These productive, decorative plants are a good choice for high altitudes. Pixwell is a
popular, tart variety enjoyed for pies, jellies and jams. 'Leppa Red,' 'Sylvia,' and others produce a larger,
sweeter berry excellent for fruit bowls or just eating out of hand. Gooseberries like full sun but will tolerate
partial shade.
Currant (Ribes sp.)'Red Lake' is a standard in many Denver gardens. It is very productive, with a sweet-tart taste and it is
great for cooking, making wine or attracting birds.
Blackberry ( Rubus sp.) The thornless variety 'Chester' is great for eating fresh or for cooking. It is hardy in Denver but
not in the mountains. Blackberries like fertile, somewhat acidic soil, with a pH 5.5, so add plenty of peat moss
when planting.
Grapes (Vitis vinifera) Always a favorite, grapes are easy to grow and are very tolerant of poor soil, but require good
drainage. They are easily trained to arbor or fence. Enrich the soil with organic matter when planting. Prune
back hard each spring to enhance production.
Apple ( Mains sp.) These hardy trees are the descendents of the fruit of early settlers. There are in excess of 5000
varieties of apple, many still maintained by aficionados. Available as dwarf (8-10 feet), semi-dwarf (12-15
feet) and standard (18-25 feet) trees. Plant in full sun. Mix plenty of peat moss in the soil. While most apples
are self fertile, two or more varieties will improve fertilization.
Cherry ( Pntnus sp.) Very popular in Denver, cherries are one of the earliest trees to bloom in the spring. 'Montmorency',
growing approx. 15 feet tall, is the standard for pie cherries. 'North Star' is a dwarf variety growing to about
10 feet when mature. The sour cherries arc self-fertile, however, the sweet cherries such as 'Bing' or 'Black
Tartarian' required cross pollination.
Plum ( Primus sp.) Plums are very desirable for small properties, rarely grow over 12-15 feet. With proper pruning they
can easily be maintained between 8 and 10 feet. The European varieties will grow well in heavy soils whereas
the Japanese varieties prefer a light, loamy soil.
Peach ( Primus persica ) One of Colorado's favorite fruits, the peach generally does quite well in our winters. However,
because it blooms relatively early there is always the danger of loosing the crop to a late frost or snow storm.
Peaches are also susceptible to rot and borers so they require a bit more vigilance than fruits such as apples.
Apricot ( Pninus anneniaca) Apricots are an "iffy" tree in the Denver area but are quite reliable in the inner city where
there is more protection. The apricot is the earliest fruit tree to bloom and generally gets nipped by a frost. If
you have the right location, in a protected spot on the north side where it will stay dormant longer, it can be a
very rewarding addition to your garden.
Pear ( Pyms communis) Pears tend to be the tallest of the fruit trees with an upright growing habit that requires forced
spreading of the branches. They are hardy in the Denver area but may not do well at the higher elevations.
They produce an abundance of succulent growth therefore must be pruned heavily. Plant two varieties to
assure pollination.
Table 3, Herbs.
Barbara Moore, Chairman
[B = month of beginning bloom; F = month of final bloom; HT(Height); S(Sun): 1 = full shade, 9 = full sun; SL(Soil):
l = acid peat, 9 = alkaline clay; W(Water): l = wet, 9 = dry; C: P = perennial, A = annual, B = biennial; H: H = hardy,
T = tender, F = half hardy]
COMMON NAME
LATIN NAME
B
F
HT
S
SL
W
C
H
Aloe
Aloe barbadensis
__
_
12-24"
5
5
8
P
T
Angelica
Angelica archangelica
7
8
5-6'
7
5
4
B
H
Anise
Pimpinella anisum
7
8
18-24”
9
5
8
A
T
Arugula
Eruca vesicaria sativa
—
—
18"
9
5
6
A
T
Basil, cinnamon
Ocimum basilicum 'Globe'
8
8
2’
9
5
4
A
T
Basil, globe, spicy
Ocimum basilicum 'Spicy Globe’
8
8
2’
9
5
4
A
T
Basil, Green Ruffles
Ocimum basilicum ’Green Ruffles'
8
8
2’
9
5
4
A
T
Basil, lemon
Ocimum basilicum 'Lemon'
8
8
2’
9
5
4
A
T
Basil, licorice
Ocimum basilicum Licorice'
8
8
2’
9
5
4
A
T
Basil, opal
Ocimum basilicum Dark Opal'
8
8
2
9
5
4
A
T
Table 3. Herbs, continued...
COMMON NAME
LATIN NAME
B
F
HT
S
SL
W
C
H
Basil, Holy
Ocimum basilicum 'Sanctum'
8
8
2'
9
5
4
A
T
Basil, Piccolo
Ocimum basilicum 'Piccolo'
8
8
2
9
5
4
A
T
Basil, Purple Ruffles
Ocimum basilicum 'Purple Ruffles'
8
8
2
9
5
4
A
T
Basil, Sweet Green
Ocimum basilicum 'Sweet Green’
8
8
2
9
5
4
A
T
Bay
Laurus nobilis
--
—
10'
5
5
3
P
T
Bee Balm
Monarda didyma
7
8
3'
7
5
3
P
H
Bergamont
Monarda fistulosa
--
—
3'
—
—
—
P
—
Borage
Borago officinalis
7
9
12-18"
9
5
4
A
H
Burnet, Salad
Sangidsorba minor
6
9
12"
9
5
7
P
H
Calendula
Calendula officinalis
6
9
12"
9
5
6
A
H
Caraway
Carum carvi
6
7
2
8
5
7
B
H
Catnip
Nepeta cataria
7
9
3'
8
5
6
P
H
Celeriac
Apium gravenolens
—
--
1'
—
—
—
A
—
Chamomile (German)
Matricaria recutita
6
6
2
9
5
4
A
H
Chamomile (Roman)
Anthemis nobilis
6
9
4-12"
7
5
4
P
H
Chervil
Anthriscus cerefolium
_
_
1-2'
5
5
4
A
T
Chicory
Cichorium intybus
7
9
3-6'
9
5
5
P
H
Chives
Allium schoenoprasum 'Grolau'
6
9
1'
8
5
4
P
H
Chives, Garlic
Allium tuberosum
6
9
12"
8
5
4
P
H
Cicely, Sweet
Myrrhis odorata
6
6
2-3'
5
5
3
P
H
Comfrey
Symphytum officinale
6
9
2-3'
5
5
3
P
H
Coriander
Coriandrum sativum
7
7
2-3'
9
5
6
A
H
Costmary
Chrysanthemum balsamita
7
7
2
6
5
8
P
H
Cress, Garden, Pepper Cress
Lepidium sativum
~
—
18"
5
5
6
A
H
Cress, Uplant, Winter Cress
Barbare vulgaris
5
9
18"
6
5
4
P
H
Cumin
Cuminum cyminum
7
7
6-8"
9
5
5
A
H
Dill
Anethum graveolens
7
9
3'
9
5
5
A
H
Epasote
Chenopodium ambrosioides
7
9
3-4'
5
5
5
P
H
Fennel
Foeniculum vulgare
—
—
4'
9
5
5
A
H
Garlic, Society
Tulbaghia violacea
—
—
12-18"
9
5
5
P
H
Germander
Teucrium chamaedirs
7
9
6-18"
9
5
3
P
H
Heliotrope
Heliotropium peruvianum
6
9
6-12"
7
5
5
A
T
Horehound
Mamibium vidgare
6
9
2
8
5
8
P
H
Hyssop
Hyssopus officinalis
7
8
2
9
5
5
P
H
Joseph's Coat
Amaranthus tricolor
7
7
5'
9
5
5
A
T
Lady's Mantle
Alchemilla vulgaris
7
8
16"
8
5
7
P
H
Lamb's ear
Stachys byzantina
7
7
12-18"
9
5
5
P
T
Lavender, English
Lavandula angustifolia
7
8
18"
9
5
5
P
H
Lavender, French
Lavandula dentata
7
8
1-3’
9
5
5
P
H
Lavender, Munstead
Lavandula dentata 'Munstead'
7
8
18"
9
5
5
P
H
Lemon Balm
Melissa officinalis
7
9
2-3’
5
5
5
P
H
Lemon Grass
Cymbopogon citratus
-
—
4'
9
5
5
P
T
Lemon Verbena
Aloysia triphylla
8
9
2
5
5
5
P
T
Lion's Ear
Leonotis leonums
8
9
—
9
5
5
P
H
Lovage
Levisticum officinale
8
9
4-6'
6
5
4
P
H
Marjoram, Creeping golden
Origanum vulgare 'Aureum'
—
--
4-6"
9
5
5
P
H
Marjoram, sweet
Origanum majorana
8
9
12"
9
5
5
A
T
Mint, Apple
Mentha suaveolens
--
--
18"
5
5
4
P
H
Mint, Corsican
Mentha requienii
--
—
1"
3
5
3
P
H
Mint, Curly
Mentha crispa var.
12
8
4
P
H
Mint, Lemon
Monarda citriodora
—
—
4-6"
8
5
4
P
H
28
Table 3. Herbs, continued...
COMMON NAME
LATIN NAME
B
F
HT
S
SL
W
C
H
Mint, orange
Mentha piperita citrata
—
—
1-2'
8
5
4
P
H
Mint, Peppermint
Mentha piperata
—
—
12"
8
5
4
P
H
Mint, Pineapple
Mentha suaveolens variegata
—
—
10"
8
5
4
P
H
Mint, Spearmint
Mentha spicata
—
—
2'
8
5
4
P
H
Oregano, Greek
Origanum vulgare 'Greek'
—
—
12-20"
8
5
5
P
H
Parsley, Curly
Petroselinum crispum
7
8
12"
8
5
4
B
H
Parsley, Italian
Petroselinum crispum 'Neopolitanum'
7
8
12"
8
5
4
B
H
Pennyroyal, English
Mentha pulegium
—
—
3"
5
5
3
P
T
Perilla, Green
Perilla frutescens var.
—
2-4'
8
5
5
A
T
Perilla, Red
Perilla frutescens
—
—
2-4'
8
5
5
A
T
Pimpernel, Scarlet
Anagallis arvensis
—
—
6"
9
5
5
P
T
Rosemary
Rosmarinus officinalis
—
—
2-3'
9
5
5
P
T
Rosemary, Blue
Rosmarinus officinalis 'Tuscan Blue'
—
—
2-3'
9
5
5
P
T
Rosemary, Pink
Rosmarinus officinalis
—
—
2-3'
9
5
5
P
T
Rue, Herb-of-Grace
Ruta graveolens
7
8
2-3'
8
5
5
P
H
Sage, Garden
Salvia officinalis
7
8
2'
9
5
5
P
H
Sage, Pineapple
Salvia elegans
9
9
3'
8
5
5
P
T
Sage, Tri-color
Salvia officinalis 'Tri -color'
7
8
2'
9
5
5
P
H
Santolina, Lavender cotton
Santolina chamaecyparissus
—
-*
2'
9
5
7
P
H
Savory, Summer
Satureja hortensis
7
7
18"
8
5
4
A
T
Savory, Winter
Satureja montana
6
7
12"
5
5
5
P
H
Sorrel, French
Rumex acetosa
-
—
2'
8
5
4
P
H
Southernwood
Artemisia abrotanum
—
—
2-3'
5
5
5
P
H
Sweet Woodruff
Galium odoratum
6
6
6"
3
5
3
P
H
Tansy
Tanacetum vulgare
9
—
3’
9
5
5
P
H
Tarragon, French
Artemisia dracunculus
-
~
2'
8
5
5
P
H
Thyme, Caraway
Thymus herba-barona
7
8
6-8"
9
5
5
P
H
Thyme, Creeping Lemon
Thymus x citriodoms
—
-
3-6"
8
5
7
P
H
Thyme, English
Thymus vulgaris
—
--
6-8"
9
5
7
P
H
Thyme, Mother-of-Thyme
Thymus pracox 'Coccineum'
—
—
3-6"
9
5
7
P
H
Thyme, Silver
Thymus vidgaris 'Argenteus'
—
—
6-12"
9
5
7
P
H
Thyme, Wooly
Thymus psuedolanuginosus
—
—
2"
9
5
7
P
H
Valerian
Valeriana officinalis
7
8
3’
8
5
5
P
H
Watercress
Nasturtium officinale
—
--
3”
5
5
3
P
H
Wormwood, Absinthe
Artemisia absinthium
—
—
2'
8
5
8
P
H
Table 4, Perennials.
John Reber, Chairman
[B: month of first bloom; F: month of final bloom; HT: hight in
9 = full sun; SI (soil): 1 = alkaline clay, 9 = acid peat; WT (water):
inches; SP: spread in
l = wet, 9 = dry]
inches;
S (sun):
1 =
full shade,
LATIN NAME
COMMON NAME
COLOR
B
F
HT
SP
S
SI
WT
Achillea filipendulina 'Coronation Gold'
Yarrow
Gold
6
9
36
24
8
5
6
Achillea filipendulina 'Moonshine'
Yarrow
Yellow
6
9
22
20
8
5
6
Achillea millefolium 'Red Beauty’
Yarrow
Red
7
10 24
24
8
5
7
Achillea ptannica 'The Pearl'
Yarrow
White
6
9
24
24
8
5
6
Aconitum anthora
Monkshood
Yellow
6
7
30
12
4
5
5
Aconitum x bicolor
Bicolor Monkshood
Bl/Wh
7
8
40
15
5
4
5
Aconitum napellus
Monkshood
Purple
7
8
48
18
4
5
5
Aegopodium podagraria variegatum
Bishop's Weed
White
6
7
10
36
3
5
5
Table 4. Perennials, continued...
LATIN NAME
COMMON NAME
COLOR
B
F
HT
SP
S
SI
WT
Alchemilla vulgaris
Lady's Mantle
Charturse5
6
18
15
5
5
5
Allium cemuum
Nodding Onion
Rose
7
8
15
6
7
6
5
Amorpha canescens
Leadplant
Purple
7
8
48
24
9
7
8
Anchusa azurea 'Regal'
Bugloss
Blue
5
6
48
24
8
5
5
Anchusa azurea 'Royal Blue'
Bugloss
Blue
5
6
48
24
8
5
5
Andropogon scoparius
Little Bluestem Grass
Grass
8
10
48
24
8
5
7
Anemone sylvestris
Windflower
White
4
5
15
10
5
4
4
Anemone vitifolia 'Robustissima'
Grape-Leaved Anemone
Pink
8
10
48
24
4
5
4
Anemone x hybrida 'Honorine Jobert'
Japanese Anemone
White
8
10
60
24
5
4
4
Anemone x hybrida 'Prinz Heinrich'
Japanese Anemone
Rose
8
10
24
16
5
4
4
Anthemis biebersteiniana
Filigree Daisy
White
5
8
12
12
9
6
7
Aquilegia caemlea
Rocky Mountain Columbine
Blue
5
7
15
12
5
5
5
Aquilegia canadensis
American Columbine
Rd/Yel
5
6
18
12
4
4
4
Aquilegia elegantula
Columbine
Rd/Yel
6
7
8
8
4
5
6
Aquilegia saximontana
Dwarf Columbine
Blue
5
7
8
6
4
5
5
Aquilegia x 'Blue Bird'
Columbine
Blue
5
7
18
12
4
5
5
Aquilegia x 'Cardinal'
Columbine
Red
5
7
18
12
4
5
5
Aquilegia x 'Crimson Star'
Columbine
Red
5
7
18
12
4
5
5
Aquilegia x 'McKana Hybrids'
Mckana Hybrid Columbine
Mix
5
7
18
12
4
5
5
Anneria maritima 'Splendens'
Sea Pink
Pink
5
7
8
8
8
5
6
Amieria maritima 'Dusselford Pride'
Sea Pink
Red
6
7
10
10
8
5
6
Artemisia schmidtiana
Silver Mound Sage
Silver
--
—
10
12
8
5
6
Aruncus diocus 'Kneiffii'
Goat's Beard
Cream
6
7
36
18
4
3
4
Asclepias tuberosa
Butterfly Weed
Orange
7
10
18
12
8
6
8
Aster alpina
Alpine Asler
Mix
5
7
10
10
7
5
5
Aster novae-angliae
New England Aster
Lavender 8
10
48
24
7
5
5
Aster xfrikartii
Wonder Of Staffa Aster
Lavender 7
10
30
18
8
5
6
Aster x 'Fall-Tali'
Aster
Mixed
8
10
48
24
7
5
5
Astilbe taquetii
False Spirea
Lavender 8
9
48
30
5
4
4
Astilbe x arendsii 'Deutchland'
False Spirea
White
6
7
20
26
4
4
3
Astilbe x 'Fanal'
False Spirea
Red
6
7
20
26
4
4
3
Astilbe x 'Rheinland'
False Spirea
Pink
6
7
20
26
4
4
3
Athyrium filix-femina
Lady Fern
—
—
—
30
15
2
4
3
Aubrietia deltoidea
Rock Cress
Magenta
5
6
6
15
7
5
6
Aurinia saxatil
Basket Of Gold
Yellow
4
5
12
24
9
5
7
Avena sempervirens
Blue Avena Grass
Grass
8
9
30
24
8
5
6
Baptisia australis
Wild Indigo
Indigo
6
8
36
20
8
4
4
Belamcanda chinensis
Blackberry Lily
Orange
7
8
24
12
7
5
5
Bergenia cordifolia
Leatherleaf
Pink
4
5
12
18
5
5
5
Bergenia cordifolia 'Silver Light'
Leatherleaf
White
4
5
12
18
5
5
5
Bergenia cordifolia 'Perfect'
Leatherleaf
Plum
4
5
18
18
5
5
5
Bergenia purpurencens
Leatherleaf
Dk. Lilac 4
5
16
18
5
5
5
Bouteloua curtipendula
Blue Grama Grass
Grass
7
9
24
10
8
5
6
Bnmnera macrophylla
Siberian Bugloss
Blue
4
6
15
12
4
4
4
Campanula persicifolia
Peach-leaf Bellflower
Blue
6
9
30
12
7
5
5
Campanula rotundifolia
Native Harebell
Blue
6
9
12
10
7
5
5
Catananche coemlea
Cupid's Dart
Blue
6
9
18
12
9
6
7
Centaurea dealbata
Rose Cornflower
Pink
6
7
20
20
8
5
6
Centaurea montana
Perennial Bachelor Button
Blue
6
7
24
24
8
6
7
Centranthus ruber
Jupiter's Beard
Coral
6
8
30
15
8
5
5
Chelone obliqua
Turtle Head
Pink
7
8
36
20
4
6
4
Table 4. Perennials, continued.
LATIN NAME
COMMON NAME
COLOR
B
F
HT
SP
S
SI
WT
Chrysanthemum leucanthemum
Ox-Eye Daisy
White
6
8
20
15
8
6
6
Chrysanthemum maximum 'Alaska'
Shasta Daisy ,
White
6
8
24
24
8
6
6
Chrysanthemum maximum 'Silver Princess'
Shasta Daisy .
White
6
8
12
12
8
6
6
Chrysanthemum maximum 'Marconi'
Double Shasta Daisy
White
6
8
24
24
8
6
6
Chrysanthemum maximum 'Miss Muffet'
Dwarf Shasta Daisy
White
6
8
10
15
8
6
6
Chrysanthemum x morifolium
Hardy Fall Mums
Assort.
8
11
24
24
8
5
5
Cimicifuga simplex 'Autopurpurea'
Ivory Spires
White
9
10
36
18
4
4
4
Clematis orientalis
Clematis
Yellow
6
7
Vn
—
8
6
6
Clematis x jackmanii
Clematis 'Jackman's'
Purple
6
8
Vn
--
6
5
5
Clematis x ’Mme Andre'
Clematis
Pink
6
7
Vn
—
6
5
5
Clematis x 'Ramona'
Clematis
Blue
6
7
Vn
--
6
5
5
Clematis x 'Lanuginosa Candida'
Clematis
White
6
7
Vn
—
6
5
5
Coreopsis grandiflora 'Gold Fink'
Double Dwarf Coreopsis
Yellow
6
8
10
12
8
5
6
Coreopsis grandiflora 'Baby Sun'
Double Dwarf Coreopsis
Yellow
6
8
10
12
8
5
6
Coreopsis grandiflora 'Early Sunrise'
Double Dwarf Coreopsis
Yellow
6
8
10
12
8
5
6
Coreopsis lanceolata
Lance-leaf Coreopsis
Yellow
6
8
18
18
8
5
6
Coreopsis verticillata 'Moonbeam'
Thread-leaf Coreopsis
Yellow
5
10
10
15
7
5
5
Coropsis verticillata 'Zargreb'
Thread-leaf Coreopsis
Yellow
6
10
15
15
7
5
5
Delospenna cooperi
Hardy Iceplant
Magenta
6
10
4
15
9
5
8
Delospenna nubigenum
Hardy Iceplant
Yellow
6
9
2
15
8
5
8
Delphinium x
Delphinium
Mixed
6
7
60
24
8
5
5
Delphinium x 'Connecticut Yankee'
Delphinium
Mixed
6
7
36
28
8
5
5
Dianthus caryophyllus
Carnation
Mixed
6
8
15
12
9
5
6
Dicentra eximia 'Luxuriant'
Fringed Bleeding Heart
Pink
5
10
12
12
4
4
4
Dicentra spectabilis
Bleeding Heart
Pink
5
6
24
24
3
4
4
Dicentra spectabilis 'Alba'
Bleeding Heart
White
5
6
24
24
3
4
4
Digitalis ambigua
Foxglove
Yellow
6
8
30
12
5
5
4
Dryopteris marginalis
Leatherwood Fern
--
—
—
30
24
2
3
3
Echinacea pallida
Pale Cone flower
Lavender 7
10
36
18
8
6
5
Echinacea purpurea
Purple Coneflower
Wine Pk
7
10
36
24
8
6
6
Echinops ritro
Globe Thistle
Blue
7
8
36
18
8
5
6
Epilobium angustifolium
Fireweed
Dp Pink
7
8
36
24
6
6
7
Erigeron compositus
Whiplash Daisy
White
4
10
4
6
8
7
8
Euphorbia polychroma
Cushion Spurge
Yellow
5
6
15
15
5
5
5
Festuca ovina glauca
Blue Fescue Grass
Grass
5
9
12
10
8
7
6
Filipendula hexapetalla
Meadow Sweet
Cream
6
7
18
15
7
6
5
Filipendula purpurea
Meadow Sweet
Carminer 6
7
36
15
7
6
5
Gaillar dia arista ta
Indian Blanket
Rd/Yel
6
10
24
18
9
6
8
Gaillardia x grandiflora 'Baby Cole’
Indian Blanket
Rd/Yel
6
10
10
12
9
6
8
Gaillardia x grandiflora 'Burgundy'
Indian Blanket
Burgundy 6
10
24
18
9
6
8
Gaillardia x grandiflora 'Goblin'
Dwarf Indian Blanket
Rd/Yel
6
10
15
12
9
6
8
Geranium endressii 'Wargrave Pink'
Pyrenean Cranesbill
Pink
6
8
15
24
6
5
5
Geranium macrorrhizum 'Ingwersen Variety'
Cranesbill
Rose
5
7
12
24
5
5
5
Geranium psilostemon
Armenian Cranesbill
Magenta
5
8
30
20
5
5
5
Geranium sanguineum 'Album'
Bloody Cranesbill
White
5
8
10
24
5
5
5
Geranium x 'Claridge Druce'
Cranesbill
Purple
5
8
24
24
5
5
5
Geum guellyon 'Mrs. Bradshaw'
Geum
Red
6
8
15
12
6
5
5
Geum quellyon 'Lady Stratheden'
Geum
Yellow
6
8
15
12
6
5
5
Geum triflonim
Prairie Smoke
Pink
5
7
10
8
5
5
5
Geum x borisii
Geum
Scarlet
5
7
12
12
6
5
5
Goniolimon tartaricum
German Statice
White
6
7
10
12
9
6
6
30
Table 4. Perennials, continued...
LATIN NAME
COMMON NAME
COLOR
B
F
HT
SP
S
SI
WT
Gypsophila paniculata
Baby's Breath
White
6
8
36
36
8
5
6
Gypsophila paniculata 'Bristol Fairy'
Double Baby's Breath
White
6
8
36
36
8
5
6
Gypsophila paniculata 'Pink Fairy'
Double Baby's Breath
Pink
6
8
36
36
8
5
6
Gypsophila repens
Creeping Baby's Breath
White
5
8
6
24
9
5
7
Helenium autumnale
Sneeze Weed
Yel/Org
8
10 40
24
8
5
5
Helianthemum nummularium
Sunrose
Assort.
5
7
10
18
8
5
7
Heliopsis helianthoides 'Summer Sun'
False Sunflower
Yellow
7
10 40
18
9
5
7
Hemerocallis middendorffi
Daylily
Yl/Org
5
6
28
20
8
5
6
Hemerocallis x 'Baha'
Day lily
Ruby
6
7
30
24
8
5
6
Hemerocallis x 'Canary Glow' (tetraploid)
Daylily
Yellow
6
7
30
24
8
5
6
Hemerocallis x 'Channel Islands'
Daylily
Yellow
7
8
24
24
8
5
6
Hemerocallis x 'Crimson Pirate'
Daylily
Rd/Yel
6
7
24
24
8
5
6
Hemerocallis x 'Elaine Strutt' (tetraploid)
Daylily
Pink
6
7
30
24
8
5
6
Hemerocallis x 'Frans Hals'
Daylily
Orange
6
8
30
24
8
5
6
Hemerocallis x 'Halls Pink'
Daylily
Pink
7
8
20
24
8
5
6
Hemerocallis x 'Tawny'
Daylily
Buff
5
7
38
24
8
5
6
Heuchera micrantha 'Palace Purple'
Purple-Leaf Coral Bells
White
6
7
24
16
5
5
5
Heuchera sanguinea
Coral Bells
Coral
6
8
12
12
5
5
6
Heuchera sanguinea alba
Coral Bells
White
6
8
12
12
5
5
6
Hibiscus moscheutos
Hardy Hibiscus
Rd; Wt
7
9
40
18
7
5
4
Hosta fortunei 'Aoki'
Hosta
Lavender 7
8
18
18
3
4
3
Hosta capitata
Heart-Shaped Hosta
Lavender 7
8
10
18
3
4
3
Hosta lancifolia
Lance-Leaf Hosta
Lavender 8
9
18
15
3
4
3
Hosta sieboldiana 'Elegans'
Blue Giant Hosta
Lavender 7
8
30
24
3
4
3
Hosta sieboldiana 'Frances Williams'
Blue Giant Hosta
Lavender 7
8
30
24
3
4
3
Hosta undulata 'Albo Marginata'
White-Edged Hosta
Lavender 7
8
20
20
3
4
3
Hosta undulata 'Erromena'
Hosta
Lavender 7
8
30
30
3
4
3
Hosta ventricosa 'Aurea Marginata'
Hosta
Lavender 7
8
30
30
3
4
3
Hosta xtardiana 'Blue Wedgewood'
Blue Edger Hosta
Lavender 7
8
10
24
3
4
3
Hosta x tardiana 'Hadspen Blue'
Blue Hosta
Lavender 7
8
24
24
3
4
3
Hosta x 'Francee'
Hosta
Lavender 7
8
24
24
3
4
3
Hosta x 'Honeybells'
Light Green Hosta
Lavender 8
9
30
24
3
4
3
Hosta x 'Royal Standard'
Hosta
Lavender 7
8
36
24
3
4
3
Hosta x 'Zounds'
Hosta
Lavender 7
8
28
24
3
4
3
Iberis sempervirens
Evergreen Candytuft
White
4
5
8
18
6
6
5
Imperata cylinrica 'Rubra'
Japanese Blood Grass
Grass
—
—
18
12
8
5
5
Iris enstata 'Activity'
Japanese Iris
Lt. Blue
6
7
32
18
7
1
3
Iris enstata 'Emotion'
Japanese Iris
Wt/Blue 6
7
32
18
7
1
3
Iris enstata 'Innocence'
Japanese Iris
White
6
7
30
18
7
1
3
Iris enstata 'Iso-no-nami'
Japanese Iris
Lt.Purple 6
7
32
18
7
1
3
Iris enstata 'Velvety Queen'
Japanese Iris
Dp. Blue
6
7
32
18
7
1
3
Iris missouriensis
Blue Flag Iris
Blue
5
6
12
15
6
4
5
Iris palada
Zebra Iris
Lavender 5
6
24
15
7
5
6
Iris siberica
Siberian 1 ris
Purple
5
6
36
30
7
5
5
Iris siberica 'Fourfold White'
Iris, Siberian
White
6
7
36
30
7
5
5
Iris x gennanica
German Bearded Iris Hybrids Assort.
5
6
24
18
7
5
6
Kasmanthia spp.
Northern Sea Oats
Grass
9
10
24
28
5
5
5
Kniphofia uvaria
Red Hot Poker
Orange
7
8
24
15
9
5
6
Kniphofia uvaria 'Primrose Beauty
Torch Lily
Yellow
7
10 40
24
9
5
6
Kniphofia uvaria 'Pfitzer's Hybrid'
Red Hot Poker
Orange
7
8
24
15
9
5
6
Lavandula angustifolia
English Lavender
Lavender 7
8
15
12
8
5
6
32
Table 4. Perennials, continued..
LATIN NAME
COMMON NAME
COLOR
B
F
HT
SP
S
SI
WT
Liatris punctata
Dwarf Gayfeather
Purple
8
9
12
10
9
6
8
Liatris pycnostachya
Cat-Tail Gayfeather
Purple
7
9
36
12
9
6
7
Liatris spicata
Spiked Gayfeather
Purple
7
9
24
12
8
5
7
Ligularia przewalskii 'The Rocket'
Ligularia
Yellow
7
8
60
30
6
4
3
Limonium latifolium
Wide-Leaved Sea Lavender
Purple
7
8
18
12
8
5
7
Linum flavum
Yellow Flax
Yellow
6
7
10
12
9
6
6
Linum perenne
Wild Blue Flax
Blue
5
8
24
18
8
6
7
Lonicera japonica 'Halliana'
Honeysuckle, Hall’s
Cream
6
8
Vn
—
5
5
5
Lunaria annua
Moneyplant, Silver Dollar
Prp; Wht
6
7
36
12
5
5
5
Lupinus x polyphyllus 'Chandelier'
Lupine
Yellow
6
7
30
24
6
5
5
Lupinus x polyphyllus 'Governor'
Lupine
Blue
6
7
30
24
6
5
5
Lupinus x polyphyllus 'Nobel Maiden'
Lupine
White
6
7
30
24
6
5
5
Lupinus x polyphyllus 'Popsicle’
Lupine
Assort.
6
7
24
20
6
5
5
Lupinus x polyphyllus ’Russel Hybrids'
Lupine
Assort.
6
7
30
24
6
5
5
Lupinus x polyphyllus 'Red Flame'
Lupine
Red
6
7
30
24
6
5
5
Lychnis chalcedonica
Maltese Cross
Scarlet
6
7
36
15
8
5
6
Lychnis viscaria 'Splendens'
German Catchfly
Red
6
7
36
15
8
5
6
Lythrum salicaria
Loosestrife
Magenta
7
8
48
24
6
4
4
Macleaya cordata
Plume Poppy
Cream
7
8
7’
24
6
5
5
Matteuccia pennsylvanica
Ostrich Fern
—
—
—
40
30
3
4
4
Miscanthus sinensis var. gracillimus
Miscanthus Grass
Grass
8
9
60
24
8
5
5
Miscanthus sinensis var. zebrinus
Zebra Grass
Grass
8
9
60
24
8
5
5
Molinia caerulea 'Variegata'
Variegated Moor Grass
Grass
8
9
36
20
7
5
5
Monarda didyma 'Cambridge Scarlet'
Bee Balm
Red
6
8
24
24
7
7
5
Monarda fistulosa menthifolia
Native Bee Balm
Lavender
6
8
24
24
7
7
5
Oenothera missourensis
Missouri Evening Primrose
Yellow
6
8
12
16
9
5
7
Oxytropis lambertii
Lambert's Loco Weed
Magenta
5
7
6
18
8
6
8
Paeonia lactiflora (varieties)
Peony
Assort.
6
7
30
24
7
5
5
Paeonia suffruticosa
Tree Peony
Assort.
5
6
48
48
5
4
4
Paeonia tenufolia nibra plena
Fern Leaf Peony
Red
5
6
20
24
7
4
4
Papaver nudicaule
Iceland Poppy
Mix
6
9
14
10
9
5
5
Papaver orientate ' Salmon'
Oriental Poppy
Pink
6
6
30
24
8
5
6
Papaver orientale 'Allegro'
Dwarf Oriental Poppy
Red
6
6
24
18
8
5
6
Papaver orientale ' Goliath'
Oriental Poppy
Scarlet
6
6
40
24
8
5
6
Papaver orientale ' Perry's White'
Oriental Poppy
White
6
6
32
24
8
5
6
Papaver orientale ' Pinacle'
Oriental Poppy
Red
6
6
28
24
8
5
6
Papaver orientale ' Prince of Orange'
Oriental Poppy
Papaver orientale ' Princess V. Louise'
Oriental Poppy
Pardanthopsis dichotoma
Vesper Iris
Lavender
7
9
36
15
8
5
6
Peltiphyllum peltatum
Umbrella Plant
Rose
8
9
30
Penstemon barbatus
Scarlet Bugler Penstemon
Red
6
7
36
15
9
6
7
Pensternon barbatus
Yellow Bugler Penstemon
Yellow
6
7
36
15
9
6
7
Penstemon cardinalis
Cardinal Penstemon
Red
6
7
24
12
9
6
7
Penstemon eatonii
Firecracker Penstemon
Orange
6
7
36
15
9
6
7
Penstemon palmeri
Palmer's Penstemon
Pink
6
7
36
15
9
6
7
Penstemon pinifolius
Pine-Leaf Penstemon
Scarlet
6
8
6
10
9
5
8
Penstemon pseudospectabilis
Rose-Pink Penstemon
Pink
6
7
36
15
9
5
8
Penstemon strictus ’Bandera'
Rocky Mountain Penstemon
Purple
6
8
24
15
9
6
8
Perovskia atriplicifolia
Russian Sage
Purple
7
9
40
24
9
6
8
Phalaris arundinacea 'Picta'
Ribbon Grass
__
_
_
30
30
7
5
5
Phlomis russeliana
Jerusalem Sage
Yellow
6
8
36
15
7
5
5
Table 4. Perennials, continued...
LATIN NAME
COMMON NAME
COLOR
B
F
HT
SP
S
SI
WT
Phlox maculata 'Alpha'
Garden Phlox
Rose
6
8
32
12
7
5
5
Phlox maculata 'Delta'
Garden Phlox
Wht/Rd
6
8
32
12
7
5
5
Phlox maculata 'Rosalinde'
Garden Phlox
Rose
6
8
32
12
7
5
5
Phlox paniculata
Tall Garden Phlox
Assort.
6
8
36
15
7
5
5
Phlox subulata
Creeping Phlox
Assort.
5
6
4
15
8
5
6
Physostegia virginiana
Obedient Plant
Pk; Wt
8
9
30
20
6
5
5
Platycodon grandiflorum
Balloon Flower
Pk;Bl;Wt 7
9
24
15
6
5
5
Polemonium caeruleum
Jacob's Ladder
Blue
5
7
24
15
6
5
5
Polygonum affine
Himalayan Border Jewel
Pink
8
10
8
24
7
5
6
Polygonum aubertii
Silver Lace Vine
White
8
10
Vn
—
7
5
6
Potentilla nepalensis 'Miss Willmott'
Potentilla
Rose
6
8
14
24
8
5
6
Potentilla vema nana
Potentilla, Cinquefoil
Yellow
4
6
4
6
8
5
6
Primula denticulata
Himalayan Primrose
Lavender 3
5
10
8
5
5
5
Pulmonaria saccarata 'Mrs. Moon'
Soldiers and Sailors
Pink
4
5
12
12
3
5
4
Pycnanthemum virginianum
Mountain Mint
Wht/Grn 7
8
24
12
7
5
6
Ratibida pinnata
Tall Yellow Coneflower
Yellow
8
9
30
18
9
6
7
Rudbeckia fulgida 'Goldsturm'
Black-Eyed Susan
Gold
7
10
30
24
8
5
6
Rudbeckia hirta
Gloriosa Daisy
Assort.
6
10
30
18
8
5
6
Salvia nemorosa 'Superba'
Purple Sage
Purple
6
7
26
16
8
5
5
Santolina chamaecyparissus
Lavender Cotton
Yellow
7
8
15
12
9
5
6
Scabiosa caucasica
Pincushion Flower
Blue
6
7
18
15
8
5
6
Sedum spectabile ' Ruby Glow'
Stonecrop, Showy
Pink
8
9
12
8
9
5
6
Salidago canadensis
Canadian Goldenrod
Yellow
7
9
48
24
8
5
7
Solidago decumbens
Goldenrod, Dwarf
Yellow
7
8
12
10
9
5
7
Solidago rigida
Goldenrod, Stiff
Yellow
8
10
36
24
9
5
8
Stachys byzantina
Lamb's Ears
Silver
—
—
8
18
5
6
6
Stokesia laevis 'Blue Danube'
Stoke's Aster
Blue
7
10
16
12
8
6
5
Thermopsis divaricarpa
Golden Banner
Yellow
4
6
18
12
8
4
5
Thalictmm aquilegiafolium
Meadow Rue
Pink
5
6
48
24
5
5
5
Thalictnmi dalavayi
Meadow Rue
Lavender 7
8
60
24
5
4
4
Thermopsis montana
Golden Banner
Yellow
4
6
24
18
8
4
5
Tiarella wherryi
Foamflower
Blush
4
5
12
10
4
4
4
Tradescantia virginiana
Spiderwort
Purple
5
7
18
18
6
5
5
Tradescantia x andersoniana 'Pauline'
Spiderwort
Orchid
5
7
18
18
6
5
5
Tradescantia x andersoniana 'Red Cloud'
Spiderwort
Magenta
5
7
15
15
6
5
5
Tradescantia x andersoniana 'Snowcap'
Spiderwort
White
5
7
18
18
6
5
5
Tradescantia x andersoniana 'Zwanenburg'
Spiderwort
Blue
5
7
18
18
6
5
5
Trollius europaeus
Globeflower
Yellow
5
6
12
8
3
3
3
Trollius ledebourii 'Golden Queen'
Globeflower
Gold
5
6
30
15
4
4
3
Veronica incana
Silver Speedwell
Blue
6
7
12
10
7
7
7
Veronica spicata
Speedwell
Bl;Pk;Wh 7
8
24
18
8
5
5
Vinca minor
Periwinkle
Blue
5
7
6
24
5
5
5
Table 5, Rock Alpine / Ground Covers.
Lynda Goldstein and Kathy Borgen, Chairmen
[B: month of first bloom; F: month of final bloom; HT: height in inches; SPD: spread, in inches; SN (sun): 1 = full
shade, 9 = full sun; SL (soil): 1 = alkaline clay, 9 = acid peat; W (water): 1 = wet, 9 = dry]
LATIN NAME COMMON NAME COLOR B F HT SPD SN S W
Abies balsamea nana
Acantholimon annenum
Dwarf Balsam Fir
Armenian Spikethrift
Green
Pink
- - 12 20 5 5 4
5 7 6 10 7 7 6
34
Table 5. Rock Alpine / Ground Covers, continued.,
LATIN NAME
COMMON NAME
COLOR
B
F HT SPD
SN
S
W
Achillea ageratifolia
Greek Yarrow
White
5
6
3
14
8
6
6
Achillea serbica
Serbian Yafrow
White
5
7
6
8
8
6
7
Adiantum pedatus var. subpumilum
Dwarf Five Finger Fern
Green
—
3
8
5
5
4
Aegopodium podagaeia variegatam
Bishop's Weed
Gr/Wht
6
7
15
30
5
5
6
Aethionema 'Warley Rose'
Persian Candytuft
Rose/Pk
5
6
4
12
8
6
6
Aethyrium nipponicum var. Pitcum
Japanese Painted Fern
—
—
--
15
12
4
5
4
Ajuga reptans
Bugleweed
Lavender
5
6
4
15
5
6
5
Ajuga reptans 'Burgundy Glow'
Burgundy Ajuga
Lavender
5
6
4
15
5
6
5
Ajuga reptans 'Purple Leaf
Purple Leaf Ajuga
Lavender
5
6
3
15
8
7
6
Ajuga reptans 'Variegata'
Variegated Ajuga
Lavender
5
6
3
15
6
5
6
Allium thumbergii
Ornamental Onion
Lavender
8
1010
8
5
5
5
Anacyclus depressus
Atlas Daisy
White
4
6
3
10
8
7
7
Androsace lanuginosa
Rock Jasmine
Lavender
5
6
2
3
6
5
5
Androsace sannentosa
Strawberry Androsace
Pink
5
6
3
10
6
5
5
Androsace sempervivioides
Rosette Androsace
Pink
4
6
2
8
6
6
5
Andryala agardhii
Spanish Daisy
Yellow
5
6
5
8
8
6
7
Anemone canadensis
American Wood Anemone
White
5
6
12
24
6
6
6
Antennaria rosea
Pussytoes
Pink
5
6
3
10
8
9
7
Anthemis montana
Silverleaf Daisy
White
6
7
12
15
8
7
7
Aquilegia 'Biedermeier Dwarf
Biedermeier Columbine
Mixed
4
5
10
10
6
5
5
Aquilegia bamebyi
Barneby's Columbine
Yellow
5
6
15
10
7
7
6
Aquilegia chrysantha
Yellow Columbine
Yellow
5
6
20
12
5
4
6
Aquilegia discolor
Columbine
Blue
5
6
6
6
4
7
6
Aquilegia elegantula
Dwarf Red Columbine
Red
5
6
15
10
6
5
5
Aquilegia flabellata
Fanleaf Columbine
Blue
4
5
8
6
6
6
6
Aquilegia flabellata var. kurilensis
Kurile Columbine
Pink
5
6
5
5
6
5
5
Aquilegia jonesii
Cushion Columbine
Purple
3
4
5
5
8
8
7
Aquilegia saximontana
Rocky Mt. Dwarf Columbine
Blue
4
7
7
7
6
5
6
Aquilegia viridiflora
Black Columbine
Black
4
5
14
8
7
7
6
Aquilegia vulgaris
Common Columbine
Purple
5
6
15
15
5
5
5
Arabis blepharophylla
California Arabis
Pink
4
6
9
4
5
6
6
Arabis caucasica
Wallcress
White
4
6
5
18
6
6
6
Arabis caucasica 'Snow Cap'
Snow Cap Wallcress
White
4
6
6
12
6
6
6
Arabis caucasica 'Spring Charm'
Wallcress
White
4
6
6
12
6
6
6
Arabis caucasica 'Variegata'
Wallcress
White
4
5
8
12
6
6
6
Arabis ferdinandi-coburgi 'Variegata'
Variegated Wallcress
White
4
5
1
12
7
7
7
Arctostaphylos nevadensis
Mat Manzanita
White
3
5
8
18
7
7
7
Arctostaphylos uva-ursi
Kinnikinick
White
3
5
4
20
8
7
7
Arenaria tetraquetra
Spanish Sandwort
White
5
7
1
7
7
6
6
Artneria caespitosa
Pink Sea Thrift
Pink
5
6
3
8
7
5
6
Amteria maritima
Sea Thrift
Pink
5
7
7
12
7
5
6
Amieria maritima, dwarf
Dwarf Sea Thrift
Pink
4
7
4
6
7
7
7
Artemisia frigida
Dwarf Sage
Gray
6
8
8
12
8
6
7
Artemisia schmidtiana 'Silver Mound'
Silver Mound Sage
Gray
7
8
12
10
7
7
6
Artemisia stelleriana
Perennial Dusty Miller
Gray
7
8
15
15
8
7
6
Asarum europaeum
European Wild Ginger
Brown
6
7
4
10
5
4
4
Aspemla gussonii
Corsican Woodruff
Pink
5
7
2
10
7
6
6
Aster alpinus
Alpine Aster
Lavender
5
6
8
10
7
5
6
Aster novi-belgii 'Melba'
Melba Aster
Pink
8
9
12
12
8
7
7
Aster novi-belgii 'Professor Kippenberg'
Kippenberg Aster
Blue
8
9
12
12
8
7
7
Aster novi-belgii 'Snow Flurry'
Snow Flurry Aster
White
8
9
12
12
8
7
7
Table 5. Rock Alpine / Ground Covers, continued...
LATIN NAME
COMMON NAME
COLOR
B
F HT SPD
SN
S
W
Astilbe chinensis v. pumila
Dwarf Astilbe
Purple
7
9
10
10
5
5
5
Aubrieta deltoidea
Rock Cress
Purple
4
6
3
12
6
6
6
Aurinia saxatile
Basket of Gold
Yellow
5
6
12
12
8
6
6
Azalea x 'nakahari'
Dwarf Azalea
Red
5
6
10
15
5
3
4
Belamcanda chinensis
Blackberry Lily
Orange
6
7
24
8
8
6
6
Bergenia cordifolia
Leatherleaf
Pink
4
5
14
14
5
5
5
Bolax glebaria
Azorclla
Yellow
6
7
2
12
7
4
6
Bmnnera macrophylla
Elephant Ear Forget-Me-Not
Blue
5
6
10
20
4
6
6
Buxus microphylla
Dwarf Boxwood
—
—
~
6
8
5
5
5
Callirhoe involucrata
Wine Cups, Poppy Mallow
Purple
6
10
5
20
8
7
8
Calluna vulgaris
Heather
Pink
6
8
8
12
5
3
5
Campanula allionii
Alpine Bluebell
Blue
5
6
2
8
7
7
6
Campanula carpatica 'Blue Clips'
Carpathian Harebell
Blue
6
9
8
10
8
6
6
Campanula carpatica 'White Clips'
White Carpathian Harebell
White
6
9
8
10
8
6
6
Campanula cochlearifolia
Fairybells
Blue
6
8
3
15
7
6
6
Campanula cochlearifolia 'Alba'
White Fairybells
White
6
7
3
12
7
6
6
Campanula formanekiana
Cup Bellflower
White
5
6
10
10
8
7
7
Campanula garganica
Adriatic Bellflower
Blue
5
6
6
10
7
6
6
Campanula persicifolia
Peach Leaf Bellflower
Blue
5
7
12
9
7
6
6
Campanula portenschlagiana
Adriatic Campanula
Blue
6
7
3
10
7
6
7
Campanula poscharskyana
Serbian Bellflower
Blue
6
8
5
18
7
7
6
Campanula rotundifolia
Harebell
Blue
5
9
9
4
6
6
6
Cerastium tomentosum
Snow-in-Summer
White
6
7
6
20
8
7
6
Cerastium tomentosum 'YoYo'
Dwarf Snow-in-Summer
White
6
7
6
8
8
7
6
Ceratostigma plumbaginoides
Plumbago
Blue
8
10
i 9
12
6
5
5
Chamaecyparis obtusa
Dwarf Hinoki Cypress
—
--
—
36
20
5
4
5
Cheiranthus allionii
Siberian Wallflower
Orange
4
6
12
7
8
7
6
Chrysanthemum weyrichii 'Pink Bomb’
Ground Cover Mum
White
8
10
l 9
12
7
6
6
Coreopsis lanceolata
Coreopsis
Yellow
6
9
20
15
8
7
7
Coreopsis lanceolata 'Baby Sun'
Single Dwarf Coreopsis
Yellow
6
9
10
10
8
7
7
Coreopsis lanceolata 'Brown Eyes'
Brown Eye Coreopsis
Yellow
6
8
12
12
8
7
6
Cytisus x kewensis
Kew Broom
Cream
5
5
8
36
8
7
7
Daphne caucasica
Daphne
White
5
6
36
18
5
5
8
Daphne cneorum
Garland Flower
Pink
4
5
8
15
7
6
5
Daphne x burkwoodii 'Carol Mackie'
Carol Mackie Daphne
White
5
6
45
60
7
5
6
Daphne x burkwoodii 'Somerset'
Somerset Daphne
White
5
6
25
35
7
5
5
Delosperma cooperi
Hardy Iceplant
Purple
5
1C
1 2
12
9
8
7
Delospemia nubigenum
Hardy Iceplant
Yellow
4
6
1
15
8
7
6
Delphinium grandiflonim
Himalayan Larkspur
Blue
6
8
15
8
7
6
6
Dianthus alpinus
Alpine Pink
Pink
5
6
2
8
7
6
6
Dianthus anatolicus
Anatolian Pink
Pink
5
7
12
14
8
7
7
Dianthus barbatus 'Pixie'
Pixie Pink
Pink
5
6
6
10
7
6
6
Dianthus deltoides
Maiden Pink
Pink
5
6
8
8
7
6
6
Dianthus deltoides 'Zing Rose'
Zing Rose Pink
Pink
5
6
8
8
7
6
6
Dianthus erinaceus
Hedgehog Pink
Pink
6
7
2
8
7
7
7
Dianthus freynii
Cushion Pink
Pink
4
6
3
8
8
7
7
Dianthus graniticus
Granada Pink
Pink
5
7
8
12
8
7
7
Dianthus gratianopolitanus 'Tiny Rubies'
Tiny Rubies Pink
Pink
5
6
3
9
8
7
6
Dianthus nardiformis
Cloud Pink
Pink
6
1010
12
9
7
7
Dianthus nitidus
Balkan Pink
Pink
5
6
6
4
8
7
6
Dianthus noeanus
Rock Pink
White
6
7
8
10
8
7
7
Dianthus pavonius
Maritime Alps Pink
Pink
4
5
6
6
8
7
6
35
36
Table 5. Rock Alpine / Ground Covers, continued.
LATIN NAME
COMMON NAME
COLOR
B
F HT SPD
SN
S
W
Dianthus plumarius v. lumnitzeri
Spice Pink
White
5
6 8
10
8
7
6
Dianthus subacaulis
Blueleaf Pink
Pink
5
6 2
8
8
6
6
Dianthus sylvestris v. frigidus
Alpine Pink
White
6
7 12
12
8
7
6
Dicentra eximia
Fringed Bleeding Heart
Pink
5
7 9
12
4
5
5
Dodecatheon pulchellum
Western Shooting Star
Pink
5
6 12
5
7
5
3
Doronicum caucasicum
Leopard's Bane
Yellow
5
6 24
12
7
6
5
Draba aizoides
Common Draba
Yellow
3
5 2
4
8
7
7
Draba bruniifolia
Cushion Draba
Yellow
3
4 3
12
8
7
6
Draba hispanica
Spanish Draba
Yellow
3
4 3
10
8
7
7
Draba oligosperma
Mat Draba
Yellow
3
4 2
7
8
7
7
Draba rigida
Bun Draba
Yellow
3
4 3
6
8
7
6
Dracocephalum botryoides
Cutlcaf Dragonhead
Purple
5
7 3
9
8
7
7
Dryoptexis erythrosora
Autumn Fern
Rd(Spring)
— —
36
15
5
4
Epimedium grandiflorum
Barrenwort
Purple
5
6 10
10
4
4
5
Epimedium x sulphureum
Sulfur Barrenwort
Yellow
4
5 12
15
6
5
5
Erigeron chrysopsidis brevifolius 'Grand Ridge'
Erigeron compositus
Cutleaf Fleabane
Cutleaf Fleabane
White
4
9 3
3
8
8
8
Erigeron speciosus
Showy Fleabane
Blue
5
7 15
10
8
7
7
Erigeron trifidus
Cutleaf Daisy
White
5
8 5
7
8
7
7
Eriogonum subalpinum
Subalpine Sulfur Flower
Yellow
5
7 8
10
8
8
8
Eriogonum umbellatum
Sulfur Flower
Yellow
5
7 10
10
8
8
8
Eryngium alpinum
Alpine Sea Holly
Silver
6
7 12
8
7
7
5
Eschscholzia califomica
California Poppy
Orange
5
9 5
8
6
6
7
Euonymus fortunei 'Coloratus'
Variegated Euonymus
Green
4
5 15
20
6
6
6
Euonymus fortunei 'Kewensis'
Kew Euonymus
Green
-- 3
12
6
5
6
Euphorbia epitliymioides (syn. polychroma)
Spring Spurge
—
—
- 0
0
0
0
0
Euphorbia myrsinites
Succulent Spurge
Yellow
3
5 3
15
8
8
8
Fragaria americana
Wild Strawberry
White
5
7 6
8
7
7
7
Fragaria vesca
Runnerless Strawberry
White
5
7 8
8
7
7
7
Gaillardia x grandi flora 'Burgundy'
Indian Blanket
Burgundy 5
9 10
10
8
8
7
Gaillardia x grandiflora 'Goblin'
Indian Blanket
Orange
5
1010
12
8
7
7
Galium odoratum
Sweet Woodruff
White
5
6 8
12
4
4
6
Gentiana acaulis
Trumpet Gentian
Blue
4
6 3
8
7
5
5
Gentiana loderi
Lodcr's Gentian
Blue
6
7 5
8
7
6
6
Gentiana septemfida
Summer Gentian
Blue
7
9 10
10
8
7
6
Gentiana sino-omata
Himalayan Gentian
Blue
7
9 3
7
7
4
5
Gentiana triflora
Japanese Gentian
Blue
6
8 25
8
7
5
5
Gentiana vema
Star Gentian
Blue
4
5 2
6
8
4
4
Geranium 'Johnson's Blue'
Johnson's Blue Crane's Bill
Blue
5
7 15
15
7
6
6
Geranium endressii 'Wargrave Pink'
Meadow Crane's Bill
Pink
6
8 18
10
7
6
6
Geranium macrorrhizum
Balkan Crane's Bill
Pink
5
7 10
18
6
7
8
Geranium sanguineum
Bloody Crane's Bill
Magenta
5
8 15
30
8
7
6
Geranium sanguineum v. lancastriense
Lancaster Crane's Bill
Pink
6
7 4
12
8
7
6
Geum borisii
Balkan Geum
Orange
6
7 12
10
7
7
7
Geum chiloense 'Mrs. Bradshaw'
Mrs Bradshaw's Geum
Pink
5
7 15
12
7
6
6
Globularia punctata
Clum p Globularia
Blue
5
6 9
5
7
6
6
Gypsophila repens
Dwarf Baby's Breath
Pink
5
7 4
12
8
7
6
Gypsophila repens 'Rosea'
Rose Baby’s Breath
Pink
5
6 7
15
8
7
7
Hebe 'Carl Teschner'
Carl Teschner Hebe
Blue
5
6 4
10
6
5
4
Hebe camosula
Green Hebe
White
4
5 10
15
8
7
6
Hebe pimelioides
Pimelia Hebe
Lavender
7
8 12
10
7
6
6
Table 5. Rock Alpine / Ground Covers, continued...
LATIN NAME
COMMON NAME
COLOR
B
F HT SPD
SN
S
W
Hebe pingiiifolia 'Pagei'
Page's Hebe
White
6
7
5
12
8
7
6
Hedera helix
English Ivy
Green
6
8
4
12
4
4
4
Hedera helix 'Green Finger'
Green Finger Ivy
Green
—
—
50
20
6
5
5
Helianthemum guttatum
Gray Sunrose
White
5
7
10
18
8
7
6
Helianthemum numullarium
Sunrose
Mixed
5
8
8
15
8
7
7
Helichrysum virgineum
Mt. Athos Everlasting
Mhite
5
6
8
12
8
7
7
Helleborus niger
Christmas Rose
White
1
4
10
10
6
5
5
Hemiaria glabra
Rupt urewort
Green
4
5
1
10
8
6
6
Heuchera cylindrica var. glabella
Alumroot
White
5
6
8
8
6
6
6
Heuchera sangidnea
Coral bells
Red
5
9
15
8
6
5
5
Hosta lancifolia
Lanceleaf Hosta
Lavender
7
8
15
10
5
5
5
Hosta sieboldiana
Blueleaf Hosta
Lavender
8
9
36
20
5
6
5
Hosta undulata
Undulate Hosta
Lavender
8
9
15
10
5
5
5
Hutchinsia alpina
Hutchinsia
White
4
5
2
7
7
6
6
Hypericum reptans
Creeping StJohn's Wort
Mixed
5
8
0
0
8
7
7
Iberis gibraltarica
Gibraltar Candytuft
White
4
6
12
10
8
7
7
Iberis say ana
Candytuft
White
5
6
2
12
7
7
7
Iberis sempervirens
Candytuft
White
5
6
10
14
8
7
7
Ilex sp. 'Rock Garden'
Dwarf Holly
—
—
—
12
5
4
5
Iris missouriensis
Native Blue Iris
Blue
4
5
18
12
8
7
5
Iris pumila
Dwarf Bearded Iris
Assorted
3
4
3
6
8
7
7
Iris setosa v. canadensis
Canadian Iris
Ppurple
5
5
8
8
5
5
5
Juniperis communalis compressa
Dwarf Irish Juniper
—
--
—
30
12
5
5
5
Lamium maculatum 'Beacon Silver'
Silver Nettle
Pink
6
7
3
12
6
4
5
Leontopodium alpinum
Edelweiss
White
6
7
6
6
6
6
6
Lewisia cotyledon
Bitter Root
Pink
5
6
12
10
6
6
6
Liatris punctata
Blazing Star
Purple
7
9
10
5
8
8
8
Liatris spicata
Spiked Gayfeather
Lavender
7
9
12
12
8
8
7
Limonium latifolium
Purple Sea Lavender
Lavender
7
9
24
12
8
7
7
Linum flavum
Yellow Flax
Yellow
5
6
12
10
8
7
7
Linum flavum 'Compactum'
Dwarf Yellow Flax
Yellow
5
6
8
10
8
7
7
Linum perenne
Blue Flax
Blue
5
7
18
10
8
7
6
Lobelia cardinalis
Cardinal Flower
Red
8
9
30
10
5
5
4
Lysimachia nummularia
Moneywort
Yellow
5
6
2
45
6
5
6
Machaeranthera coloradoensis
Colorado Aster
Pink
4
6
3
6
8
7
7
Mahonia repens
Creeping Grape Holly
Yellow
5
6
12
14
7
7
8
Malva moschata 'Alba'
White Musk Mallow
White
5
8
18
10
7
6
7
Matricaria matricarioides 'Golden Feather'
Feverfew
Yellow
5
8
15
8
7
7
7
Melampodium leucanthum
Black foot Daisy
White
7
9
10
10
8
8
8
Mimulus cardinalis
Monkeyflower
Red
7
8
18
18
5
5
7
Mimulus guttatus
Monkeyflower
Yellow
5
7
3
8
7
4
3
Monarda didyma 'Cambridge Scarlet’
Bee Balm
Red
6
8
24
20
8
7
6
Myosotis alpestris 'Indigo Blue'
Indigo Forget-Me-Not
Blue
4
5
4
6
7
6
6
Myosotis rupicola
Dwarf Forget-Me-Not
Blue
4
5
5
4
6
5
6
Oenothera missouriensis
Missouri Evening Primrose
Yellow
5
7
8
12
8
7
7
Origanum libanoticum
Lebanese Oregano
Pink
7
9
10
15
8
7
8
Papaver alpinum
Alpine Poppy
Assorted
5
8
5
4
8
6
6
Papaver miyabeanum
Miyabe's Poppy
Yellow
5
6
6
3
7
6
6
Papaver nudicaule
Iceland Poppy
Orange
5
6
14
6
8
5
6
Parthenocissus tricuspidata
Boston Ivy
—
—
4 +
—
0
0
0
Paxistima canbyi
Ratsl riper
Brown
5
6
8
12
7
6
6
37
38
Table 5. Rock Alpine / Ground Covers, continued.,
LATIN NAME
COMMON NAME
COLOR
B
F HT SPD
SN
S
W
Paxistima myrsinites
Mountainlover
Brown
5
6 20
10
5
6
7
Penstemon alpinus
Mountain Penstemon
Blue
5
6 18
6
7
6
6
Penstemon ambiguus
Phlox Penstemon
White
6
9 12
7
9
8
8
Penstemon barbatus
Shark's Head Penstemon
Red
6
7 36
8
8
7
8
Penstemon barbatus 'Schooley's Yellow'
Yellow Penstemon
Yellow
6
7 36
8
8
7
8
Penstemon cardin a lis
Cardinal Penstemon
Red
7
8 25
8
8
8
8
Penstemon cardwellii
Cascade Penstemon
Lavender
4
5 10
18
6
6
6
Penstemon cardwellii 'Roseus'
Rose Penstemon
Pink
4
5 8
10
6
6
5
Penstemon davidsonii
Davidson's Penstemon
Purple
4
5 1
8
7
6
6
Penstemon digitalis
Foxglove Penstemon
White
6
8 30
10
7
6
6
Penstemon eatonii
Firecracker Penstemon
Red
6
7 30
8
7
8
7
Penstemon fmticosus
Shrubby Penstemon
Lavender
5
6 12
18
7
6
6
Penstemon fmticosus v. serratus 'Holly'
Holly Penstemon
Lavender
4
5 3
6
7
6
6
Penstemon grandifloms
Shell-leaf Penstemon
Pink
5
6 25
8
8
6
6
Penstemon hallii
Hall's Penstemon
Purple
4
5 7
10
8
7
7
Penstemon jamesii
James' Penstemon
Lavender
5
6 15
7
8
8
8
Penstemon linarioides
Toadflax Penstemon
Lavender
5
7 10
12
7
7
8
Penstemon linarioides v. coloradoensis
Silvermat Penstemon
Blue
5
6 8
12
8
7
7
Penstemon ovatus
Ovate Penstemon
Blue
5
6 12
8
7
7
7
Penstemon palmeri
Palmer Penstemon
Pink
6
8 60
15
8
7
7
Penstemon pinifolius
Pineleaf Penstemon
Red
6
9 10
15
8
7
7
Penstemon richardsonii
Richardson's Penstemon
Pink
7
9 18
18
8
8
8
Penstemon rostrifloms
Bridge's Penstemon
Red
6
9 28
30
8
7
7
Penstemon secundifloms
One-sided Penstemon
Lavender
5
6 20
8
8
8
8
Penstemon semdatus
Sawtooth Penstemon
Lavender
5
6 15
15
7
7
7
Penstemon strictus 'Bandera'
Bandera Penstemon
Blue
5
6 25
8
8
7
7
Penstemon teucrioides
Germander Penstemon
Blue
5
6 1
8
7
6
6
Penstemon thompsoniae
Grayleaf Penstemon
Purple
5
6 1
10
8
8
8
Penstemon virens
Foothills Penstemon
Blue
4
5 10
8
7
7
6
Penstemon whippleanus
Whipple's Penstemon
Purple
6
7 15
8
7
6
6
Perovskia atriplicifolia
Russian Sage
Lavender
7
1060
50
9
8
8
Phlox 'Arroyo'
Mexican Phlox
Pink
5
1010
12
8
7
6
Phlox 'Crimson Beauty'
Mexican Phlox
Crimson
4
6 3
20
8
6
6
Phlox 'Daniel's Cushion'
Mexican Phlox
Lavender
4
6 3
20
8
6
6
Phlox 'Manzana'
Mexican Phlox
Pink
6
9 8
10
8
7
6
Phlox 'Mary Maslin'
Mexican Phlox
Red
6
9 8
10
8
7
6
Phlox 'Paul Maslin'
Mexican Phlox
Yellow
6
9 8
10
8
7
6
Phlox 'Tangelo'
Mexican Phlox
Orange
6
9 10
12
8
7
6
Phlox 'Vanilla'
Mexican Phlox
White
6
9 8
10
8
7
6
Phlox 'White'
Mexican Phlox
White
6
9 8
10
8
7
6
Phlox bifida
Cleft Phlox
Blue
5
6 6
12
7
5
5
Phlox 'Boothman's Variety'
Creeping Phlox
Lavender
4
6 3
18
8
7
6
Phlox bifida 'Colvin's White'
Cleft Phlox
White
5
5 8
12
7
5
5
Phlox subulata
Creeping Phlox
Pink
4
5 2
12
7
6
6
Phlox subulata 'Ronsdorf Beauty'
Dwarf Creeping Phlox
Pink
4
5 1
8
7
6
6
Picea abies 'Little Gem'
Min. Birds Nest Spruce
—
—
-- 12
12
5
5
6
Platycodon grandifloms 'Apoyama'
Dwarf Balloon Flower
Blue
6
7 8
8
7
7
7
Platycodon grandifloms v. mariesii
Balloon Flower
Blue
6
8 20
8
7
7
6
Polygonum affine
Border Jewel
Pink
7
9 15
30
8
7
7
Polygonum cuspidatum v. comp actum
Knotweed
Pink
6
8 30
20
8
7
7
Potentilla argyropliylla v. atrosanguinea
Scarlet Cinquefoil
Red
5
6 12
8
9
6
6
Table 5. Rock Alpine / Ground Covers, continued...
LATIN NAME
COMMON NAME
COLOR
B
F HT SPD
SN
S
W
Potentilla hippiana
Horse Cinquefoil
Yellow
6
7
12
10
8
7
7
Potentilla tabemae-montana
Carpet Cinquefoil
Yellow
4
6
2
15
7
6
5
Potentilla tabemae-montana var. nana
Cushion Cinquefoil
Yellow
5
6
2
7
8
7
7
Potentilla thurberi
Thurber's Cinquefoil
Red
7
9
28
10
7
7
7
Potentilla vema nana
Cushion Chinquefoil
Yellow
5
6
2
10
7
6
6
Primula auricula
Auricula Primrose
Mix
4
5
6
8
5
6
5
Primula denticulata
Drumstick Primrose
Pink
3
4
8
6
5
5
5
Primula elatior
Oxlip Primrose
Yellow
4
5
8
6
5
5
5
Primula juliae
Juliana's Primrose
Purple
4
5
2
6
5
5
3
Primula saxatilis
Siberian Primrose
Pink
5
6
12
8
5
5
5
Primula sieboldii
Woodland Primrose
Pink
4
5
8
9
5
5
5
Primula veris
Cowslip Primrose
Yellow
4
5
8
6
5
5
5
Ptilotrichum spinosum 'Roseum'
Spiny Alyssum
Purple
5
6
10
14
8
8
8
Ranunculus gramineus
Buttercup
Yellow
5
7
10
6
7
7
7
Ranunculus repens
Creeping Buttercup
Yellow
5
6
6
20
8
6
6
Raoulia australis
N. Zealand Scabplant
Yellow
6
7
1
10
8
6
5
Rhododendron H-l
Rhododendron
Wht/Pnk 5
6
36
24
4
3
6
Rhododendron yakushinanum
Rhododendron
White
5
6
36
36
4
3
6
Rosularia aizoon
Rosularia
Yellow
5
6
6
5
7
6
7
Rosularia chrysantha
Hairy Rosularia
Yellow
5
6
6
10
8
7
7
Salix hylomatica
Nepalese Willow
Red
4
4
3
24
7
7
3
Salvia argentea
Silver Sage
White
6
7
30
18
8
7
8
Santolina chamaecyparissus
Lavender Cotton
Yellow
6
8
25
30
8
7
7
Saponaria ocynioides 'Rubra Compacta'
Soap wort
Pink
5
5
3
12
7
7
7
Saponaria ocymoides 'Splendens'
Soapwort
Pink
5
6
8
15
8
7
7
Saxifraga caespitosa
Purple Robe Saxifrage
Red
4
6
7
15
5
5
5
Saxifraga cotyledon
Silver Saxifrage
White
5
6
25
10
6
6
6
Saxifraga ferdinandi-coburgi
Balkan Saxifrage
Yellow
3
4
3
12
6
6
5
Saxifraga moschata v. kingii
Small Mossy Saxifrage
White
5
6
3
20
5
6
5
Saxifraga paniculata
Silver Saxifrage
White
5
6
6
10
6
5
6
Saxifraga paniculata 'Millstream'
Red Silverleaf Saxifrage
Red
5
6
12
8
6
6
5
Saxifraga x 'Mossy Variegated'
Variegated Mossy Saxifrage
White
5
6
6
12
4
4
5
Scabiosa graminifolia
Grassleaf Scabious
Lavender
6
8
10
10
8
7
7
Sedum acre
Sedum
Yellow
5
6
3
15
8
8
8
Sedum hybridum
Double-flowering Sedum
Yellow
5
9
3
10
8
8
8
Sedum kamtschaticum
Kamtschatka Sedum
Yellow
6
9
5
10
8
8
8
Sedum kamtschaticum 'Variegatum'
Variegated Stonecrop Sedum Yellow
6
8
3
10
6
6
6
Sedum pachyclados
Pakistan Stonecrop Sedum
White
6
7
3
8
7
6
6
Sedum sieboldii
Autumn Sedum
Pink
8
9
5
10
7
6
5
Sedum spathulifolium 'Cape Blanco'
Pacific Sedum
Yellow
5
6
3
7
5
6
5
Sedum spurium 'Red Carpet'
Dragon's Blood Sedum
Pink
7
8
4
12
8
8
8
Sempervivum arachnoideum
Cobweb Houseleek
Pink
6
8
7
10
8
7
6
Sempervivum ciliosum 'Borisii'
Balkan Houseleek
Yellow
5
6
7
8
8
7
6
Silene acaulis
Moss Campion
Pink
4
5
1
8
7
6
5
Silene glauca
Beach Catchfly
White
5
6
4
10
7
5
5
Silene schafta
Fall Catchfly
Pink
7
9
3
8
7
6
6
Sisyrinchium convolution
Yellow-eyed Grass
Yellow
5
6
8
4
8
6
5
Sisyrinchium montanum
Blue-eyed Grass
Blue
5
6
8
4
7
5
5
Stachys lanata
Lamb's Ears
Pink
5
6
15
15
8
7
7
Stanleya pinnata
Prince's Plume
Yellow
5
6
30
15
8
8
8
Talinum calycinum
Famcflower
Purple
7
1015
8
8
7
8
40
Table 5. Rock Alpine / Ground Covers, continued.,
LATIN NAME
COMMON NAME
COLOR
B
FHTSPD
SN
S
W
Talinuni spinescens
Spiny Fameflower
Pink
6
8
6
8
9
8
7
Tanacetwn densum var. amain
Partridge Feather
Yellow
6
7
10
15
6
7
7
Teucrium chamaedrys 'Prostratum'
Creeping Germander
Pink
7
9
8
15
8
7
8
Thalictrum aquilegifolium
Columbine Meadow Rue
Lavender
5
6
30
15
6
5
5
Thymus 'Peter Davis'
Peter Davis' Thyme
Lavender
5
6
7
10
7
7
7
Thymus doerfleri
Hairy Thyme
Lilac
6
7
1
7
8
7
7
Thymus glabrescens v. loevyanus
Biglcaf Mat Thyme
Lilac
6
7
2
18
8
7
8
Thymus herba-barona
Carroway Thyme
Lavender
6
7
1
18
8
8
8
Thymus necefii
Crossleaf Thyme
Pink
4
5
2
10
8
7
7
Thymus pseudolanuginosus
Wooly Thyme
Lavender
6
7
1
12
8
8
8
Thymus serpyllum 'Minus’
Dwarf Thyme
Lavender
6
7
1
6
8
7
7
Thymus vulgaris 'Argenteus'
Silver Thyme
Lavender
6
7
8
10
8
7
7
Thymus x citriodorus (pulegioides x vulgaris )
Lemon Thyme
Lavender
6
7
1
15
8
7
7
Townsendia grandiflora
Giant Easter Daisy
White
4
5
4
6
8
7
7
Verbena bipinnatifida
Native Verbena
Purple
5
9
3
10
8
8
8
Veronica bombycina
White-leaf Speedwell
Blue
5
6
2
6
8
7
8
Veronica cinerea
Gray Veronica
Blue
5
6
5
12
8
7
7
Veronica fHifonnis
Bird's Eye Veronica
Blue
4
5
1
9
7
6
6
Veronica incana
Silver Speedwell
Blue
6
7
12
10
7
7
7
Veronica liwanensis
Turkish Veronica
Blue
4
6
1
15
8
7
8
Veronica orientalis
Oriental Veronica
Blue
5
6
5
12
8
7
7
Veronica pectinata
Blue Wooly Veronica
Blue
4
6
3
12
8
7
7
Veronica pectinata 'Rosea'
Wooly Veronica
Pink
5
6
2
9
8
7
7
Veronica prostrata
Mat Veronica
Blue
5
6
3
18
7
7
7
Veronica repens
Creeping Veronica
Blue
4
5
3
10
8
7
7
Veronica spicata 'Red Fox'
Pink Speedwell
Pink
5
6
12
10
8
7
7
Vinca minor
Periwinkle
Blue
3
5
8
18
5
5
5
Viola comuta
Horned Violet
Mix
5
6
6
10
6
5
5
Viola Corsica
Corsican Viola
Purple
3
9
5
7
7
6
5
Waldsteinia temata
Barren Strawberry
Yellow
4
12
4
10
5
6
6
Zauschneria califomica
Fire Chalice
Red
7
10
7
15
8
7
7
Zinnia grandiflora
Hardy Zinna
Yellow
6
10
3
12
9
9
1
Table 6, Summer Bulbs.
Janet Sickafuse, Chairman
[B = beginning month of bloom; F = final month of bloom; HT = height, in inches; SP = spread, in inches; S = Sun
requirements: 1 = full shade, 9 = full sun; SL = soil requirements: 1 = acid peat, 9 = alkaline clay; W = water
requirements: 1 = wet, 9 = dry; D = planting depth, in inches; G = suggested number in a group; H: H = hardy, T =
tender]
LATIN NAME
COMMON NAME COLOR
B
F
HT SP
S
SL W
D
G
H
Acidanthera bicolor 'Murielae'
Abyssinian
Gladiolus White/Maroon8
9
30
6
7
5
6
2
10
T
Canna x 'City of Portland'
Canna
Salmon Pink
7
9
48
24
7
4
5
2
3
T
Canna x 'Pfitzer's Primrose'
Canna
Yellow
7
9
24
24
7
4
5
2
3
T
Canna x 'Lucifer'
Canna
Yellow/Red
7
9
24
24
7
4
5
2
3
T
Canna x 'The President'
Canna
Red
7
9
36
24
7
4
5
2
3
T
Crocosmia x crocosmiflora
Montbretia
Mixed
7
7
20
4
6
5
7
2
10
_
Dahlia x 'Apache'
Dahlia
Orange Red
7
9
48
24
7
4
6
6
1
T
Dahlia x 'Christina'
Dahlia
Lilac/White
7
9
48
24
7
4
6
6
1
T
Dahlia x 'David Howard'
Dahlia
Orange
7
9
48
24
7
4
6
6
1
T
Dahlia x 'Eveline'
Dahlia
White
7
9
48
24
7
4
6
6
1
T
Table 6. Summer Bulbs, continued. . .
LATIN NAME
COMMON NAME
COLOR
B
F
HT
SP
S
SL W
D
G
H
Dahlia x 'Garden Wonder'
Dahlia
Deep Red
7
9
48
24
7
4
6
6
1
T
Dahlia x 'Golden Emblem'
Dahlia
Bright Yellow
7
9
48
24
7
4
6
6
1
T
Dahlia x 'Pinwheel'
Dahlia
Red/White
7
9
48
24
7
4
6
6
1
T
Dahlia x 'Rosella'
Dahlia
Rose Purple
7
9
48
24
7
4
6
6
1
T
Gladiolus nanus
Hardy Gladiolus
Mixed
6
6
18
6
7
5
6
2
10
H
Gladiolus x hortulanus
Garden Gladiolus
Mixed
7
8
54
6
7
5
6
5
3
T
Liatris spicata
Gayfeather
Purple
8
9
12
12
8
7
7
1
5
H
Liatris spicata alba
White Gayfeather
White
8
9
12
12
8
7
7
1
5
H
Lilium tigrinum
Tiger Lily
Assort.
8
9
60
6
5
6
7
5
3
H
Lilium x 'Black Dragon'
Trumpet Lily
Maroon /White 8
9
72
6
6
5
7
5
3
H
Lilium x 'Blushing Pink'
Oriental Lily
Pink/White
7
8
60
6
5
4
7
5
3
H
Lilium x 'Brushmarks'
Asiatic Lily
Orange/Red
6
6
36
6
6
5
7
5
3
H
Lilium x 'Casa Blanca'
Oriental Lily
White
8
9
60
6
5
4
7
5
3
H
Lilium x 'Cherished'
Asiati Lilyc
Rich Pink
6
6
40
6
6
5
7
5
3
H
Lilium x 'Connecticut King'
Lily, Asiatic
Bright Yellow
6
7
36
6
6
5
7
5
3
H
Lilium x 'Enchantment'
Asiatic Lily
Nasturtium
6
7
36
6
6
5
7
5
3
H
Lilium x 'Grand Commander'
Rubrum Lily
Crimson Red
8
9
60
6
6
4
7
5
3
H
Lilium x 'Mabel Violet’
Trumpet Lily
Magenta Pink
6
6
30
6
6
5
7
5
3
H
Lilium x 'Red Knight'
Asiatic Lily
Cherry Red
6
7
36
6
6
5
7
5
3
H
Lilium x 'Star Gazer'
Oriental Lily
Crimson Red
8
8
36
6
6
4
7
5
3
H
Lilium x 'Sterling Star'
Asiatic Lily
Cream/White
6
7
60
6
6
5
7
5
3
H
Lilium x 'Tamara'
Asiatic Lily
Pink/Cream
6
6
36
6
6
5
7
5
3
H
Lilium x 'Unique'
Asiatic Lily
Pink/ White
6
6
36
6
6
5
7
5
3
H
Lilium x 'Uchida'
Rubrum Lily
Rosy Red
8
9
30
6
6
4
7
5
3
H
Lilium x 'White Mountain'
Oriental Lily
White/Gold
7
8
60
6
5
4
7
5
3
H
Omithogalum sp.
Star of Bethlehem
White
6
7
24
12
8
5
5
3
10
T
Polianthes tuberosa
Tuberose
White
7
8
30
4
6
5
5
2
5
T
Tigridia pavonia
Tigridia
Mixed
7
8
20
48
7
5
7
2
10
T
Table 7, Trees and Shrubs.
Eva Littlefield, Chairman
[HT: height, in feet; SP: spread, in feet; SN (sun): 1 = full shade, 9 = full sun; SL (soil): 1 = alkaline clay, 9 = acid peat;
W (water): l = wet, 9 = dry]
LATIN NAME
COMMON NAME
TYPE
COLOR
HT
SP
SN
SL W
Amelanchier alnifolia
Native Serviceberry
Shrub
White
12
8
9
8
8
Aronia arbutifolia
Red Chokeberry
Shrub
Red
12
8
9
8
8
Berberis thunbergi
Crimson Pygmy Barberry
Shrub
Yellow
5
6
9
5
2
Buddleia davidii 'Charming'
Butterfly Bush
Shrub
Pink
8
5
9
5
7
Buddleia davidii 'White Profusion'
Butterfly Bush
Shrub
White
8
5
9
5
7
Buxus sempervirens microphylla
Wintergreen Boxwood
Shrub
---
20
20
6
8
7
Caragana arborescens 'Winter Gem'
Dwarf Siberian Pea Shrub
Shrub
Yellow
10
6
9
8
9
Caryopteris x clandonensis
Blue Mist Spirea
Shrub
Blue
2
2
8
2
7
Cercocarpus ledifolius
Curlleaf Mtn. Mahogany
Shrub
—
20
12
9
5
9
Cercocarpus montanus
Mountain Mahogany
Shrub
—
20
12
9
5
9
Chaenomeles speciosa 'Texas Scarlet’
Flowering Quince
Shrub
Red
6
6
6
5
7
Chamabatiara sp.
Fernbush
Shrub
White
4
3
9
3
8
Chrysothamnus nauseosus pumila
Dwarf Blue Rabbitbrush
Shrub
Yellow
3
2
9
5
9
Chrysothamnus nauseosus greenei
Green Rabbitbrush
Shrub
Yellow
4
3
9
5
9
Comus kousa
Kousa Dogwood
Shurb
White
20
20
8
5
5
41
42
Table 7. Trees and Shrubs, continued. . .
LATIN NAME
COMMON NAME
TYPE
COLOR
HT
SP
SN
SLW
Comus sericea 'Baileyi'
Baily Redtwig Dogwood
Shrub
White
10
8
5
5
4
Comus sericea 'Isanti'
Isanti Dwarf Dogwood
Shrub
White
5
4
5
5
4
Comus sericea 'Kelseyi'
Kelsey Dogwood
Shrub
White
2
1
5
5
4
Cotoneaster apiculata
Cranberry Cotoneaster
Shrub
Pink
3
4
7
4
7
Cotoneaster dammeri 'Coral Beauty'
Cotoneaster
Shrub
Coral
1
6
7
7
7
Cotoneaster divaricatus
Spreading Cotoneaster
Shrub
Pink
8
8
4
5
5
Cowania mexicana
Cliffrose
Shrub
Yellow
8
8
8
3
9
Cytissus x praecox
Warminster Broom
Shrub
Yellow
5
8
9
2
8
Daphne cneorum
Daphne
Shrub
Pink
3
2
4
6
2
Euonymus alata
Burning Bush
Shrub
10
8
6
5
5
Euonymus alata 'Compacta'
Dwarf Burning Bush
Shrub
—
4
4
6
5
5
Euonymus fominei
Wintercreeper Euonymus
Shrub
White
1
20
5
5
7
Fallugia paradoxa
Apache Plume
Shrub
—
4
5
7
4
9
Forsythia x intermedia 'Northern Sun'
Forsythia
Shrub
Yellow
5
3
7
5
5
Hibiscus syriacus 'Diana', Others
Rose-of-Sharon
Shrub
Wht, Assort.
10
10
6
7
5
Hypericum calycinum 'Hidcote'
St. John's-wort
Shrub
Yellow
2
1
7
5
9
Ilex x meservae 'Blue Prince'
Holly
Shrub
—
7
5
5
2
2
Ilex x meservae 'Blue Princess'
Holly
Shrub
—
7
5
5
2
2
Ilex verticillata
Sparkle Berry
Shrub
White
6
4
9
8
2
Juniperus communis
Common Mt. Juniper
Shrub
—
10
8
5
4
7
Ligusturm vulgare 'Cheyenne'
Cheyenne Privet
Shrub
White
6
6
5
4
7
Ligustunn vidgare 'Lodense'
Lodense Privet
Shrub
White
4
2
6
5
7
Nandina domestica
Heavenly Bamboo
Shrub
White
3
2
5
5
7
Perovskia atriplicifolia
Russian Sage
Shrub
Purple
5
5
9
1
9
Philadelphus x 'Dwarf Minn. Snowflake'
Dwarf Mockorange
Shrub
White
10
10
5
7
5
Physocarpus opulifolius 'Darts Gold’
Ninebark
Shrub
Pink
9
6
6
5
6
Physocarpus nanus
Dwarf Ninebark
Shrub
White
2
2
6
4
6
Picea abies (selections)
Blue Spruce
Shrub
—
—
—
8
5
5
Picea pungens (selections)
Blue Spruce
Shrub
—
—
--
8
5
5
Pinus mugho
Mugho Pine
Shrub
—
15
15
9
6
8
Potentilla fruticosa 'Abbotswood'
Potentilla
Shrub
White
3
3
9
5
6
Potentilla fruticosa 'Gold Drop'
Potentilla
Shrub
Yellow
4
3
9
5
6
Potentilla fruticosa 'Gold Finger'
Potentilla
Shrub
Yellow
4
4
9
5
6
Potentilla fmticosa 'Jackmani'
Potentilla
Shrub
Yellow
6
6
8
5
8
Potentilla fruticosa 'Kathryn Dykes'
Potentilla
Shrub
Yellow
5
5
8
5
7
Potentilla fmticosa 'Tangerine'
Potentilla
Shrub
Yel-Org
2
4
9
5
9
Pninus tomentosa
Nanking Cherry
Shrub
White
6
5
7
5
5
Pmnus virginiana 'Canada Red’
Chokecherry
Shrub
—
20
8
6
5
6
Pyracantha sp.(espaliered)
Firethorn
Shrub
White
10
—
7
5
9
Quercus gambelii
Gamble Oak
Shrub
—
15
12
8
6
9
Rhododendron x (varieties)
Rhododendron
Shrub
Var.
_
_
2
9
2
Rhus aromatica 'Gro Low'
Sumac
Shrub
Yellow
2
6"
7
9
7
Ribes alpinum
Alpine Currant
Shrub
Green
15
5
4
5
6
Rosa foetida bicolor
Austrian Copper Rose
Shrub
Yel/Red
6
4
7
5
7
Rosa mgosa 'Magnifica'
Rose, Rugosa
Shrub
Red
6
6
8
6
6
Rosa x 'Bonica'
Shrub Rose
Shrub
Pink
5
5
8
5
7
Salix discolor
Pussywillow
Shrub
---
20
20
9
3
3
Salix purpurea nana
Dwarf Artie Willow
Shrub
---
5
5
7
5
4
Spiraea japonica 'Little Princess'
Spirea
Shrub
Pink
5
5
6
5
5
Spirea nipponica
Snowmound Spirea
Shrub
White
5
5
8
5
9
Spirea x 'Anthony Waterer'
Spirea
Shrub
Red
4
3
6
6
5
Table 7. Trees and Shrubs, continued. . .
LATIN NAME
COMMON NAME
TYPE
COLOR
HT
SP
SN
SLW
Syringa meyeri
Meyer's Lilac
Shrub
Violet
6
9
8
5
7
Syringa patula 'Miss Kim'
Dwarf Lilac
Shrub
Lavender
5
4
8
5
7
Syringa viliosa
Vilosa Lilac, Late
Shrub
Lavender
5
5
5
5
5
Syringa vulgaris
Common Lilac
Shrub
Purple
15
12
8
5
8
Syringa vulgaris
Common Lilac
Shrub
White
15
12
8
5
8
Syringa x chinensis
Chinese Lilac
Shrub
Lavender
10
8
8
5
7
Tamarix pentandra
Tamarisk
Shrub
Pink
15
10
9
3
5
Taxus cuspidata densifomius
Dwarf Yew
Shrub
---
4
8
2
5
4
Thuja occidentalis 'Hetz'
Hetz Arborvitae
Shrub
—
3
2
3
5
4
Viburnum dentatum
Arrowwood Viburnum
Shrub
White
8
10
6
4
5
Viburnum lantana
Wayfaring Tree
Shrub
White
15
12
5
5
5
Viburnum plicatum tomentosum 'Mariesii'
Doublefile Viburnun
Shrub
White
10
12
7
7
5
Viburnum pninifolium
Black Haw Viburnum
Shrub
White
15
10
5
5
5
Viburnum x 'Juddii'
Judd's Viburnum
Shrub
Pk/Wht
6
4
7
7
4
Yucca sp.
Yucca
Shrub
White
2
2
9
2
9
Acer platanoides 'Royal Red'
Red Maple
Tree
Gr/Yel
50
60
9
3
5
Aesculus glabra
Ohio Buckeye
Tree
Gr/Yel
40
40
6
7
4
Catalpa speciosa
Catalpa
Tree
White
60
40
5
7
5
Celtis occidentalis
Western Hackberry
Tree
—
60
60
9
5
5
Cercis canadensis
Eastern Redbud Eastern
Tree
Pink
25
10
5
4
5
Crataegus phaenopyrum 'Toba'
Washington Hawthorn
Tree
White
25
10
7
5
5
Gymnocladus dioicus
Kentucky Coffeetree
Tree
Gr/Wht
50
40
9
4
8
Magnolia x loebneri 'Merrill'
Magnolia
Tree
Yellow
20
12
7
5
5
Moms alba
Weeping Mulbery
Tree
Pink
6
6
7
5
7
Picea pungens glauca
Colorado Blue Spruce
Tree
—
100
30
8
5
5
Pinus aristata
Bristle Cone Pine
Tree
---
8
3
9
5
6
Pinus nigra
Austrian Pine
Tree
---
45
20
9
5
6
Pinus strobus
White Pine
Tree
---
60
20
9
2
7
Pmnus cerasifera 'Newportii'
Newport Purple Plum
Tree
Pink
20
12
6
5
5
Quercus rnbra
Northern Red Oak
Tree
_
60
40
8
4
5
Sorbus occidentalis
Mountain Ash
Tree
White
25
15
7
6
4
Table 8, Vegetables.
Knobby Brown, Chairman
[* denotes new varieties]
Artichoke
‘Green Globe
Onion
‘Carmen Red’
Squash, Acorn
‘Jersey Golden’
Improved’
Par-cel*
—
Squash, Patty Pan
‘Sunburst’
Broccoli
‘Green Duke’
Pepper
‘Gypsy’
Squash, Spaghetti
—
Brussels Sprouts
‘Jade Cross E’
Pepper,
—
Squash, Zucchini*
‘Green Magic’
Cabbage
‘Emerald Cross’
Anaheim chili
—
Squash, Zucchini
‘Gold Rush’
Cabbage
‘Ruby Perfection’
Pepper, Bell
‘Golden Summer
Tomatillo
Cantalope
‘Chaca’
Hybrid’
Tomato
‘Better Boy’
Cauliflower
‘Snow Crown’
Pepper Bell
‘New Ace’
Tomato
‘Celebrity’
Celery*
‘Utah 52-70 R
Pepper, Bell
‘Oriole’
Tomato
‘Early Girl’
Improved’
Pepper, Bell
‘Purple Bell’
Tomato
‘Park’s Better Bush’
Cucumber
‘Sweet Success’
Pepper, Bell
‘Sweet Chocolate’
Tomato
‘Superfantastic’
Eggplant
‘Dusky’
Pepper, Cherry
‘Sweet Cherry’
Tomato, Beefsteak
‘Burpee’s Supersteak’
Eggplant
‘Easter Egg’
Pepper, Chili
‘Zippy’
Tomato, Cherry
‘Gardener’s Delight’
Eggplant
‘Ichiban’
Pepper, Hot Bell
‘Mexi Bell’
Tdmato, Cherry
‘Gold Nugget’
Leek
‘Titan’
Pepper, Jalapeno
‘Jalapeno M’
Tomato, Cherry
‘Sweet Million’
Melon, Honey dew
‘Earli-Dew’
Pumpkin
‘Bushkin’
Tomato, Yellow*
‘Lemon Boy’
Okra
‘Annie Oakley
Pumpkin
‘Jack Be Little’
Tomato, Yellow
‘Yellow Plum’
Hybrid’
Radicchio
‘Giulio’
Watermelon
‘Burpee Bush
Onion
‘Walla Walla’
Squash, Acorn
‘Table King’
Sugar Baby’
44
Table 9, Water Gardening.
Len and Doris Freestone, Chairmen
[FL = Flower type: Fit = floating, Cat = catkin, Lrg = large, Med = medium, Sml = small; H = Height, in inches; Sp = Spread,
in inches; BL = Blooming time: Smr = summer, Sp = spring, F=j= fall; S = Sun requirement: 1 = full shade, 9 = full sun; C:
P = perennial, A = annual; H: H = hardy, T = tender, F = half-hardy]
LATIN NAME
COMMON NAME
COLOR
FL
H
SP
BL
S
C
H
Azolla sp.
Azolla
_ _
Fit
_ _
_
Smr
5
P
T
Cannas
Water Canna
Yellow
—
48
—
Smr
9
A
T
Cannas
Water Canna
Red
—
48
—
Smr
9
A
T
Cannas
Water Canna
Pink
—
48
—
Smr
9
A
T
Colocasia esculenta
Green Taro
Yellow
—
36
—
Smr
7
P
T
Cyperus altemifolius
Umbrella Palm
—
—
72
—
—
6
P
T
Cypems haspens
Dwarf Papyrus
—
—
30
—
30
7
A
T
Cypems papunis
Giant Papyrus
—
—
72
—
smr
7
A
T
Eichomia crassipes
Water Hyacinth
Blue
Fit
—
—
Smr
7
A
T
Eleocharis tuberosa
Water Chestnut
—
—
36
—
Smr
7
A
T
Hydrocleys nymphoides
Water Poppy
Yellow
—
—
—
Smr
7
A
T
Iris pseudacoms
Iris, Yel Water
Yellow
—
48
—
Spg
9
P
H
Iris versicolor
Iris, Blue Water
Blue
—
24
—
Sp
7
P
H
Jussiaea repens
Primrose Creeper
Yellow
—
—
—
Smr
9
A
T
Lenina minor
Duck Weed
—
Fit
—
—
Smr
5
A
T
Marsilia mutica
Water Four Leaf Clover —
_
_ _
Smr
5
A
T
Myriophyllum aquaticum
Parrot's feather
—
—
—
—
Smr
7
P
H
Nymphaea odorata gigantea
Water lily
White
Lrg
—
4' +
Smr
9
P
H
Nymphaea cv. Amabalis'
Water lily
Pink
Lrg
—
3-4'
Smr
9
P
H
Nymphaea cv. 'Arc-en-Ciel'
Water lily
Pink
Med
—
3-4'
Smr
7
P
H
Nymphaea cv. Attraction'
Water lily
Red
Lrg
_
3’ +
Smr
7
P
H
Nymphaea cv. 'Carmine Ladeker'
Water lily
Pink
Med
—
3-4'
Smr
9
P
H
Nymphaea cv. 'Charlene Strawn'
Water lily
Yellow
Med
—
3-4'
Smr
7
P
H
Nymphaea cv. 'Charles de Meurville'
Water lily
Red
Med
---
3-4'
Smr
9
P
H
Nymphaea cv. 'Colonel A.J. Welch'
Water lily
Red
Med
—
3-4'
Smr
9
P
H
Nymphaea cv. 'Comanche'
Water lily
Change
Med
_
1-3'
Smr
9
P
H
Nymphaea cv. 'Dwarf White'
Water lily
White
Sml
---
1-2'
Smr
9
P
H
Nymphaea cv. 'Escarboucle'
Water lily
Red
Lrg
—
3' +
Smr
9
P
H
Nymphaea cv. 'Faebiola'
Water lily
Pink
Med
---
1-3’
Smr
9
P
H
Nymphaea cv. 'Firecrest'
Water lily
Pink
Lrg
—
3-4’
Smr
9
P
H
Nymphaea cv. 'Flammea'
Water lily
Red
Lrg
_
3-4'
Smr
9
P
H
Nymphaea cv. 'Formosa'
Water lily
Pink
Med
---
3-4'
Smr
9
P
H
Nymphaea cv. 'Frobeli'
Water lily
Red
Sml
---
1-2'
Smr
9
P
H
Nymphaea cv. 'Giant Fragrant'
Water lily
White
Lrg
---
4' +
Smr
9
P
H
Nymphaea cv. 'Gladstone'
Water lily
White
Lrg
—
3' +
Smr
9
P
H
Nymphaea cv. 'Gloire deTemple-sur-lot'
Water lily
Pink
Lrg
_
3' +
Smr
9
P
H
Nymphaea cv. 'Gloriosa'
Water lily
Red
Sml
---
1-2'
Smr
7
P
H
Nymphaea cv. 'Gonnere'
Water lily
White
Dbl
---
3' +
Smr
9
P
H
Nymphaea cv. 'Hal Miller'
Water lily
White
Lrg
---
3' +
Smr
7
P
H
Nymphaea cv. 'Hermine'
Water lily
White
Med
—
1-4’
Smr
9
P
H
Nymphaea cv. 'Hollandia'
Water lily
Pink
Dbl
_
3' +
Smr
9
P
H
Nymphaea cv. 'James Brydon'
Water lily
Red
Med
---
1-4'
Smr
7
P
H
Nymphaea cv. 'Laydekeri Fulgens'
Water lily
Red
Med
—
3-4’
Smr
9
P
H
Nymphaea cv. 'Mansaniello'
Water lily
Pink
Med
---
3’ +
Smr
7
P
H
Nymphaea cv. 'Marliac White'
Water lily
White
Sml
—
3-4'
Smr
7
P
H
Nymphaea cv. 'Marliac Flammea'
Water lily
Pink
Med
_
3-4'
Smr
9
P
H
Table 9. Water Gardening, continued. . .
LATIN NAME COMMON NAME
COLOR FL
H SP BL
S C H
Nymphaea cv. 'Marliac Rose’
Nymphaea cv. 'Marliac Carnea'
Nymphaea cv. 'Marliac Chromatella'
Nymphaea cv. 'Mexicana'
Nymphaea cv. 'Moorei'
Nymphaea cv. 'Norma Gedye'
Nymphaea cv. 'Peter Slocum'
Nymphaea cv. 'Picciola'
Nymphaea cv. 'Pink Opal'
Nymphaea cv. 'Pink Sensation'
Nymphaea cv. 'Pygmaea Helvola'
Nymphaea cv. 'Ray Davies'
Nymphaea cv. 'Red Ladeker'
Nymphaea cv. 'Rose Arey'
Nymphaea cv. 'Rosy Morn'
Nymphaea cv. 'Sioux'
Nymphaea cv. 'Splendida'
Nymphaea cv. 'Sulphurea grandiflora'
Nymphaea cv. 'Sultan'
Nymphaea cv. 'Sumptuosa'
Nymphaea cv. 'Sunburst'
Nymphaea cv. 'Sunrise'
Nymphaea cv. 'Texas Dawn'
Nymphaea cv. 'Virginalis'
Nymphaea cv. 'Wilfrum Gonnere'
Nymphaea tuberosa
Nymphoides crenata var.
Nymplioides cristatum
Nymphoides geminata
Nymphoides indica
Nymphoides indica giganta
Peltandra virginica
Pistia stratiotes
Pontederia cordata
Pontederia cordata
Pontederia cordata
Sagittaria lancifolia
Salvinia minima
Thalia dealbata
Thalia geniculata
Typha angustifolia
Typha latifolia
Typha minima
Water lily
Pink
Water lily
Pink
Water lily
Yellow
Water lily
Yellow
Water lily
Yellow
Water lily
Pink
Water lily
Pink
Water lily
Pink
Water lily
Pink
Water lily
Pink
Water lily
Yellow
Water lily
Pink
Water lily
Red
Water lily
Pink
Water lily
Yellow
Water lily
Change
Water lily
Red
Water lily
Yellow
Water lily
Red
Water lily
Pink
Water lily
Yellow
Water lily
Yellow
Water lily
Yellow
Water lily
White
Water lily
Pink
Water lily
White
Snowflake. Fringed Yell
Yellow
Snowflake. White
White
Snowflake. Yellow
Yellow
Snowflake, Water
White
Snowflake, Giant Wtr
White
Water Arum
White
Water Leli uce
—
Rush, Prp Pickerel
Purple
Rush, Blue Pickerel
Blue
Rush, Pickerel
Pink
Arrowhead
White
Salvinia
—
Thalia
Blue
Thalia, Red Stemmed
Violet
Cattail, Narrow Leaf
Brown
Cattail, Common
Brown
Cattail, Dwarf
Brown
Med
—
3' +
Smr
9
P
H
Med
—
1-4'
Smr
9
P
H
Sml
—
1-4
Smr
7
P
H
Sml
—
3’ +
Smr
9
P
H
Med
_
3-4
Smr
9
P
H
Med
—
3-4'
Smr
9
P
H
Dbl
—
3-4'
Smr
9
P
H
Med
—
1-4
Smr
9
P
H
Med
—
1-4
Smr
9
P
H
Lrg
_ _
3-4'
Smr
9
P
H
Min
—
1-2'
Smr
7
P
H
Med
—
3-4
Smr
9
P
H
Sml
—
1-2'
Smr
9
P
H
Sml
—
1-4
Smr
9
P
H
Med
_
3-4
Smr
9
P
H
Med
—
3-4
Smr
9
P
H
Lrg
—
3-4’
Smr
9
P
H
Sml
—
1-4
Smr
7
P
H
Med
—
3-4
Smr
9
P
H
Dbl
_
1-4
Smr
9
P
H
Med
—
3-4
Smr
9
P
H
Lrg
—
3' +
Smr
9
P
H
Med
—
3-4'
Smr
9
P
H
Med
—
3' +
Smr
9
P
H
Med
_
3-4
Smr
9
P
H
Med
—
3-4
Smr
9
P
H
—
—
—
Smr
7
A
T
—
—
—
Smr
7
A
T
—
—
—
Smr
7
A
T
_
_
_
Smr
7
A
T
---
—
---
Smr
7
A
T
---
24
---
Smr
7
P
T
Fit
—
---
Smr
7
A
T
—
12
—
Sp,F
7
P
H
—
12
—
Sp,F
7
P
H
---
12
—
Sp,F
7
P
H
---
24
---
Smr
7
P
H
Fit
—
—
Smr
5
A
T
—
72
—
Smr
9
A
T
_
72
_
Smr
9
A
T
Cat
84
...
Smr
7
P
H
Cat
84
---
Smr
7
P
H
Cat
24
—
Smr
7
P
H
Mountain, Plain
and Garden
The Magazine of Denver Botanic Gardens ■ Autumn/Winter 1990
Published by:
Denver Botanic Gardens, Inc.
909 York Street
Denver, Colorado 80206-3799
Mrs. Thomas E. Taplin, President
Bruce D. Alexander, Executive Director
Lauren Springer, Editor
Solange Gignac, Diane Ipsen, Bernice E.
Petersen, Copy Editors
Sent to all members of Denver Botanic Gardens. Mem¬
bership fees are as follows: Student $18, Individual
Senior $18, Senior Couple $25, Individual $25,
Family/Dual $35, Contributing $50, Supporting $100,
Patron $500, Four Seasons Member $1000.
By becoming a member of Denver Botanic Gardens,
Inc., you will receive Mountain, Plain and Garden and
the monthly Green Thumb News. You will also have
year-round admission to the gardens and borrowing
privileges from the Helen K. Fowler Library, located in
Boettcher Memorial Center at 1005 York Street.
For further information, write to Membership Coor¬
dinator, Denver Botanic Gardens, 909 York Street,
Denver, Colorado 80206, or call 331-4000.
Denver Botanic Gardens, Inc., maintains a collection of
living plants, both native and exotic, for the purpose of
acquiring, advancing and spreading botanical and hor¬
ticultural knowledge.
It is a non-profit organization supported by both public
and private funds.
Copyright 1990 by Denver Botanic Gardens, Inc.
Cover Photo: Rob Proctor
Back Cover Photo: Lauren Springer
Other Photos: Panayoti Kelaidis, Rob Proctor,
Lauren Springer
Design: Graphic Impressions, Denver
Printing: The Pressworks, Denver
Mountain, Plain ssc
and Garden ’v*
The Magazine of Denver Botanic Gardens
A Continuation of The Green Thumb
Volume 47 Number 2 Autumn /Winter 1990
Contents
Introduction
Lauren Springer . 1
Signature Plants
Rob Proctor . 4
Tethyan Plants
Panayoti Kelaidis . 8
Soil Preparation
Virginia M. Weigand . 14
Industrial-Strength Perennials
for Home and Office
Ray Daugherty . 16
From the Ground Up:
Woody Perennials
Diane Ipsen . 19
Perennials in the Mountains
Marty Jones . 21
Perennials for Fall
Lauren Springer . 22
Plant Portraits
Digitalis lanata
Angela Overy . 25
Zinnia grandiflora
Andrew Pierce . 26
Callirhoe involucrata
Kelly Grummons . 27
Tiarella wherryi
Pat Hayward . 28
Delphinium grandiflorum
Sandy Snyder . 29
Clematis recta
Jane Silverstein Ries . 30
Anemone hupehensis
Tom Peace . 31
Agastache cana
Jim Knopf . 32
Ipomoea leptophylla
Ray Daugherty . 32
Thalictrum minus
James E. Klett . 33
/
This issue of Mountain, Plain and Garden is
devoted to that remarkably diverse group of
plants, perennials. Traditionally, the rigorous
climate of the Rocky Mountain and Great Plains
regions have made gardeners here wary and con¬
servative. In recent years, with the renewed inter¬
est in gardening and in herbaceous perennials in
particular, horizons have expanded tremen¬
dously. Every year new plants are introduced by
plantsmen and women, in nurseries, adventurous
private gardens, universities, and at botanic gar¬
dens.
The most exciting part of all this is the discov¬
ery that our climate, for all its daunting extremes,
is actually superbly suited for growing one of the
most diverse palettes of perennials in the world,
from shady woodlanders, to traditional maritime
border plants, to the newest, drought-tolerant in¬
troductions from the far corners of the world, not
to mention the barely-tapped perennial flora na¬
tive to this region and so full of garden potential.
Perennial plants, strictly defined, have life-
cycles that last beyond one season of flower or
seed formation, and thus include trees and
shrubs. In this issue, however, the term perennial
is used in a less scientific, more restricted, and
garden-oriented way. Perennials here refer
mostly to herbaceous perennials, those that have
tops that die down when they go seasonally dor¬
mant. Perennials more woody in character that
nevertheless are cut to the ground annually by the
gardener to maximize their vigor and beauty are
also discussed.
One issue can hardly scratch the surface of the
huge and quite unexplored subjects of peren¬
nials and their uses in design. But here is a start:
you will find articles on ever-important soil prep¬
aration, Tethyan plants — unusual perennials for
the sunny, dry garden, signature perennials ide¬
ally suited for this region, plants to stretch the
gardening season into the fall, to add shrub-like
qualities to the garden, and for low maintenance,
as well as perennial gardening at high altitudes.
The authors represent a broad base of horticul¬
tural expertise, including experts from the green
industry, designers and landscape architects, gar¬
den writers, and Denver Botanic Gardens staff.
Their shared knowledge and advice will give you
a taste of the limitless possibilities perennials of¬
fer.
The last section, Plant Portraits, is new. Here
ten more experts have each chosen and de¬
scribed an under-used perennial of great garden
merit. Many of these plants, as well as those men¬
tioned in the articles, are available from local
Colorado nurseries. Some may be harder to find;
you’ll need to look into mail-order sources (the
Helen Fowler Library at DBG has an extensive
collection of catalogs), or grow them from seed.
With perseverance on the hunter’s part, and
interest on the part of the imaginative people who
make up our region’s green industry and those
who help organize that special horticultural
event, the DBG Plant Sale, these perennial plants
soon can become an integral part of our exciting,
ever-expanding horticultural scene.
Lauren Springer
Guest Editor i
Black-eyed susans {Rudbeckia fulgida
‘Goldsturm’) and the pale flower buds
oiSedum ‘Autumn Joy’ are a welcome
sight in August.
Late summer beauty comes in soft
tones and textures with tree mallow
{Lav at era thuringiaca), Russian sage
( Perovskia sp. ), wormwood ( Artemisia
sp.), and tender Boston daisies (Argy-
ranthemum frutescens).
2
A sunny, richly colored perennial border comes alive in mid-summer.
Form, color, and texture harmonize with peonies ( Paeonia lactiflora
‘Toro-No-Maki’), Siberian catmint ( Nepeta sibirica), and meadow-rue
( Thalictrum minus).
Late spring flowers and foliage grace the DBG Rock Alpine Garden —
silver sage ( Salvia argentea) and rock soapwort ( Saponaria
ocymoides).
In the Tethyan border at DBG, unusual perennials frolic in the heat and
dryness of the summer.
In the shade, hostas create a lush, tropical mood.
Sweeps of yarrow {Achillea filipendulina ), sage {Salvia xsuperba), and
lavender {Lavandula angustifolia) make a lovely drought-tolerant
combination.
Hot-colored yellow knapweed {Cen-
taurea macrocephala), Maltese cross
{Lychnis chalcedonica ), and Inula
salicifolia make a bold statement in the
July garden.
White-flowered native evening prim¬
rose {Oenothera caespitosa ) is a long-
blooming beauty for the sunny, dry
garden.
3
Signature Plants
by Rob Proctor
Imagine a horticultural game of enormous mag¬
nitude: drop participating gardeners (by par¬
achute, we hope) into unnamed cities across the
country. Without asking for help, can they identify
their locations simply by the plants that grow
there? Some cities might be easier than others.
Portland is known for its roses, New Orleans for
walls covered by bougainvillea, Washington D. C.
for its cherry trees, Atlanta for its peaches. Other
cities and regions take pride in other plants that
have come to exemplify those communities. Par¬
ticular flowers, where they thrive, symbolize the
heritage and lifestyle of the people who live there.
Continue the game by dropping the players in
Denver, Colorado, or any of the cities along the
Front Range. What will they make of the state of
horticulture they find, and will it lead them to the
conclusion that they have, indeed, landed in Col¬
orado? Poodle-cut junipers may throw them
off — is this a French province, perchance? They’ll
see more petunias and geraniums than they could
have imagined — no help there.
If they happen upon the best areas in the re¬
gion, they’ll find an impressive array or peren¬
nials from the four corners of the world. Unless
our players have cheated by looking west and
spotted the mountains, they might well be
confused— where the heck are they? Colorado
boasts some world-class gardens that have drawn
on many horticultural influences. Some incorpo¬
rate native plants; others do not.
It is not an accurate measure of the greatness of
a garden to judge it strictly by the quantity of
native plants it contains. To do so in Colorado is to
overlook the gardening heritage of the region,
and to ignore the tremendous inventiveness of its
gardeners. Many elements have affected our state
since pioneers first began in earnest to settle
here. Just as our cultural heritage reflects so many
influences, so, too, does our horticulture. Gar¬
deners here enjoy a unique position. We are able
,to grow many plants from other regions of the
country — perhaps not always to perfection, but
satisfactorily nonetheless. Woodland wild flowers
from New England grace some gardens, while
desert succulents of the Southwest thrive in
others. Traditional perennials from England have
made their way here, and exciting introductions
from exotic locales around the world take hold
here. Combine this with a rich native flora from
the mountains and plains, and the gardener is
staggered by an incredible diversity of options.
Why then do we see so little imagination in so
many gardens? Why do two of the most labor-
intensive plants, the “poodle” bush and Kentucky
blue grass, find such favor? Perhaps after all the
clipping and mowing, the average homeowner is
too exhausted to pursue anything more than a
cold beer and a few annuals to line the walk. Or
perhaps it is suspicion — we sometimes fear what
we do not know, and some of us worry too much
what our neighbors would think if we plowed up
our acreage of lawn to plant perennials. Money is
a consideration as well — perennials grown in gal¬
lon containers cost four or five dollars, and when
planted in the wrong spot, they die (whereas a
juniper bush is a fairly safe investment, for it will
grow like mad until it blocks all light entering the
living room, at which point it can receive a poodle
cut).
Nothing I can say will ever make much differ¬
ence, but good perennial plantings teach by
example. I learn from every garden I see, regard¬
less of the level of skill of the gardener, and good
examples are to be seen in every neighborhood
in every Colorado community. I’ve been studying
them for several years — there is nothing more
exciting (or humbling) than to visit a beautiful
garden. In doing so, a handful of perennials have
caught my attention as plants that might serve as
“signature” plants of this area. Some are native
plants, while others are exotics that have adapted
well to this climate.
The real advantage for the gardener is to be
able to draw on so many sources of inspiration.
Our close association with the Midwest is one of
the most notable, with the all-American style that
has evolved there. The East Coast has strongly
influenced our choices, though we must com¬
pensate with more water to grow those regional
plants, while the same goes for perennials from
Great Britain. Mediterranean plants flourish in
our abundant sunshine and dry heat; so do the
plants of the Southwest. Perennials from the
Orient play an important role. Most recently, new
introductions from South Africa and Eurasia have
entered the Colorado garden scene.
The largest group of perennials that might be
characterized as signature plants of our region
are those of the Compositae , the daisy tribe. The
family is a large one, but the best known is the
Shasta daisy. It is a persnickity grower, however,
sometimes dying out for no good reason, and the
blossoms often end up in a soggy mess on the
ground. The wild ox-eye daisy, Chrysanthemum
leucanthemum , offers a longer season of bloom
with less tendency for the flowers to flop. Native
to Europe, the ox-eye daisy has become natu¬
ralized in many countries. It seems perfectly at
home here, complementing our native wild flow¬
ers without overwhelming them. Flowers bloom
on twenty-inch stems for a good part of the spring
and summer if spent ones are removed periodi¬
cally. Though C. leucanthemum , too, is a short¬
lived perennial, it is likely to seed itself.
The many species and varieties of Coreopsis
enhance perennial plantings. Unfortunately, the
plant has been stuck with the common name
“tickseed” due to the supposed resemblance of
the seeds to that pest. (I’ve never paid much
attention to the shape of the seeds — “gorillaseed”
would be more apt to grab my attention — but I’ve
wondered how many gardeners decided to
forego planting tickseed for fear of an outbreak of
Rocky Mountain spotted fever in their neighbor¬
hood.) Coreopsis lanceolata has been hybridized
into many smaller and double-flowered types,
though the original wild species is quite attractive
in itself. The golden-yellow flowers are pro-
lifically produced and are a fitting counterpart to
the blue Colorado skies. Coreopsis verticillata
also produces abundant flowers throughout the
season. The original species grows to about
twenty inches, and the fine-textured foliage is
topped by small, single flowers. The cultivar
‘Moonbeam’ is highly praised for good reason;
the pale yellow blossoms cover the foot-tall plants
with little encouragement from June until frost.
The color is invaluable in most every scheme
imaginable. Coreopsis rosea is just starting to gain
a toe-hold in area gardens, where it has a promis¬
ing future. Though it closely resembles ‘Moon¬
beam,’ its flowers are pink. It is not as drought-
tolerant as the rest, so it is a candidate for stiffer
loam soils.
Another pink composite, Echinacea purpurea,
is a bold and stately plant. Though commonly
called purple coneflower, the flower petals
would be better described as wine-pink. Bristly
centers of orange are distinctive even after the
petals have fallen. I’ve often admired these seed
heads poking through snowdrifts.
Though the color seems to put some gardeners
on the defensive, it is difficult to deny Indian
blanket, Gaillardia aristata. I’m a bit put off my¬
self by those who call it blanket flower and ignore
the “Indian’part. It was for the bold two-tone red
and gold pattern of the zig-zag petals that it was
originally compared to the bright saddle blankets
of the Indians. Gaillardia has a distinctly western
mystique — a beautiful treasure of the prairie.
New cultivars are impressive; ‘Goblin’ is short¬
stemmed, growing to a little over a foot, and
‘Burgundy’ grows to the normal two foot height,
but the flowers are deep, rich red. It is stunning
planted with rue ( Ruta graveolens ) and silver
clary ( Salvia argentea ). Indian blanket requires
little attention except for dead-heading, and
thrives on heat and drought.
There are so many species of Penstemon that
they are too numerous to list. They have found
little favor outside the western states because
most penstemons resent other regions’ humidity
and heavy rainfall. While we sometimes lament
the lack of enough rainfall to satisfy a few thirsty
woodlanders, this glorious genus erases all long¬
ings for primulas and hepaticas when they burst
into bloom. P. pinifolius is sometimes called
“prairie fire,” and the folk name describes it well.
The ten-inch stems burn with brilliant scarlet,
tubular flowers. Rocky Mountain penstemon, P.
strictus, boasts two-foot spikes cloaked in blos¬
soms of rich violet-blue. Scarlet bugler, P. bar-
batus , blooms profusely through the summer
heat. The red blossoms have a coral cast and the
long flowering stems are graceful and elegant.
Blue fla x,Linum perenne, is a European import
that grows as naturally in our state as if it had
evolved here. I know a formal garden that is
situated with a view of a meadow below, framed
by pines and junipers .L. perenne has been intro¬
duced into the field and allowed to seed itself; on
a sunny morning its haze of pale blue flowers
steals the show from the carefully tended plants
above. The yellow counterpart of the blue species
\sLflavum , a shorter and less airy perennial with
butter-yellow blossoms.
Mediterranean herbs and perennials are fre¬
quently seen in our gardens. Grey and green- 5
leaved species of Santolina can be clipped into
low hedges or allowed to form spreading
mounds that are studded with button-like yellow
flowers. Thymes, lavender, and dianthus often are
used for edging or for the front of traditional
borders. Tight purple spires of Salvia x superba
punctuate many a summer garden, and other
species grow beautifully here. Perovskia atrip-
licifolia belongs to an allied genus and is called
Russian sage. The handsome, silver foliage is top¬
ped by spikes of tiny lavender-blue flowers. It is a
stately perennial, growing to four feet, and
though it certainly would not have thrived in the
political climate of the McCarthy era, today Rus¬
sian sage is a welcome foreigner in a surprising
number of area plantings.
From South Africa come the ice plants, and
yellow-flowered Delosperma nubigenum (syn.
D. congestion ) and magenta-flowered D. cooperi
grow here like nowhere else on earth — save their
homeland, of course. Since their introduction by
the DBG Rock Alpine Garden in 1980 and 1985
respectively, these ice plants have become nearly
as common as daisies. These little succulents en¬
hance rock gardens, borders, and dryland gar¬
dens with their cheerful flowers that open in the
bright sun. Other species of Delosperma are on
trial at DBG and will likely become popular.
Yuccas have begun to be appreciated in this
country, though they were ignored for years, even
though the Europeans took great pains (probably
pruning too close to the pointed needles) to grow
them and extol their virtues. Colorado native Y.
glauca , is too often paired with a wagon wheel at
the entry drive, but it is a dramatic element when
planted in irregular drifts with prairie fire pens-
temon and silver lamb’s ears (Stachys byzantina).
Adam’s needle, Y. filamentosa, sports showy
white flowers. Both yuccas bear interesting seed
pods and their architectural, evergreen foliage is
highly underrated.
Columbines ( Aquilegia ) are the quintessential
flowers of regional gardens, though hot summers
often end their blooming period prematurely. It
is nearly cause for deportation from the state not
to include them in the garden where they can
revel in rich, moist soil protected from hot after¬
noon sun. Another mountain flower, Heracleum
spbondylium, has yet to make an impact in area
gardens, though it is a magnificent plant of orna¬
mental and architectural interest. Known as cow
parsnip or cartwheel flower, its thick stems rise
above large, coarse leaves to four or five feet.
6 Huge umbels of white flowers crown the leaves,
something like Queen Anne’s lace with a glandu¬
lar problem. The seed heads are dramatic even
after the flowers fade. H. spbondylium thrives
along stream banks in its mountain habitat, but
performs well (at the back) in a traditional bor¬
der.
What a lovely punctuation mark to a signature
planting is made by species of Liatris. The spikes
of lavender-purple flowers open from the top
down, a feat nearly unequaled in the floral king¬
dom, where most flowers follow the reverse
habit. These unusual flowers grace gardens in
mid-to-late summer when most of us could use
some invigoration.
So many perennials of the plains offer colorful
options for personal statements and combina¬
tions. The color of sulphur flower, Eriogonum
umbellatum , is aptly described by its common
name. The name “wine cup” also suits Callirhoe
involucrata. Most of the evening primroses,
species of the genus Oenothera , belie their name
by blooming by day. The best known is Ozark
sundrop, O. missouriensis , which glows with pro¬
lific lemon-yellow flowers. The night-blooming
O. biennis is naturalized near old homesteads and
in mountain gold-mining towns. O. caespitosa
blooms with dramatic cup-shaped flowers of pris¬
tine white, and O. speciosa covers itself with
lovely pink-tinted blossoms. The evening prim¬
roses possess the fragile beauty of wild flowers
but bloom with the determination of petunias.
Gaura lindbeimeri has no common name to
my knowledge, so I’ll propose “apple blossom
grass,” for the small white flowers are blushed
Gaura lindbeimeri
with pink and exude the translucent, ethereal
quality of apple blossoms. They are borne on wiry
stems held like wands over the narrow olive-
I green leaves. The plant blooms from June until
frost, and is among the most elegant of the signa¬
ture plants. It is rather rare in commerce, though
a local nursery offered it last summer — blooming
madly in gallon containers — and it sold like hot-
cakes. G. lindheimeri seeds itself prolifically when
planted in sunny, well-drained sites, so its off-
I spring will no doubt be shared among friends and
become local favorites.
Coral bells, Heuchera sanguined, is an all-
American native that has long been a cottage gar¬
den favorite. It seems to grow in Colorado like
nowhere else, and performs well in a number of
situations from sunny to shady. If it is planted in
optimal conditions in partial shade, it will bloom
most of the summer. The white-flowered and
pastel hybrids are useful in beds where brighter
flowers of the species are not appropriate.
Not all of these perennials will thrive in every
garden, but when situated properly, they will per¬
form admirably. Their use in the garden may help
define our horticultural traditions as well as our
commitment to the future. These perennials
serve to give this region a unique feel, not a
rubber-stamp copy of any other. As water be¬
comes an ever more valuable resource, they may
replace thirsty lawns and commercial plantings
designed by out-of-state landscapers with no
knowledge of our climate. I continue to be in¬
furiated by vast areas of blue grass turf (in berms,
yet) installed where nobody will ever set foot, or
water-guzzling flowers planted en masse at new
shopping centers and median strips. I shook my
head at the planting of hundreds of astilbes I saw
last summer planted in full sun next to a parking
lot. Don’t misunderstand — I love astilbes grow¬
ing in shady gardens, but they require gallons of
water planted next to acres of asphalt, and they
dry up quickly in arid heat.
I recall a story a local nurseryman told me of an
out-of-town landscape architect who was design¬
ing for a new commercial building. He ordered
two thousand pots of lily turf, Liriope platyphyl-
la, for the project. Lily turf is popular in parts of
Texas and California for such projects, because
the evergreen grassy foliage crowds out weeds
and spikes of lavender flowers bloom in the
summer. Unfortunately, Liriope is not reliably
hardy in Colorado — I know of a few protected
gardens where it sneaks through the winter — but
when told this by the nurseryman, the out-of-
towner said fine, he’d have it shipped in, and
stormed out. I haven’t a clue what happened to
this doomed venture, though I suspect the
grounds now feature acres of bindweed.
Even had lily turf been hardy here, would there
be any point in planting it? Would our cities be .
enriched by copying Texas or California? When
discussing the merits of a garden or planting, a
question that should be asked is, “Is there any
There there?” In other words, can the observer
(our participants in the game — remember
them?) tell where they are? Does a garden reflect
the sensibilities of the region and complement
the natural landscape? Do the colors, textures,
and choice of plants impart any sense of place?
Once again, this is not an indictment of any
style of garden that seeks to create a feeling of
another culture or region. Shaded inner-city
homes, by virtue of their age and architecture, are
more likely to be surrounded by gardens with
strong traditional, perhaps even formal, influ¬
ences. Inclusion of appropriate signature plants
in any area garden regardless of its approach,
however, adds a unique touch.
In truth, we have barely begun to scratch the
surface of what can be successfully grown here
and what may become important signature plants
(and we’re not going to get much deeper unless
we’re willing to devote less space to socially-
correct impatiens and vinca). There is no such
thing as a bad plant — though I’ve cussed a few in
my day — only dull and unimaginative uses and
misuses. Well-chosen signature perennials, even
in limited numbers, can transform a mediocre
garden in short order. The character of peren¬
nials is so broad as to offer, literally, something
for everyone. Every horticultural effort, no matter
how different from one’s own taste, should be
applauded and encouraged, especially when the
gardener displays the courage of his or her con¬
victions. (There are, of course, some astroturf-
and-lava-rock-people out there, but they are, most
likely, victims of unhappy childhoods, and they
should be discussed in a different forum, such as
Psychology > Today.)
The perennials I’ve highlighted as indicative of
our regional horticulture (and there are other
plants, especially trees and shrubs) signify the
special quality of our gardens and the beauty of
the natural landscape. They evoke the grandeur of
the plains, the mystery of the mountains, and the
dramatic palette of color with which nature
painted the land. Most of all, they reflect the spirit
of the people who call Colorado home. 7
Rob Proctor is the author of Antique Flowers: Perennials
(Harper and Row, 1990) and the forthcom i ngAntique Flowers:
Annuals (Harper and Row, 1991) He combines his love for
gardening with his botanic drawing; he writes and illustrates
for many publications, including The Denver Post column
“Front Range Gardeners.”
Sources for More Information on Perennials
Armitage, Allan M. Herbaceous Perennial Plants: A
Treatise on Their Identification, Culture, and Gar¬
den Attributes. 1989. Varsity Press, Athens, GA.
Brown, Emily. Landscaping with Perennials. 1986.
Timber Press, Portland, OR.
Chatto, Beth. The Dry Garden. 1978. J. M. Dent and
Sons, London.
Clausen, Ruth R. and Nicolas H. Ekstrom. Perennials for
American Gardens. 1989. Random House, New
York.
Coates, Margaret K. Perennials for the Western Garden:
The Amateur Gardener’s Fieldbook for the Growing
of Perennials, Biennials, and Bulbs. Pruett Publish¬
ing Co., Boulder, CO.
Cox, Jeff. The Perennial Garden: Color Harmonies
through the Seasons. 1985- Rodale Press, Emmaus,
PA.
Drew, John K. Pictorial Guide to Hardy Perennials.
1984. Merchants Publishing Co., Kalamazoo, MI.
Harper, Pamela and Frederick McGourty. Perennials :
How to Select, Grow, and Enjoy. 1985- HP Books,
Tucson, AZ.
1 Hill, Lewis. Successful Perennial Gardening: A Practi¬
cal Guide. 1988. Storey Communications, Pownal,
VT.
Hudak, Joseph. Gardening with Perennials. 1985.
Timber Press, Portland, OR.
Lima, Patrick. The Harrowsmith Perennial Garden:
Flowers for Three Seasons. 1987. Camden House
Publishing, Camden East, Ontario.
Sinnes, A. Cort. All About Perennials. 1981. Ortho
Books, San Francisco, CA.
Taylor Guide to Perennials. 1986. Houghton Mifflin,
Boston, MA.
Thomas, Graham S. Perennial Garden Plants. 1976.
J.M. Dent and Sons for the Royal Horticultural Soci¬
ety, London.
Ibid., Plants for Ground-cover. 1970. J.M. Dent and
Sons for the Royal Horicultural Society, London.
Wyman, Donald. Shrubs and Vines for American Gar¬
dens. 1969- Macmillan Co., New York.
The Tethyan Garden
by Panayoti Kelaidis
In an age when information and materials can be
transmitted around the globe in a matter of mo¬
ments, it is hard to imagine the early pioneers
including a few potted fruit trees and even flow¬
ers on the first treks into the West. As they moved
their wheelbarrows and wagons farther and
farther into drier and more desolate regions,
more and more possessions were discarded.
Early accounts describe the Oregon trail littered
with chests of drawers, sets of china, excess cloth¬
ing, and other nonessential possessions of the
naive pioneers. No doubt, many of their potted
plants perished. Those that survived were among
the most treasured trophies of the trip, and these
form the core of our Western garden-plant
palette.
It’s ironic that the shrub roses, lilacs, and old-
*
fashioned perennials that were first planted in the
new land to remind the settlers of the Midwest
were usually natives of Europe or Asia. They had
changed many hands and generations from the
time they were first domesticated, traveling pro¬
gressively westward in the process. To this day,
only a fraction of the plants sold in Western nurs¬
eries are Western natives. Many plants being sold,
however, do have a good deal of tolerance for
drought, heat, and cold bred into them simply by
surviving the trip, not to mention surviving over
time in the Western landscape.
\
,
The perennial “boom”
Over the last ten years, there has been a great ,
resurgence of interest in traditional garden
plants, particularly herbaceous perennials, f
Peonies, daylilies, daisies of all sorts, and the
whole range of flowering trees and shrubs are
joining in to liven up the dull and uniform look of
turf- and conifer-planted suburbia. In the water¬
conscious Western states, this movement some¬
times hybridizes with xeriscape: creative garden¬
ers attempt water-thrifty flower borders to re¬
place the endless expanses of green.
I have always had an interest in sensible,
water-wise gardens. High mountain ranges of the
world catch the moisture borne by prevailing
winds, producing rain shadows, or dry areas, on
the leeward side. These areas are home to a great
many vigorous, heat-tolerant perennials useful
for covering ground around the periphery of the
Rock Alpine Garden. I aim to select heat- and
drought-tolerant plants since this garden is fully
exposed to the sun and wind. Water systems in¬
variably break down during long vacations and
hot spells, so plants that can endure or even thrive
on neglect are always preferable. After a number
of years, I noticed that plants able to thrive during
the hottest weather share many similarities. Most
are silvery or grey of leaf. They often have thick,
attractive foliage that holds up well in the hot sun
and worst summer weather. Their flowering sea¬
son tends to last longer, and they can be planted
with impunity during the hottest spells.
Again and again I have observed that the per¬
ennials that perform best in Colorado gardens
tend to be members of the same group of
families: the Composites are particularly numer¬
ous, as are plants in the Figwort, Mint, Cress, Pea,
and Borage families. These families include some
of the showiest native plants in the American
Southwest. They also include the largest groups
of plants that occur throughout the Mediterra¬
nean Basin, and Western and Central Asia where
our Western American climate finds its closest
parallel in temperatures and moisture regimes.
Thousands of wild flowers occur in the cold, dry
steppes of Eurasia, and only a fraction of these
have ever been grown, tested or observed for
their potential as ornamental plants in our region.
Why not create a garden where a representative
sample of these could be tested? And why not test
them so they can resemble a real perennial bor¬
der, with artistic coordination by size and color?
In the autumn of 1986, the first seeds were or¬
dered for a delightful experiment I have come to
call the Tethyan border, for reasons I will explain
later. An east-facing strip 90 feet long, across from
the Hildreth Garden pool at DBG, was selected
where only temporary displays had been featured
in the past. The soil there probably had been
amended years before, and was left as is, a deep
clay loam. When there is a shortage of rain, the
garden receives about an inch of water by over¬
head irrigation every two weeks or so. No mulch
has been applied, and we take great care not to
step on the soil, which is easily compacted. The
Mediterranean flavor of this garden might be en¬
hanced by an informal planting of Mediterranean
and Western Asian wild flowers.
The Daisy Family (Compositae)
Various daisies are characteristic of and so abun¬
dant throughout the Rocky Mountains that one
eminent Englishman has recommended the
range be renamed the Daisy Chain. Some groups
of daisies that occur in Colorado, like the yarrows,
pussytoes, and fleabanes, are identical to species
found throughout the mountains of the Northern
Hemisphere. The yarrow selected for this border
is the almost succulent, ever-silver Greek yarrow
( Achillea ageratifolia ) from the Balkan penin¬
sula. This is offered by a number of nurseries in
the Denver area, although it is rather uncommon
elsewhere around the country. The flowers are
larger and more daisy-like than other yarrows, on
stems only five or six inches high. The thick mat of
foliage, present at all times of the year, makes this
plant an ideal small-scale ground cover.
Like the achilleas, hawkweeds are exception¬
ally well-represented in the Old World. The
woolly hawkweed ( Hieracium lanatum ) unfor¬
tunately is not evergreen. Nevertheless, its prin¬
cipal appeal is also its leaves, which are oval and
similar in size and whiteness to a sand dollar. It
produces a constant succession of foot-high stems
with soft yellow dandelions just pretty enough to
let be. This may not sound irresistible, but
everyone who sees those velvety white leaves
wants the plant.
The genus He lichry sum (sometimes known as
curry plants due to their spicy, characteristic
aroma) is distributed primarily in the Southern
Hemisphere. A secondary center of distribution
occurs in the Mediterranean. One of the best-
known species of curry plants is the Virgin’s plant,
Helichrysum virgineum, from a few islands and
the Athos Peninsula of Greece. The wide, plush
cushions of bluish-white leaves are appealing,
and the everlasting flowers are attractive both in
pink bud and when they open their rustling
flower clusters.
Virtually every weed has a glamorous cousin
that may even be a challenge to grow. This is 9
certainly true of knapweeds, which have become
serious pests on our highways, but plants like the
pinecone bachelor’s button ( Centaurea conifera
or Leuzea conifera ) are never quite common
enough. This rare Spaniard produces a basal
rosette of jagged foliage that is certainly attractive
in its own right. The real show begins in July with
huge, pinecone-like buds with overlapping sil¬
very scales. The flower itself is a small tuft of blue
that lasts only a few days, while the huge
handball-size seedhead, now resembling an ar¬
tichoke, keeps expanding. In August, the
pinecone suddenly opens to release the fluffy
seedheads. The involucre is just as beautiful after
flowering or when releasing its seeds as most
plants are in the peak of flower. This delightful
plant attracts a great deal of interest throughout
the long summer months.
Centaurea bella is found at the other end of the
Mediterranean, around the Black Sea. The jagged
leaves have an interesting two-toned color. They
form a neat mat, with large pink bachelor’s but¬
tons produced on foot-tall stalks for most of the
month of June. This is a fine edging plant with
ground cover potential. In recent years, it has
appeared in several local nurseries.
The Figwort Family (Scrophulariaceae)
In the Rockies, few spectacles impress visitors
more than the vast fields of penstemons and
paintbrushes that color the high mountains blue,
scarlet, pink, and purple for much of the summer
season. Both genera ( Penstemon , Castilleja ) are
practically restricted to Western North America,
and both are in the Figwort family. In Eurasia, two
large, abundant genera of Figworts are the
foxgloves and mulleins. Both are mainstays of
traditional gardens, and yet, aside from the com¬
mon purple foxglove {Digitalis purpurea), most
Digitalis are sun-loving, drought-tolerant
Mediterraneans that thrive in Colorado.
Three species are incorporated into this bor¬
der so far. A tall form of the giant yellow foxglove
{Digitalis grandiflora), discovered by Jim and
Jenny Archibald, the premier collectors of unus¬
ual alpine and perennial seed in the wild, was
found in Southern Europe. Here in Denver, it
stands at the back of the border. This form not
only has larger flowers than do the forms in culti¬
vation locally, it also is a more vibrant yellow. This
fine plant is a vigorous, long-lived, long-blooming
perennial for the Colorado garden that seems to
tolerate almost any soil or sun exposure.
Seed of the rusty foxglove {Digitalis fer-
ruginea) was also collected by the Archibalds in
Greece. This species resembles the better-known
woolly foxglove {Digitalis lanata ), only the stems
are even taller — commonly passing four feet in
height — and the pouchy flowers are stained deep
orange-brown. From a distance, this plant makes
little impact, but up close it is strangely alluring.
Thus far, three mulleins have been incorporated
into the garden. Verbascum olympicum grows up
to ten feet in height, and a grouping looms over
the back of the border like a benevolent bevy of
giants. Through the summer, the modestly
branching inflorescences produce an almost con¬
stant succession of yellow flowers resembling
butterflies. Verbascum bombyciferum is an out¬
standing foliage plant, growing a huge rosette of
felted white foliage like a tobacco plant in ermine.
The flower stalk is just as woolly, shorter than
the previous species and more interesting than
pretty. Even out of bloom, the gaunt flower stalk
holds a sort of cactoid fascination, like an
anorexic saguaro.
Verbascum densiflorum has the same fascinat¬
ing rosettes, felted with tan indumentum. Here
the flowering stems are finely branched into an
intricate mesh of tiny yellow flowers. The weedy
tendencies of common mullein {Verbascum
thapsus) have frightened many gardeners away
from the dozens of stately wild mulleins of the
Mediterranean Basin.
The Mint Family (Labiatae)
No family is more characteristic of the Mediterra¬
nean than the mints. Anyone who has traveled in
Spain or Greece in the summer will remember
the rich aroma that hangs over the countryside,
imparted by thymes, lavenders, and innumerable
other mints. Most people associate the mint fam¬
ily with herb gardens, but many garden peren¬
nials belong here, too. A number of unusual
species of creeping thyme are used as edgings in
this garden, but the real treasures of this family lie
in the genera Salvia and Stachys.
Clary sage {Salvia sclarea ) is an important
medicinal herb, and its essential oil is valuable in
a number of industries including perfume and I
tobacco. There are two little-known variants of ^
traditional garden clary: the variety turkestanica
appears to be reliably perennial. It blooms in late
June and early July, and is generally a yard in
height at most. The Archibalds noted a clary of
special size and brilliance in Anatolia, and col¬
lected seed. They call this “Super clary,” since it
grows six feet tall or more and has bracts of
especially luminous purple. It has a remarkably
protracted bloom season extending through July
and much of August. It is biennial, but produces
such a bounty of seed that its future in cultivation
is assured.
Numerous variations on the common Euro¬
pean meadow sage occur throughout Eurasia.
Salvia pratensis itself has paler and brighter color
forms, and there are giant cousins such as Salvia
haematocalyx that are sometimes submerged
into the common species. A number of spire-like
meadow sages are dispersed through this border
for their long season of bloom and bright blue or
purple flowers. Salvia hypargeia, another Ar¬
chibald introduction from Turkey, has luminous
lavender spires in June. Its large flowers are en¬
hanced by woolly, white, strap-shaped leaves that
make it attractive even when it’s not blooming.
The most famous foliage plant in the genus is
silver sage ( Salvia argentea ). It was purposefully
omitted from the border because of its floppy
flowers, but several close relatives are here. Sal¬
via microstegia has leaves only slightly less silver
than 5. argentea ; its flower stems are sturdy, up¬
right, and up to five feet in height. The white
flowers glisten through much of June. This has
proven itself a reliably perennial background
plant for the border.
Two dwarf silver sages are just as woolly as
their better-known cousin. Salvia candidissima is
rarely more than a foot in height in full bloom. Its
leaves have shiny white, adpressed hairs, and are
attractive through the entire growing season.
They have ragged leaf margins that distinguish
even the smallest seedlings from the other silver
sages. It is the earliest salvia to bloom in Col¬
orado, starting as early as April most years. It is a
fine addition to the front of the border. Salvia
frigida blooms a few weeks later, with congested
clusters of lavender flowers on 8” stems. The neat
foliage rosettes are gray rather than silver, but
pleasing in a quiet, reserved way.
The Archibalds have made a point of seeking
out some of the more obscure Turkish salvias,
and many years will be required to evaluate all of
their collections. From my observations, two of
their introductions seem to have unquestionable
merit as garden plants. Salvia cyanescens may be
one of the smallest-flowered salvias, but the
blooms are produced in such numbers, and are
such a lively tone of blue-lavender that it merits
space in all but the most gaudy of borders. Here
again the lovely flowers are set off by foliage; this
plant’s is absolutely gorgeous. The unflowered
rosettes have such sleek, silvery white hairs and
crisp leaves that they resemble some exotic
gesneriad— yes, even Jankaea, that impossible
cliff plant of Mt. Olympus — while being easily
accommodated in any Colorado soil or garden.
Salvia ringens dispenses with subtlety and de¬
licate charms. Here, gigantic two-inch electric
blue flowers are flaunted for much of the first half
of summer, on five- or six-foot stems. The foliage
is attractive as well, a deep blue-green mound of
pinnate leaves that are heavily textured like some
sort of expensive corduroy fabric.
The variety of salvias in this small garden repre¬
sents only a small fraction of the wealth contained
in the genus. The few representatives of the genus
Stachys likewise hint of greater wealth that must
still exist in the wild. Stachys usually calls to mind
the common lamb’s ear ( Stachys byzantina ), with
soft, furry foliage and negligible flowers. It has a
number of close relatives with similarly furry
foliage, but with much more dramatic bloom:
Stachys germanica is something of a giant with
large pink blossoms over downy white leaves on
stems a yard or more high. Stachys thirkei is a
compact mat-former with fuzzy leaves and deep
pink flowers. Possibly the most promising new
Stachys is S. inflata, which forms a shrubby
mound rather like a lavender, only with foliage of
powdery whiteness. The flowers have baggy
calyces, hence the specific epithet, and very attrac¬
tive large pink trumpets. The most dramatic de¬
parture for the genus is S. alopecuroides which
forms neat green rosettes, and has flowers on 10”
stems in a lovely shade of primrose yellow.
As xeriscape and water-conscious gardening
gain popularity, so too will the role of the mints in
our gardens. Not only are most members of this
family drought-resistant, but their bloom season
extends for weeks on end in the summer months.
Once spent flowers are removed, the foliage is
often attractive for much of the remaining year.
The Cress Family (Cruciferae)
Only a few cresses have been included in this
border. Alyssum montanum is found over a wide
range of elevations and habitats in the Mediterra¬
nean. In gardens, it can make long-blooming edg¬
ing, a rock garden specimen, or a small-scale
ground cover. It resembles a prostrate basket-of-
gold ( Aurinia saxatilis ), with better foliage that
keeps the plant decorative when the flowers are
not in evidence. Barbarea vulgaris is one of the
many universal yellow cresses that have natu¬
ralized around the world. The variegated cultivar,
however, has a strange attractiveness even when
the cheerful yellow flowers are past bloom. It
seems to come absolutely true from seed, and
therefore makes a much more welcome garden
plant than its weedy progenitor.
The Pea Family (Leguminosae)
Astragalus may be the largest genus of showy,
temperate climate plants in both Eastern and
Western hemispheres. In the garden, unfortu¬
nately, more than most other groups of hardy
plants, the peas tend to be either temperamental
or thoroughly weedy. A single broom ( Cytisus
caucasicus) is slowly establishing itself in the
back rank of the garden.
The Euphorbia, Campanula, Poppy and
Scabiosa Families (Euphorbiaceae, Campanu-
laceae, Papaveraceae, Dipsacaceae)
Although euphorbias occur in the New World,
they comprise a far less conspicuous element of
our natural landscape than they do in Africa and
Eurasia. Shrubby euphorbias often dominate hill¬
sides throughout the Mediterranean, and some of
these make outstanding garden plants. Two com¬
pact, succulent euphorbias from the Eastern
Mediterranean make a year-round impact in the
border. Euphorbia rigida resembles the rather
weedy E. myrsinites that is often used as a ground
cover or xeriscape plant in the Denver area. It is
almost twice as tall, however, and far less prone to
invasiveness. The flowers are a vivid chartreuse
that combines surprisingly well with other colors.
Euphorbia anacampseros promises to be another
fine addition to the local garden scene, for this
low succulent, looking like some giant prostrate
sedum, has flowers of a deep purple-red in early
spring.
A number of campanula species occur
throughout North America, but in Western Asia
and Southern Europe several hundred species
thrive in practically every habitat imaginable.
Some of the loveliest of these are considered
greenhouse plants in wet climates, but are easily
grown under ordinary garden conditions in Col¬
orado. Campanula incurua is a relatively lo¬
calized plant that grows on cliffs in northern
Greece. Seed of a particularly attractive ice-blue
form was collected by the Archibalds, and it has
proven perennial in part shade under the buck¬
eye at the north end of this garden. The large,
tubby flowers resemble Canterbury bells, but the
silvery, hairy foliage rosette is evergreen, and the
12 entire habit of the plant is very pleasing in a
garden setting.
Closely allied to Campanula, the genus
Michauxia commemorates a great French family
of botanists who pioneered botanical explora¬
tion in both the Eastern Mediterranean and the
Southeastern United States. Possibly the most
dramatic species in this genus is sure to strike
terror in the mouths of most of us: Michauxia
tchihatchewii is a monocarpic perennial, dying
after blooming and setting seed, that forms a
large, deep blue-green rosette of toothed, sym¬
metrical leaves its first and second years. If the
conditions are perfect, it shoots up a stem a yard
or more in height, with more than a dozen pure
white flowers, each 3 to 4 inches across. Superfi¬
cially, it resembles some sort of widely flared,
nodding lily far more than a campanula. Bloom¬
ing as it does for weeks on end in midsummer,
this is sure to be a valuable addition to sunny
gardens in warm climates.
In the Rockies, the best-known member of the
poppy family is prickly poppy, Argemone
platyceras, although many more species of pop¬
pies occur at lower altitudes in the Southwest.
Poppies are an important element of the Eurasian
steppe flora. The horned poppies are particularly
widespread in coastal areas and on sandy deserts
of Western Asia. The yellow horned poppy
( Glaucium flavum ) may be the most common in
cultivation. It forms a neatly scalloped basal
rosette, covered with fuzzy white hairs. The flow¬
ering stems rise to a foot or foot and a half, with
honey-colored flowers opening daily for weeks in
early summer. When the petals drop, the stigma
and ovary swell into a long, horn-like seed pod
responsible for the common name. It makes for a
dramatic specimen in or out of bloom.
The Scabiosa family contains a number of gen¬
era that form an important component of sunny
meadows throughout Eurasia. Particularly strik¬
ing in large gardens, the genus Cephalaria has
many giant species with huge, yellow blossoms
resembling giant scabiosas. These tolerate a wide
range of soils and exposures and make vigorous
additions to large borders. Since some species
can grow over 8 feet tall, it is important to place
them with thought for their ultimate dimensions.
Cephalaria tatarica grows over a wide range in
Central Asia. It is particularly lovely in midsum¬
mer when its pale yellow pincushion-like flowers
combine elegantly with late-season lavenders and
blues.
Combinational themes
in the Tethyan Garden
Most perennial gardens are designed for the
combinational effect of their flowers. Since so
many Mediterranean and Steppe climate plants
have substantive foliage that holds up well most of
the year, leaf color and texture can become a
gratifying way of organizing such a garden. After
all, few plants bloom satisfactorily for more than a
fraction of the calendar year, but evergreen
foliage in our sunny climate is a year-round pro¬
position. Most Tethyan plants have flowers in pas¬
tel shades: lavenders and blues, whites, pinks, and
primrose yellows. Few of the plants in this garden
have flowers with colors that clash against one
another, so color coordination is mostly a matter
of balancing and combining pastel shades in
pleasing ways. The dramatic contrasts of foliage
color and shape, as well as plant size, demand
greater attention. In order to enhance the illusion
of distance, plants with larger flowers and leaves
are generally concentrated to the front of the
border, while those with finer-textured flowers
and leaves are massed to the back. In order to
avoid a cluttered feeling, plants with leaves of
similar sizes and tints are concentrated together,
excepting for plants of particularly dramatic
forms and shapes, such as Michauxia and Leuzea
which demand and deserve to stand out from the
rest of the pack.
The Sea of Tethys
Like evolution, continental drift seems to be mov¬
ing from the realm of controversial theory to
near-universal acceptance as fact. A generation
ago, botanists regarded the prospect of continents
drifting about and running into one another as
preposterous. As early as the thirties, however, a
Soviet botanist named M.G. Popov noted tremen¬
dous parallels not only among families, but gen¬
era and even species of plants of the American
Southwest, the Mediterranean Basin, and Western
and Central Asia. He coined the term Tethyan (for
the ancient sea that was common to both hemis¬
pheres) to characterize the plants common to
these regions. He postulated that many of the
plants now separated by mountains and oceans
derived from common ancestors that, during the
Age of Reptiles, grew along the coasts of a vast sea
that bordered the region to the south of the area
now split into East and Western Hemispheres.
Herbaceous plants are notoriously absent from
the fossil record. However, whatever their pre¬
cise origin or genetic relationship in the mists of
time, a strong current of commonality unites the
floras of the American Southwest and the Eura¬
sian steppes.
Plants from these Tethyan regions have, aside
from good aesthetics, a durability, a resilience in
the landscape, that puts them in the front ranks of
our gardens. Whether they drifted with the conti¬
nents or traveled on wagon trains to the West,
Tethyan plants form the basis of horticulture in
semi-arid Continental climates. Come and ob¬
serve a little-known selection of species from the
Eastern Hemisphere of Tethys that are growing
in a dryland border here at Denver Botanic
Gardens.
Panayoti Kelaidis has been Curator of Denver Botanic Gar¬
den’s Rock Alpine Garden for ten years. His interests extend
far beyond conventional alpines to include native wild flowers
and drought-tolerant plants from both Northern and Southern
Hemispheres.
References for Tethyan Plants
Eyre, S.R., comp. World Vegetation Types. 1971. Co¬
lumbia University Press, New York.
Gleason, Henry A. The Natural Geography of Plants.
1964. Columbia University Press, New York.
Good, Ronald D. The Geography of the Flowering
Plants. 1974. 4th edition. Longman, London.
Sauer, Jonathan D. Plant Migration: The Dynamics of
Geographic Patterning in Seed Plant Species. 1988.
University of California Press, Berkeley.
Takhtadzhian, Armen L. Floristic Regions of the World.
1986. University of California Press, Berkeley.
13
Successful gardeners agree that soil preparation
is the secret to a flourishing perennial garden.
Proper soil not only provides the plants with
nourishment, it also creates an environment for
healthy root development and water absorption.
A vast majority of perennials like well-drained
soil; standing water will kill most plants by suf¬
focating the roots. Loose, rich, deeply cultivated
soil lets excess water drain away and encourages
strong root growth.
Rototilling an area can’t do the job required for
deep cultivation, because a tiller only digs the soil
four to six inches deep. Perennials need deeper
cultivation; the more area they can use for root
growth, the more food and water is available to
them. A spade should be used to turn the soil 10 to
12 inches deep. Although this may seem a task,
plants respond to such deep cultivation with
stronger and more substantial growth.
Don’t work the soil when it is very wet because
you’ll encourage the formation of hard clods.
However, the soil should be slightly moist when
you spade it; dry soil is difficult to work and
erodes easily.
Very poor, hard-to-work soil may require
trenching. This procedure ensures deep cultiva¬
tion and aeration, and offers the opportunity to
get additives like organic matter and fertilizer
deep down into the soil. Dig a trench along the
proposed garden bed, stacking that soil to one
side on a tarp or placing it in a wheelbarrow. Then
shovel the spaded soil from the next trench into
the first area. Continue this to the end of the plot,
filling the last trench with soil taken from the first
trench.
One of the finest additives for soil is compost. It
14 provides organic matter for soil and acts as a
Soil Preparation
for Perennials
Virginia M. Weigand
conditioner. Compost is made from leaves, grass
clippings, small twigs, vegetable scraps from the
kitchen, and garden soil. Composting recycles
wastes, thus cutting down on the amount of mate¬
rial hauled to the dump.
Gardeners can make their own compost pile
neater and more manageable by piling the com¬
posting materials in a wooden bin or a chicken
wire enclosure about three feet high and four feet
square, placed in a convenient corner. When the
lawn is mowed, grass clippings can be dumped
into the enclosure. Add leaves, small twigs, and
other plant refuse. Layer the material with garden
soil to provide the bacteria and other organisms
that are needed for the decaying process. The
material should be turned occasionally with a
spading fork to aerate it, which also speeds up
decay, making your compost ready for the gar¬
den.
Don’t put weeds that have gone to seed, or
animal wastes like fat and meat scraps in the
compost pile. Weed seeds will come back to
haunt you, and animal products can make the
compost heap smell, become moldy, and draw
flies and other insects.
Compost improves drainage and soil structure,
and is a real boon to Rocky Mountain gardeners
since soils in this area need organic matter.
Within one 50-foot garden plot, soil can vary from
being too clayey to being too sandy. Organic mat¬
ter like compost will improve both these condi¬
tions. Don’t add sand to clayey soil; it turns the soil
into something akin to concrete.
Many brands of commercial compost are on
the market, available through garden centers,
nurseries, grocery stores and other outlets. Some
of these may contain sawdust, wood chips, straw,
stemmy plants and other products with very little
nutritional value. If you only need to improve
your soil’s structure, these lower-grade composts
are fine, but the best quality commercial compost
products are generally those that have been mar¬
keted by established companies for many years.
Barnyard manure, peat moss and other organic
materials can be expensive and may not be avail¬
able when needed for the garden. Making com¬
post in the backyard means you have a source of
organic matter readily available and at no cost.
Compost can be added to the garden anytime, but
ideally it’s done in the fall.
Before the ground freezes, place two inches of
compost on top of the soil. Two to three inches of
shredded sphagnum moss also may be added to
lighten and aerate the soil even more. Then spade
the garden plot deeply, leaving it in large clumps.
Don’t rake the soil; let the winter snows and the
freezing and thawing during the cold months
soften it. This will provide the gardener with soil
that’s easy to rake and till in the spring. If the plot
is spaded in the spring when soil is usually at its
wettest, clods may result that can’t be broken up
during the entire summer season.
Fertilizers may need to be added to provide a
good growing medium, if your soil is deficient in
nutrients. You can supplement your plants’ nutri¬
tional needs with commercial, synthetic fertiliz¬
ers or ones from natural sources. Both types of
fertilizers are sources of phosphorus, nitrogen,
potassium and other elements necessary for op¬
timal plant growth. Barn manure is an excellent
additive, as long as it is aged. Fresh manure will
burn and destroy plants because of its high am¬
monia content.
Finally, be patient. Soil conditioning is a con¬
tinual process. Once the perennial garden is es¬
tablished, of course you won’t, and can’t spade it
every year. This is all the more reason to prepare
the soil well at the outset.
Insect and weed control, and normal watering
are all that are needed for the perennial garden’s
first year or two. But perennials spread, usually
from side shoots or runners, which causes crowd¬
ing. Plants can be removed for division and re¬
planting by carefully lifting them with a spading
fork. This is also your chance to rework the soil,
spading deeply and using additives as suggested
above. Then replant the perennials as soon as
possible.
As the garden grows, perennial plants will
show the effects of good soil. Strong stems, beau¬
tiful and abundant blossoms, and a gorgeous,
natural effect will repay the gardener for all this
work.
Editor’s Note: The above describes soil prepara¬
tion for a perennial garden using traditional gar¬
den perennials, most of which require a relatively
moist, rich soil. For those seeking to experiment
with native and/or xeric (drought-tolerant)
plants, you may only want to cultivate the soil and
disregard the amendments. These plants survive
on, and often demand, an infertile, dry soil.
Virginia M. Weigand, a graduate of Colorado University Col¬
lege ofjournalism, gardens in Golden, CO. She wrote a news
column for The Golden Transcript for forty years; she con¬
tinues to write a weekly weather column, incorporating gar¬
den tips.
Sources for More Information on Soil Preparation
Balfour, Evelyn B. The Living Soil. 1950. Revised edi¬
tion. Devin-Adair, New York.
Donahue, Roy L. Soils.- An Introduction to Soils and
Plant Growth. 1983. 5th edition. Prentice-Hall, En¬
glewood Cliffs, NJ.
Harpstead, Milo I. Soil Simplified. 1988. 2nd edition.
Iowa State University, Ames, LA.
Logsdon, Gene. The Gardener’s Guide to Better Soil.
1975. Rodale Press, Emmaus, PA.
Organic Fertilizers: Which Ones and How to Use Them.
1973. Rodale Press, Emmaus, PA.
Parnes, Robert. Organic and Inorganic Fertilizers.
1986. Wood End Agricultural Institute, Vernon, ME.
Severson, Ronald C. Essential Elements and Soil
Amendments for Plants. 1988. U.S. Govt. Printing
Office, Washington, D.C.
Tompkins, Peter. Secrets of the Soil. 1989. Harper &
Row, New York.
Tate, Robert L. Soil Organic Matter: Biological and
Ecological Effects. 1987. Wiley, New York.
Sources for More Information on Compost
Campbell, Stu. The Mulch Book: A Guide for the Family
Food Gardener. 1973- Garden Way Publishing Co.,
Charlotte, VT.
Catton, Chris. The Incredible Heap: A Guide to Compost
Gardening. 1984. St. Martin’s Press, New York.
Community Composting Education Program. Master
Composter Resource Manual. 1987. The Program,
Seattle, WA.
Hills, Lawrence D. Fertility Without Fertilizers: A Basic
Approach to Organic Gardening. 1977. Universe
Books, New York.
Howard, Albert. Aw Agricultural Testament. 1940. Ox¬
ford University Press, New York.
Minnich, Jerry, The Rodale Guide to Composting. 1979.
Rodale Press, Emmaus, PA.
Organic Gardening and Farming. The Complete Book
of Composting. I960. Rodale Books, Emmaus, PA. 15
Industrial-Strength
Perennials for Home and Office
by Ray Daugherty
My interest in what I call industrial-strength per¬
ennials began at an early age, when I first became
fascinated by seeds. How could a plant produce a
little package that, after being scooped out of a
fruit, allowed to dry, and set on a shelf for an
extended period, then suddenly burst forth into a
strong new plant when put in the garden? This
is truly the most basic form of the concept
industrial-strength. Later, I learned that many of
my favorite plants weren’t grown from seeds at
all, but from cuttings, which, to my amazement,
were actually pieces of plant amputated from the
mother plant. My awe of the amount of abuse that
plants can not only survive, but even thrive on,
continues to this day, and has led me on a quest to
find, understand, and cultivate the toughest of the
tough, and to help introduce them to gardeners
and professionals in the green industry.
Over the last several years I’ve been happy to
notice an increase in the use of perennials, both
in large landscapes and in the home garden. At
the same time, I’ve been dismayed at the misun¬
derstandings and mistakes that occur regarding
when and how perennials are used in a commer¬
cial landscape, as well as how they fit into the
smaller, residential garden to help solve those
“problem spots.’’ In both these situations, indus¬
trial-strength perennials should take center stage.
What exactly is an industrial-strength peren¬
nial? First of all, it is an adaptable plant. Most
perennials that deserve this label (and it is a high
honor) will withstand sudden changes in their
16 environment without major damage to their
looks or their health, while other less-adaptable
plants are curling up and dying. Also, they are
usually hardy as well as heat-tolerant. Many can
take a good deal of drought, with some able to
thrive on only the sparse summer rains of Col¬
orado.
Secondly, industrial-strength perennials are
competitive. This means that they are big enough
to choke out surrounding weeds before the
weeds choke them out, or if they are smaller
plants, they can maintain themselves well enough
to come back vigorously once maintenance is
finally provided. This doesn’t mean that they have
to be invasive. In fact, it is often better that they
stay in place so that they meet the last criterion —
low maintenance .
Ideally, an industrial-strength perennial would,
once established, never require further mainte¬
nance. Unfortunately, all plants seem to produce
some part that becomes ugly if left in place on the
plant, be it last year’s withered foliage, old flower
stalks, unattractive seed heads, or the like. There¬
fore, a more realistic definition is that an indus¬
trial-strength perennial requires only minimal
removal of these unattractive parts, preferably
once a year in early spring. Also, the plant must
not be attacked by insects or disease to the point
of disfigurement, and it must be long-lived.
As with annuals, perennials can be used to
create summer-long color. This is done by using
one particularly long-blooming species, or by
combining several with different, yet overlapping
bloom times. Threadleaf tickseed ( Coreopsis ver-
I tied lata ) and pink tickseed ( Coreopsis rosea )
both work well as single-species mass plantings
due to their extended bloom period. Daylilies
( Hemerocallis hybrids) can be used alone, and
still achieve a long season of color, by mixing
cultivars that bloom at different times. One excel¬
lent daylily combination includes the cultivars
‘Pizza,’ Hyperion,’ and ‘September Gold,’ giving
color from early June until frost.
Combined plantings can be very subtle, or vi¬
brating with contrast, depending on the interplay
of texture, form, and color. A dynamic grouping
for a sunny, dry area might combine showy stone-
crop ( Sedum spectabile ), torch lily ( Kniphofia
uvaria), ravenna grass ( Erianthis ravennae),
hardy ice plant ( Delosperma nubigenum ), and
pineleaf penstemon ( Penstemon pinifolius').
Perennials can be used for more than summer
color. By choosing species with evergreen foliage
and/or early flowers, you can give a planting
color and mass before annuals can be safely
planted out and long before they fill in. In a large
commercial landscape, perennials can be used
near entryways to provide needed interest and
color all year long, or in large beds with shrubs
and annuals, for added permanence as well as
seasonal change.
One major advantage of using perennials
properly in a large landscape, as compared with
annuals, is to reduce maintenance costs.
Industrial-strength perennials, requiring only
cutting back and raking in the spring, offer great
savings in labor costs compared to annuals, which
need yearly soil preparation, planting, establish¬
ment, and removal. Some of the lowest mainte¬
nance perennials for large, shady landscapes are
lily-of-the-valley ( Convallaria majalis ), vari¬
egated bishop’s weed ( Aegopodium podagraria
‘Variegata’), and plantain lily ( Hosta species and
hybrids). Although some people malign the first
two for being weedy, for large plantings where
they won’t run over other plants, they are my
favorites. In sunny locations, threadleaf tickseed,
Siberian iris ( Iris sibirica ), butterfly iris ( Iris
spuria ), many ornamental grasses, and plume
poppy ( Macleaya cor data) are blessed with good
looks that require only a spring mowing to main¬
tain.
In the smaller landscape, industrial-strength
perennials can be used in unlimited ways. Larger
* ones like plume poppy and Arundo donax might
screen a private patio. Others, like Siberian iris,
showy stonecrop, Yucca sp., torchlily, and peo¬
nies ( Paeoniasp . ), can make small hedges, create
points of interest as specimen groupings, or form
the backbone of a perennial border. With charac¬
teristic longevity, non-invasiveness, and low
maintenance, they form a mature core of plants
around which more ephemeral perennials, bien¬
nials, and annuals can be planted, and prevent
that newly-planted look. Due to their tough con¬
stitutions, industrial-strength perennials’ most
desirable role may be in beautifying those “im¬
possible sites,’’ where conditions are formidable
and/or maintenance difficult.
A list follows that contains some of the best
industrial-strength perennials. Many are quite
common, but I think it’s important that we not
lose sight of their value simply because John Doe
already has them in his garden. Plants should be
judged solely on their individual merits. There’s
often good reason why a plant is popular. I hope
that many of the less common industrial-strength
perennials will also find their way into the hearts
and plantings of homeowner and commercial
landscaper alike.
Ray Daugherty received his B.S. in landscape horticulture
from Colorado State University. He is the propagator at Green
Acres Nursery in Golden, CO, where he focuses on bringing
industrial-strength, native, and unusual plants into the trade.
17
Some Industrial-Strength Perennials
Botanical Name
Month
of Bloom
Height
Moisture
Sun
Remarks
Achillea filipendulina vars.
Jun-Aug
2-5’
mod/dry
full
excellent midsummer color
Anemone hupehensis vars.
Aug-Sept
2-4’
mod
sun/shade
bold foliage, late color
Asclepias tuberosa
Jun-Jul
1’
dry
full
comes up late, sandy soil
Ceratostigma plumbaginoides
Aug
1-1/2’
mod/dry
sun/shade
good fall color
Cimicifuga racemosa
Jul
3-5’
mod
partial
excellent with shrubs
simplex
ramosa Atropurpurea’
Aug-Sep
3-4’
mod
partial
blooms later
Aug-Sep
3-4’
mod
partial
bronze leaves
Convallaria majalis
May-Jun
6”-l’
mod
shade
will tolerate dense shade
Coreopsis grandiflora
Jun-Sep
1-3’
mod
full
many varieties
verticillata vars.
May-Oct
1-2’
mod/dry
full
excellent in mass
rosea
May-Oct
1-2’
wet
full
best for wet spots
Dictamnus albus vars.
Jun
2-3’
mod
full
long-lived, pink or white flowers
Echinacea purpurea
Jun-Sep
2-4’
mod/dry
sun/shade
striking rose-pink flowers
Eremurus species and hybrids
Jun-Jul
3’
drv
sun
needs good drainage, showy spikes
Euphorbia epithymoides
May
2’
mod
sun
excellent foliage/fall color
Geranium x cantabrigiense
Jun-Sep
8-10”
mod
sun/shade
long-flowering ground cover
x ‘Johnson’s Blue'
May-Jun
2’
mod
sun/shade
may require cutting back
x oxonianum ‘Claridge Druce’
Jun-Aug
1-1/2'
mod
sun/shade
best pink geranium
psilostemon
Grasses:
May-Aug
2’
mod
sun/shade
excellent magenta flowers
Arundo donax
Sep-Oct
12’ plus
wet/dry
sun
use as screen, drought-tolerant
Calamagrostis arund. vars.
Jul-Dec
4-8’
mod
sun
fall and winter interest
Erianthis ravennae
Aug-Dec
6-8’
mod/dry
sun
long-lived, fall and winter interest
Helictotrichon sempervirens
Jul-Sep
2-4’
mod/dry
sun
evergreen blue-grey foliage
Hosta species/varieties
Jul-Sep
8”-3’
mod
shade
long-lived, foliage texture
Ipomoea leptophylla
Jun-Sep
3’
dry
sun
native, willow-like perennial
Iris aril-breds
May
2-3’
dry
sun
interesting colors
x germanica hybrids
May-Jun
2-4’
dry
sun
spectacular flower shower
pumila hybrids
Apr-May
6-12”
dry
sun
profuse early bloom, tough plants
sibirica hybrids
Jun
1-4’
wet/dry
sun
long-lived, excellent foliage
spuria hybrids
Jun-Jul
3-4’
mod or dry
sun
very drought-tolerant
Kniphofia uvaria hybrids
Jun-Oct
4-5’
mod/dry
sun
requires good drainage
Liatris punctata
Jul-Aug
1’
dry
sun
native
Liatris spicata
Jul-Aug
2-3’
dry
sun
showy spikes of purple flowers
Macleaya cordata
lul-Aug
4-8’
mod/dry
sun
bold foliage, use as screen
Mirabilis multiflora
Jun-Oct
2’
dry
sun
native, won’t transplant
Paeonia lactiflora hybrids
May-Jul
to 4'
mod/dry
sun/shade
very long-lived (50+ years)
Paeonia officinalis
Polygonum cuspidatum
May
2’
mod/dry
sun
earlier than P. lactiflora
‘Compactum’
Jul-Aug
2-3’
mod/dry
sun
excellent bank cover
Salvia x superba varieties
Jun-Jul
2’
mod
sun
bracts showy after flowers finished
Saponaria ocymoides
May-Jun
1-1/2’
mod/dry
sun
excellent for planted walls
Veronica liwanensis
May
2-6”
mod/dry
partial
fabulous blue flowers, evergreen
groundcover
Waldsteinia ternata
Apr-May
6-8"
mod
partial
evergreen, nice ground cover
Yucca baccata
Jun
2-4’
dry
sun
fruit edible, coarse texture
filamentosa
Jun
2-3’
mod/dry
sun
soft leaves, best flowers
glauca
jun
2-3’
dry
sun
fine leaves
Zinnia grandiflora
Jun-Sep
6”
dry
sun
excellent as mass planting
Shrubs That Can Be Used As Industrial-Strength Perennials
Botanical Name
Month
of Bloom
Height
Moisture
Sun
Remarks
Caryopteris incana
Aug-Sep
3-4’
mod/dry
sun
blue flowers, winter texture
Gutierrezia sarothrae
Sep-Oct
1-1/2”
dry
sun
yellow flowers, like dwarf
Chrysothamnus (rabbitbrush)
Hypericum patulum ‘Hidcote’
Jun-Oct
2-3’
mod
partial
huge yellow flowers
Perovskia atriplicifolia
Jul-Aug
3-4’
dry
sun
blue flowers with silver foliage
Vitex agnus-castus
Aug-Sep
4-5’
mod
partial
excellent, late blue flowers
From the Ground Up:
Woody Perennials
by Diane Ipsen
When we speak of perennials, most people as¬
sume this refers to the long-lived flowering plants
of the garden. In this context, perennials mean
herbaceous plants whose stems die back to the
ground in cold weather while their roots survive.
There are woody perennials as well, which in¬
clude trees, shrubs, and vines whose top growth
survives winter without dying.
In Colorado and other cold climates, a number
of shrubs are treated like herbaceous perennials
in that they are pruned to the ground in early
spring, either annually or every few years. This is
done for several reasons.
For one, the stems of certain woody plants
normally die down to the ground in Colorado
winters. Sometimes (but not too poetically) these
are called “die-back shrubs.” Another reason for
pruning certain shrubs to the ground is that they
look better if this is done. Compact growth can be
restored to a sprawling, leggy shrub, and addi¬
tionally, cutting back particular shrubs encour¬
ages more exuberant flowering.
Do not, however, impose this type of pruning
indiscriminately on other shrubs in the garden.
The woody plants that are treated like herbaceous
perennials all bloom on “first-year wood,” the
current year’s growth, as opposed to shrubs such
as lilacs or flowering almonds, whose flower
buds are formed the previous year. That is why
only the former can be cut to the ground in early
spring and still be covered with blossoms in
summer.
The following are a few of the woody plants that
should be treated as herbaceous perennials in
Colorado:
Annabelle Hydrangea ( Hydrangea arbores-
cens ‘Annabelle’)
This is a small, easily-grown shrub with large,
dark-green leaves and bold, white flower clusters
in mid-summer. It performs best when given a
moisture-retentive soil in light shade. Though
hardy, its top growth sometimes dies back in
winter. When this occurs, the stems are cut to four
inches or lower in early spring. As with all the
shrubs listed here, I recommend cutting back
‘Annabelle’ hydrangea in spring rather than fall
because of the mass and interest it adds to the
winter landscape. Hydrangeas, in particular, hold
their bronzy, dried flower heads all winter and
look attractive in a snowswept garden.
Blue Mist Spirea ( Caryopteris incana, C. xclan-
donensis )
Although the stems of this popular garden shrub
may not always die back in a harsh winter, a more
pleasing form and better flower display can be
achieved with a severe pruning at least every
other year. Without such treatment, the plant be¬
comes open and rangy, getting up to four feet in
height. By pruning it to the ground, blue mist
spirea is kept suitably small for use in the sunny
perennial garden. A haze of blue flowers appears
on the new growth in mid to late summer, provid¬
ing cool contrast to hot colors. The plant is
drought-tolerant as well. The tan seed heads of
blue mist spirea are handsome in the winter gar¬
den, so again, reserve pruning for early spring. 19
Kelsey Dogwood ( Comus sericea ‘ Kelsey f)
This dwarf, red-stemmed dogwood is another
woody plant whose top growth dies entirely dur¬
ing a cold winter. Since the stems turn a more
brilliant red when frozen, do not cut them back
until spring in order to enjoy the color against the
snow. Kelsey dogwood becomes quite leafy and
dense in one season, reaching a tidy two feet in
height. It needs a moderate amount of moisture.
Potentilla ( Potentilla fruticosa)
The woody varieties of potentilla thrive on being
pruned to the ground periodically. These long-
flowering shrubs tend to get squashed by the
snow, making them sprawl in an unattractive
manner. To correct this habit, potentillas can be
cut back every third spring. Because they bloom
on the current year’s growth, potentillas will pro¬
duce their yellow, white, apricot, or copper flow¬
ers faithfully the same year they are pruned.
Orange- Eye Butterfly Bush ( Buddleia davidii )
Sometimes called summer lilac in catalogs, this
species of butterfly bush behaves like an her¬
baceous perennial where winters are cold. Even
in the South, it is recommended to cut this plant
back to six inches before its spring growth begins,
since it blooms on current year’s wood. For this
effort, the gardener is rewarded with a long
bloom period: fragrant flower spikes last from
summer till fall, attracting butterflies all the while.
There are numerous varieties, with flower colors
ranging from pink to lavender, purple and white.
Rabbitbrush ( Chrysothamnus nauseosus )
Apache Plume ( Fallugia paradoxa )
These two are dryland native shrubs that do not
die back, yet benefit from periodically being cut
to the ground. Both grow four to six feet in height.
After the yellow flower heads of rabbitbrush have
bloomed in early fall, they dry to tan and are
lovely in the winter landscape. Apache plume’s
white stems bear single white flowers and drama¬
tic plume-like seed heads simultaneously, creat¬
ing a unique display. Sometimes, particularly
when irrigated, rabbitbrush and Apache plume
may grow too open and leggy. This is the time to
take them back to the ground. Both plants grow
rapidly, and some people recommend cutting
them back every spring.
Russian Sage ( Perovskia atriplicifolia )
Another drought-tolerant plant that one can ex-
1 20 pect to prune to the ground annually is Russian
, Chrysothamnus nauseosus
sage. This handsome plant is classified as a sub¬
shrub, and it dies back most years in Colorado.
Even if it doesn’t, flowering and overall strength
are bolstered by this treatment. Russian sage
grows three to five feet tall in a single season, and
is a striking accent plant. Its showy spikes of tubu¬
lar lavender-blue flowers in mid and late summer
are beautiful against its lacy grey-green foliage.
Other sub-shrubs which may die back in Col¬
orado include lavender ( Lavandula angus-
tifolia ), and some species of Hypericum.
Tree Mallow ( Lavatera thuringiaca )
This woody perennial is quite new to American
horticulture. At DBG, it has survived undaunted
for several years. Its large, clear-pink, mallow-like
flowers appear from mid-summer until frost. The
variety ‘Barnsley’ has white flowers with a rose
eye. Sun-loving tree mallow offers handsome,
sage-green foliage that is unusually lush and large
for a drought-tolerant plant. It grows three to five
feet tall in one season, and must be pruned to the
ground each spring for best effect.
Diane Ipsen holds a master’s degree in landscape architecture
and her practice focuses on residential design. She em¬
phasizes water-wise landscapes and likes transforming clients
into enthusiastic gardeners.
Perennials
in the Mountains
by Marty Jones
I first began landscaping in the mountains in
1974. As I learned more about plants, I became
frustrated by the lack of varieties recommended
for the mountain climate, as well as by the limited
offerings of wholesale suppliers, so I started to
experiment. In 1985, I found a permanent loca¬
tion for a garden center, and immediately began
planting perennials around the nursery wherever
I could. This made an attractive and informative
display for customers and myself as well. Every
year we have added to the garden, and continue
to do so. It is the best salesman I have.
However, it wasn’t until my involvement in
developing the Betty Ford Alpine Gardens that I
really had the opportunity to test a wide range of
perennials directly under my care and supervi¬
sion. Here, at an altitude of 8200 feet, these plants
have taught me an enormous amount in three
short years. I learn more every time I go in the
garden.
The main thing I’ve learned is that the moun¬
tain climate is ideal for growing perennials. They
thrive on the cool, dry, sunny days and cooler
nights, producing firmer, greener foliage, and a
more brilliant flower display for a longer period
of time. Also, the early, long-lasting snow cover
could not be a better mulch. In Vail, it usually
snows before the ground freezes, and lasts until
late March or early April, changing the climate at
ground level drastically. The low air temperature
last year was almost minus 25 degrees Fahrenheit,
while at soil level, the low was only 5 degrees
above zero. This accounts for the success of plants
that were thought not to stand a chance here, like
Raoulia australis, Delosperma nubigenum,
Euryops acraeus, heathers (. Erica and Calluna
species), barrenworts ( Epimedium spp. and hy¬
brids), waterlilies, Mexican phlox {Phlox meso-
leuca ), brooms {Cytisus, Genista species), and
many others.
These exotics aside, the old standby perennials
also thrive in high-altitude gardens: lupines
{Lupinus polyphyllus ), Delphinium hybrids,
shasta daisies {Chrysanthemum x superbum ),
irises, lilies, and columbines {Aquilegia x hy-
brida ), among others. Unfortunately, there are
many cultivars of these and other old favorites
that are not commonly offered, due to a Catch 22.
Garden center and nursery owners and person¬
nel are reluctant to carry plants they aren’t famil¬
iar with, and the public can’t buy a plant that isn’t
being offered.
Fortunately, there are some solutions to this
problem. One is for nurseries to plant substantial
demonstration gardens so their customers can
see what a mature plant looks like. This is espe¬
cially important with perennials, since they rarely
come close to their full potential while in a small
container. Another idea is for interested people,
both homeowners and professional plants peo¬
ple, to support and get involved with local botanic
gardens. These institutions should be on the cut¬
ting edge of horticulture, demonstrating new
plants to the public, and making material avail¬
able to the trade. Then the clamoring begins. A
new plant is shown and everyone wants it. Sud¬
denly there are availability problems — there’s a
demand for a plant that was unknown just last
year. Nurseries gear up, and sales are great. Then
the novelty wears off, and sales slump, sometimes
to the point where good plants are pushed out of
production once again, and so goes the cycle.
I’ve found that displaying plants in a garden
setting helps sales grow annually. Once the plants
are seen in friends’ and neighbors’ gardens,
interest continues to grow. Most gardeners like
diversity, so the better the selection, the better for
both the customer and the business.
It is sometimes difficult to obtain desired
plants. Searching, patience, and perseverance are
the secrets. I've searched for five years just to
obtain the seed of some plants, and then had to
wait another three or four to have enough to sell.
Sometimes it is as easy as attending the Denver
Botanic Gardens plant sale in the spring, or look¬
ing in the catalog selection at the Helen Fowler
Library for a mail order source.
Now, how to grow perennials best. The ques¬
tions most often asked of me are “What’s your
secret? How do you grow such vigorous plants?
How come mine don’t look like this?’’ There are 21
two answers: first, good soil preparation. We used
liberal amounts of peat and well-rotted manure in
the soil mix at the Betty Ford Alpine Garden, up to
50% peat and manure, and 50% rich topsoil for the
woodland and mixed perennial beds (some of
the other beds were leaner, depending on the
plants’ needs). This not only provides a great
medium for plant growth and water retention, it
also makes weeding much easier.
The other reason for the beauty and health of
our perennials has little to do with human effort.
It is the wonderful mountain climate. When peo¬
ple from out of town ask me, “How do you get
your plants to look like that?” I tell them to give
plenty7 of sun, night temperatures of 40 degrees,
and days not exceeding 85. Add two to four feet of
snow in November and don’t remove until April.
Where else can you provide this recipe but in the
glorious Rocky Mountains? So if you’re a gardener
in the high country, don’t despair. Rejoice. A
beautiful garden, filled with perennials, is within
your grasp.
Marty Jones owns and runs Colorado Alpines, Inc., a mail¬
order business specializing in rare alpine plants in Vail, CO.
This self-taught horticulturist is also garden director of the
Betty Ford Alpine Gardens, where he oversees over a
thousand different alpines and other perennial plants.
Perennials for Fall
by Lauren Springer
Come fall, green finally bids the leaves farewell,
making way for new foliage colors that before
only existed in blossoms. Gazes turn to the as¬
pen’s glamorous show. Gone are the deep blue
delphiniums, foamy gypsophilas, soft pink
peonies. Has the perennial garden closed up
shop for the season? Not necessarily.
After the seduction by the voluptuous floral
display of early summer, gardeners often face the
rest of the season with lagging enthusiasm. One
look at the changing beauty on the prairies and in
the foothills and mountains should cure this. Our
rich flora offers inspiring autumnal scenes. Fall is
not a wimpering finale; it can be a reprise of early
summer, in deeper, earthier, more mature tones.
There’s no reason why fall’s purple asters,
goldenrods, sunflowers, and deep blue mountain
gentians can’t come together in a garden as the
soulmates they are in the wild. Add a smattering of
native fall-bloomers from other parts of the coun¬
try, and a few exotics. Ornamental grasses rustling
in the cooler breezes, their panicles and plumes
backlit by a mellow autumn sun, help complete a
garden picture to bring the growing season to a
lovely close. Only the earliest scenes of spring —
sweeps of crocus and Iris reticulata in still-
22 dormant buffalo grass, wild bluebells ( Mertensia
oblongifolia ) and snow lilies ( Erythronium
grandiflorum ) found on a soggy, early-spring
hike — give me as much pleasure as do those
perennials that save their best for last.
Colors are different in the fall. The quality of
light changes with the seasons, and as the sun
drops lower in the fall sky, the light — unlike the
strong, bald sun of early spring and the assertive
brightness of summer — becomes a warmer
golden-amber. The cooler temperatures intensify
the plants’ pigments, adding to the richness. Pas¬
tels are rare, and the purest colors of the spec¬
trum dominate, deep and smoldering, as if hold¬
ing summer’s heat and sun within their leaves and
flowers. The low sun creates dramatic backlit ef¬
fects in the morning and late afternoon, especially
lovely on flowers with delicate petals or the in¬
florescences of ornamental grasses.
Somehow, in autumn, color combinations that
might make your hair stand on end during the
spring or summer don’t seem to clash. Rather
than being an affront to the artistic gardener’s
finely-tuned color sensibilities, purple asters and
magenta colchicums beneath a sumac with red
leaves on fire are a welcome sight. A daring gar¬
dener might try the soft lavender flowers of Aster
‘Professor Kippenburg’ next to an orange-spiked
variety of red-hot poker ( Kniphofia triangularis ).
For the more faint at heart, cream-yellow
Kniphofia ‘Little Maid’ blends well with low-
growing, light pink cultivars of New York asters.
Deeper yellow kniphofias with the lavender-blue
daisies of Aster x frikartii echo that classic fall
color combination of nature — purple and gold.
Even if some of the wilder color combinations
aren’t for everyone, no autumn garden with a dry,
sunny spot should be without at least one of the
several wonderful, red-flowered Zauschneria
species. Blue or grey-leaved, drought-tolerant
perennials like rue ( Ruta graveolens ) and par¬
tridge feather ( Tanacetum densum var. amani )
add a subtle background to the show-stealing,
fiery trumpets of Zauschneria .
Asters are probably the genus most deserving
of the title harbingers of fall. There are asters from
soggy bogs, parched prairies, cool alpine mea¬
dows, even the dry shade of pine forests. Aside
from the ever-popular novi-belgi cultivars, the
New York asters, and the lovely, yet ungainly
giants, the New England asters ( Aster novae-
angliae), there are many others worthy of more
garden space. Two especially good ones that
thrive in our climate without an excess of addi¬
tional moisture are bristle aster ( Aster linarii-
folius ) and Aster lateriflorus ‘Horizontalis.’ Both
are fine-textured and dainty in demeanor, and
rarely rise above two feet unless given too much
water. Bristle aster is smaller and blooms earlier
in fall, with sprays of small, lavender daisies
over narrow stems clothed in needle-like foliage.
Later , Aster lateriflorus ‘Horizontalis’ is densely
covered in sprays of the tiniest mauve flowers
with deep maroon centers, borne on horizon¬
tally-branched stems, hence the name. The mauve
and maroon colors are echoed in the tiny,
purple-tinted leaves. Try it with the late, white
flower clusters of pearly everlasting, Anaphalis
margaritacea, also an American native. This
plant’s narrow, silvery-grey leaves will add to the
subtle combination.
Sedum ‘Autumn Joy,’ contrary to its name and
well-deserved popularity, is actually one of those
unbelievably rare finds — a four-season peren¬
nial. In the spring, Brussels sprout-like shoots
poke through the ground. Come summer, lovely
succulent, blue-green leaves are topped with
clusters of buds, similar to broccoli in the palest
of greens. Orange butterfly weed ( Asclepias
tuberosa ) makes a drop-dead combination with it
in July. In the fall, the flowers open, changing
from green to pale pink to rose to brick red. By
December, the dried flower heads have turned a
rusty red; as winter takes hold, they become a
warm brown, and continue that way until the
gardener sees fit to remove them to make way for
the new spring crop of “Brussels sprouts.”
The particular rose-red tone of the sedum’s
fall-blooming flowers is difficult to combine with
the prevalent purples, lavenders, yellows, reds,
and oranges of autumn. A successful marriage
occurs between Sedum ‘Autumn Joy’ and several
of the ornamental grasses. In many gardens, these
plants have become regular garden partners. But
a garden cliche is never as wearying as a literary
one; old roses still go beautifully with catmint and
lavender, pansies continue to enhance tulips, the
French marigold and dusty miller still make a
great couple. Combining Sedum ‘Autumn Joy’ and
grasses is always a delight.
Early-blooming varieties of maiden grass (Mis-
canthus sinensis) — ‘Silberfeder’ and ‘Purpura-
scens’ — are best for dramatic backlit effects. Be¬
cause their tassels appear in midsummer rather
than in the fall, they’ve already dried and are
silvery-white by the time autumn rolls around.
Miscanthus sinensis ‘Purpurascens,’ the shorter
and more erect of the two, has foliage that turns
shades of flame, burnt orange, red, and maroon. A
lone clump of this plant, proudly carrying gleam¬
ing white plumes over a deep red mound of
linear leaves, makes a fine specimen plant. The
profuse white spray of thousands of small daisies
tumbling from Boltonia asteroides ‘Snowbank’ in
early fall might make a good companion. Both
these plants perform best in full sun, with a 23
medium amount of water.
The narrow-leaved, gently arching Miscanthus
sinensis ‘Gracillimus,’ is one of the last grasses to
bloom, waiting until fall to put out its silken,
mauve-colored tassels. This five-foot garden giant
might be combined with a late-blooming peren¬
nial that can match it in size and effect: Eupa-
torium maculatum, known as Joe Pye weed in the
Midwest and East, where it grows wild in
water — retentive clay soils in full sun. This plant’s
old-rose-colored flowers attract late-season but¬
terflies and bees, and the cultivar ‘Purpureum’
echoes the mauves of the combination in ma¬
roon-tinted stems and leaves.
One other grass that waits until fall for its show,
is Chasmanthium latifolium. This native grows
from one to two feet, therefore is integrated into
the small garden with greater ease than the
maiden grasses. Its leaves turn a subdued golden
color; its dangling flower spikelets, a warm cop¬
per. A versatile little grass, Chasmanthium
latifolium tolerates moist to quite dry soils, and
sun to part shade. The deep yellow flowers of
Rudbeckia fulgida ‘Goldsturm,’ still going strong
in autumn after two months of bloom, make a
good companion.
Without question, trees and shrubs add most of
the foliage color to the fall landscape, but there
are a few perennials that turn equally brilliant.
Poor soil and full sun bring out the most fiery
tones. The large, waxy, evergreen leaves of
Bergenia cordifolia turn a warm scarlet-tinged
mahogany and remain through the winter, Bal¬
loon flower’s (. Platycodon grandiflorus) foliage
becomes a bright straw yellow. On occasion, even
peonies have been known for a good fall foliage
show. An almost surreal fall color combination is
the deep, true blue of the last flowers of false
plumbago ( Ceratostigma plumbaginoides),
glowing on its scarlet foliage. As the year draws to
a close, the tough groundcover Himalayan bor¬
der jewel ( Polygonum affine) also sets its leaves
on fire. Plant a few late-blooming gentians like
Gentiana septemfida close by for more of that
vibrant red and blue effect.
In the shady fall garden, bright colors are more
the exception than the rule. Blue and red is still
possible, however, with Eastern native cardinal
flower C lobelia cardinalis) and the hooded,
blue-purple flowers of Aconitum carmichaelii,
the latest monkshood to bloom. Cardinal flower
supposedly likes moist areas, but I’ve grown it
quite dry. Many “rules” for plants can be broken,
24 even hardiness-zone information. It’s much more
helpful to find out where the plant grows natu¬
rally, and just give the poor thing, albeit branded
“zone X,” a try.
Blue-flowered willow gentian ( Gentiana
, asclepiadea) is a late-blooming candidate for the
moister shade garden. The graceful, drooping
yellow and chartreuse foliage of Hakonechloa
macra ‘Aureola,’ a rare variegated grass for shade,
would make a lovely accompaniment.
Light colors — white and the pastels— are at
their best in the shade. The pale pink or white
flowers of Japanese anemone, Anemone x hy-
brida are carried high above the grape-like leaves
on airy, yet sturdy stems. The flowers, charmingly
simple of face, might make a nice contrast to the
white bottle-brush spikes of another fall-
bloomer, Cimicifuga simplex . A newer, more un¬
usual form of this perennial, C. simplex ramosa
‘Atropurpurea,’ has leaves and stems a dark
plum-brown color, showing off the white flowers
to great advantage. The silver and burgundy
fronds of Japanese painted fern ( Athyrium nip-
ponicum ‘Pictum’) would front it well, with a
spangle of rose-pink, fall-blooming cyclamen
( Cyclamen hederifolium), threaded throughout.
Away from the shade, a rich yellow sun shines
and the sky is deeper blue now than it’s been all
summer: blue and yellow — always a classic pair.
The fall garden, not to be outdone, responds with
its own spots of sunlight and sky: warm yellow
Sternbergia lutea, looking like a big crocus with¬
out leaves, next to the haze of blue mist spirea,
Caryopteris x clandonensis. Or a pair of tall na¬
tives: airy Salvia azurea, sending up spires of
gentian-blue flowers alongside the sunny gold
faces of Maximilian’s sunflower ( Helianthus
maximiliani). Add the deepening red foilage of a
sumac, burning bush (. Euonymus alata), or
Amelanchier as a backdrop, and you will truly
drink from the richness that is fall gardening.
These are but a few of the possibilities. Come
fall, when you see the roadsides lined with
sunflowers, a haze of lavender and white asters
beneath the ponderosa pines, and the fields
ablaze with purple liatris, goldenrod, and swaying
grasses, let them inspire you to create a wonder¬
ful fall perennial garden for yourself.
Lauren Springer received her master’s degree in horticulture
from Penn State, and gardened in public and private gardens
on the East Coast, in England, and Ireland before settling in
northern Colorado. Her artistic approach to plants and gar¬
dening is reflected in her designs, photography, teaching, and
writing.
Digitalis lanata
by Angela Overy
“Digitalis” derives from the Latin word for finger,
but I prefer the name foxglove — and the image of
these cunning animals donning silky gloves to
perform their more dubious tasks. Digitalis
lanata, of Eastern Mediterranean origin, is a
splendid flower to grow in Colorado. It should
not be confused with the purple foxglove we are
familiar with from Celia Thaxter’s garden at the
Denver Botanic Gardens, or from the moist, tradi¬
tional English woodland garden.
Digitalis lanata is a much tougher plant, more
suited to a Front Range xeriscape garden. It can be
biennial, flowering its second year and then dy¬
ing, or sometimes a short-lived perennial. The
first year, it makes a rosette of dark green foliage,
about nine inches high. Do not be tempted, how¬
ever, to put other plants too close the following
spring. In June, spires shoot up to four feet high.
Buds open into cream-colored “gloves,” laced
with coffee-brown veins; the lower edge of the
flower has a drooping white lip that almost glows
in the early morning and evening light.
Digitalis lanata blooms for six weeks or more.
It is also an excellent cut flower, adding interest
and unusual brown color to a bouquet, and last¬
ing in water for a week or more. This foxglove
requires a sunny location, and only occasional
extra waterings beyond Colorado’s natural rain¬
fall. With liquid fertilizer added about every two
[weeks in June and July, a grouping will produce a
dazzling display. They form prolific amounts of
seed, which germinates readily, so you need not
be concerned about the relatively short lifespan
of the individual plants.
The unusual cream and soft brown color of the
flowers blends beautifully with buff flagstone and
adobe. Don’t try to mix it with too many other
plants, however. Its elegant beauty is best ap¬
preciated separately.
Angela Overy teaches botanical illustration and floral design at
Denver Botanic Gardens. Her garden will appear in Fine
Gardening this winter.
Angela Overy
Shari Jones
Zinnia grandiflora
by Andrew Pierce
This native perennial, known as Rocky Mountain
zinnia, has had its botanical name changed, like so
many others. Originally it was classified as Cras-
sina grandiflora (Nutt.) Kuntze, but since 1923,
its name has honored Johann Zinn, an eigh¬
teenth-century German known for his botanical
work in New Mexico.
Zinnia grandif ora's pretty little 3/4 inch flow¬
ers may not live up to the name given it by Nuttall,
“grandiflora,” on an individual basis, but when
massed together, they certainly are “grand,” due
to their profusion. The plant doesn’t look at all
like the common, multi-colored, annual garden
zinnia. The golden flowers have four or five ray
florets, resembling papery7 petals, that form a
complete circle. The disk florets in the center
form a darker, reddish eye. The plant blooms a
very long time — from May until September.
Rocky Mountain zinnia is a semi-woody peren¬
nial, becoming more shrubby farther south. It
grows naturally at elevations between 4,000 and
6,000 feet, but still may not always be completely
hardy in the Denver area.
Zinnia grandiflora' s stems may be up to eight
inches long, but they tend to flop, resulting in a
plant rarely more than a few inches high. In Jewels
of the Plains , Claude Barr, one of the greatest
plant collectors, called this plant a golden gem,
and suggested “freer increase would be wel¬
come.” Today, it is finding its way into the listings
of many local nurseries.
In 1980, Panavoti Kelaidis and I introduced
Rocky Mountain zinnia into cultivation by taking
cuttings from a few plants scattered on the rough
slopes of Phantom Canyon near Canon City. Since
then, it has been widely propagated by seed, and
is usually available at the DBG spring plant sale.
Growth may appear slow at first, but the plant’s
fine roots penetrate a moderately well-prepared
soil rapidly. Then a series of shoots develop, and
by July, masses of flowers appear that continue
blooming until frost. Good drainage helps insure
overwintering.
It seems that Zinnia grandiflora is not a long-
lived perennial in cultivation. Sometimes only a
few underground runners survive, or a handful of
self-sown seedlings, which help prolong the life
of group plantings.
No matter how long its life in the garden, Rocky
Mountain zinnia is an unusual native beauty that
is garden-worthy, especially for its long season of
show and drought-tolerant qualities. It is hoped
that the plant’s popularity will continue to grow,
and that springtime shoppers will see the poten¬
tial in not-yet-flowering specimens, and not
forego them in favor of their gaudy cousins.
Andrew Pierce is Assistant Director of the Denver Botanic
Gardens. His garden in Evergreen, CO, was recently featured
in Fine Gardening.
26
Callirhoe involucrata
by Kelly Grummons
Growing up in the southern Black Hills of Wyom¬
ing and South Dakota instilled me with a great
appreciation of prairie flora. One of my favorite
native flowers is the prairie winecup, Callirhoe
i involucrata.
My mother, also a lover of this chest of botani¬
cal treasures, told me a childhood story about the
winecup. She was spending a summer on her
great-aunt Esther’s ranch in South Dakota. On the
way back from a hot, dusty hike, my mother came
i across a most glorious flower. Knowing Aunt
Esther bred African violets and was a lover of
plants, Mom pulled up the mass of rambling
stems and wine-rose flowers of Callirhoe in¬
volucrata to give to her aunt. Esther’s apprecia¬
tion quickly turned sour upon discovering that
the plant was crawling with large, neatly-
camouflaged buffalo leaf-hoppers. In spite of the
bad experience with the bugs, Mom still has
prairie winecup in her Wyoming garden.
Callirhoe involucrata grows sparsely in the
southern Black Hills, becoming more abundant
in the sandier soils of western Nebraska, Kansas,
I eastern Colorado, Oklahoma, and Texas. Gen¬
erally you will find it growing on flat grasslands at
elevations between 1000-3500 feet. Its two-inch,
i wine-rose flowers bloom abundantly from June
through September and are held well above the
rambling, dark-green foliage. In July and August,
if you drive slowly through western Kansas you
will be rewarded by acres of glorious gayfeather
(Liatris sp.), asters, and winecups. I don’t under-
! stand why people call this area a vast wasteland.
Prairie wine-cup is one of the easiest wild flow¬
ers to cultivate in your garden. It thrives in clay or
sand, with moderate or little water. The drier the
soil, the more compact the plant. Callirhoe in¬
volucrata enjoys full sunshine but will tolerate
quite a bit of shade. It fits wonderfully into infor¬
mal mixed borders, especially when allowed to
ramble among the other plants. Its wine-rose
flowers are shockingly delightful with many other
colors, but especially when seen peeking through
the silver leaves of artemisias, Stachys byzantina,
or some Salvia species. This native perennial eas¬
ily gives as much seasonal color as many annual
flowers.
Prairie winecup deserves more attention from
the nursery trade. It has been promoted as a
xeriscape plant for several years, yet supplies
have been limited. Some local nurseries carry it,
and the plant is propagated by seed sown in the
garden in October or November.
Kelly Grummons received joint degrees in horticulture and
landscape management from Colorado State University, and is
horticulturist at Paulino Gardens in Denver. He has a special
interest in prairie plants.
27
28
Tiarella wherry i
by Pat Hayward
Until recently, new and different perennials for
shade have been hard to come by in Front Range
nurseries. Because of the interest in dryland and
native plants, local growers have emphasized the
growing and introduction of sun-lovers and sur¬
vivors of heat and drought.
But what about those of us with older gardens
that are shaded by tall trees? Whether for the large
woodland garden, or that small, north-side-of-
the-house border, we need more interesting
shade-loving choices.
I've worked in sales and marketing at a local
nursery for six years. In the summer of 1988, we
were given the challenge of locating and growing
"new" varieties of shady perennials for the Den¬
ver Botanic Gardens plant sale. I felt impelled to
try them in my garden.
One of the biggest surprises was Tiarella wher-
ryi, also known as Tiarella cordifolia var. collina,
or foamflower. This Southeastern woodland na¬
tive was thriving beautifully in my dry, shady Col¬
orado garden. I always joke with customers who
ask for a hardy, evergreen perennial that blooms
all summer and requires no maintenance; once in
a while, a real prize like this actually shows up.
Foamflower emanates softness. It is a tidy,
non-spreading perennial with medium-green,
fuzzy, palmately-lobed leaves. In the fall and
winter, reddish-bronze tones become more pro¬
nounced in the semi-evergreen foliage. Six to
twelve inch spikes of pink-edged, white flowers,
shaped like tiny stars, float above the four to six
inch mound of leaves. Blossoms are heavily pro¬
duced in May and June, then more subtly the rest
of the summer. It is common for my young, two-
year-old plant to have fifteen spikes in bloom at
the same time.
To compensate for my lack of interest in, and
time for watering, I purposely made my shady
bed heavy in soil, mixing compost and peat with a
mostly-clay base. The clay holds the water well,
and the peat adds just enough richness and acid¬
ity. My foamflower seems happy with the mix,
along with painted fern ( Athyrium nipponicum
'PictunV), Hebe 'Carl Teschner Hepatica triloba,
Alchemilla mollis, and others.
Tiarella wherryi is usually propagated by divi¬
sion, as seed is rarely available. This plant may not
be flashy or loud, nor will it make the list of the
top ten most colorful perennials. But it is subtle,
attractive, hardy, looks good in the winter, and
grows and blooms in shady gardens here in Col¬
orado, where it deserves a better place.
Pat Hayward is a perennial specialist at Little Valley Nursery in
Brighton, CO. She writes and teaches extensively.
Delphinium grandiflorum
by Sandy Snyder
i, Many gardeners I know have a terrible time trying
i to grow gentians or the blue Himalayan poppy
A ( Meconopsis betonicifolia ). Then they must
i forego that breathtaking color, cobalt blue, in
their gardens, unless they know about Del¬
phinium grandiflorum, also known as D.
chinensis. This plant is a gardener’s delight: it is
easy to grow, the color is unsurpassable, and it
! provides a burst of flowers in midsummer, when
most gardens need a lift.
I have fallen in love with Delphinium grandi¬
florum. It gives my garden a sweep of gentian
blue, my favorite color. My form of this plant is
deep blue, but L. H. Bailey in The Garden of
Larkspurs says that bouquet larkspur, one of its
common names, comes in all ranges of blue and
' blue-purple, mauve, reddish, and clear white.
Delphinium grandiflorum is a perennial from
China and Siberia. It is so easy to grow that I had
forgotten I had it until mid-July. Suddenly, on
two-foot, airy stems, a crowd of little blue flowers
magically appeared. I had done nothing to en-
I courage these plants, and they still put on a show.
Next year I will observe them closely to see how
truly perennial they are.
By mid-August, the plants still are blooming a
little, but mostly look like dry candelabras of seed
heads. I let these silhouettes remain to encourage
them to send wherever they want. If I decide to
arrange them along the front of one of my peren¬
nial borders, as one book suggests, I will dig up
the seedlings in the spring and rearrange them as
I replant them.
Delphinium grandiflorum has no pests or dis-
1 eases, behaves itself in the garden, and is easily
shared and propagated just by shaking the dried
flower stalks around. I can still be enticed to travel
far to see gentians and the blue poppy, but the
rich blue sweeps in my summer garden make it
easier to wait for those trips to faraway places.
Sandy Snyder is a gardener in the Rock Alpine Garden at
Denver Botanic Gardens. She also has her own landscaping
and consulting business, and writes and teaches on the side.
Her garden in Littleton, CO, has been the subject of several
articles, both locally and nationally.
Shari Jones
Clematis recta
by Jane Silverstein Ries
The perennials in my urban garden are a constant
source of joy. Most of the plants must fight for
space and sunlight; some of the best are seldom
seen in other gardens. One of my favorites is
Clematis recta. Though I grow a number of the
climbing species and hybrids of the genus, I find
this clematis special in that it grows upright to
only three feet, making it suitable for the peren¬
nial border. The abundant moisture in the early
part of 1990 (never have I witnessed a more per¬
fect spring) encouraged Clematis recta to grow an
additional foot in height, as did many other per¬
ennials.
Clematis recta blooms in June with clusters of
sweet-smelling, creamy white flowers. The plant
needs a bit of inconspicuous support, such as
stakes or a hoop, to be seen to advantage. Though
my garden is fairly shady, this plant thrives in a
position where it receives sun during midday for
three or four hours.
Clematis recta is native to southern Europe. It is
amazing — and frustrating — that this wonderful,
old-fashioned plant has virtually disappeared
from commerce. It was formerly grown on a large
scale in Denver for the cut flower trade. Although
it has not expanded in size or seeded itself, the
one plant in my garden has grown for more than a
decade and returns faithfully every year.
In the garden, this plant combines well with
other under-used perennials. For example,
Clematis recta may be planted in front of another
of my favorites, feathery Valeriana officinalis.
Clematis recta's attractive, fluffy seed heads are
accented when in front of the purple spikes of
monkshood ( Aconitum napellus ). The outstand¬
ing foliages of coral bells ( Heuchera sp.), lady’s
mantle ( Alchemilla mollis ), and barrenworts
( Epimedium sp. ) look beautiful planted at its feet.
One of the country's first women landscape architects, Jane
Silverstein Ries has been designing gardens, as well as tending
her own, for over fifty years in Denver. The American Society
of Landscape Architects Colorado Chapter award for excel¬
lence in land use bears her name and is given in her honor
annually.
Anemone hupehensis
by Tom Peace
One of the highlights of August is the advent of the
pink, pearly buds of Japanese anemone. The
large, dark green leaves with their bold, angular
. shape grace the partly shaded perennial border
or woodland garden for most of the summer. As
the buds arise from the foliage on strong, yet
delicate stems, the anticipation of a floral fantasy
amid the late-summer doldrums builds.
Japanese anemone is currently classified as
Anemone hupehensis, although A. japonica is
sometimes still used, and other species, cultivars,
) and hybrids incude Anemone x hyhrida and A
vitifolia ‘Robustissima.’ A gardener is lucky to find
any of these hardy, versatile perennials, but I
prefer Anemone hupehensis over the others. It
blooms a bit earlier, and on shorter stems. Fortu¬
nately, it is easy to multiply by crown division,
‘ root cuttings, or by simply allowing a plant
1 enough room to make a dense colony. When the
gardener finds the form of this flower he or she
likes best, it’s soon possible to have it everywhere.
Versatile Anemone hupehensis can be planted
in sun or shade, and performs well as long as it is
1 in a moist, well-drained garden loam. Established
plants can tolerate more dryness. The dramatic
leaves grow from twelve to eighteen inches high,
with white undersides. The flower stems rise an
additional foot above the foliage. Unsurpassable
clear pink flowers, two inches across, bloom from
the middle of August until a hard frost stops them.
Japanese anemone has no predisposition to
pests or disease. The only problem the gardener
encounters is the wait for late summer’s bounty of
bloom. High altitude gardeners can also enjoy
this plant; I have grown it successfully in the
Aspen Valley. I have found that an asexually-
propagated clone of Anemone hupehensis
formed buds at the same time in Carbondale,
Denver, and Austin, Texas.
Colorado State University-trained Tom Peace is a freelance
landscape designer in Colorado and Texas.
31
Agastache cana
by Jim Knopf
This perennial smells just like old-fashioned
Double Bubble gum, so I like to call it double
bubble mint. It is very showy, easy to grow,
doesn’t need much water, hummingbirds love it,
it blooms for a long time, and is easy to propagate
from seed. It’s also considered rare, and possibly
endangered, in New Mexico.
You may wonder how a plant with so many
desirable traits can remain almost unknown to
local perennial sleuths for so long. It probably has
a lot to do with an old bias toward introduced
over native plants. Fortunately, this is changing.
Agastache canas fragrant, pink flowers bloom
from late July until mid-October. The foliage is
fragrant as well, but more minty than bubble-
gummy. The plant grows to three feet and is
about two feet wide. It thrives in full sun, tolerat¬
ing dry situations, but growing to its most lovely
potential when given about 3/4 inch of water
weekly in midsummer when there is no rain.
Double Bubble mint is easily grown from seed
that has been given a period of cold, damp condi¬
tions for two months. Its showy, fragrant, long-
blooming flowers, ability to grow in semi-arid
garden conditions, and strong attraction for
hummingbirds all make it a wonderful addition to
the perennial palette.
Our region is bountiful in “weeds with poten¬
tial.” Chocolate flower ( Berlandiera lyrata ) and
Indian pink ( Silene laciniata) are two more.
Many local “weeds,” occasionally defined as
plants with a greater will to live, or plants we
haven’t learned to love yet, are worthy of serious
attention. In fact, given new names and some
exposure, these plants are likely to change from
targets of misguided local weed ordinances to the
coveted status of “designer weeds,” and we are all
the richer for it.
Jim Knopf is a maverick landscape designer based in Boulder,
who specializes in designer weeds.
Ipomoea
leptophylla
by Ray Daugherty
Ipomoea leptophy’lla, also known as bush morn¬
ing-glory, is a herbaceous perennial locally
abundant on the plains of Wyoming, Colorado,
and New Mexico, especially along roadcuts and
on sandy slopes. This deep-rooted plant is remin¬
iscent of a small willow in leaf. Its showy, two to
three inch, funnel-form flowers bloom all sum¬
mer in shades of rose-purple and violet. Bush
morning-glory is drought-tolerant, but may go
dormant under extremely dry conditions. It pre¬
fers sandy soils, but tolerates clay if very good
drainage is provided.
In the garden, Ipomoea leptophylla works well
as an erosion-controlling plant on steep slopes, as
a small shrub-like feature in the back of the dry¬
land border, or as an accent plant near large
stones. Take great care to insure perfect drainage,
32
especially during the winter. This plant has an
enormous root that can reach twelve feet or more
in length and depth and that may be as big around
I as a person’s leg. Due to this root, bush morning-
glory is nearly impossible to transplant from the
wild, or to move after establishment.
At this point, it is still scarce in commerce, so
seed is the best method for obtaining it. Germina¬
tion is quick and easy after the seeds are soaked
overnight in hot water. Plant the seeds at a depth
of about 1/4 to 1/2 inch, where it is to grow.
Ray Daugherty is propagator at Green Acres Nursery in
Golden, CO.
Thalictrum minus
by James E. Klett
This perennial, also known as low meadow rue,
forms an airy mound of foliage reminiscent of
maidenhair fern ( Adiantum pedatum ). It grows
to approximately one and one half feet in height,
and two feet in width. Thalictrum minus blooms
along the Front Range of Colorado from late May
to early July. The plant is an asset in the garden
throughout the growing season because of its
excellent foliage. The flowers consist of tufts of
dangling green-yellow stamens of modest orna¬
mental value. Bright red fruits follow a few weeks
after bloom, and are quite showy.
Low meadow rue seems to grow best in partial
shade and fairly moist, rich soil. In cooler areas,
and especially at higher elevations, it tolerates full
sun. The beautiful, dainty foliage can also be cut
and used in flower bouquets. A related species,
Thalictrum adiantifolium, is taller and more in¬
vasive.
We have grown this plant for over ten years in
our perennial trials at the W.D. Holley Plant En¬
vironmental Research Center, and it has never
suffered any winter damage. It is most vigorous
when planted in a partially shaded spot and given
some additional moisture. Hostas make attractive
companion plants, creating contrast of leaf form
and texture.
James E. Klett is Associate Professor of Ornamental Horticul¬
ture at Colorado State University. Eleven years ago, he started
the extensive perennial trial gardens there.
Mountain, Plain
and Garden 7vr
The Magazine of Denver Botanic Gardens ■ Spring/Summer 1991
ANNUALS
Published by:
Denver Botanic Gardens, Inc.
909 York Street
Denver, Colorado 80206-3799
Newell M. Grant, President
Bruce D. Alexander, Executive Director
Lauren Springer, Editor
Solange Gignac, Diane Ipsen, Bernice E.
Petersen, Copy Editors
Sent to all members of Denver Botanic Gardens. Mem¬
bership fees are as follows: Student $18, Individual
Senior $18, Senior Couple $25, Individual $25,
Family/Dual $35, Contributing $50, Supporting $100,
Patron $500, Four Seasons Member $1000.
By becoming a member of Denver Botanic Gardens,
Inc., you will receive Mountain, Plain and Garden and
the monthly Green Thumb Neivs. You will also have
year-round admission to the gardens and borrowing
privileges from the Helen K. Fowler Library, located
in Boettcher Memorial Center at 1005 York Street.
For further information, write to Membership Coor¬
dinator, Denver Botanic Gardens, 909 York Street,
Denver, Colorado 80206, or call 331-4000.
Denver Botanic Gardens, Inc., maintains a collection of
living plants, both native and exotic, for the purpose of
acquiring, advancing and spreading botanical and hor¬
ticultural knowledge.
It is a non-profit organization supported by both public
and private funds.
Copyright 1991 by Denver Botanic Gardens, Inc.
Front Cover: Jim Knopf
Verbena tenera sets a berm on fire at Denver
Botanic Gardens.
Back Cover: Rob Proctor
Verbena bonariensis, fountain grass (Pennisetum
setaceum ), black-eyed susan ( Rudbeckia hirta),
Verbena rigida and creeping zinnia ( Sanvitalia
procumbens ) evoke the colors of late summer and
fall on the prairie.
Design: Graphic Impressions, Denver
Printing: The Pressworks, Denver
Mountain, Plain
and Garden W'
The Magazine of Denver Botanic Gardens
A Continuation of The Green Thumb
Volume 48 Number 1 Spring /Summer 1991
Contents
A Taste of Annuals as Seen
from Denver Botanic Gardens
Andreiv Pierce . 1
1990 Annual Trials at
the Denver Botanic Gardens
Carol Pelehowski . 5
Annuals and Biennials
for Flower Arranging
Robin Preston . 6
Annual Grasses
Joedy Arnold . 8
Volunteers Benefit Denver’s Flower Beds
Amy Pulver . 11
The Garden-less Gardener:
Containers to the Rescue
Tom Peace . 12
For the Love of Cut Flowers: An Annual Ritual
Diane Ipsen . 14
Dressing for Success— Clothing
the Garden with Annuals
Angela Overy . 17
An Annual Process: Growing
Bedding Plants Commercially
Kelly D. Grummons . 20
Annuals in the Perennial Border
Keith Funk . 22
Annuals for the Connoisseur
Lauren Springer . 24
Plant Portraits
Torenia fournieri
Rob Proctor . 27
Cleome hasslerana
Alcinda Cundiff . 27
Ipomopsis rubra
Sandy Snyder . 28
Lotus berthelotii
Eleanor Welshon . 29
Dyssodia tenuiloba
Pat Hayward . 30
Verbena tenera and Verbena tenuisecta
Jim Knopf . 32
Kallstroemia grandiflora
Ray Daugherty . 34
Maurandya antirrhiniflora
Ray Daugherty . 35
Talinum paniculatum
Laura Lee Cutler . 36
Bibliography . 37
A Taste of Annuals as Seen
from Denver Botanic Gardens
by Andrew Pierce
From just an inch or so to over six feet tall, annuals
offer a wealth of variety to please everyone. They
are the backbone of many of the Rocky Mountain
region’s summer gardens; our climate is excep¬
tionally suited to growing them well. Gardeners
in some not-so-distant areas such as Seattle find
these plants quite difficult to grow while we take
annuals for granted here; cool winters, moister
springs and hot, dry summers produce lovely
displays of annuals.
The annual summer splendor is really not what
it seems. Botanically, an annual is a plant that
grows, flowers, sets seed and dies within one
growing season. Surprisingly, many of the plants
commonly called annuals do not meet these
criteria. In many instances, these “annuals” are
actually biennials, perennials, shrubs and even
plants with storage organs such as cannas (Canna
x generalis) and dahlias. Consequently the gar¬
dener’s term “annual” actually refers to seasonal
usage rather than true botanical characteristics:
any plant that exists in the garden for only one
growing season, whether due to an inability to
live through a hard winter, a natural inclination to
die after setting seed, or simply because it is
easier and more effective to replace and replant it
yearly, is termed an annual. It would be a much
duller world if we confined ourselves to only true
botanical annuals; marvelous plants like
geraniums ( Pelargonium spp. ), the foliage plants
Coleus x hybridus and dusty miller ( Senecio
I cineraria ), bold cannas, flowering maple ( Abuti -
Ion hybridum), fragrant oleander ( Nerium
oleander ) and the luxuriant tuberous begonias
( Begonia x tuberhybrida ), among others, would
all be relegated to non-use status.
Ever since annuals were first used to a great
extent back in the early Victorian era, gardeners
have looked to them for their bold color effect to
magnify the summer spectacle in the garden.
Today a few original, non-hybridized species are
still grown, but in almost all cases, cross-pollina¬
tion and selection have improved the plants. In
1989, when trying to obtain the original species of
plants for the Celia Thaxter Garden at Denver
Botanic Gardens, we encountered considerable
difficulty finding varieties of single-flowered hol¬
lyhocks ( Alcea rosea ) and un-hybridized
bachelor’s buttons ( Centaurea cyanus ). These
older forms of annuals are rarely found in com¬
merce, and in some cases, are no longer around at
all.
A large majority of annuals originated in the
New World, including the familiar petunia
( Petunia x hybrida ), marigold ( Tagetes spp. and
hybrids), flowering tobacco ( Nicotiana alata ),
garden salvia ( Salvia splendens ) and zinnia ( Zin¬
nia elegans'). The flare of annuals’ popularity in
Europe in the 1800s was no doubt due in great
part to their introduction and novelty at the time.
From South Africa came the “geraniums” we
grow as annuals and some of the newer daisies
such as Gerber a jamesonii , star-of-the-Veldt (Di-
morphotheca spp. ) and blue marguerite ( Felicia
amelloides ). From the Mediterranean region
came pot marigolds ( Calendula officinalis ),
bachelor’s buttons and snapdragons ( Antir¬
rhinum majus ), to name a few. North America
contributed California poppies {Eschscholzia
califomica), the satin flowers {Clarkia spp. ), an¬
nual coreopsis ( Coreopsis tinctorial and
ghostweed ( Euphorbia marginata).
As Denver and the rest of the Rocky Mountain
region become more aware of environmentally
sound landscaping, annuals will be considered
for more than sheer beauty7. Already certain plants
such as moss rose (. Portulaca grandiflora ),
mealy-cup sage (. Salvia farinacea ), creeping zin¬
nia ( Sanvitalia procumbens), various Verbena
species and ghostweed are valued for flourishing
on less water than the staples petunia, snapdra¬
gon, geranium and marigold.
The broader interpretation of the term “an¬
nual” invites use of more unusual plants in that
capacity. For several years the Gardens has used
ornamental peppers ( Capsicum annuum) in
varying forms for the beauty of their fruit. Castor
bean ( Ricinus communis ) also offers showy fruit,
with bright red, spiny capsules, not to be eaten,
however, since they are very poisonous. This
year, large sub-tropical plants — oleander and Pit-
tosporum spp. — will be underplanted with drifts
of plants usually thought of as foliage house plants
but perfectly suited for annual use in the garden:
spider plant ( Chlorophytum comosum ) and wan¬
dering jew ( Tradescantia albiflora). I always
enjoy the annual display of ornamental kale and
cabbage ( Brassica oleracea ) up in the mountains
by Echo Lake Lodge at the base of Mount Evans on
the Front Range. This interesting use of annuals
has considerable merit in that not only are the
plants hardy and colorful, but the common annu¬
als they replace, such as petunias, geraniums and
zinnias, would either be frosted or fail to produce
adequate flowers at that elevation, where no
month is frost-free. An interesting effect might
include parsley ( Petroselinum crispum) as a
groundcover or edging to a border, or even or¬
namental leaf lettuce ( Lactuca sativa).
For drying, daisy-like strawflower (Helichry-
sum bracteatum ) and winged everlasting (Am-
mobium alatum) are old standbys. Globe
amaranth ( Gomphrena globosa ) is another: the
newer variety ‘Strawberry Fields,’ a rich red, drew
a good deal of attention in the Denver Botanic
Gardens cutting garden last year, as did orange
Gomphrena baageana. Statice ( Limonium
sinuatum ) is always admired but unfortunately
not easy to find as young starts on the market. Its
tall flowering spikes, in a wide range of colors, are
very eye-catching. Bells-of-Ireland ( Moluccella
laevis) have been cultivated for their dried, pa¬
pery flower calyces for many years, as have the
charming seedpods of love-in-a-mist ( Nigella
damascena ) and showy cockscombs ( Celosia
cristata ). Annual grasses contribute a grace of
form and texture to the dried arrangement.
In the casual garden, for the lazy gardener, a
number of annuals I like to call “perennial” annu¬
als come in handy. This group of versatile plants
reseed and germinate adequately enough in the
garden, without the gardener’s interference, that
they are reliably present and self-sufficient, year
after year. California poppies, annual coreopsis,
ghostweed, sweet alyssum ( Lobularia maritima),
love-in-a-mist, Cosmos bipinnatus , bells-of-
1 Ireland and even the annual herb borage ( Borago
officinalis ) all make themselves at home in the
garden enough to be considered “perennial” an¬
nuals.
During the last century several annuals were
commonly grown that are not well known today.
Clarkia, cosmos, Salpiglossis sinuata, balsams
(Jmpatiens balsamina ), stocks ( Matthiola in-
cana), larkspur ( Consolida ambigua, formerly
known as Delphinium ajacis) and poor-man’s-
orchid ( Schizanthus pinnatus) were popular.
Careful observation points out that these annuals
are all generally taller in habit, lacking the bushy,
tight “bedding” habit that is stressed in the breed¬
ing and production of annuals today. With a re¬
surging interest in old-fashioned, or “cottage”
flowers, these annuals are finding their way back
into vogue. I have found they work especially well
as overplantings in the bulb areas of perennial
borders to fill in after the bulbs are spent and to
camouflage their unattractive withering foliage.
These positions require plants of some height to
fit into the border design; the style of these old-
fashioned annuals blends much better than
would mass displays of petunias, geraniums,
zinnias or the heavy formality of Salvia splen-
dens.
Time surely changes things. Under “annuals”
in Bailey’s Standard Cyclopedia of Horticulture
of 1944, the definitive work of that period and for
many years later, there were many plants omitted
that are taken for granted today. Most notably
absent were the presently-prominent geranium,
begonia ( Begonia x semper florens- cult orum)
and dwarf impatiens {lmpatiens wallerana ).
Flowering tobacco and annual grasses did not
appear either. This was less than fifty years ago.
In Denver and at the Botanic Gardens, the his¬
tory of the use of annuals is quite rich and fascinat¬
ing. During the latter part of the 1940s, before the
Gardens were established, the city and county of
Denver had been using large-scale plantings of
annuals for many years already, much as they do
today. Marigolds, geraniums, sweet alyssum
{Lobularia maritima ), ageratum {Ageratum
houstonianum ) and petunias were the dependa¬
ble mainstays. However, they didn’t please
everyone, especially the more sophisticated gar¬
deners who worked with them. A quote from The
Green Thumb, Vol. 6, 1949 illustrates this: “To
those of us who work with them, these plants fall
into certain classifications, like the people we
know. Some are completely satisfying — they al¬
ways have such wonderful color and good growth
A pot overflows with Lobelia erinus, Mexican sunflower ( Tithonia
trailing vinca ( Vinca major ‘Vari- feet,
egata), petunias ( Petunia x hybrida)
and a spike dracaena ( Cordyline indi¬
visa').
The vibrant tones oiNicotiana alata ‘Nicki Red’ contrast with perennial
lady’s mantle ( Alcbemilla vulgaris) in light shade.
rotundifolia) is an imposing plant at six
Petunias and cannas ( Canna x gen-
eralis) compliment the soft grey carpet
of perennial lavender cotton {San-
tolina chamaecyparissias) at Denver
Botanic Gardens.
The red hot fruits of ornamental pep¬
pers ( Capsicum annuum) add spice to
a summer display.
that not even a brand new never-did-this-work-
before gardener can fail with them. Some we
remember because of their definite personalities,
or their tendency to be timid and retiring. Then
there are the irresponsible ones nobody trusts
completely. There are even some unpopular ones
that we have tried and tried, and finally given up
as hopeless.”
Several specific plants appear, disappear, and
reappear over the course of the years, proving
once again that horticultural fashions are just as
fickle and prone to cycles as are other forms of
artistic expression. In the early 1960s, a great
many trials of annuals were carried out at the
young Denver Botanic Gardens, with petunias
particularly prominent. In the latter half of the
1960s more emphasis on what would grow in the
very hot summer sun and in the shade was being
explored, and new varieties of annuals from the
All America Selections (AAS) were being tested
and evaluated. We continue to carry out the AAS
seed trials each year. (See separate article in this
issue.)
Looking forward to the new annuals of the year
is always exciting. Unlike most gardeners who
purchase their seed or plants in the late winter or
spring of the same year they plan to grow the
annuals, the staff members at the Gardens start to
put their thoughts together as early as August of
the previous year. While this may seem early, it
offers the advantage of gleaning new ideas from
the annual trials or other areas of the Gardens
while they are still in flower. For example, the tall
yellow double sunflower, Helianthus annuus
‘Goldburst’ and a variety of false saffron, Cartha-
mus tinctorius, both striking plants in the 1990
Gardens, will be featured in the peony garden
area in 1991. Gomphrena globosa ‘Strawberry
Fields' from the cutting garden last summer will
be more prominent in a large bed to the north of
the home demonstration garden, and Chrysan¬
themum parthenium ‘Bridal Robe’ will appear in
a smaller bed near the fountain. Dwarf annual
dahlias in the ‘Royal Dahlietta’ series were excel¬
lent in the 1990 trials and some will be planted
elsewhere this summer.
Around the amphitheatre there will be chroma¬
tic drifts of plants from white to blue, purple to
red. Several varieties of petunia, flowering to¬
bacco and tall back-of-the-border spider flower
( Cleome hasslerana ) will create an effect that can
be viewed from many angles. These same colors
will also appear in the area immediately below
the conservatory, one of the hotter areas, which
features plants more suited to the Western cli¬
mate. Pink Oenothera speciosa will harmonize
with whit e Melampodium leucanthum , a native,
and Verbena tenera and V. tenuisecta. These latter
4 two plants, both from South America, were in¬
credibly popular this past year on the berm to the
west of the rose garden. Verbena tenera is salmon
pink while V. tenuisecta is lavender. Though per¬
ennial in their homeland, they are not expected to
be hardy in Denver and are thus grown as annu-
*als. We did mulch some of the groups, however,
to see how they might survive the winter under
such conditions (see “Plant Portraits” for more on
these two stunning annuals.)
Large baskets of fresh blue ageratum ‘Cut Won¬
der,’ geraniums including the ivy geranium ‘De¬
cora Lavender’ ( Pelargonium peltatum) that we
used in the pergola and home demonstration
garden in 1990, the smaller-flowered petunia
‘Azure Pearls’ and trailing Vinca major will en¬
hance the beauty of the gift shop overhang. Over
the wall, to the east in the sunken garden, helio¬
trope ‘Dwarf Marine’ did extremely well last year
and will be repeated. Likewise the eye-catching
morning glory vines {Ipomoea purpurea ) on the
gazebo to the west of the main water pool will be
retained. Be prepared for a wealth of ornamental
grasses among the various displays — they are in
fashion. Some will be strictly annuals while others
are perennials used for annual effect.
We always take the opportunity to be somewhat
experimental with our selections; this is educa¬
tional for us and all our visitors and in time, some
unusual plants may become introductions to the
trade. Denver’s short frost-free season, good light,
moderately high temperatures, low humidity and
relative freedom from pests and diseases create
an excellent climate for summer annuals. There
are plenty to choose at the Denver Botanic Gar¬
dens yearly plant sale and in the trade as well. Try
to be a little adventurous — you needn’t live en¬
tirely restricted to the geranium, petunia and zin¬
nia.
Andrew Pierce is Senior Horticulture Advisor at Denver
Botanic Gardens. His garden in Evergreen, Colorado was
featured in the book The American Man’s Garden , by Rose¬
mary Verey (Little, Brown and Company, 1990), and also in
Fine Gardening magazine.
Ipomoea purpurea
1990 Annual Trials at the
Denver Botanic Gardens
Gomphrena globosa
by Carol Pelehowski
Approximately one-hundred different annuals
were tested in the annual trial gardens at Denver
Botanic Gardens in 1990. Plants are evaluated for
flower duration and color strength, form, resist¬
ance to disease and overall performance.
The fall before the annuals were planted for
1990, well-rotted horse manure was dug into the
beds. After planting, the annuals received an inch
of irrigation every week, broken into three water¬
ings per week while the young plants were get¬
ting established, and then twice a week for the
remainder of the growing season. The beds re¬
ceived a broadcasting of granular 8-10-8 general
purpose fertilizer three times during this time.
The following annuals are a few of the best
from the 1990 annual trial beds at Denver Botanic
. Gardens.
Helianthus annuus ‘Goldburst’ was without a
doubt the most talked-about new addition to the
trial beds. This unique double-flowered sunflow¬
er reached a mature height of six feet with the
upright habit typical of sunflowers and a spread of
approximately twenty inches. The flowers have
good gold color and measure six inches across. If
you missed this unusual flower in the trial beds
last summer, look for it in the 1991 annual display
beds.
Helichrysum bracteatum ‘Frosted Sulphur’ and
3 ‘Silvery Rose’ proved to be good candidates for
future use in the cutting garden. These strawflow-
(ers reached a height of fifty-two inches and a
spread of eighteen inches. Their long, strong
stems make them ideal for cutting and drying. The
soft silvery pink combined nicely with the pale
cream in an attractive blend.
(Although much is written about the All America
Selections (AAS), there are two worth mentioning
again here because of their superior performance
in our trials. If by chance you missed them last
year, they will be grown once again in the 1991
trial beds.
Gaillardia pulcbella ‘Red Plume’ (AAS 1991)
performed very well throughout the growing sea¬
son. The two-inch, ball-shaped blooms of rich
brick red created a strong mass of color all sum¬
mer long. Plants were uniform in habit, measur¬
ing eighteen inches tall and spreading twelve in¬
ches.
Zinnia elegans ‘Scarlet Splendor’ (AAS 1991) is
also worth mentioning. As the name implies, the
flowers are bright, true red and measure four to
five inches across on strong stems. This upright
plant stands thirty-two inches tall, with a spread of
approximately twenty inches. Outstanding in
both form and color, this annual showed no signs
of disease until late August when slight traces of
powdery mildew began to appear on the foliage.
Venidium fastuosum ‘Zulu Prince’ was one of
the most interesting plants evaluated in the 1990
trial garden. This member of the Composite fam¬
ily has large, four-inch white daisy-like flowers
with showy black centers, yet reached a height of
only eighteen inches and a spread of fourteen
inches. Look for this unusual plant again in 1991
in the trial garden.
Dahlia xhybrida ‘Royal Dahlietta’ proved to be
prolific bloomers. Four of the six colors available
of this series were evaluated in the trial beds.
Averaging twelve inches tall and wide, these
sturdy, compact plants flowered profusely all
summer long, even during the hottest periods.
These beautiful, reliable plants will be offered at
the 1991 Denver Botanic Gardens plant sale.
Carol Pelehowski was formerly Horticulture Assistant at Den¬
ver Botanic Gardens. She received a B.S. in Horticulture from
Purdue University; she enjoys annuals, and has a special inter¬
est in woody landscape plants and cacti and succulents.
Annuals and Biennials
for Flower Arranging
by Robin Preston
No two bouquets are ever the same. When I ar¬
range flowers, either for myself or for clients,
each creation is unique. The diversity of annuals
allows the arranger to explore many moods and
themes. Some people prefer a bouquet with a
contemporary look — clean, sophisticated and
dramatic. Others like a romantic feeling which
includes many styles and shapes. We all have
occasion for that bold, festive, happy bouquet.
Annuals call to mind bright zinnias ( Zinnia
elegans ), airy cosmos ( Cosmos bipinnatus ) and
fragrant nicotiana ( Nicotiana alata) — A\ the
bounty of the summer garden. I think of the sea¬
sonal flowers as old friends which appear year
after year after a winter absence and I can’t wait
until the first appear. Some annuals are available
almost year-round commmercially, such as stocks
( Matthiola incana), snapdragons ( Antirrhinum
majus ) and blue lace flower ( Trachymene
coerulea ) because they are either easy to grow in
cool greenhouses or are imported. The annuals
that thrive on heat and sunshine, however, are
usually available only in spring and summer. Both
amateur and professional designers look forward
to using their seasonal favorites.
Professional growers take care to cut flowers
from the growing fields as early in the morning as
possible. For most annuals, the foliage is stripped
away from the bottom of the stem which is cut at
an angle at the base to allow the maximum surface
area for the stem to absorb water. Then the flower
is plunged into deep, lukewarm water for an hour
or so, after which it is put into a cooler for harden¬
ing off. A preservative is added to the water. Any¬
time a flower is out of water, the stem must be
re-cut before it is put into water again.
To use a flower for an arrangement to its best
advantage, consider its form and color. Some
6 flowers have a naturally old-fashioned air while
others possess a stately elegance. There are no
strict rules but I think the best designs have a
theme or mood.
For a contemporary arrangement, generally
speaking, less is more. Think of dramatic lines
using twigs, branches or flowers with strong, ver¬
tical shapes. Annuals that can give a contemporary
feel if arranged simply and sparingly are tall,
dramatic foxgloves ( Digitalis purpurea ‘Foxy,’ a
variety that blooms the first year from seed, while
the others are biennial, blooming the second
year). Or let a few sunflowers stand alone with
very little muss or fuss. Other strong, bold annu¬
als that might be used include the daisy-like ger-
beras ( Gerbera jamesonii ) and the vibrant red
tassels of love-lies-bleeding ( Amaranthus
caudatus ). Biennial clary sage {Salvia sclarea )
has stiff, opalescent flower spikes tailor-made for
a simple, clean arrangement.
My favorite theme for arranging is the romantic
style, highly versatile and very popular right now.
Professional floral designers frequently get re¬
quests for these types of arrangements. Terms
often used to describe this look are Victorian,
English garden, precious, Flemish and loose
country arrangements. In this case, more is better.
Queen Anne’s lace (biennial Daucus carota or
annual Ammi majus) is the romantic flower ar¬
ranger’s dream. Like the blue lace flower, it is soft
and always seems to bend in the direction you
want it to go for a magical touch. Nicotiana is great
fun. It can keep an arrangement from becoming
too rigid. It tends to get away from you, creating
an effect that is hard to achieve on purpose. The
sweet scent of the white-flowered varieties is an
added pleasure. The soft green color of the vari¬
ety ‘Nicki Lime’ is unique and invaluable, blend¬
ing with all colors and bringing out the best in
them.
Other annuals that are perfect for the romantic
look are stock for its fragrance and plump, full
spikes, long-lasting native prairie gentian, Eus-
toma grandiflorum , with large purple, pink or
white blossoms and love-in-a-mist ( Nigella dam-
ascena) — oh so delicate and precious. Others
include mallow-cup ( Lavatera trimestris ) — sweet
and demure, borage ( Borago officinalis ) with its
hairy demeanor, true-blue flowers and lush
foliage, and once again, love-lies-bleeding —
often a plant can portray quite different moods,
depending on how it is arranged and in the com¬
pany of what other flowers — for its droopy,
casual attitude. A large or small overstuffed
bouquet, regardless of the theme, relies on diver¬
sity of form, texture and color. All of this lushness
can be emphasized with grasses and foliage cut
from garden shrubs. Foliage is not just a filler. It
can be chosen to provide texture and interest.
Grasses, twigs, flowering branches and berries
add something to almost any bouquet.
Another romantic treat is a bouquet of only one
type of flower bunched together and literally
packed into a container. I will always remember
the time I saw dozens of vibrant home-grown
sweet peas ( Lathyrus odoratus ) stuffed into a
whimsical collection of containers at a friend’s
home. The effect was at once unpretentious and
stunning. Try for the same effect with other
annuals — cosmos, zinnias (incredible color!) or
perhaps nasturtiums ( Tropaeolum majus). Try
this simple, natural, yet luxuriant approach now
and again — it never fails to delight.
Color can be carefully controlled or totally
riotous depending on your mood. A festive theme
is fun and the brighter the better. Imagine a
bouquet with the bold colors and shapes of ger-
beras combined with zinnias, dark blue bache¬
lor’s buttons ( Centaurea cyanus ), purple globe
amaranth ( Gomphrena globosa ), hot pink can¬
dytuft ( Iberis umbellata ), bright yellow sunflow¬
ers ( Helianthus annuus ) and all shades of asters
(Callistephus cbinensis ). This is not a bouquet for
the faint-hearted. Bright bouquets help celebrate
happy times and they make a great gift for a man.
When men ask me to do an arrangement and I
have them choose flowers from the cooler or the
garden, they seem to choose the brightest, bold¬
est, most off-the-wall color combinations, and
oddly enough, to my surprise, the flowers usually
come together beautifully. One of my favorite
color combinations is orange and pink-
different combinations using zinnias, dahlias,
sunflowers, celosia ( Celosia cristata ), gerbera,
snapdragons and geraniums ( Pelargonium xbor-
torum ) pull this off with panache.
For bouquets of any theme, I like to add blue
for contrast and definition. Unfortunately the
choice of blue annuals is more limited, but I
never tire of larkspur ( Consolida ambigua ),
bachelor’s buttons, pansies ( Viola x wittrocki-
ana) and sometimes I even stuff in some trailing
lobelia ( Lobelia erinus).
When arranging flowers, I try to remind myself
to let go of the rules and overly tasteful restraints
and relax. I try to have fun with the containers,
shapes and moods. It helps both the arranger and
the arrangement to maintain an easy-going at¬
titude towards each creation, be it simple or
elaborate. Let yourself discover and rediscover
the limitless possibilities the flowers offer, alone
or in combination. It is an utter joy to take part in
an activity where the natural inclination of the
materials used — the flowers — suggest how best
to use them. That is what flower arranging is all
about — a delicate and pleasurable balance be¬
tween the hand, heart and eye of the creator and
the intrinsic beauty of the plants.
Robin Preston is a floral designer with the shop “Bouquets” in
Denver. She has styled arrangements for several books, in¬
cluding Antique Flowers: Annuals by Rob Proctor, (Harper-
Collins, New York, 1991).
Annual Grasses
by Joedy Arnold
Gardeners are always searching for plants that
will grow and flourish in difficult situations and
remain free of disease and insect attacks. In our
region, drought tolerance has become one of the
most sought-after traits in plants. Tough, depend¬
able and attractive — this describes ornamental
grasses. Using grasses in the garden is not new,
although the recent flurry of interest in them
might have one believe they were just discovered.
Perennial grasses have fallen in and out of hor¬
ticultural favor in the United States throughout
this century. Annual grasses, on the other hand,
have never been extensively available. In 1912,
Boddington’s Spring Garden Guide listed 20
types of grass seed. Included were three annual
grasses: Agrostis nebulosa (cloud grass), Briza
maxima (large quaking grass), and Pennisetum
longistylum . In garden literature and in American
landscapes, perennial grasses have consistently
dominated the annuals.
As I have become more familiar with the
seldom-mentioned annual grasses, I realize that
they, although perhaps a tad less dramatic than
their perennial counterparts, are just as striking
and full of movement. My interest in annual
grasses began eight years ago. I was desperately
looking for something new to add to the collec¬
tion of plants offered in the children’s section of
Denver Botanic Gardens annual plant sale. I had
already ordered the tried-and-true, easy-to-grow
flowers of every color, all the vegetables Peter
Rabbit liked, plants attractive to butterflies, flow¬
ers to dry, herbs to pinch and smell, and so on. I
wanted something new. So, through page after
page of catalogs, I searched for “child-appropri-
ate’plant names — sweet dumpling squash, rattail
radish, bumble bee beans. . . . And there I found
hare’s tail grass, squirrel’s tail grass, foxtail
millet— that started it all. I ordered.
The sweet dumpling squash sold. Peter Rabbit’s
vegetables were a great success. But the hare’s tail
and squirrel’s tail grasses were not a hit. Unable to
bear the failure of my new finds, I bought the
remaining plants. I simply loved the new garden
8 additions.
Originality when selecting plants often pays off,
but design skills are needed to create a truly
beautiful garden. It took several years of experi¬
menting before I found good plant combinations
for my grasses. In general, annual grasses need no
special care. Ordinary soil and full sun to light
shade are all most of these undemanding plants
require. Many tolerate quite a bit of drought.
Annual grasses are not grown for their foliage,
which often looks unkempt and a bit weedy. It is
their flowers and seeds that earn them their place
in the garden, from the rosy-red panicles of ruby
grass ( Rhynchelytrum roseum ) to the pale green
and ivory plumes of hare’s tail grass ( Lagurus
ovatus). Some annual grasses flower profusely
for only a short time and then quickly turn brown
and die. These short-lived types include cloud
grass, little quaking grass ( Briza minor ) and Ca¬
nary grass ( Phalaris canariensis). They need to be
carefully combined with other plants to offset
their shorter period of attractiveness.
The longer-lasting annual grasses offer a wide
variety of colors and textures. Incorporating them
with other annuals, perennials or shrubs is a chal¬
lenge, but when successful, can be strikingly ef¬
fective. In 1988, a marvelous display at Denver
Botanic Gardens combining fountain grass ( Pen¬
nisetum setaceum ), pink-flowered ruby grass,
white Nicotiana sylvestris and the purple, pink
and red foliage of Joseph’s coat ( Altemanthera
ficoidea ) stopped traffic. The foliage of fountain
grass is gracefully narrow and mounded, remain¬
ing attractive throughout the growing season. In
late summer the flowers, 10" spikes in pink and
mauve, begin to bloom. They make excellent cut
flowers, but shatter easily when dry. Ruby grass
can reach three to four feet in height. Its airy,
rose-colored panicles are effective from July into
October.
Pennisetum setaceum ‘Rubrum’ and ‘Cupre-
um,’ with leaves a deep wine red, also give out¬
standing color over a long period of time. Feather
top ( Pennisetum villosum ) is also a long-lasting
annual grass. Last year at the Gardens, a solid wave
of feather top accompanied visitors along the path
on the south side of the conservatory. Red cannas
( Canna xgeneralis ), geranium ‘Sincerity’ ( Pelar¬
gonium x hortorum ) and Salvia farinacea ‘Vic¬
toria’ were spotted throughout. Pansy ‘Black Dev¬
il’ ( Viola x wittrockiana ) appeared at the edge. It
was exhilarating to walk the path with all its mo¬
tion and shifting colors and light. Grasses make a
garden come alive.
Both feather top and Pennisetum setaceum
make great container plants. In large, square wood¬
en planters, combined with small tufts of peren¬
nial blue sheep’s fescue ( Festuca ovina var. glau-
ca ), the grasses create a simple, soft feeling. The
huge, nine-inch red, rose or white flowers of the
Hibiscus ‘Disco Belle’ series make them diffi¬
cult, domineering plants to mix in the garden. In a
pot they look less out of place; in the garden, with
graceful feather top as a foil, they are smashing.
A late-summer combination that works well in
my garden allows perennial mugwort ( Artemisia
lactiflora), four-foot tall with fragrant ivory flow¬
ers, to mingle with the creamy plumes of feather
top. The late-blooming, deep blue flowers of tall,
tender perennial Salvia guaranitica are set off
beautifully by the creamy mugwort and grass.
The best annuals to combine with grasses are
often the more open, natural-looking ones. They
blend easily, contributing to the spontaneous,
easy feeling grasses give a garden. This mood,
evocative of the prairie, was exemplified last year
by the lovely planting on the south berm in the
Hildreth garden at Denver Botanic Gardens.
There, Pennisetum setaceum , ruby grass, Rud-
beckia hirta ‘Irish Eyes’ — a green-centered ver¬
sion of black-eyed susan — and creeping zinnia
‘Gold Braid’ ( Sanvitalia procumbens ) mingled
with the purples of tall, airy Verbena bonariensis
and shorter Verbena rigida. This drought-tolerant
gold, mauve and purple composition mirrored
the colors that dominate the grasslands in sum¬
mer and fall.
I have found that several of the medium-sized
annual grasses, especially foxtail grass ( Setaria
lutescens ), mix wonderfully with native golden-
rod ( Solidago spp. ), blue sage {Salvia farinacea ),
gold and maroon calliopsis {Coreopsis tinctoria )
and the rose-crimson flowers of Mexican sage
{Salvia greggii ). In the shorter part of this bed, I
grow mahogany and gold miniature marigolds
{Tagetes tenuifolia pumila ‘Tiger Eyes’ and ‘Star
Fire’) and Zinnia elegans ‘Old Mexico,’ which
mirrors the marigolds’ colors. Squirrel’s tail grass
{Hordeum jubatum ), with its silky, light-catching
flowers twisting and turning, softens the colors
and textures of the annual flowers.
Some of the larger grasses need bold compan¬
ion plants. Black millet {Sorghum bicolor), a giant
at eight to ten feet tall, makes mighty clumps of
straight, strong stems — highly architectural. Or¬
namental corn {Zea mays) is similar in effect,
although somewhat shorter. Its leaves are gaily
striped with pink, yellow and purple, beckoning
for imaginative companion plantings that pick up
on these colors.
I interplant a perennial thicket of Jerusalem
artichoke {Helianthus tuberosus) with tall annual
grasses and annual sunflowers {Helianthus an-
nuus). Sunflowers, quite drought-tolerant and
very easy to grow, now come in varieties with
more elegance and suitability for cutting than the
original form. ‘Color Fashion Mix,’ offering a wide
range of flower colors from deep gold to the
palest yellow and including burgundy, brick red
and bicolors, provides excitement before the
Jerusalem artichokes bloom. ‘Luna,’ a 5-foot,
branching variety bearing pale yellow flowers
with chocolate centers, or the most manageable
sunflower, ‘Piccolo,’ at only four-feet and covered
in small black-eyed flowers, are two other op¬
tions.
My favorite annual grass is little Lagurus
ovatus, hare’s tail grass. How terribly it has been
misused; it cuts and dries so well that it has be¬
come known more for dying the flowerheads
electric pink, green or yellow than growing them
in the garden. Children love to touch the soft, yet
firm little “hare’s tails.” Hare’s tail grass should be
planted in drifts for the best effect. It mingles well
with little Swan River daisy {Brachycome iberi-
difolia ), dwarf larkspur {Consolida ambigua
‘Dwarf Hyacinth’), Cosmos sulphureus ‘Sunny
Mix, ’ Chrysanthemum carinatum ‘Court Jester’
and Chrysanthemum coronarium ‘Primrose
Gem,’ two colorful annual mums, among others.
Older garden books repeatedly say annual
grasses belong only in the cut flower or vegetable
garden; newer publications ignore the annual
grasses while inspiring the perennial lover. It’s
about time we made room, even in the smallest
garden, for both flowers and annual grasses, and
together, not separate. The real fun lies in choos¬
ing the combinations.
A short description of 13 annual grasses fol¬
lows:
Agrostis nebulosa (cloud grass)
8-20", blooms June through July, sometimes into
August. Loosely-tufted grass with sparse foilage,
slender leaves, leggy stems. Large delicate,
cloud-like clusters of flowers are good for cutting
and drying but not dyeing. Dies quickly after
blooming. Well-drained soil, sun or light shade.
Germinates in three weeks when sown outdoors. 9
Briza maxima
(puffed wheat, large quaking grass)
1- 2', blooms mid-June through July for 6-10
weeks. Loosely-tufted annual grass, can be a bit
ungainly and reach 3' with extra water and rich
soil. Foliage of medium texture, light green
maturing to straw yellow and finally rich brown.
Flower spikelets are pale green to purplish green
and wave and bob in the slightest breeze. When
dry, the panicles of florets rattle nicely if left in the
garden and are equally suited to drying and dye¬
ing. Pick the panicles before the florets open. Dye
them in a hot water solution. Germinates in 10-14
days if sown indoors, can be sown directly in
place. Well-drained soil and full sun.
Briza minor
(little quaking grass, lesser quaking grass)
6-18", blooms 4-6 weeks sometime betweenjune
and September, usually just as B. maxima has
finished. Dies shortly after flowering. Charming
2- 4" light green panicles of heart-shaped florets
make this a good grass for cutting and drying.
Botanical variety B. minor var. minima stays 6".
Fertile soil, full sun, not drought-tolerant. Is flat¬
tened by heavy rain, wind or forceful hosing.
Bromus lanceolatus ( B . macrostachys )
(brome grass)
2', blooms mid-June through mid-August for 6-10
weeks. Other species of brome grass are noxious
weeds. This densely-tufted grass has an erect,
4-7" spiky inflorescence, with showy slender
bristles. It starts off pale green, turning beige with
age. Difficult to dry but very beautiful. Full sun,
average moisture. Sow direct in spring.
Coix lachryma-jobi (Job’s tears)
3- 4', insignificant spikelets followed late in the
summer by showy, hard, bead-like fruits. Fruits
start green, turning shiny greyish-mauve in the
fall, and finally nearly black, contrasting nicely
with the broad, flat, stiff leaves. Fruits have been
used for jewelry and rosary beads for centuries. In
the Orient, seeds are ground into flour. Best to
start as plants since it takes a long season to ripen
the seeds. Grow in part shade with ample mois¬
ture for best results. To hasten germination, soak
seeds in water for 24 hours before planting.
Hordeum jubatum (squirrel’s tail grass,
foxtail barley)
20-30", blooms early June through July for 6
weeks. Open-tufted short-lived perennial or an¬
nual grass. Feathery, plume-like flower spikes can
be green, dark red or purple, and twist and curl.
Pick before fully mature for fresh arrangements;
they shatter easily when dried. Full sun, moist or
dry soil. Bristles cause problems in livestock,
which has led to the ban of the grass in certain
regions.
Lagurus ovatus (hare’s tail grass)
10 10-20", blooms June through August. Loosely-
tufted grass with dense, pale-green flower spikes
that do not shatter with age. Foliage is attractive
pale greyish-green. Stems and leaves soft and
downy. Full sun or light shade with average mois¬
ture for best flower production; tolerates
drought. Easy to grow, can be sown directly.
Phalaris canariensis (Canary grass)
2 14 ' , blooms June through mid-August. Tufted
annual grass reaching 4' in optimum conditions.
Flower spikes variegated green and cream, good
in dried bouquets, difficult to dye. After flower¬
ing, plants decline rapidly. Widely cultivated for
birdseed for wild and domestic canaries. Often
grows at the dump where the papers lining the
bottom of bird cages end up. Full sun, well-
drained soil, average moisture. Self-sows readily.
Pennisetum setaceum (P. ruppelii )
(fountain grass)
2-3', blooms late July through October for 10 or
more weeks. Similar in size and habit to the per¬
ennial Australian fountain grass, Pennisetum
alopecuroides . Forms graceful, fine-textured,
arching mound, very useful in softening harsh
areas such as paths, driveways and walls. Flowers
8-10" long, narrow, rose-colored panicles, great
for fresh flower arrangements. Full sun to light
shade, ordinary garden soil. Varieties ‘Rubrum’
and ‘Cupreum’ have broader leaves and are more
upright. ‘Rubrum’ has rose-purple leaf-blades and
flowers, ‘Cupreum’ red-brown foliage and cop¬
pery flowers.
Pennisetum villosum (P. longistylum)
(feather top)
IV2 — 2V2' , blooms mid-July through late Sep¬
tember. A short-lived perennial in warmer cli¬
mates. Green, medium-textured, mounding
foliage. Numerous flowers are quite heavy and
arch and droop, producing a graceful effect.
Feathery bristles on the pale-green to white, 3-5"
long flowers give them a feathery appearance.
They turn buff with age. Full sun to light shade.
Fertile soil and average moisture produce the
best plants, yet feather top can tolerate some
drought. Easy from seed started inside or sown
outside when the ground is warm.
Rhynchelytrum repens (R. roseum, Tricholaena
rosea ) (ruby grass, Natal grass, champagne grass)
2-3', blooms mid-July through early October, for
about 10 weeks. Loosely-tufted, upright annual
grass, perennial in warmer climates — in the
South, especially Florida, it has naturalized along
the highways. Green leaf blades about 1", flat and
tapered to a point. 6-10" ruby-red flower heads
turn pink and finally silvery white over a long
season of attractiveness. It is excellent for fresh
arrangements — pull the stem out of the leaf
sheath rather than cutting it when harvesting. It
loses its color rapidly and shatters when dried.
Stems root if the nodes touch the ground. Offsets
can be detached and potted up, grown in a cold
greenhouse over the winter and planted in the
garden the following spring. Full sun, well-
drained soil. Ruby grass is heat- and drought-
tolerant.
Setaria italica (foxtail millet, Italian millet)
3', blooms mid-June through August. First grown
in ancient China in 2700 B.C., where it was con¬
sidered sacred. In China today it is a major cereal
crop. During the Middle Ages, it was cultivated as
a grain in Europe; presently it is an important
source of birdseed. Foxtail millet’s 3-7", loose
panicles of white, cream, yellow, red, brown or
black flowers turn golden tan in late summer. Sun
to light shade, ordinary garden soil. Can take light
drought. Easy from seed sown directly in spring.
Sorghum bicolor ( S . vulgar e)
(great millet, dari, durra)
8-10', blooms in the summer, inconsequential —
seed is decorative. Sorghums have been used
since prehistoric times. The juice of the stems is
used to make molasses, syrup and an alcoholic
drink. One variety is made into flour, another is
grown for silage and fodder for cattle. The dried
panicles of another are used for brooms. 2 '-long
leaves are light green with specks of brown or
curry and make excellent additions to the flower
arranger's palette. The shiny black seed panicle is
loosely formed, varying in size and shape. It starts
off erect, becoming more pendulous as it ripens.
Often green, white and pink grains are mixed in
with the black and brown ones, making the pani¬
cle a prime candidate for fresh arrangements as
well. The seeds fall out quickly, so drying is not as
successful. Full sun, ample moisture. Do not set
out until all danger of frost is past.
Joedy Arnold is one of the 12 founding members of the
original Denver Botanic Gardens volunteer group formed 30
years ago. As head of the annuals division of the Gardens plant
sale, she offers over 500 species and varieties of annuals each
year, making the sale one of the best retail sources for unusual
annuals in the country.
Volunteers
Benefit
Denver’s
Flower Beds
by Amy Pulver
Denver’s nationally recognized city flower beds
have been admired by visitors and loved by Den¬
ver residents for one-hundred years: 1990 was
their centennial anniversary. During the past
three summers, some of these flower beds have
received an extra dose of tender loving care from
participants in Denver Parks and Recreation’s
Volunteers in Parks (VIP) program.
Denver Parks and Recreation employees pre¬
pare the beds, plant the flowers and then work
with VIPs to provide training, answer questions
and ensure the work is accomplished regularly.
VIPs weed and cultivate the beds, pinch back the
plants and remove spent blossoms. The success of
the program has led over the past few years to
include beds in Observatory Park, Huston Lake
Park, Pinehurst Park, Seventh Avenue Parkway
and Rosamond Park.
The various VIP groups organize their efforts
and volunteers differently. In Observatory Park,
for example, families sign up for maintenance
duties for several days or a week during the sum¬
mer months, while in Huston Lake Park, the entire
group convenes regularly and works together.
The beauty of the program is that it can be de¬
signed to fit the needs, demographics and work
patterns of each participating neighborhood,
making it a rewarding and enjoyable experience
for participants of all ages while beautifying Den¬
ver for everyone.
Since 1989, more than one-hundred volunteers
have participated and the potential for expansion
is nearly limitless. For additional information,
contact Volunteer Program Administrator De¬
laine Deal at (303) 458-4794.
Amy Pulver is Director of Communications for Denver Parks
and Recreation.
Coreopsis
tinctoria
The Garden-less Gardener:
\
Containers to the Rescue
by Tom Peace
Container gardening is the most versatile way of
bringing plants into your life. Some of these serve
as portable gardens, grown in anything from clay
flower pots to whiskey barrels; others are as large
and esoteric as the rare case of a swimming pool
filled in and planted after the owner grew tired of
pool maintenance.
Although gardening in containers is the logical
solution to a shortage of real garden space, it is
also the best approach for would-be gardeners
with lots of space but no real soil. Many gardeners
have experienced the agony of trying to plant
flowers and vegetables in ground more suited for
making bricks or being a driveway. And while
almost any land can be amended and worked into
viable and vital soil, it is definitely easier to fill a
pot with a particular mix and plant in that.
Necessity is not the only reason to delight in
container gardens. Even an established garden
can use well-planted pots and boxes. Many excel¬
lent perennial borders and landscapes are en¬
hanced by potted blooms on the terrace; they add
a cohesive, integrating element between the nat¬
ural part of the garden and the non-living land¬
scape— the paths, patios, terraces — near the
house.
One of the advantages of pot culture is the
ability to move containers and redecorate the
terrace, balcony or patio for parties, on a whim or,
as the weather cools, to bring favorites inside for
prolonged bloom. Again, if the containers are
light-weight, the task of moving them about will
be so much easier. Therefore, try to fill the bot¬
tom portion of especially large pots with some¬
thing light so that only twelve to fifteen inches of
soil mix are needed to fill the pot to just below
the rim. At last there is a noble use for those
styrofoam packing bits. Bark can also be used, as
well as tree leaves from last fall’s pile, or even
emptied, inverted six-packs from store-bought
annuals. With large containers offering greater
opportunities for garden design and more of an
impact on an area than smaller ones, it’s nice to
know the entire garden allowance needn’t be
12 spent on the soil to fill them.
The most important consideration for the
planted container is size. Small pots dry out
rapidly in our hot, dry summers and the joy of
gardening will quickly diminish if you are forced
to water several times a day. To avoid this and
reclaim the summer for more engaging activities,
don’t plant any pot less than six inches deep and
ten inches in diameter (eight inches in diameter if
in the shade).
However, if you find the perfect urn and it
happens to be on the small side, don’t hesitate to
fill it with geraniums ( Pelargonium x hortorum,
P. peltatum) or trailing verbena ( Verbena x hy-
brida, Verbena tenera), or a few of the other,
more drought-tolerant annuals. There are several
that tolerate frequent drying out and still look
quite pert. Larger pots will offer a more constant
growth environment for those flowers and plants
without a cast-iron constitution.
The choice of container is a combination of
imagination and resource, artistry and budget.
While I wouldn’t reject outright any container
chosen by the creative gardener, I will say that the
“tulip-cut” old tire could be laid to rest for a while.
I admit to the fantasy of antique claw-foot bath
tubs brimming with brilliant blue, red and pink
flowers of de Caen anemones ( Anemone coro-
naria ), so I know how easy it is to cross the fine
line that separates the unique from the absurd.
Let your imagination run wild even if your
wallet cannot, but don’t be too timid to consult a
friend for artistic advice. Terra cotta pots can be
expensive in the larger sizes, although their famil¬
iarity is soothing. Storing them in a dry place away
from extreme temperature changes during the
winter will help them last for many years. Baskets,
brass, wood, glass or even plastic with a coat of
special spray enamel that adheres well are just a
few of the materials possible.
Once the containers are selected, it’s time to fill
them. There are many potting soils and soil-less
mixes from which to choose; some gardeners mix
their own. When I mix mine (I feel that paying for
soil is like buying sunshine or air) I start with a
good garden loam or sandy loam and add perlite
or vermiculite in equal proportions. The suffix
these latter two ingredients share is key here —
“lite," even if misspelled, since the finished con¬
tainer should be more easily and painlessly
moved to any of several locations during its life. I
also add organic matter in the form of leaf mold,
compost or peat moss in the same volume as the
soil so that the resulting mix is one-third soil,
one-third “lite” ingredients and one-third organic
matter.
Whether you are going to landscape with your
miniature “gardens” or just embellish a spot, start
by looking at where the container will go before
you plant it. The site will dictate both what can be
grown as well as what plants will look best in
terms of color, size, form and texture. Always ask
yourself, “what will grow here?” as a first step so
you don’t end up with tender shade lovers frying
on the sunny south-west patio while the sun- and
heat-loving plants languish under the cool shade
of the maple tree. The right plants in the right
place will result in reliable performance all sum¬
mer long, barring heat waves and hail storms.
A few artfully placed pots combining airy as¬
paragus fern ( Asparagus densiflorus ), blue and
white trailing lobelia ( Lobelia erinus), yellow¬
leaved coleus ( Coleus x hybridus) and variegated
trailing vinca ( Vinca major ‘Variegata’) will create
a cool, breezy ambiance on a shaded terrace. In
an east-facing area, sheltered from the hot after¬
noon sun, try a few white planters filled with
simple yet lush Martha Washington geraniums
( Pelargonium xdomesticum ), whose flowers re¬
semble the most beautiful azaleas. Just as easily a
sultry tropical garden tub can be created with
dramatic red-leaved castor bean ( Ricinus com¬
munis) and cannas ( Canna x generalis), hot-
colored hibiscus ( Hibiscus rosa-sinensis) and yel¬
low lantana ( Lantana camara) glowing on a hot,
sunny patio (provided the container is large
enough to be kept evenly moist).
I do not mean to ignore petunias ( Petunia x
bybrida ), pansies ( Viola x wittrockiana) or
geraniums and the like. Rather, many of the
delightfully-colored hybrids of these old stand¬
bys, when grown and displayed in pots, become
visually revived and invite reveling in their colors,
singly or in combination. I particularly love a
basic terra cotta pot overflowing with plum or
burgundy petunias, or a bright mix of festive nas¬
turtiums ( Tropaeolum majus ) trailing over the
edge of a clay azalea pot.
I am also fond of raucous, gaudy palettes for a
splash of contemporary landscape color. Some¬
how floral combinations that in the border might
call to mind a velvet painting, leap to acceptable
and exciting heights as containerized composi¬
tions. The exuberance of plant color, form and
texture is celebrated in the confines of a tub as
purples, yellows, reds and oranges consort like
the notes of the Hungarian Rhapsody.
I recommend including at least one type of
non-blooming plant in the combination for
foliage appeal. It may seem a loss to forego the
unabashed verve of a flowering annual for some¬
thing more subtle, but the subdued effect of
foliage color and form works wonders in con¬
tainers, just as it does in the garden. One of my
favorite ensembles includes yellow and bur¬
gundy coleus and silver dusty miller ( Senecio
cineraria) around a dracaena ( Cordyline indi¬
visa) spike with an edging of lacy lobelia trailing
over the edge. Garden perennials and herbs can
also be used for foliage effect, such as variegated
ribbon grass ( Pbalaris arundinacea ‘Picta’), blue
fescue (Festuca ovina var. glauca), bergenia
( Bergenia cordifolia), hosta, lavender ( Lavan¬
dula angustifolia), scented geraniums ( Pelar¬
gonium spp.) or rosemary ( Rosmarinus offici¬
nalis) to name just a few.
A cool look for a hot spot might include blue
fescue with grey-leaved lavender and lacy dusty
miller backed by white geraniums. This collec¬
tion would also tolerate considerable drought.
For a simple urn in light shade, combine bergenia
or hosta with large-leaved dusty miller, ribbon
grass and either white or pastel impatiens ( Impa -
tiens waller ana) or pansies. Variegated gerani- 13
ums are a valuable addition to a container garden
even if they refuse to bloom. The mottled tropical
foliage of the white or yellow summer callas
C Zantedeschia albomaculata andZ elliottiana )
is also stunning in a pot, even after the showy
blossoms fade.
When springtime enthusiasm and available
space allow for a vast array of potted possibilities,
the big landscape picture should be kept in mind.
Allow for different themes to develop in certain
areas, encouraging this by the repetition of cer¬
tain forms, colors, textures, and particular plants.
This will also successfully harmonize an other¬
wise hodge-podge collection of containers. By
establishing a rhythm of color or form, for in¬
stance by repeating a favorite accent plant in every
pot, a unified, harmonious and beautiful con¬
tainer landscape emerges. No gardener need re¬
main garden-less.
Colorado State University-trained Tom Peace is a freelance
landscape designer in Colorado and Texas. He was a
wholesale grower for the florist trade for seven years; he
especially enjoys growing unusual plants and has had great
success pushing the limits of hardiness.
For the Love of Cut Flowers:
An Annual Ritual
by Diane Ipsen
Viola x wittrockiana
Chryse Hutchins just loves it when Valentine’s
Day is over. Not that she’s unsentimental or
abhors boxed chocolates. It’s just that that’s when
she “knows it’s coming.” Chryse is referring to the
long-awaited annual event of planting her cutting
garden, and she speaks of this with a passion in
her voice that might be reserved for an upcoming
trip to Tahiti or at least the end of the school year
(she is a teacher). But for this amateur gardener,
like so many others, it is the anticipation of the
cherished rituals that come with the gardening
season that quickens her pulse in February.
“The process is such an important part of it.
That’s what I love as much as anything,” she says
with fervor.
There is, first of all, Making the List. Then comes
the Search: snooping around in all the garden
centers. “I have certain places I go for each
variety — and I have all these memories — like
when I go to Evergreen’s Half Acre. I love going
there when there’s a big thunderstorm — I just
hope that I’ll hit it each year because I remember
the feelings of being in that place — that’s not
really an indoor garden, it’s kind of outdoors as
well. . . And, you know, the canvas flaps are blow¬
ing. . She trails off, in a reverie, lost among the
bedding plants in a rainstorm.
“And that is part of the whole ritual of all this. I
don’t know. . . I do this every year, and I bet I
spend over $400 — easily. But, you know,” she
14 laughs, “it’s cheaper than a shrink.”
Chryse would be the first to admit that her
garden has little winter interest. Few perennials
are visible in early spring for she reserves almost
every inch of garden soil for setting out bedding
plants in May. The reason she has dedicated her
garden to annuals is that one of her deepest satis¬
factions in life is to arrange great bunches of
homegrown flowers in every basket, bowl or vase
she can get her hands on and give them to her
lucky friends. When you have as many friends as
Chryse has, this requires a bounteous crop of
flowers for cutting all summer long and that
means planting mostly annuals. Chryse Hutchins
is a gardener with a purpose.
“I’m real funny about all of this; I know exactly
what I want. I’m not very adventurous,” Chryse
protests in defense of what she considers to be
her modest palette of bedding plants. “But every¬
thing I plant, I plant to cut. I don’t plant for it to
look aesthetic.” That means three criteria must be
met for a flower to earn its keep in this garden,
where space and sun are at a premium: the color,
a good stem, and its staying power in a bouquet.
(The exception is electric blue lobelia ( Lobelia
erinus), which Chryse must have in the garden,
though she doesn’t use it for cutting.)
“The main thing I plan all the other flowers
around in an arrangement are the dahlias, which
are wonderful cutting flowers,” says Chryse. She
only grows the big types, buying them as large
plants in May — and she doesn’t dig the tubers up
in fall as many gardeners do. “The seed dahlias
are okay for an arrangement, but the stem isn’t
long enough,” she says. “If a stem is too short or
hairy, that’s bad.”
Besides dahlias, her not-exotic-bucreliable
regulars for cutting include bronze French
marigolds ( Tagetes patula ), pink and white
nicotianas ( Nicotiana alata ), zinnias ( Zinnia ele-
gans), cosmos ( Cosmos bipinnatus), impatiens
( Impatiens wallerana ), pansies ( Viola x wittrock-
iana ), and her favorite — ‘Little Darling’ snapdra¬
gons ( Antirrhinum majus), a semi-dwarf variety.
“I just adore them. In an arrangement, they are so
precious; people ask: ‘what is this?’ They look just
like a little rose — and they won’t flop over when it
hails or storms. I buy several flats of little Darl¬
ings’ and if I keep them cut and fertilized, I can get
three big harvests — but that variety can be a little
harder to find.”
Chryse may call herself “unadventurous” but
every year she initiates something new. Last
summer she had high expectations for Nemesia
strumosa and planted all the colors: orange, yel¬
low, pink and deep pinkish-purple. But nemesia
didn’t perform well in partial shade, and Chryse
feels it needed a sunnier location. Even though
she fed the plants regularly, the ingrates quit
blooming. Stocks ( Matthiola incana ) were also
allowed into the club but they behaved them¬
selves, contributing a spicy fragrance to her
bouquets and proving to be long-blooming. (“In
fact, at Thanksgiving I still had some going out
there.”) She minces no words in reviewing the
performance of her third provisional plant: she
hated gazania. “That should remain in your
garden — it should not ever be cut!” she warns,
still wounded by its betrayal. Blossoms of
Gazania rigens close up with shade, so of course
they exhibited that cantankerous habit in her
flower arrangements as well.
According to Chryse, upcoming summer ex¬
periments may include perennial Salvia x su-
perba, white coralbells ( Heuchera sanguinea )
and hollyhocks ( Alcea rosea), which she thinks
are regaining popularity because they remind
people of the past.
Another old-time favorite making a come-back
is feverfew, which Chryse discovered last sum¬
mer. Passionate gardeners become keen observ¬
ers of any new developments on the local hor¬
ticultural scene. On her daily walks, Chryse kept
noticing a white chrysanthemum-like flower
growing in neighbor’s gardens. Checking around,
she found out it was Chrysanthemum parthenium
‘White Stars' — sometimes sold as Matricaria and
grown as a half-hardy annual. “The reason I’m so
excited about this plant is that it’s white. I have so
much pink and yellow in my garden that I love
finding anything that’s white. It’s charming in ar¬
rangements and it has such a long blooming sea¬
son!" Feverfew definitely made it into the inner
sanctum.
“After the daisies go, petunias and nicotianas
are the only white flowers that are left. And white
dahlias. I need to find more white annuals! I
noticed that I didn’t have enough white so this
past year I tried white gerbera daisies ( Gerbera
jamesonii ), but they only produced one or two
flowers the whole season. They’re gorgeous
when you get one. They’ll last two weeks.”
Gardening snobs may thumb their noses at
petunias, but Chryse finds ‘White Cascade’ pro¬
vides a terrific source of the long-lasting white
blossoms she finds difficult to keep stocked.
Another petunia Chryse favors is ‘Midnight’ which
sports streaks of deep purple against white and
has a longer stem.
Chryse understands that variety in flower form
and size is essential to the beauty of a bouquet.
She lists her perennial coralbells and pink ver¬
onica ( Veronica spicata ) along with annual blue
Salvia farinacea as favorite flower forms to spray
out from an arrangement and contrast with
rounder flowers. But flowers don’t compose the
whole picture either. Some of the most important
plantings in Chryse’s garden are the annuals she
grows for foliage: dusty miller ( Senecio
cineraria) and pink-tinged varieties of coleus
( Coleus x hybrida) — for she has a very defined
method when she sets out to arrange a basket of
cut flowers. “I like to separate flowers by color; I
usually don’t put pink next to yellow — that’s real
important to me. Instead, I separate colors with
dusty miller or coleus. I just love how it frames the
flowers! Or I use white nicotiana and put colorful
flowers around it."
Her fascination with arranging flowers began
quite casually, back in the days when Chryse was
still trying to figure out how to reconcile a ram¬
bunctious Labrador retriever, a free-roaming pet
rabbit and a garden of flowers. She created some
modest centerpieces and shared them with
friends. Recipients got hooked. Soon she was
urged to offer her bouquets as an item for bid at
the annual fund-raising auctions at her children’s
schools. Chryse offered one flower arrangement
a month for June, July and August and it prompted
a generous bid. Now she offers two such pack¬
ages. “I realize how much joy other people re¬
ceived from my doing that,” she says with honest
amazement.
Surprisingly, Chryse seldom uses fresh flowers
in her own home. “I give them all away. It’s just
more fun to make sure someone is at home, drop
them off and say ‘Enjoy!’ It’s really a kick for me. . .
Some people say: ‘Oh Chryse, I tried to get your
flowers at the auction this year and I was outbid
so I put those people on my list too. Sometimes a 15
friend will call and say: ‘you told me to tell you
this, but we’re having a dinner party tonight —
would you mind?’ And I love that!” Throughout
the summer, she bestows her flower arrange¬
ments at the rate of three a week — which should
just about qualify her for Fairy Godmother status.
“Oh, but the planning is great — the ritual of
going out every morning with my cup of coffee
and kind of planning: ‘Well, if I wait two more
days I’ll have a purple-white dahlia and an all
white dahlia’ and then watching to see what other
things would be available to fill in. . . and not
taking too much of the coleus for this particular
bouquet and leaving it for another one down the
road.”
But for Chryse the optimal experience, the
harmony and connectedness that accompany a
state of focused concentration, comes with the
creative act of making the bouquet. “I just love
having all my flowers laid out on the kitchen
counter, and standing back, and putting them in
the containers, and looking at them — I just love
that feeling. . . and then they’re there and I think:
‘Who can I give these to today?’ It’s a total escape;
flower arranging does that for me. I can let the
dinner burn. . . I don’t feel guilty about doing that
because I feel so fulfilled when it’s over. I’ve
never read a book about flower arranging — I
probably should. I’ve never taken a class. People
say, ‘How'd you learn to do this?’ I don’t know if
they look good or not — but I just feel so much
better when I’m all done!”
“Everything that I’ve learned has been through
trial and error or standing for hours and reading
signs in garden centers and asking salespeople
questions. That’s how I’ve learned everything —
just reading all those signs and thinking of trying
these things out. It’s been kind of my own discov¬
ery process, which I like about it.”
Chryse continues, “It’s such a different ap¬
proach from what I use with my job [as a writing
teacher for The Denver Coalition and the Stanley
British Primary School]. I’ve read dozens of books
and I’ve attended lectures, taken classes. . . I’ve
done everything I could to find out about the
writing process. This [the gardening] is a real
personal search."
The question comes up: perhaps we have come
to rely too heavily in our culture on the so-called
experts — we have stopped trusting (and there¬
fore lost the resulting joy of discovery from) our
own first-hand experiences and observations.
Perhaps the fascination with and wonderful thing
about gardening is that you can try something
you’re not sure of, goof up, and it doesn’t really
matter: it isn’t a big risk — plus, you get to try it
again and maybe get it right next year.
Chryse thinks about that for a moment. She still
feels she ought to research gardening more in
books. “I do need to find more white annuals.”
She smiles. “But I’m happy with the way it is.”
Diane Ipsen holds a master’s degree in landscape architecture
and her practice focuses on residential design. She em¬
phasizes water-wise landscapes and likes transforming clients
into enthusiastic gardeners.
To help solve her problem with white, Chryse was delighted to learn about the many white annuals she could try:
Alcea rosea hollyhock biennial
Ammi majus annual Queen Anne's lace
Ammobium alatum winged everlasting
Argemone platyceras prickly poppy
Begonia spp. begonia
Brachycome iberidifolia Swan River
daisy
Browallia speciosa browallia
Callistephus chinensis China aster
Campanula medium Canterbury bells,
biennial
Catharantbus roseus Madagascar peri¬
winkle
Centaurea cyanus bachelor's button
Crepis rubra hawk’s beard
Chrysanthemum spp. garden mums,
feverfew
Clarkia spp. satin flower
Cleome hasslerana spider flower
Consolida ambigua larkspur
Cynoglossum amabile Chinese forget-
me-not
Dahlia hybrids
Datura spp. angel’s trumpet
Daucus carota biennial Queen Anne’s
lace
Dianthus chinensis garden pinks
1 6 Digitalis purpurea biennial foxglove
Dimorphotheca spp. Cape marigold
Eschscholzia californica California
poppy
Euphorbia marginata ghostweed
Eustoma grandiflorum prairie gentian
Gazania rigens treasure flower
Gomphrena globosa globe amaranth
Gypsophila elegans annual baby’s
breath
Helichrysum bracteatum strawflower
Heliotropium arborescens heliotrope,
fragrant
Helipterum roseum strawflower
Hesperis matronalis sweet rocket, bien¬
nial, fragrant
Iberis spp. candytuft, fragrant
lmpatiens spp. impatiens
Ipomoea purpurea morning glory
Lantana camera lantana
Lathyrus odoratus sweet pea, fragrant
Lavatera trimestris shrub mallow
Limonium sinuatum statice
Linum usitatissimum annual flax
Lobularia maritima sweet alyssum,
fragrant
Lunaria annua honesty, biennial
Malcomia maritima Virginia stock,
fragrant
Mirabilis jalapa four-o'clock
Myosotis sylvatica biennial, fragrant
Nemesia strumosa nemesia
Nicotiana spp. flowering tobacco, fra¬
grant
Nierernbergia hippomanica cupflower
Nigella damascena love-in-a-mist
Oenothera acaulis Mississippi evening
primrose, fragrant
Omphalodes linifolia navelwort
Papaver spp. poppy
Pelargonium spp. geranium, fragrant
Pensternon gloxinioides penstemon
Petunia x hybrida petunia, fragrant
Phlox drummondii annual phlox, fra¬
grant
Portulaca grandiflora moss rose
Salvia spp. sage
Scabiosa atropurpurea pincushion
flower
Schizanthus spp. butterfly flower
Senecio cineraria dusty miller
Torenia foumieri wishbone flower
Verbena spp. verbena
Viola a wittrockiana pansy
Venidium fastuosum Cape daisy
Xeranthemum annuum immortelle
Zinnia elegans zinnia
Dressing for Success —
Clothing the Garden with Annuals
by Angela Overy
Trees, shrubs and perennials form the skeleton,
the bone structure of the garden. I see annuals as
the clothes on the body frame, always changeable,
providing quick transformations of personality,
be it from the boldly glamorous to the elegantly
efficient to the dreamily romantic.
Some older gardens have been planned so
beautifully over the years that they need only a
few little touches of added color here and there to
keep them exquisite all summer long. In such
gardens, the shrubs, perennials and herbs have
been carefully orchestrated over the seasons so
that an annual is almost an intrusion into the
symphony. There also is often very little spare
space.
Few gardeners have worked themselves into
this enviable position, however. Even those who
have might consider setting aside a small area just
for annuals, perhaps in the sunny part of the front
yard for a yearly dazzle that you and your guests
can enjoy every time you drive up to the house.
Such a planting makes a statement, a signature for
the home; friends and neighbors will eagerly an¬
ticipate arriving at your place to discover what
interesting and attractive annuals you have plant¬
ed this year.
We all fall into habits; it is easy to plant the same
geraniums interspersed with the same dusty mil¬
lers, bright petunias or marigolds, year after year.
These are fail-safe garden plants for all but the
highest elevations of Colorado, much like the
wool suit and cotton shirt that will get you any¬
where, but it is fun to explore some other hor¬
ticultural fashions with annuals.
To make an impact from across the street, mid¬
sized annuals massed together in bright colors
are best, for example scarlet annual penstemons
( Penstemon hartwegii hybrids), a vivid display of
mixed zinnias ( Zinnia elegans ), or crystalline
white flowering tobacco ( Nicotiana alata).
Gardeners who have a good skeleton of shrubs
and perennials may want to add annuals to fill the
gaps in their flowering calendar, replace a
winter-killed plant with quick color or disguise
fading spring bulbs in May and June. Gaily col¬
ored annuals poked into the gaps are the answer.
However, sibling rivalry can run riot in the beds
and needs to be controlled by good planning at
the outset. Tending a garden is much like having a
family or being a teacher — you have to protect
the sweet, quiet ones from the loud, boisterous
ones. Similarly, it is important to prevent the
noisier annuals from overshadowing favorite
perennials. In my garden, nothing is allowed too
close to my beloved perennial Penstemon or De-
losperma species. There are, however, a number
of filler annuals that grow vigorously yet can be
adequately controlled.
Petunias ( Petunia xhybrida ) have a reputation
as the K-Mart polyester pantsuit of the horticul¬
tural world. But I have found that with careful
selection they are invaluable additions in flower
beds: they provide instant color, from the mo¬
ment you get them home in their tiny six-packs
(now often only four-packs). It is wise to pinch
them back immediately, sacrificing the flowers
that made you buy them in the first place. Think of
these initial flowers as mere samples to help
color-coordinate the garden before the real show
begins a few weeks later.
My all-time favorite petunia is ‘Azure Pearls,’ a
glorious periwinkle blue that appears more pur¬
ple in the afternoon and evening. The flowers are
single and not as large as some of the overblown
varieties, but they bloom profusely all summer
and each fall I bring in a few pots to continue their
bloom indoors. Similar petunias are ‘Azure Sails’
(blue) and ‘Yellow Magic,’ the latter very pretty in
a sunny, hot, all-yellow bed with perennial
Coreopsis verticillata, Zinnia grandiflora, furry- 17
leaved hawkweed ( Hieracium villosum ), Ozark
sundrop ( Oenothera missouriensis ), Penstemon
barbatus ‘Schooley’s Yellow,’ and small, bright
annual Gazania rigens.
For those who enjoy wearing a few sequins or
black tie once in a while, I recommend the flam¬
boyant petunia ‘Total Eclipse.’ The blossoms are
single, brilliant and deep purple with white mar¬
gins and a good choice for a bed that can deal with
their delicious flamboyance.
Another choice filler is globe amaranth, Gom-
phrena globosa . Its flowers look like woolly balls;
the bright heads provide color — pink, rose, pur¬
ple and white — in the late summer months. The
plants are compact, usually a foot or so in height,
so they do not crowd out other plants. Globe
amaranth is slow to get going but by late July this
annual will flower and keep flowering until after
the first frost. Be sure to pick the flowers soon
thereafter for dried winter arrangements. White
globe amaranth is a good choice where a spar¬
kling, consistent white color is needed. ‘Buddy’ is
brilliant magenta, similar to the ‘Total Eclipse’
petunia in effect. My favorite is ‘Strawberry
Fields,’ with amusing red flowers that have white
spots like a strawberry.
Snapdragons ( Antirrhinum majus ) are only
just a notch above petunias in the flower fashion
hierarchy. But with florists charging $1.00 or
more for a long stem, it is well worth growing
your own, as they are invaluable in summer
bouquets. They come in a number of colors but
the pale pink, peach and cream varieties are hard
to beat for large foyer arrangements and summer
weddings. Buy the tall, not dwarf varieties. Show
children how to squeeze the corolla to make the
“dragon” open its “mouth.” The newer butterfly
snapdragons are particularly attractive and not
quite so old-fashioned. Snapdragons are easy,
hardy through at least September and sometimes
will reseed or winter over — definitely a good
value.
1 8 You won’t win any points for innovation, but in
shady beds you can’t grow wrong with a sensible
costume of the old standbys wax begonia {Be¬
gonia x semperflorens-cultorum) and impatiens
{Impatiens wallerana) to fill dull spots. The red¬
leaved begonias are tolerant of full sun as well. Do
not try to grow either of these annuals under a
blue spruce or juniper, however; even these stal¬
wart annuals cannot tolerate that treatment.
When manufacturers can only afford to make
an item or dress of one color, they usually choose
blue; tests have shown that most Americans prefer
blue to any other color. If you love the blues as I
do you might want to consider a whole group of
blue annuals to make a beautiful cool corner in
the bright part of the garden. This might be next
to a sunny patio where the icy colors would create
a refreshing ambiance on a hot day. Assuming you
have a basic backbone of blue perennials in
place — perhaps tall spires of blue delphiniums
{Delphinium elatum hybrids), Colorado’s own
columbine {Aquilegia caerulea ) and blue mist
spirea {Caryopteris x clandonensis) — add all-
season blue color with annuals. Kingfisher daisy
{Felicia amelloides ) is a true daisy with a yellow
center, only about a foot high, pretty and rela¬
tively unusual. It prefers the cooler spring and
fall, and appreciates some shade during the
height of the summer heat. True sky-blue Cyno-
glossum amabile, also known as Chinese
forget-me-not, thrives in light shade, as does blue
Asperula orientalis, resembling its close cousin,
perennial sweet woodruff {Galium odoratum)
with its lacy, whorled foliage and delicate
flower-heads. Browallia speciosa, a trailing an¬
nual excellent for containers on lightly shaded
porches and patios, blooms profusely in soft
periwinkle blue, its flowers like a refined, small¬
er, star-shaped petunia.
In full sun, true-blue, hairy borage {Borago
officinalis ) makes a two-foot statement. On the
lavender side of the blue spectrum, Scabiosa
caucasica , pincushion flower, sends up a gener¬
ous number of long-stemmed, intricate, misty
lavender-blue flowers. Pincushion flower is easy
to grow. Do get the bluest ones; the other greyish
tones are only good if you want an ethereal look
and like to dress in dove grey.
There is nothing like the rich, deep, almost
navy blue o {Salvia farinacea for anchoring a blue
bed. To get a good effect, plant at least six close
together, preferably twelve, rather than dotting
them about with a spike here and a spike there.
The dark color emphasizes paler blues and is a
dramatic accent in a flower arrangement. Add
blue varieties of statice {Limonium sinuatum ), an
annual that stays under two feet and lasts indefi¬
nitely in dried-flower arrangments. Don’t forget
airy, one-foot-tall love-in-a-mist {Nigella dama-
scena ), as romantic as its name. The seedpods are
also excellent subjects for drying, but be sure to
leave a few around to sow seed for next year.
There are other situations in the garden where
annuals are invaluable. For covering a fence or
some redwood lattice, try ‘Heavenly Blue’ morn¬
ing glory ( Ipomoea purpurea) grown from seed
for an instant blue bower. Although each flower
only lasts a day, they come in such profusion that
there is constant color all summer. Equally easy
from seed and carefree in the garden are the
nasturtiums ( Tropaeolum majus ). They are de¬
licious in salads and come in a variety of heights.
The old-fashioned climbing yellow and orange
ones might make a cheery accompaniment to the
well-named ‘Heavenly Blue' morning glories.
I Nasturtiums need wire, twine or another plant for
support if they are to climb. Otherwise, they can
be left to trail as a lush, colorful annual
groundcover. In part shade, variegated annual
hops vine ( Humulus japonicus ‘Variegatus’) adds
a cool, sophisticated touch to a fence or even the
trunk of a tree.
Do you have an ugly metal fence or trash cans
to hide? Consider buying a pack of insignificant¬
looking little spider flower starts ( Cleome
hasslerana) in May, plant them at the back of a
bed with plenty of room and watch out. They
grow to about four feet and are scratchy and
bossy, but in August will delight you with huge
pink, rose, purple or white inflorescences,
enough to pick and still have a glamorous display.
Very pretty against a grey weathered fence (to
which it may need to be tied in a windy situation),
cleome is spectacular anywhere you have space; it
is an annual I would not want to spend the sum¬
mer without.
Another easy-to-grow annual of enormous size
is the giant sunflower (Helianthus annuus). It is a
must for two reasons: it is the perfect plant for
captivating children and for attracting birds. Help
a child plant giant sunflower seeds in an out-of-
the-way corner of the garden, show him or her
how to water and weed the patch, encourage him
to measure the “Jack and the Beanstalk” progress
of this fast-growing annual as it grows to eight or
ten feet, and you may have created a life-long
gardener. Show him how the flowers always turn
toward the sun (so try to situate them where they
will face into your yard, not the neighbor’s).
These giants need staking and even that may not
prevent the dinner-plate size flowers from droop¬
ing under their own weight.
Finally show the child how to collect some of
the seeds and save them for the birds. Sunflowers
will attract bluejays, finches and, if you are lucky,
the brilliant goldfinches that bounce up and
down on the leaves like acrobats. If you don’t have
children, borrow one — this is a good project for
you and the birds.
Two more large, easy plants for children to
grow and for screens against fences are the airy
pink, rose and white daisies of cosmos ( Cosmos
bipinnatus) and the old-fashioned spires of hol¬
lyhocks ( Alcea rosea), the latter making a real
fashion comeback after years in the back of the
horticultural closet. Hollyhocks are biennial or
short-lived perennials, so you need to plan ahead
for a display. They sometimes grow to six feet in
height and are available in many colors. My favor¬
ite is a double pink that rivals the pink peony in
charm. The height of these large annuals gives a
new dimension to many regional gardens where
color tends to stop at waist height. This is because
in our rugged climate the smaller, more compact
plants tend to survive better and the intense sun¬
light, wind and dearth of water discourages lanky,
luxuriant growth. The best way to add more color
at eye level is to plant some really fast-growing,
tall annuals.
Another old-fashioned biennial or short-lived
perennial coming back into style is sweet william
( Dianthus barbatus). Its frilly white, pink and
maroon flower heads bloom at the time the per¬
ennial white ox-eye daisy ( Chrysanthemum
leucanthemum) does, in late spring. Together
they make a lovely couple, both in the garden and
in the vase.
Scabiosa atropurpurea
19
For easy care and reliable self-sowing,
drought-tolerant California poppies ( Eschschol -
zia californica ) mix well with sweet alyssum
( Lobularia maritima ) in a jumble of orange and
white. Colors in the pink, purple and rose hues
are also available for both these plants. Let the
little Californian native Phacelia campanularia ,
in deep blue, join the carefree melee. These three
annuals are so tough that they come up casually in
the cracks of the sidewalk.
The most compelling reason to grow annuals
every year is to plant patio pots. Because pots dry
out fast, it is better to have a few really big ones
stuffed full of plants than lots of smaller pots that
may need watering twice a day during a heat
wave. Remember you are going for maximum
effect in minimum space here. Think of patio pots
, as fashion accessories; now you have a complete
•outfit. (See separate article on gardening in con¬
tainers, p. 12.)
Angela Overy has been an instructor of botanical illustration at
Denver Botanic Gardens for ten years. She is a master gar¬
dener from Douglas County, Colorado; her walled garden was
featured in the January/February 1991 issue of Fine Garden¬
ing.
An Annual Process:
Growing Bedding Plants Commercially
by Kelly D. Grummons
The winter solstice has passed and the last strag¬
gler of a successful poinsettia crop has found a
home. Some plants are opening sleepy eyes to
what they think is spring: in actuality, they are
being forced out of dormancy for the January
opening of the Colorado Garden and Home
Show. Plant labels abound in disorganized stacks,
newly arrived from the printer. Micky is filling
trays with sowing medium, “not too fine, not too
coarse,” just like his father used to do. New seed
lots come in daily, and pots of New Guinea impa-
tiens are already taking root. The ladies over in
greenhouse number nine are quietly transplant¬
ing the last of the perennial seedlings. A sense of
anticipation permeates the nursery. This is the
season for annual flowers. The men have sani¬
tized the two-and-a-half acres under glass one
more time, providing a clean canvas that soon will
be painted with a sea of annual flowers for the
1991 gardening season.
It’s quite a process, producing enough flowers
to fill countless Colorado gardens, but what a
lovely task. Surely we put in more hours than
almost any other industry, save perhaps tax ac¬
countants, at this time of year. Long winter nights
of scheduling hundreds of species now see frui¬
tion.
The use of bedding plants started sometime
hundreds or even thousands of years ago; no one
seems to know for certain. The first American
20 gardens in the late 1600s were graced with lovely
wallflowers ( Cheiranthiis cheiri), violets ( Viola
spp.) and other flowers available at the time. Ad¬
vertisements for “plants to set out” can be found
as far back as the 1700s in the United States.
Today, hundreds of millions of dollars are spent
on annual flowers at the wholesale level alone.
Denver’s Paulino Gardens started as a truck farm
in 1915, supplying produce to the Denver market.
In the 1960s, the Paulinos found that customers
didn't squabble nearly as much about the price of
a geranium as they did about the price of a to¬
mato. Gradually, the entire operation evolved
into the ornamental horticulture business it is
today — the fourth largest retail garden shop in
America.
As seeds arrive at the nursery, they are sorted
according to varying sowing dates. Some require
a treatment such as refrigeration, but most seeds
are ready to go. The medium of Micky’s trays is
moistened and slightly packed with a “row-
maker” board. The seed is then evenly broadcast
down each row with nimble, calculating fingers.
Some seeds require a light top-dressing of ver-
miculite, others do not. Very' large seeds such as
nasturtium ( Tropaeolum majus ), morning glory
(Ipomoea purpurea ), sweet pea ( Lathyrus odor-
atus) and four-o’clock ( Mirabilis jalapa ) are
sown in their final containers.
Most of the trays are placed on sand beds that
radiate heat from buried cables, then covered
with sheets of plastic and shade cloth. The seeds
need to be warm, but not cooked, to germinate.
Grandpa “Gramps” Paulino showed his son
Micky, and Micky taught me how to make sure the
conditions are just right. Twice a day we peek
under the cloth. As soon as a few little heads poke
up, we pull those trays out to a brightly-lit table at
room temperature.
The annual seedlings develop quickly. Within a
week or two, true leaves appear above the first
seed-leaves, called cotyledons, and the ladies,
with loving skill, pluck the young plants from the
flat and plant them gently in appropriately sized
cell-packs or pots. This excruciatingly tedious
work lasts for months, ten hours a day until the
season is over, about the middle of May.
Gardeners along the Front Range are becom¬
ing quite sophisticated horticulturally, expecting
new flower varieties every year. All America
Selections award winners are added to our an¬
nual line-up, along with requested and promising
new varieties. If we grew only the things we liked,
we would be out of business. The current trend in
annual flowers is toward petite, less bold forms
and textures and softer colors. Nonetheless, red
geraniums {Pelargonium x hortorum), petunias
{Petunia x hybrida) and marigolds {Tagetes spp.
and hybrids) are still very popular. These annuals,
the backbone of our business, are starting to give
way to pot dahlias, impatiens {Impatiens wal-
lerana ) and dozens of other annuals that are
more durable, drought-tolerant or just plain dif¬
ferent.
There is a saying posted in our store that be¬
gins, “If our customers only knew how many
bushels of soil it took. . .” and ends “then they
would find the price of our plants very reason¬
able.’’ Annuals are a labor-intensive product with
a great deal of overhead expenses: heating and
cooling costs are well over one dollar per square
foot per year. The biggest challenge is finding
qualified people willing to do the work required
to produce a marketable crop.
At Paulino’s, we grow the varieties we are good
at producing. Other growers supply us with cer¬
tain crops that require conditions or expertise we
don't have. For example, some varieties require
growth-regulating chemicals to make them mar¬
ketable in pots. Others, such as fuchsia, need
months of pruning and shaping to create the per¬
fect plant. As for cost, some seed is very reason¬
able, while some, such as hand-hybridized vari¬
eties, cost ten cents or more per seed, resulting in
a six-pack production cost of sixty cents or more
just in seeds alone.
As traditional as our business is, new tech¬
nologies are moving into the picture. Comput¬
erized environmental control helps maintain an
optimum atmosphere in the greenhouse but I still
need to have a daily and personal relationship
with all of the plants. Styrofoam and long-lived
plastic containers are now beginning to be re¬
placed by more environmentally sound materials.
Soil and part-soil media have given way to the
convenience of packaged soil-less media. Now
that the once-economical peat moss is becoming
scarce, other inert materials such as rock wool are
being substituted. Less expensive locally-avail-
able aspen humus is replacing exotic peats.
Interestingly, the nursery business is somewhat
recession-proof. During financially hard times,
people tend to postpone vacations and spend a
little more on the home and garden. Flowers and
gardening do more for the state of mind than
most people realize. Who wouldn't find his or her
spirits lifted by walking into a garden billowing
with spikes of larkspur {Consolida ambigua ),
fragrant stock {Matthiola incana') and satiny
godetia {Clarkia amoena ). If everyone would
plant a flower garden this year, the world would
be a lovelier place and our problems would di¬
minish.
Above my kitchen sink hangs a plaque with a
verse especially appropriate today:
When all the world wearies,
And society ceases to satisfy,
There is always the Garden.
— Minnie Aumonier
Kelly Grummons, horticulturist at Paulino Gardens in Denver,
came from northeastern Wyoming with a passion for plants
from the Great Plains. He earned joint degrees in horticulture
and landscape management from Colorado State University.
He enjoys exploring the prairie in search of new garden
prospects with other hard-core gardeners.
Annuals in the
Perennial Border
by Keith Funk
Most gardeners who grow perennials eventually
tire of the same plants in the same place year after
year, and start to play the inevitable game of musi¬
cal chairs with them. Older and more common
varieties lose their place to newer and more un¬
usual species. The plants that remain must con¬
tend with the shock of being moved, divided or
simply disturbed by the relocation of neighbors.
The end result of all this juggling is hodge-podge
of newly planted, recovering and established
plants, in no way resembling a finished border,
which takes several years to mature.
Creativity in the garden doesn’t always mean
growing the newest varieties or the most exotic
species. More often than not, the creative gar¬
dener simply combines familiar plants in new and
different ways — like adding annuals to the per¬
ennial border, for instance.
To save my mature, well-established perennials
from trauma, I incorporate annuals to satisfy my
need for change. Because annuals are quick to
grow and bloom from seed, are fairly inexpensive
and bloom nearly all season, they are invaluable
for tying together the various blooming seasons
of perennials. Best of all, I can experiment with
colors and textures each year to create new com¬
binations.
Tall back-of-the-border annuals are not easy to
come by. Nicotiana sylvestris, a bold yet elegant
plant, produces a broad rosette of oval leaves,
from which rises a 4-5 foot flower stalk. Clusters
of pendant white flowers open from midsummer
to frost. Planted in groups of three to five,
Nicotiana sylvestris contrasts nicely with a dark
wooden fence as a backdrop. It blooms equally
well in full sun and part shade, and has a sweet
fragrance in the evening. The lush foliage helps
cover gaps left by early-blooming plants that die
down after flowering, such as oriental poppies
( Papaver orientalis ), bleeding heart {Dicentra
spectabilis ) and spring bulbs.
Mexican sunflower {Tithonia rotundifolia ) is
one of the largest plants grown as an annual.
22 Huge, coarse leaves nearly a foot long clothe the
sturdy 5-6' stems. In mid-July the plant begins
producing brilliant fiery red-orange flowers with
yellow centers that resemble large zinnias. The
color is intense — a little goes a long way. Mexican
sunflower’s size and coarse texture fill gaps in the
.background of a sunny border.
Cosmos {Cosmos bipinnatus ) is another tall,
back-of-the-border annual, but has a delicate ef¬
fect due to its ferny foliage and airy stems. Daisies
in shades of lavender, magenta, pink and white
are borne in great numbers from midsummer
until frost. They make fine cut flowers. The finely-
textured foliage softens bolder plants such as
roses, peonies {Paeonia lactiflora ), phlox {Phlox
paniculata ) and the more dramatic annuals Mex¬
ican sunflower andNicotiana sylvestris . A smaller,
pure white variety, ‘Sonata,’ is ideal for gardens
short on space.
Two seldom-planted but pretty members of the
mallow family are Lavatera trimestris and Malva
sylvestris. Both make dense, bushy plants, and
generously produce rose-pink flowers very simi¬
lar to a hollyhock’s {Alcea rosea), minus the prob¬
lems with staking or rust. Both are easy to grow
and give continuous color from July until frost. I
like them best planted with daylilies {Hemerocal-
lis hybrids) and shasta daisies {Chrysanthemum x
superbum).
Throughout the middle of the border, the fun
starts in earnest. This is where the garden gyp¬
sies— annuals that self-sow — grow and bloom,
creating endless combinations with the more
static perennials. Letting chance design the bor¬
der isn’t for everyone; order and predictability
are flung by the wayside.
A true border vagabond is Shirley poppy
{Papaver rhoeas). Its blue-green foliage is a per¬
fect foil for the large, diaphanous blossoms that
come in a wide range of soft, clear colors. Shirley
poppy only blooms for a few weeks in early sum¬
mer, but then politely dies to the ground and
disappears, making room for later-developing
plants. This lovely annual’s ability to reseed in just
the right spots among my iris (Iris germanica),
blue flax (Linum perenne ) and penstemon (Pens-
temon spp. ) guarantees my abiding love for it.
Larkspur (Consolida ambigua) is a sentimental
favorite of mine, evoking fond memories of my
grandmother’s garden. It is often called the an¬
nual delphinium because it has much of the same
beauty and vertical elegance. However it is short¬
er and has ferny foliage, lending it a more casual
look. Larkspur is also much easier to grow than
delphinium and blooms for a longer time in
shades of white, blue, pink and purple. A spot
lightly shaded from the hottest sun will keep the
plant in flower for the longest time. Larkspur
combines beautifully with old-fashioned peren¬
nials such as oriental poppies, lilies (Lilium spp.
and hybrids), Siberian iris (Iris sibirica) and gol¬
den coreopsis (Coreopsis grandiflora ). After a
few years of self-seeding, the blues and purples
predominate. This can be prevented by cutting
large, long-lasting purple and blue bouquets for
the house and leaving the lighter-colored plants
in the garden to set seed for the next year.
The perfect plant to hide unattractive bearded
iris leaves during the summer is nati ve Euphorbia
marginata, sometimes called snow-on-the-
mountain but not to be confused with the peren¬
nial groundcover of the same name (Aegopodium
podagraria ‘Variegata’), variegated cousin to the
evil goutweed. Euphorbia marginata grows into
a bushy, 2-foot plant. Its succulent, grey-green
leaves have white margins and the tiny flowers are
accompanied by large, leafy, pure white bracts.
This annual relative of the poinsettia is happy in
any soil, in full sun and through the heat of the
summer. The young plants wait their turn while
the irises bloom, then grow quickly to cover the
unsightly iris foliage, imparting a pale green and
white coolness on hot summer days. Thin out all
but a few seedlings each year or else crowding
will shade the iris too much.
The gloriosa daisy (Rudbeckia hirta var. pul-
cherrima ) has all the rugged durability one would
expect from a prairie native. There are many vari¬
eties, but I prefer the ‘Pinwheel’ selection with
large, single flowers in yellows, golds, oranges
and mahoganies, all with chocolate-brown cen¬
ters. They grow and self-sow in most any soil and
bloom beautifully in the most intense summer
sun. The flowers have an assertive quality that
needs the company of soft textures and colors —
blue salvia (Salvia farinacea ), cosmos, blue flax
and ornamental grasses all make lovely compan¬
ions.
Near the front of the border, plants must toler¬
ate some abuse. Mowers, children and pets all
take their toll on slow-growing, brittle and gen¬
erally wimpy plants. Fortunately there are several
annuals that meet the challenge.
Madagascar periwinkle (Catharanthus roseus )
is a gem for gardens where intense summer sun,
drought and heat limit the choice of plants. Its
glossy, dark-green leaves and delicate pink, white
or purple flowers remain crisp and healthy in
conditions that would wilt nearly any other plant.
It makes a great city plant, being pollution-
tolerant as well. Few other annuals are as ver¬
satile, offering lush, clean, insect-free foliage, a
multitude of flowers and a low, neat form. Finally
Madagascar periwinkle is getting well-deserved
attention from gardeners and hybridizers alike.
Though there are many less-common plants to
choose from, I often rely on sweet alyssum (Lo-
bularia maritima). Fragrant white, pink or pur¬
ple flowers cover this plant from late spring until
a hard frost. Children, pets and even devastating
hail don’t stop this plant from carpeting the
ground with color. It will reseed year after year.
Alyssum is usually planted as an edging in the
front of the border, but thanks to its ability to
self-sow and its small, delicate demeanor, alys¬
sum is also excellent naturalized in a rock garden,
between paving stones or as an informal ground-
cover under taller, open and leggy' plants such as
hollyhocks, roses or four o’clocks (Mirabilis
jalap a).
Brilliant flecks of gold over a low, dense carpet
of ferny, emerald-green foliage describe Dahl-
berg daisy (Dyssodia tenuiloba). The busy gar¬
dener couldn’t ask for an easier plant. A perfect
edging annual, it is particularly charming in the
rock garden, in crevices of rock walls or among
paving stones. Good companions to grow behind
it include flowering tobacco (Nicotiana alata ),
dusty miller (Senecio cineraria) or red salvia
(Salvia splendens).
One other little-known and hard-to-find annual
worth some searching for is cup flower (Nierem-
bergia hippomanica). Neat low, spreading
mounds of foliage are smothered with blue-violet
bell-shaped flowers all summer long. Substitute
this plant for lobelia (Lobelia erinus) in hot places
where the latter dies out. Combine it with blue
sheep’s fescue (Festuca ovina var. glauca), mari¬
golds (Tagetes spp.), sweet alyssum, calendula
(Calendula officinalis ), snapdragons (Antir¬
rhinum majus) or Dahlberg daisy.
Keith Funk, a Colorado resident for twelve years, received a
B.S. in landscape design and an M.S. in ornamental horticul¬
ture from Kansas State University. He has been Retail Manager
of Echter s Garden Center in Arvada, Colorado for nine years,
and is an avid gardener.
23
Annuals for the Connoisseur
\
by Lauren Springer
Until two years ago, when I finally bought a house,
my gardens were always dominated by annuals.
I’m a postmaster’s nightmare: my personal record
of tenure at one address is 30 months. These
gypsy habits led to an unnaturally large, well-
worn collection of trunks and cartons in the
basement and a finely-honed appreciation of un¬
usual annuals.
The public and private gardens I toiled in to
earn a living only strengthened my devotion to
perennials and native plants. Petunias and mari¬
golds offered at nearby garden centers seemed
barely a step away from plastic; any plant whose
tag described it as “an even mound smothered in
large, brilliant flowers,” I abhorred. I was deter¬
mined to create my own garden in the image of
the subtle, graceful perennial borders, rock gar¬
dens, and woodland and meadow plantings I
tended for a living, but I needed to accomplish
this with annuals.
The answer came in the form of several good
seed catalogs. Clothes in the closet gave way to a
mini-greenhouse of seedlings under fluorescent
shop-lights bought on sale at Sears. Discarded
pots were salvaged from local nurseries’ dump¬
sters, milk cartons were cut into containers. Sev¬
eral cottage gardens of annuals ensued, some
beautiful, some less so.
A decade of this kind of experimentation re¬
warded me in my new house’s first-season gar¬
den. After three months of sod-stripping, digging,
manure-hauling and planting trees, shrubs and
perennials, I ran out of steam and money. The
young plants looked forlorn and large areas were
left unplanted. Annuals came to the rescue, and
never were they more lovely than in and among
the fledging perennials and shrubs.
There are several distinct areas in my garden,
both in terms of light exposure and in terms of
color and overall mood. The east side of the
garden gets afternoon shade, making it a perfect
area for traditional garden plants that need extra
water and some protection from the hot, drying
Colorado sun. Here I allow myself to express
nostalgia for the Irish and English gardens I have
worked in.
A dozen large, hardy old garden roses —
24 gallicas, mosses, damasks and albas — bloomed
only sparsely the first year, in shades of blush
pink, lavender and white. It will be three years
before they reach their full size and flowering
strength. An underplanting of perennials, domi¬
nated by chartreuse-flowered lady’s mantle (Al-
chemilla vulgaris ), late-blooming pink and white
Japanese anemone ( Anemone x hybrida ), blue
monkshood ( Aconitum napellus ), blue and la¬
vender milky bellflower ( Campanula lactiflora )
and pale yellow columbines ( Aquilegia chry-
santha) — compliments the soft feeling and gen¬
tle color scheme of the roses, but was modest at
best the first season, as perennials are apt to be. A
wonderful birthday present of 50 unusual lily
bulbs from a close friend (only a good friend
would know that a box smelling of sphagnum
moss rather than perfume is what excites a real
gardener) should make a splash in the coming
years. What made this garden a success the first
year, a mere two months after planting, were
some truly wonderful annuals.
In this lightly-shaded, old-fashioned garden, I
planted pale pink, white and lime flowering to¬
bacco ( Nicotiana alata ) in large sweeps. Toward
the back, near the grey and white clapboards of
the house, tall white Nicotiana sylvestris and the
drooping chartreuse bells of Nicotiana langs-
dorffii mingled with the largest of the roses. I
dotted half a dozen large clumps of the two-foot
tall, white, double-flowered feverfew ( Chrysan¬
themum parthenium ‘White Wonder’) through¬
out, which I cannibalized for cut flowers from
June until frost without noticeably harming the
garden display.
Nicotiana sylvestris
V
TZ
.o
—
-
S
/ /fC r [
A — \ Nicotiana langsdorffii
To blend with the chartreuse nicotianas and the
pale yellow columbines, which were the most
floriferous of the perennials the first season, I
grew ‘Cut Wonder,’ a tall, 18" , lavender-blue form
of popular flossflower ,Ageratum houstonianum .
It had a perennial’s grace of habit, yet bloomed
nonstop from late June into September. It also
proved to be a great cut flower, and attracted
butterflies in the morning when the sun lit that
part of the garden.
The front of the garden borders on a sidewalk.
To soften the edge, airy lavender Swan River
daisies ( Brachycome iberidifolia ) flopped and
trailed onto the pavement. Velvety purple and
blue johnny-jump-ups {Viola tricolor ‘Helen
Mount,’ ‘King Henry,’ V. comuta ‘Cuty’) bloomed
from April into November with the help of after¬
noon shade. Sweet alyssum {Lobularia mari-
tima ) wove in and among the front plantings,
filling the air with its honey scent.
At dusk, the palest flowers glowed the bright¬
est, transforming the garden. Mauve, pink and
white evening stock {Matthiola longipetala ssp.
bicomis) wafted its sweet perfume over passing
teenagers celebrating their graduation late into
the night. I would leave the livingroom windows
open all night to let the scent into the house. Two
fierce shearings rejuvenated this plant and
brought on more flowers until hail put an end to it
the last weekend in July. Who knows how long it
would have lasted without the intervention of
golfballs from the sky.
Next year the roses and perennials should con¬
tribute their share of color and scent, but I was so
enamored of the annuals, I will be sure to include
them again. Tall biennials I planted last year will
add to the old-fashioned, cottagy feel: foxgloves
{Digitalis purpurea ‘Apricot Beauty’), pale yellow
evening primrose {Oenothera biennis ), pastel
hollyhocks {Alcea rosea), and fragrant lavender
and white sweet rocket {Hesperis matronalis).
On the other side of the house, a totally differ¬
ent garden is taking shape. Dwarf conifers,
shrubs, evergreen groundcovers, herbs and na¬
tive plants will give this area year-round interest
as they mature. The colors are more vibrant, the
textures and forms tighter and more precise, and
the plants heat-, sun- and drought-tolerant. Again,
the perennials were small and puny the first year,
save for some overly-eager iceplant {Delosperma
nubigenum), thyme {Thymus spp. ) and pussytoes
{Antennaria spp. ).
Several annuals lifted my spirits during the
long, hot summer days. I had sprinkled seed of
native prickly poppy, Argemone platyceras, the
fall before, having admired it along the roadsides.
It came up well and gave a long succession of
what a neighbor’s child called “fried-egg flowers,”
four-inch white cups with bold yellow centers.
The same child tried to pick one and was painfully
chastised by the thorny plant.
Sky blueNolanaparadoxa sprawled nearby. It
lost its flowering pizzazz by the beginning of
August, but had combined so well with orange
and yellow California poppies {Eschscholzia
califomica) earlier in the summer that I’m de¬
termined to grow them together again. Low-
growing golden Dahlberg daisy {Dyssodia ten-
uiloba) mingled with deep blue Pbacelia cam-
panularia and white and yellow moss roses {Por-
tulaca grandiflora) along my sandstone path. I'm
hoping a few will seed themselves in the cracks
next year.
Deep in the beds of this area, I let burgundy,
white and pink sleepy poppies {Papaver som-
niferum), purple Verbena bonariensis, white
Lavatera trimestris ‘Mont Blanc,’ purple-leaved
beefsteak plant {Perilla frutescens ) and bronze¬
leaved fennel {Foeniculum vulgare ‘Purpur-
eum’) fill the many empty spaces between the
undersized shrubs and perennials. The large,
pale yellow flowers of Hibiscus trionum, with
chocolate eyes, were fennel’s ideal partner. The
fennel left a delicate anise scent on my clothes
and in the air whenever I brushed against it. I
expect seedlings of all these annuals to emerge in
full force next year, thanks to their parents’ copi¬
ous production of seed, but I collected a bit just in
case. Two sun-loving, drought-tolerant biennial
giants formed massive 2-3' wide foliage rosettes:
the woolly silver mulleins Verbascum olympicum
and V. bombyciferum , and platinum scotch thistle,
Onopordum acanthium. Next year they will
match me in height as they bloom, set seed and
then die, and hopefully will resow themselves to
start the cycle anew.
I had left a large, 13 x 10' area totally devoid of
plants, due in part to a shrunken wallet and in part
to a load of hot manure that burned the few
perennials I had planted there. In June, when
everything elsewhere was growing vigorously
and the garden’s brown areas were rapidly reced- 25
ing, this patch of bare earth rankled me to no end.
I found a few old packets of deep purple Verbena
rigida, white Cleome hasslerana ‘Helen Camp¬
bell’ and orange-red Cosmos sulphureus ‘Sunny
Red.’ My instincts warned that this would be an
awful combination, but I sowed the seeds any¬
how, in great sweeps, desperate to cover the
ground. It turned out to be a wonderfully attrac¬
tive surprise. Aside from their vibrant colors, the
plants brought wildlife into the garden. Cleome
buzzed with bees and the verbena attracted a bevy
of butterflies, among them swallowtails, check-
erspots, red admirals, painted ladies, viceroys and
monarchs. Late in the fall, birds, especially
finches, fed on the seed of the cosmos.
I was blessed with another unplanned success
in the area near my old, run-down shed and the
trash bins. I had fought the insidious puncture
vine (Tribulus terrestris ) there the summer and
fall before, and wanted to plant something just to
gloat over my victory, a beautiful annual or two to
proclaim I had won over this patch of soil, much
like a flag raised on newly-captured territory.
Again, my creative juices were running dry and
my choice of seedlings was limited by the time I
got around to planting the area. On one end, I
sowed leftover seeds of pink Rocky Mountain bee
plant ( Cleome serrulata) — another native I’d
coveted and collected from the roadside — huge
white Cosmos bipinnatus ‘Purity,’ and deep blue
and purple larkspur ( Consolida ambigua). The
other end received a perfunctory planting of a few
flats of pathetically overgrown, lanky seedlings of
blue bachelor’s button ( Centaurea cyanus), cal-
liopsis {Coreopsis tinctoria), Queen Anne’s lace
{Ammi majus ), tassel flower {Emilia javanica ),
blue sage {Salvia farinacea ) and Texas scarlet
sage {Salvia coccinea ), all originally slated for the
cutting garden but left out for lack of room. Both
areas, hot and dry, were given more attention by
passersby and guests than by this gardener. They
were the hits of the summer garden, colorful yet
unkempt enough to evoke a natural scene. I think
the fact that half of the plants were native Ameri¬
can wildflowers contributed to this effect.
The one place where unnatural, exotic beauties
are allowed to revel is on my porch, in containers.
The close association with the house keeps the
plants from jarring as they would if interplanted
among the rest of the garden plants. For some
reason, contrary to fashion, I have never liked
combining many plants of different colors and
textures in pots. I like the pots simple as well —
plain terracotta, preferably hand-thrown and in
the more beige or pink clays. I also have grown to
love the cedar boxes my husband slapped to¬
gether for me from left-over fence pickets. The
cedar has slowly weathered to a soft, silvery tan.
26 On the shaded part of the porch, I let white
flowers dominate, to go with the peeling white
wicker furniture we sink into on hot days. White-
flowered, fragrant angel’s trumpet {Datura
suaveolens) begins blooming in late summer. It
never reached the proportions I was accustomed
to from conservatories, but at four feet, it made
me very happy. Smaller pots filled with Caladium
‘Candidum’ and ‘White Christmas,’ two white-
and-green veined varieties of this foliage plant,
carried on the white theme, as did a box planting
of white impatiens {Impatiens wallerana ‘Super
Elfin White’) and the pretty foliage of polkadot
plant {Hypoestes pbyllostachya ‘White Splash ).
Houseplants, not my forte, have been reduced to
a few hanging plants that the cats can’t reach. The
asparagus fern {Asparagus densiflorus ‘Spren-
geri’) and several spider plants {Chlorophytum
comosum ‘Variegatum’) were put out to pasture
on the porch for the summer, and mingled nicely
with the white-flowered annuals, adding a lush,
tropical feeling.
On the sunny part of the porch, I hid a small pot
of dowdy mignonette {Reseda odorata) among
the showier plants, just for its wonderful scent.
Shrimp-pink, airy twinspur {Diascia barbarae)
spilled from two hanging baskets, as did lavender
Verbena x hybrida ‘French Blue,’ which I mixed
with feathery little Mexican fleabane, Erigeron
karvinskianus . In several pots I jammed a con¬
glomeration of various scented geraniums {Pel¬
argonium spp. ) and let their leaves subtly con¬
trast. My favorite pot lasted only two months, and
then was thrown to its death off the porch wall by
a violent cat fight. I will repeat it this year, if I can
find the plants. I had grown unusual Anisodontea
capensis (also known as Malvastrum capensis)
from seed. It formed a 2-foot shrublet with many
small, shrimp-pink, round flowers. At its base, I
stuffed the velvety silver and chartreuse sprays of
Helichrysum petiolatum and its variety ‘Lime¬
light,’ which I had to buy as plantlets through the
mail, and some ‘Purple Ruffles’ basil {Ocimum
basilicum). Containers beg for experimentation;
it is the rare case when I repeat a planting, but this
one, extinguished in its prime, must be tried
again.
As the garden matures, I'm sure the annual
players will become less important. But to be
entirely without them would be to lose out on
some of the loveliest, most rewarding plants that
make their home in a garden. Many a plant snob
has said to me, “oh, but that’s just an annual.” To
which I reply, “and a mighty fine plant it is.”
Lauren Springer received her master’s degree in horticulture
from Penn State. She teaches, photographs and writes a
weekly gardening column for The Denver Post. In her north¬
ern Colorado garden, she grows over 800 species of plants
from seed, including nearly 100 annuals.
Torenia foumieri
by Rob Proctor
The unusual arrangement of twin stamens inside
the throat of Torenia foumieri inspired the
common name wishbone flower. Its yellow throat
is surrounded by blue petals with violet tips. The
individual trumpet-shaped blossoms are small,
less than an inch across, but are produced abun¬
dantly throughout the summer.
Wishbone flower is a boon to shade gardeners,
for it extends the color range available in bedding
plants. Hybridists have recently developed color
breaks that have produced flowers in pink, laven¬
der, and mauve tones. The original blue flowers
are the most charming, however, topping bushy
plants that grow up to a foot tall. The lobe-shaped
leaves are an attractive bronzy green.
T. foumieri may be easily raised from seed
sown in March at 70° F. Germination takes 10 to 15
days, and the seedlings need about two months in
the greenhouse before they are ready for life
outdoors. Due to its Vietnamese origin, wishbone
flower requires heat and moisture to thrive.
Plants that are set out too early will stunt if night
temperatures drop below 50° F.; planting should
usually be delayed until late May or early June.
Because the plants are compact and grow
evenly, they are useful for edging and formal
designs in semi-shady areas. Clumps of wishbone
flowers planted among hostas and ferns are
charming. They enliven porch and patio contain¬
ers, although care should be taken that they do
not dry out. Imagine the violet flowers planted
with yellow tuberous begonias {Begonia x
tuberhybrida ), their yellow throats echoing the
larger begonia flowers. Asparagus fern {As¬
paragus densiflorus ‘Sprengeri’), dusty miller
{Senecio cineraria ), and pink or white impatiens
{Impatiens wallerana ), make handsome com¬
panions as well.
Rob Proctor is the author of Antique Flowers: Perennials
(1990) and Antique Flowers: Annuals (1991). He is gardening
columnist for The Denver Post and teaches botanic illustration
at DBG.
Cleome hasslerana
by Alcinda Cundiff
I never thought annuals would have a place in my
foothills garden until I realized they could help in
the struggle against my major garden pest: deer.
My first attempts to garden in the unfenced and
untamed area behind my house were a disaster.
The deer wiped out the vegetable garden next to
the porch in late summer with one lightning raid.
The following spring, they consumed large por¬
tions of a new border right against the house. I
then realized that their destruction was confined
to times of the year, spring and late fall, when
their preferred foods — the apples, sumac and
other plants in our mini-wilderness— were ab¬
sent or dormant. This suggested that I could plant
annuals around the house after the deer had re¬
treated to the natural areas. Ideally, the plants
would become established, bloom and be on the
wane before the deer returned.
Many annuals are too flamboyant and too
labor-intensive for my gardening style. But I had
recently put a small, grassy play yard next to the
porch and wanted some colorful, even fantastic,
plants for the children’s area. One bed bordered a
garage and faced the natural area across a small
terrace. Flowers there needed to harmonize with
the garage, be compatible with the nearby wild 27
plants and require little care in the exposed, east¬
facing location. I had seen a dramatic plant in
municipal plantings nearby that seemed to meet
all my requirements: Cleome hasslerana, spider
flower, a member of the caper or Capparaceae
family. I decided to put it in back of the border.
Cleome hasslerana reaches four to six feet,
sometimes requiring staking. Its width is influ¬
enced by how close together it is planted. I den¬
sely planted the seedlings I found at a local gar¬
den center and let competition select the largest.
They filled in well and bloomed from mid¬
summer through September. The flowers are
large, open in appearance and have very long
stamens, hence the common name, spider flower.
I used pink varieties; shades of crimson and pur¬
ple and an all-white variety, ‘Helen Campbell,’ are
also available. They should not require much
water but my plants did wilt on the hottest days, a
condition that should improve once the soil in
this new area is amended with some moisture-
retentive organic matter. The entire border es¬
caped the deer, encouraging me to experiment
with more annuals next year. I think this was due
to the timing of the planting — the annuals went
into the ground after the spring deer foray, and
were pretty much over by mid-fall when the hun¬
gry animals returned. The strong foliage scent
and somewhat spiny nature of the spider flowers
may have deterred them as well.
Cleome hasslerana is a model of the plant many
gardeners are seeking: it has modest cultural re¬
quirements and fits well into landscapes that are
neither purely native nor imported. This is prob¬
ably because it has native relatives — we are accus¬
tomed to seeing Cleome serrulata , Rocky Moun¬
tain bee plant, blooming in the foothills and on
the plains in July and August. I for one eagerly
await more annuals with these characteristics.
Alcinda Cundiff is a researcher in biology at the University of
Colorado in Boulder. A former editor of The Green Thumb ,
she has written articles on butterflies and grasshoppers for
Fine Gardening magazine.
Ipomopsis rubra
by Sandy Snyder
Ipomopsis rubra is worth any attention you might
give to get it started in the garden. This tall
trumpet-flowered biennial seems to lead two
lives. The first year it catches the eye with an
unusual, ground-hugging foliage rosette a bit
larger than a half-dollar. The leaves look like
many one-inch needles criss-crossing each other.
The second year this plant becomes a four- to
six-foot tall spike with bright red one-and-one-
half-inch long trumpet flowers running up and
down it. It is perfect in the background or scat¬
tered among other plants in a perennial border.
28 The angel trumpet or standing cypress, both
common names for Ipomopsis rubra , is an excel¬
lent late-summer bloomer. Sometimes the flow¬
ers begin halfway down from the top of a single
stalk, but more often the top third of the plant
forms additional spikes, each one loaded with red
flowers. This makes the plant look top heavy, yet it
rarely breaks or falls over. It just sways in the
wind, attracting both hummingbirds and people
from quite a distance.
Ipomopsis rubra grows in my garden with very
little help. All I have to do is scatter its white seeds
around my garden. The seeds are ready for sow¬
ing when they begin to fall out of their pods in late
October. Sowing the seeds is fun. I have spread
this plant around my neighborhood because I
like to pick the stalk and use it like a magic wand,
shaking the seeds into gardens, fields and rock
piles. No matter where I scatter them, they seem
to grow. With a lot of water they reach six feet;
with limited moisture, they stay around three feet
or so. If they are not growing where you want
them, move the feathery foliage rosettes in the
spring of their first year.
Ipomopsis rubra is difficult to find in nurseries,
probably because the plants look awful in pots
and people won’t buy them unless they know that
they need only one desperate-looking plant to
start a whole colony of angel trumpets in their
gardens.
Ipomopsis rubra is sometimes still called Gilia
rubra. Phlox, Gilia and Ipomopsis are all in the
same family — Polemoniaceae or the phlox fam¬
ily. It is found growing wild from South Carolina
to Florida and Texas.
Ipomopsis rubra does very well in many types
of gardens along the Front Range. At this time,
these gardeners are the best sources for seed. The
plant is so tall, bright and showy that it is easy to
spot from the car once you know what to look for.
Gardeners, as so often is the case, have kept this
plant going in spite of its being virtually ignored
by magazines, books and commercial sources.
They know how easy Ipomopsis rubra is to grow,
how colorful and dramatic it looks, and how satis¬
fying it is to give away to others. This summer I
urge you to search the nursery and garden terri¬
tory to stake out plants and seed sources of
Ipomopsis rubra. Once it is established in your
garden, you will enjoy this well-behaved and
beautiful plant without giving it another thought.
Sandy Snyder is a gardener in the Rock Alpine Garden at
Denver Botanic Gardens. She also has her own landscaping
and consulting business, and writes and teaches on the side.
Her garden in Littleton, Colorado, has been the subject of
several articles, both locally and nationally.
Lotus berthelotii
by Eleanor Welshon
I first met the lotus vine, or parrot’s beak, as a
houseplant. The fine silver foliage tumbled from a
hanging basket. It had the effect of an asparagus
fern ( Asparagus densiflorus ‘Sprengeri’) but the
leaves and stems were a beautiful grey-green
color, silky soft rather than prickly. I loved it on
sight and promptly took it home.
About a year later, I saw it used in container
gardens. The fine, whorled, pinnate foliage was a
marvelous foil for petunias ( Petunia xhybrida ) in
pinks and lavender-blues, and blue ageratum
( Ageratum houstonianum ) centered with taller
white marguerites ( Argyranthemum frutescens).
Another pretty planting was a combination of pale
yellow petunias, yellow marguerites and lemon
marigolds ( Tagetes patula ). I’ve used it to edge
my porch boxes of hot pink or red geraniums
( Pelargonium xhortorum) and deeper-colored
petunias. Silver foliage has a way of enhancing
most garden flowers and Lotus berthelotii is no
exception.
Lotus vine grows to about six or eight inches
tall before the stems relax and start to drape over
the edge of the pot. The flowers are a light red and
bloom in early summer, resembling a parrot’s
beak.
In the Canary Islands and Cape Verde where
this plant originates, and in the frost-free areas of
this country, lotus vine is used as a low-growing
perennial shrub or groundcover, spilling over
rocks and walls very gracefully. I’ve found it to be
a little hardier than the petunias and geraniums it
was planted with. When the first hard frost killed
off those annuals, only the tips of the branches of
the lotus vine were hit. I cut one back and brought
it into the house where it continues to fill out
quite nicely on a sunny windowsill. 29
My first hanging basket ended in disaster. I
failed to notice it needed water and every single
leaflet shriveled, dried and fell off. It’s a good idea
to check the plant daily since you won’t be forgiv¬
en if you forget. Outsid e, Lotus berthelotii thrives
in containers with the same care as its compan¬
ions. Pinching back encourages branching and
keeps it fat and sassy. Propagation is by cuttings or
from seed.
Lotus vine is still quite uncommon as an orna¬
mental plant in gardens. It is a member of the
Leguminosae, or pea family. Winged pea and
coral gem are two other common names. It bears
no resemblance to what is usually thought of as
lotus, that exotic water plant associated with
Cleopatra and the Nile. The closest relative of
Lotus berthelotii in cultivation seems to be the
yellow-flowered forage crop bird’s foot trefoil,
Lotus corniculatus . How such dissimilar plants
, came to share the same name remains a mystery
, best left to the taxonomists. Lotus vine is available
at some Denver garden centers as starter plants
and as hanging baskets.
Eleanor Welshon, Perennial Department Manager at Echter’s
Garden Center in Arvada, Colorado, and a master gardener for
Jefferson County, has had a life-long love affair with plants,
since her earliest days in the five acres of nursery and demon¬
stration gardens of her family’s business.
Dyssodia tenuiloba
by Pat Hayward
One would think a flower that blooms all summer
and prefers it hot and dry would be a top seller in
this region, but the word isn't out yet that Dahl-
berg daisy, Dyssodia tenuiloba (formerly known
as Thymophylla tenuiloba ) is a perfect annual for
the high, dry plains.
This little annual has been called “dogweed”
and “fetid marigold” in its native Texas, names
that I’m sure haven’t increased its popularity.
Dahlberg daisy is rarely available at local garden
centers, but someday this adaptable, ferny-leaved
yellow daisy will rightfully compete with the best
of the annuals.
Dahlberg daisy is a small-flowered, golden-yel¬
low composite, native to south-central Texas and
nearby Mexico. It is 4-6" tall, self-sows, loves heat,
and is a half-hardy annual tolerant of light frost. Its
bright green, lacy foliage is both unusual in tex¬
ture and functional, helping conserve water for
this drought-tolerant plant.
There are many wonderful ways to use Dahl¬
berg daisy. You might combine it with other little
annual daisies such as Chrysanthemum mul-
ticaule (yellow daisy) and C. paludosum (white
creeping daisy), and pink and blue Swan River
daisy ( Brachycome iberidifolia ). It is one of the
few annuals that can be mingled attractively into
the rock garden, thanks to its small, natural¬
looking demeanor. One gardener I know lets
Dahlberg daisy grow down through a dry wash in
his rock garden because it provides color all
30 summer long and is so drought-tolerant.
A professional grower I know has also fallen for
the charms of this little annual. She likes to let the
profuse bloomer trail over the edges of her raised
beds. For a hot combination, she has grown it
with bright pink Verbena x hybrida ‘Romance.’
Dahlberg daisy’s golden-yellow flowers also look
good with blue, whether it be the bright blue of
Salvia farinacea , the paler blue of perennial blue
flax, Linum perenne, or the lavender-blue of
another American native, Tahoka daisy ( Machae -
r anther a tanacetifolia ).
So now that you want Dahlberg daisy in your
garden, where to find it? Local growers say it is
relatively easy to grow from seed, but some years
seed has not been available. The few local retail
sources that offer plants say they sell out in a
matter of weeks, while wholesalers claim it is not
big enough of a seller to warrant growing more of
it. The Denver Botanic Gardens annual plant sale
has offered it and will continue to do so in 1991.
A xeriscape annual. . . a trailing daisy. . . a
ferny-leaved self-sower that loves the heat. . . Soon
Dahlberg daisy will bloom in gardens all over the
region from June until frost, just as the spring¬
blooming yellow daisies of hardy iceplant {De-
losperma nubigenum ) do now.
Pat Hayward is a perennial specialist at Little Valley Nursery in
Brighton, Colorado. She writes and teaches extensively and
has championed the use of water-efficient plants in regional
landscapes.
Dahlberg daisy ( Dyssodia tenuiloba ) is a dainty yet robust little native
daisy perfect for sunny, dry gardens.
At Denver Botanic Gardens, this berm covered in brilliant, drought-
tolerant Verbena tenera and V. tenuisecta was one of the highlights of
the 1990 displays.
The double sunflower Helianthus annuus ‘Goldburst’ proved to be a
winner in the 1990 Annual Trials at Denver Botanic Gardens.
Ipomopsis rubra , a native biennial, at¬
tracts both people and hummingbirds
with its tall, long-blooming red spikes.
The rich colors of tuberous begonia
( Begonia x tuberhybrida) and Coleus x
hybridus lend a tropical feeling to a
shady corner.
31
Verbena tenera and
Verbena tenuisecta
by Jim Knopf
Last year, a xeric planting at Denver Botanic Gar¬
dens stole the show as one of the most colorful
and pleasing designs there. This delightful,
water-efficient mix of perennial grasses, native
shrubs and two verbenas, Verbena tenera and V.
tenuisecta, was a huge hit on the steep berm near
the annual trial beds.
Both verbenas are tender perennials of South
American origin, to be grown as annuals here,
and have proven to be highly tolerant of heat and
drought. Their spreading habit creates a thick yet
finely-textured groundcover; their profuse flow¬
ering, in complimentary scintillating lavender (V.
tenuisecta ) and bright rose (V. tenera ), continues
from June through most of autumn, even after
several light frosts, before tapering off in mid-
October. That’s a considerably longer period of
color than many traditional annuals can provide,
and the Denver Botanic Gardens planting thrived
on less than one-half inch of irrigation every other
week in rainless midsummer Denver weather.
The verbena carpet was the idea of former
Gardens horticulturist Gayle Weinstein. The
steep area had always been difficult to irrigate and
the soil is typical “Denver adobe” — heavy clay, a
common regional challenge. The verbenas were
tested in a different location before going in en
masse on the slope. They were propagated from
cuttings. Both verbenas can be raised from seed
as well.
Verbena tenuisecta is slightly smaller in height
and spread than V. tenera and has more finely
dissected foliage. The plants make lovely hanging
baskets and have white forms for the gardener
who shies away from pinks and purples. Clearly,
dry doesn’t have to be dull. Verbenas are just one
example of the many annuals and perennials with
32 colorful potential in the dry garden.
Jim Knopf, a landscape architect based in Boulder, teaches and
writes about how to create beautiful gardens with tough,
attractive plants. He is working on a book about waterwise
flower gardening for the Rocky Mountain region.
Annuals and Biennials That Need Little Water
L: low water requirement, about 1/2" every other week
M: moderate water requirement, about 3/4" weekly
Agrostis nebulosa cloud grass L-M
Alcea rosea hollyhock M biennial
Ammi majus Queen Anne's lace L-M,
cool weather
Antirrhinum majus snapdragon M
Argemone spp. prickly poppy L
Atriplex hortensis ‘Rubra' red orach L-M
Baileya multiradiata desert marigold L
Borago officinalis borage M
Brachycome iberidifolia Swan River
daisy L-M
Calandrinia umbellata rock purslane L,
cool weather
Calendula officinalis pot marigold M,
cool weather
Catharanthus roseus Madagascar
periwinkle L-M
Centaurea cyanus bachelor’s button M
Cheirantbus allioni Siberian wallflower
M, fragrant, biennial
Cleome hasslerana spider flower M
Cleome serrulata Rocky Mountain bee
plant L
Consolida ambigua larkspur L-M
Coreopsis tinctoria calliopsis L-M
Cosmos bipinnatus pink cosmos L-M
Cosmos sulpbureus yellow cosmos L
Crepis rubra hawk’s beard L-M, cool
weather
Daucus carota Queen Anne’s lace M,
cool weather, biennial
Diantbus cbinensis annual pinks L-M
Diascia spp. twinspur L-M
Dimorphotheca pluvialis Cape marigold
L-M
Dorotheantbus bellidiformis Living¬
stone daisy L
Dyssodia tenuiloba Dahlberg daisy L
Ecbium lycopsis viper’s bugloss L-M cool
weather
Emilia javanica tassel flower L-M
Erigeron karvinskianus Mexican flea-
bane L-M
Eschscholzia californica California
poppy L
Euphorbia marginata ghostweed L-M
Felicia amelloides blue marguerite L-M,
cool weather
Foeniculum vulgare fennel L-M, fra¬
grant
Gaillardia pulcbella annual Indian
blanket L-M
Gazania rigens treasure flower L-M
Glaucium flavum horned poppy L,
biennial
Gomphrena globosa globe amaranth
L-M
Gypsophila elegans annual baby's
breath M, cool weather
Hedysarum coronarium french honey¬
suckle L-M, fragrant
Helianthus annuus sunflower M
Hordeum jubatum squirrel-tail grass
L-M
Hunnemannia fumariifolia Mexican
poppy L
Ipomopsis aggregata sky rocket L
Ipomopsis rubra standing cypress L,
biennial
Kochia scoparia burning bush L-M
Lagurus ovatus hare’s-tail grass L-M
Latbyrus odoratus sweet pea L-M, cool
weather, fragrant
Layia platyglossa tidy-tips L, cool
weather
Lavatera trimestris shrub mallow L-M
Limonium sinuatum statice L-M
Linaria maroccana toadflax L, cool
weather
Linum grandiflorum annual flax L-M,
cool weather
Linum usitatissimum annual blue flax
L-M, cool weather
Lobularia maritima sweet alyssum L-M,
fragrant
Machaerantbera tanacetifolia Tahoka
daisy L
Mentzelia decapetala blazing star L
Mesembryantbemum crystallinum ice
plant L, cool weather
Mirabilis jalapa four o’clock L
Nigella damascena love-in-a-mist L-M
Nolana paradoxa L
Oenothera spp. evening primrose L-M,
some are fragrant
Onopordum acanthium scotch thistle
L-M, biennial
Papaver nudicaule Iceland poppy L-M,
fragrant, cool weather
Papaver rboeas Shirley poppy M
Papaver somniferum sleepy poppy L-M
Pennisetum setaceum fountain grass
L-M
Pennisetum villosum feather top L-M
Perilla frutescens beefsteak plant L-M
Pbacelia campanularia desert blue¬
bells L
Phlox drummondii annual phlox L-M,
fragrant, cool weather
Portulaca grandiflora L-M
Rljyncbelytrum repetts ruby grass L-M
Rudbeckia hirta black-eyed susan M
Salvia coccinea scarlet Texas sage L-M
Salvia farinacea blue sage L-M
Salvia sclarea clary sage L-M, fragrant,
biennial
Sanvitalia procumbens creeping zinnia
L-M
Senecio cineraria dusty miller L-M
Setaria italica foxtail millet L-M
Silene armeria pink catchfly L
Silybum marianum milk-thistle L-M,
biennial
Tagetes spp. marigold M
Tbelesperma burridgeanum L
Titbonia rotundifolia Mexican sun¬
flower M
Trachymene coerulea blue laceflower
L-M, cool weather
Tropaeolum majus nasturtium L-M
fragrant
Ursinia antbemoides L cool weather
Ven idium fastuosum Cape daisy L-M
Verbascum spp. mullein L-M, biennial
Verbena spp. L-M
Xeranthemum annuum immortelle
L-M
Zinnia angustifolia narrow-leaf zinnia
L-M
Zinnia haageana Mexican zinnia L-M
Ruth Harold
Kallstroemia
grandiflora
Last summer while visiting Arizona and New
Mexico, I came across an annual I had never seen
in Denver gardens but that would be a worthy
addition to the dry cottage garden.
I found the plant growing along sunny, well-
drained roadsides in the mountains of eastern
Arizona. You can imagine my joy when I thought
I’d found an apricot-flowered callirhoe, or prairie
wine-cup. Later a friend identified the specimen
I’d taken as Kallstroemia grandiflora. Although
given the name Mexican or desert poppy and
resembling a mass of apricot California poppies
( Eschscholzia calif ornica), this six- to eight-inch
tall, sprawling annual vine is actually a member of
the caltrop, or Zygophyllaceae family, known for
the weedy puncture vine, Tribulus terrestris. I’ve
been assured, however, that the fruit of the Mexi¬
can poppy is not nearly as likely to inflict pain as
that of the puncture vine, and that this plant is
quite worthy of inclusion in a xeric or wildflower
garden.
Although I am not usually a fan of orange in the
garden, the apricot-hued Mexican poppy inspired
me to concoct many a potentially happy combina¬
tion for it in regional gardens. It seems tailor-
made for inclusion in a naturalistic border with
such native perennials as yellow Zinnia grandi¬
flora, the red and bi-colored forms of Mexican hat
( Ratibida columnifera) or Indian blanket ( Gail -
lardia x grandiflora), or with the white flowers of
Oenothera caespitosa and Eriogonum niveum,
adding the silver foliage of Artemisia species.
Other drought-tolerant annuals to romp
34 alongside the apricot Mexican poppy might in¬
clude the brightly-toned daisies of Gazania ri-
gens, the white or newly available orange globe
amaranths ( Gomphrena globosa ), the tiny, pro¬
fuse daisies of Dyssodia tenuiloba and rich blue
Phacelia campanularia .
In combination with a more traditional selec¬
tion of garden perennials, also sun-loving and
quite tolerant of low-moisture conditions, Kall¬
stroemia grandiflora might combine well with
silver lamb’s ears ( Stachys byzantina), white hol¬
lyhocks ( Alcea rosea), blue fescue ( Festuca ovina
‘Glauca’), blue avena grass ( Helictotrichon sem-
pervirens), and golden yarrow ( Achillea filipen-
dulina). As with all new and exciting plants, the
possibilities for combination are virtually limit¬
less.
At this time, sources for Kallstroemia grandi¬
flora are limited:
Plants of the Southwest
930 Baca Street
Santa Fe, NM 87501
Southwestern Native Seeds
Box 50503
Tucson, AZ 85703
Native Seed
2073 E. ASU Circle
Tempe, AZ 85284
Ray Daugherty received his B.S. in landscape horticulture
from Colorado State University. He is propagator at Green
Acres Nursery in Golden, Colorado, where he has developed
an extensive trial and display garden, and brings native and
unusual plants into the trade.
Maurandya antirrhiniflora
by Ray Daugherty
I discovered the showy climbing snapdragon,
Maurandya antirrhiniflora, in New Mexico last
summer while visiting Plants of the Southwest, a
nursery in Santa Fe. In the greenhouse, the beauty
of several hanging baskets in full flower over¬
whelmed me. Imagine my surprise when I found
this same plant (along with several other native
maurandyas) listed in the 1991 Thompson and
' Morgan seed catalog, under the synonym Asarina
antirrhiniflora .
This vining annual, with lovely leaves resem¬
bling a glaucous-green ivy geranium ( Pelar¬
gonium peltatum ), comes in two distinct color
forms: a light violet blue and a ruby red, sup¬
posedly the more showy form. Both make beauti¬
ful hanging baskets, or they may be allowed to
twine up a trellis or sprawl over the ground. Give
climbing snapdragon average to dry conditions;
the plant can take a variety of light and tempera¬
ture conditions.
Perfect company for this plant might be other
vining plants such as morning glory ( Ipomoea
purpurea ) or hyacinth bean ( Dolichos lablab )
twining with it on a trellis behind white annual
Lavatera trimestris. Perhaps allow it to twine
through the stalwart perennial Artemisia ludovic-
iana ‘Silver King,’ or over a picket fence, or to
meander among blue bachelor’s buttons (Cen-
taurea cyanus ) and sweet alyssum ( Lobularia
, maritima ). Once seen, this beautiful native an¬
nual vine should stimulate even the most unad¬
venturous gardener to find exciting uses for it.
Sources for Maurandya antirrhiniflora in¬
clude:
Plants of the Southwest
930 Baca Street
Santa Fe, NM 87501
Southwestern Native Seeds
Box 50503
Tucson, AZ 85703
Thompson & Morgan
P.O. Box 1308
Jackson, NJ 08527
Talinum
paniculatum
by Laura Lee Cutler
I came to gardening through a love of flower
arranging. Even as a young girl in southern Col¬
orado, I remember the pleasure of putting flow¬
ers in vases to place in our home. Once I had my
own garden, I depended on roses and some per¬
ennials to give me that plentiful supply of flowers
I wanted for arranging. But I soon discovered that
I wanted more from the landscape, and found
how much fun and variety annuals can add to the
garden.
An out-of-the-ordinary plant I grow for interest
in the garden and in arrangements is jewels-of-
Opar or fameflower, Talinum paniculatum , also
known as T. crassifolium . This dainty flower is
native to the southern United States, Mexico and
Central America, where it is perennial. In the
harsher climate of my Denver garden, it acts as an
annual, replenishing itself each year with a mul¬
titude of self-sown seedlings.
The foliage of jewels-of-Opar is glossy green,
reminiscent in color and texture of Euonymus
kiautschovicus ‘Manhattan.’ In late June, airy
wands begin to grow above the foliage to a height
36 of two feet or so. These are the flower panicles.
The stems are maroon in color, with tiny buds all
along them. When the buds open, a few at a time,
there appear tiny pink florets. Often the buds,
pink flowers and tiny orange seed pods appear on
the panicle at the same time. This continues all
summer long.
Talinum paniculatum likes a sunny location, is
undaunted by heat and seems to withstand
drought. It doesn’t look its best massed together
due to its dainty, open nature; a more effective
way to grow it is to spot it here and there in the
garden. It combines well with ‘Purple Ruffles’
basil ( Ocimum basilicum), the short, variegated
ribbon grass ( Phalaris arundinacea ‘Picta’) and
pink zinnias ( Zinnia elegans ). Dainty, fun and
easy, Talinum paniculatum will reseed and
bring you new plants for the garden and the vase
each spring for many years.
Laura Lee Cutler is a native Coloradan and has gardened in
Denver for thirty years. She is a consulting rosarian for the
American Rose Society and grows a wide assortment of flower¬
ing plants in her garden.
Bibliography
Books on Annuals and Biennials
Annuals. Time-Life Encyclopedia of Gardening. 1988:
Time-Life Books, Alexandria, VA.
Annuals. Garden Way Publications. 1989: Doubleday
Book and Music Clubs, Garden City, NY.
Ball, Jeff, and Charles O. Cresson. The 60-Minute
Flower Garden. 1987: Rodale Press, Emmaus, PA.
Beckett, Kenneth A. Annuals and Biennials. 1984: Bal-
lantine Books, New York.
Brooklyn Botanic Garden. Handbook on Annuals.
1982: Brooklyn Botanic Garden, Inc., Brooklyn, NY.
Color with Annuals. Ortho Books. 1987: Ortho Books,
San Francisco, CA.
Crockett, James Underwood. Annuals. 1971: Time-Life
Books, New York.
Crockett, James Underwood. Crockett’s Flower Garden.
1981: Little, Brown and Co., Boston, MA.
Fell, Derek. Annuals: How to Select, Grow, and Enjoy.
1983: HP Books, Tucson, AZ.
Fish, Margery. Cottage Garden Flowers, reprinted 1980:
Faber and Faber, London.
Foster, Catharine Osgood. Organic Flower Gardening.
1975: Rodale Press, Emmaus, PA.
Gardening with Color. Ortho Books. 1977: Ortho
Books, San Francisco, CA.
Hersey, Jean. Women’s Day Book of Annuals and Pe¬
rennials. 1977: Simon and Schuster, New York.
Jekyll, Gertrude. Annuals and Biennials . 1916: Charles
Scribner’s Sons, New York.
Loewer, Peter. The Annual Garden. 1988: Rodale Press,
Emmaus, PA.
Newcomb, Peggy Cornett. Popular Annuals of Eastern
North America. 1985: Dumbarton Oaks Research
Library, Washington, D.C.
Proctor, Rob. Antique Flowers: Annuals. 1991: Harper-
Collins, New York.
Prucha, Jaroslav. Flowers from Seed. 1976: Hamlyn, NY.
Reilly, Ann. Park’s Success with Seeds. 1978: Park Seed
Co., Greenwood, SC.
Rice, Graham. A Handbook of Annuals and Biennials.
1986: Timber Press, Portland, OR.
Rockwell, Frederick Frye. The Complete Book of An¬
nuals. 1955: American Garden Guild, New York.
Sinnes, A. Con. All About Annuals . 1981: Ortho Books,
San Francisco, CA.
Sunset Books. Garden Color: Annuals and Perennials.
1981: Lane Books, Menlo Park, CA.
Sunset Books. How to Grow Annuals. 1974: Lane
Books, Menlo Park, CA.
Taylor’s Guide to Annuals. Taylor Encyclopedia of
Gardening. 1986: Houghton Mifflin Company, Bos¬
ton, MA.
Toogood, Alan R. Garden Annuals and Bulbs. 1971:
Macmillan, New York.
Mountain, Plain
and Garden
The Magazine of Denver Botanic Gardens • Fall/Winter 1991
Why Evergreens ?
Mention the word “evergreen” and most
people think of pine, fir or spruce trees. They
are, after all, the most obvious plants in a
winter landscape whether it be around a
home, a park or a mountain vista.
This issue of Mountain, Plain and Garden
features evergreens not only to show that they
are much more than pines, firs and spruces
but a wide array of plants with broad, flat
leaves as well as scale-like and needle-like
leaves, that vary in size from prostrate ground
covers to shrubs and the tallest of trees.
At this time of year, evergreens take on
special meaning. The Christmas tree, the gar¬
lands and wreaths made of holly, pine and fir
boughs, symbolize, to many, the promise of
life eternal. Unlike their deciduous counter¬
parts, evergreens, when used in the home
landscape, provide year-round evidence of life
even when it is bitter cold and a gray, gloomy
sky hangs overhead.
The articles in this issue have been writ¬
ten to describe the versatility that evergreens
provide in a landscape. Some even present
challenges for more avid gardeners.
As you read through this publication,
keep in mind that it is not intended as a
“monograph” of all possible evergreens but,
rather, a careful selection by the authors,
drawing from their knowledge and experience.
I hope you will find the information con¬
tained in this publication enjoyable as well as
useful in your own gardening pursuits.
— James R. Feucht,
Extension professor, horticulture,
Colorado State University
Mountain, Plain
and Garden "w
The Magazine of Denver Botanic Gardens
Volume 48 W Number 2 •’ Fall/Winter 1991
Contents
A Botanical History
of Evergreens . 3
Using Conifers in a Xeriscape . 4
Broad-leaved Evergreens . 9
Ground Covers . 13
Are You Confused? . 16
Insect Pests Associated
with Conifers . 17
Dwarf Conifers for
Rocky Mountain Gardeners . 23
Pines & Spruces for
Colorado Landscapes . 25
Growing Evergreens
in Containers . 29
Why Not Try Limber Pine? . 32
Southwestern White Pine -An
Underused Landscape Plant . 33
Blue Hollies: Tough New
Hybrids for Our Climate . 35
Manzanitas . 36
A Few False Cypress for
Your Landscape . 38
Bibliography . 39
On the cover, a mugo pine and blue spruces
frame a year-round garden
cover photo: Alan Rollinger
© 1991, Denver Botanic Gardens, Inc. • 909 York Street • Denver, Colorado 80206-3799 • (303) 331-4000
Newell M. Grant, president
Larry Latta, managing editor
Jampc T? PYmrht cniP>Qt pHit/vr
Richard H. Daley, executive director
Bernice Peterson and Helen Zeiner, copy editors
Diane Ipsen and Andrew Pierce, photo editors
A continuation of The Green Thumb • Produced by the Marketing and Public Relations Department of Denver Botanic Gardens
Denver Botanic Gardens and Chatfield Arboretum are established and maintained by Denver Botanic Gardens, Inc., for the people of the City and County of
Denver and for the general public in cooperation with the Denver Parks and Recreation Department. Denver Botanic Gardens is also grateful for funds from the
Scientific & Cultural Facilities District (SCFD), which enable the Gardens to expand services and enhance the quality of programs and exhibits.
DENVER BOTANIC GARDENS
> HELEN FOWLER LIBRARY
?1909 York St. Denver, Colo. 80206
SIAN 1 l 1992
A Botanical History of Evergreens
Helen Zeiner
Evergreens fall into two categories — nee¬
dle-leaved coniferous evergreens and broad¬
leaved evergreens. Coniferous evergreens are
a well-defined, related group. Broad-leaved
evergreens, on the other hand, are represent¬
ed in different unrelated families. Both are
useful in home landscaping.
Furthermore, coniferous evergreens are
gymnosperms, which means “naked seed,”
because the seeds are borne openly on cone
scales rather than enclosed within an ovary
as in the angiosperms, the group to which all
the flowering plants belong.
The gymnosperms are an ancient group
with a long geologic history. Fossil evidence
indicates that needle-leaved coniferous ever¬
greens first appeared hundreds of millions of
years ago in the Paleozoic era. They evolved
from the Cordiatales, which had large, strap-
like leaves and whose seeds were loosely
arranged in racemes instead of being com¬
pacted into cones. They reached the climax of
their abundance during the Carboniferous
period of the Paleozoic era and were an
important part of the extensive coal deposits
laid down at that time. Gradually they
waned, but remained dominant plants for
millions of years. Today, far fewer than in
their zenith, they still constitute a group of
great importance to man.
Angiosperms appeared in geologic history
later than gymnosperms and are considered
to be the most highly evolved of the seed
plants. The broad-leaved evergreens are
found in many different families of this group.
Helen Zeiner is honorary curator of the Kathryn
Kalmbach Herbarium of Denver Botanic Gardens.
It’s an interesting quirk that a few conif¬
erous evergreens, such as the larch (Larix)
are deciduous; and, while needle-like leaves
are dominant feature of conifers, a few such
as the araucarias, which are widely distribut¬
ed in the Southern Hemisphere, are relatively
broad-leaved. The junipers have very small
scale-like or awl-shaped leaves, with some,
curiously, having needle-like leaves only on
their juvenile growth. Juniper berries are
actually fleshy-scaled cones.
Though depleted by the activities of civi¬
lization, coniferous evergreens still form
extensive forests across northern North
America and Eurasia, with extensions occur¬
ring southward in the mountains where cli¬
matic conditions are similar to those of north¬
ern latitudes. Engelmann spruce forests just
below timberline and Douglas-fir and pon-
derosa pine forests at lower elevations are
prominent features of the Rocky Mountains
in Colorado.
Evergreens are well adapted to cool cli¬
mates with very cold winters and short grow¬
ing seasons. Their needle-like leaves are pro¬
tected from freezing and dehydration by a
waxy cuticle with underlying layers of thick-
walled cells. In some, starch changes to sugar
in the coldest months to prevent their cell
contents from freezing. Chlorophyll is present
the year around, and food manufacture can
take place whenever conditions permit.
Conifers are of great importance both eco¬
logically and commercially. Great lumber
industries are based on needle-leaved ever¬
green trees. There are also many ornamen¬
tals among the conifers, ranging from speci¬
men trees to shrubs.
Top right, the variety 'Canaertii' of the
common Virginia juniper enlivens the
xeriscape with exceptionally plentiful
fruit.
Above, Veronica incana is an ever¬
green perennial suitable as a ground
cover in dry locations.
Right, another non-traditional evergreen,
blue fescue, Festuca ovina glauca, is a
4 striking non-spreading perennial grass.
Using Conifers in a Xeriscape
Curtis E. Swift
The term “xeriscape” is used to define
landscaping that, among other things, takes
advantage of placing together in the same
area plants that need the same amount of
water. This gives you the capability of irrigat¬
ing plants in “zones” according to their water
needs. As a result, you can significantly
reduce your use of water and still prevent
water stress in your plants. Properly
arranged, plants that need more water than
others can be irrigated adequately without
over-irrigating low- water requiring plants at
the same time. For example, junipers, which
generally require little water, should not be
planted in the same area as spruces, which
thrive only with abundant moisture. While
these are sometimes seen growing successful¬
ly side by side, it is more common to see one
or the other suffering. Either the juniper
turns yellow from the inside, due to the high
soil moisture provided the spruce, or the
inner needles of the spruce take on a purple-
to-brown cast, due to little moisture given to
the juniper.
Curtis E. Swift is the Grand Junction, Colorado, area
extension agent for horticulture in the Colorado
State University Cooperative Extension Service,
where he has developed innovative horticultural pro¬
grams that include Xeriscaping. He has written
numerous publications for the extension service
and articles for trade journals and gardening
magazines.
Several years ago a contractor in the
Grand Junction area installed thousands of
dollars worth of trees and shrubs in a shop¬
ping mall. Within a couple of months the
majority of these plants were dead. The land¬
scaping contract had been awarded to the low
bidder, and, to cut comers, the contractor
eliminated soil amendments necessary for the
heavy clay soil. Also, he installed a sprinkler
system that did not take into account the
need to zone the shrub beds and turf sepa¬
rately. While the heavy, tight soils should
have been amended with organic matter to
improve air infiltration, the death knell for
the trees and shrubs was a sprinkler system
that watered lawngrass in the same zone. As
a result, the roots of the shrubs and trees rot¬
ted, while the new turf flourished.
Proper planning, as with all landscape
endeavors, is critical to success in using ever¬
greens in a xeriscape. To zone evergreens, you
need to know their water requirements. This
information, however, is not readily available.
A list of “drought-tolerant” conifers was
put together by Steve Flickinger in the late
1970s (Stephen Flickinger, “Drought Tolerant
Plants for the Pikes Peak Region,” CSU Coop¬
erative Extension, El Paso County).
Flickinger’s literature review separated trees
and shrubs into the various water regimes
needed to successfully establish them. 5
His rule of thumb for watering to estab¬
lish coniferous shrubs is as follows:
1st year
Once every 14 days for 8 weeks
Once every 14 to 21 days after 8 weeks
Once a month during the winter
2nd year
Once every 14 to 21 days during the
growing season
Once a month during the winter
3rd year
Once every 21 days
Once a month during the winter
4th year
Generally never; however, in extreme
drought, once a month
Once a month during the winter
Flickinger’s rule of thumb for establish¬
ing coniferous trees is:
1st year
Once every 21 days for 6 weeks
Once a month after 6 weeks
Once a month during the winter
2nd & 3rd year
Once every month
4th year
Generally never; however, in extreme
drought, once every month
Consider these recommended irrigation
schedules only as general rules of thumb.
Sandy soils require more frequent irrigation,
whereas clay soils generally require less fre¬
quent. The way to determine the actual need
is to dig near the plant roots, check the soil
moisture and apply water accordingly.
Regardless of the type of watering sched¬
ule you are on, note that Flickinger recom¬
mends watering on an infrequent basis. It
should also be done deeply. This is nearly
impossible, for the health of the grass, if your
evergreen trees and shrubs are in the same
zone as the turf.
While the general guidelines above indi¬
cate that, typically, no water is necessary the
fourth year and beyond, Flickinger noted that
some authors recommend up to four irrigations
each year for established evergreens. Some
woody ornamentals were reported to require
6 no supplemental irrigation (see Table, page 7).
Listings such as Flickinger’s provide pit-
falls, especially when we consider that some
of the publications used to compile his list
were written in the eastern United States
where a drought is considered to occur when
the precipitation drops from 40 inches to 20
inches in a year. Many areas of Colorado’s
Front Range receive in a normal year no
more than 15 inches. In the Grand Junction
area, the average annual precipitation is less
than 8 inches, well below what many Eastern
authors consider a severe drought.
Another way to separate drought-tolerant
plants is by considering their tolerance for
salts in the soil. Sometimes you can assume
that the higher their salt tolerance, the more
drought-tolerant they are. Mary Graves, a
former Tri-River Area master gardener, com¬
piled several lists of salt-tolerant plants
which included evergreens ( Ornamentals &
Their Salt Tolerance, compiled by Mary McN-
ertney-Graves, CSU Cooperative Extension,
Tri-River Area). This compilation has serious
drawbacks. In many of the references the
actual salt level in the soil was not tested. In
addition, the concentration of salts changes,
and there is no way to know if each soil sam¬
ple was collected when the plant was being
subjected to its highest level of salts. Soil salt
concentrations tend to fluctuate depending on
the amount of moisture in the soil. In western
Colorado a dry winter increases soil moisture
evaporation and the movement of soluble
salts into the upper levels of the soil. Salts
accumulate on the soil surface and are very
obvious after a dry spring. If the spring is
wet, the salts dissolve and are taken down¬
ward to below the root zone, so salt levels
vary with the depth of the soil. A sample test¬
ed for salts would average these concentra¬
tions and not necessarily reflect the true salt
level to which the absorbing roots of the plant
are actually exposed.
However, regardless of the problems with
accepting the salt-testing technique, Graves’
list provides support for Flickinger’s.
The Sunset Western Garden Book (Sunset
Publishing Corporation, Menlo Park, Califor¬
nia, 1990) provides further support by includ¬
ing pines in their list of drought-tolerant
plants. They indicate that many pines will
thrive with little or no water during a normal
dry season, once they are established.
One final thought: When you plant ever¬
greens in a xeriscape (or even in a conven¬
tional landscape) and you have considered
the water requirements of all your plants,
remember that many trees and shrubs have
far-reaching root systems and, while the
plants may not be side by side in the land¬
scape, their roots may become intertwined.
The lists provided by Flickinger and Graves
should serve as your guide, because mixing
plants of different water needs may turn your
landscape dream into a headache of stressed,
diseased and insect-infested plants.
Conifers for xeriscape plantings.
Needing supplemental water at least twice per year after
Needing supplemental water at least four times per year after establishment
Norway spruce Picea abies
Japanese yew Taxus cuspidata
Eastern red cedar
White spruce
Colorado spruce
Juniperus virginiana varieties
Picea glauca densata
Picea pungens
Needing supplemental water every two years after establishment
Jack pine
Swiss stone pine
Tanyosho pine
Limber pine
Korean pine
Japanese white pine
Pitch pine
Eastern white pine
Scots, or Scotch pine
Japanese black pine
Virginia pine
Pinus banksiana
Pinus cembra
Pinus densiflora unbraculiafera
Pinus flexilis
Pinus koraiensis
Pinus parviflora
Pinus rigida
Pinus strobus
Pinus sylvestris
Pinus thunbergii
Pinus virginiana
Needing no supplemental water after establishment
Chinese juniper
Common juniper
One-seed juniper
Japanese garden juniper
Savin juniper
Rocky Mountain juniper
Utah juniper
Bristlecone pine
Pinyon pine
Lodgepole pine
Limber pine
Mugo pine
Austrian pine
Ponderosa pine
Southwest white pine
Juniperus chinensis varieties
Juniperus communis
Juniperus monosperma
Juniperus procumbens
Juniperus sabina varieties
Juniperus scopulorum varieties
Juniperus utahensis
Pinus aristata
Pinus edulis
Pinus contorfa latifolia
Pinus flexilis
Pinus mugo
Pinus nigra
Pinus ponderosa
Pinus strobiformis (P. flexilis rdf lexer)
7
Broad-leaved Evergreens
Larry Watson
In horticulture we refer to plants that are
not conifers, but that hold their leaves through
the winter, as broad-leaved evergreens. In the
High Plains our ability to grow this group of
plants is, at best, a challenge and, at worst, a
frustrating experience.
Taylor’s Encyclopedia of Gardening
states, outright, that, “They (broad-leaved
evergreens) do poorly or cannot be grown at
all in regions where the annual rainfall is
below 20 inches.” The lack of sufficient mois¬
ture, as well as our low humidity, contributes
to the difficulty in growing these plants. Add
to these our hot winter sun and the rapid
changes in temperature, both day to night
and day to day, and our task — or challenge —
increases. But in spite of these difficulties,
there are a number of broad-leaved ever¬
greens that we can grow with success in the
Rocky Mountain region.
There are several species and selections
we can choose from the genus Euonymus. E.
fortunei and many of its varieties seem to do
quite well. The purple-leaf wintercreeper, E.
fortunei ‘Coloratus’, can be used both as a
wall cover and a ground cover. This plant has
Larry Watson, a graduate of Colorado State University
and formerly an extension horticulturist in Jefferson
County, managed Western Evergreens and Little Val¬
ley Wholesale Nurseries, both on the Front Range.
He is an honorary life member of the Colorado Nurs¬
erymen's Association and a champion of unusual
plants in regional landscapes, especially plants
from the semi arid West.
dark green leaves in the summer which turn
plum-color in fall and winter. Like some other
varieties, this plant has a trailing or climbing
habit. When used as a ground cover, an annu¬
al pruning will help to keep the plant from
getting stringy.
The leaves of E. fortunei ‘Sarcoxie’ stay
green all winter. If it is planted so that it can
stand alone it will grow into a shrub about 4
feet tall and 3 feet wide. If, however, it is
planted near a wall or fence it will climb or
lean. This plant is one of the hardiest. More
easily found at the nurseries and garden cen¬
ters today is E. f. ‘Green Lane’. As the Lake
County (Ohio) Nursery catalog says, “It is
superior in every way to E. sarcoxie (sic) and
E. vegetus (sic), and yet intermediate between
the two. The thick, lustrous, dark green leaves
do not winter bum, but stay bright and fresh
throughout the entire year. The plant can be
grown as a shrub, creeper or climber like E. f.
var. vegetus, and in the fall will be speckled
with appealing, bright orange berries.”
There are a large number of yellow-and-
green and white-and-green selections of E.
fortunei. My experience with them indicates
they all grow well here. The green-and-gold
selections need to be planted in the sun to
retain their coloration. This does not seem to
be tme of the white-and-green selections.
Some of the better green-and-gold selections
are ‘Canadale Gold’, a Canadian Ornamental
Plant Foundation introduction; ‘Emerald ’n
Gold’ and ‘Golden Prince’. Of the green-and-
9
white varieties, I would suggest ‘Emerald
Gaiety’ and the smaller E. f. ‘Argenteo-
marginatus’. The variety ‘vegetus’ is a very
vigorous trailing wall cover. It is also known
for its production of abundant fruit.
Another euonymus which is little-used
but of great value is one I have known as E.
turkestanicus nanus, but which may more
correctly called E. nana var. turkestanicus.
This species has wiry stems and narrow
leaves and is usable as a 12-to-l 8-inch
ground cover. It should be pruned periodically
to keep it full and bushy.
The most common of this group of ever¬
green euonymus I have left for last — I feel it
is the least hardy of all: E. kiautschovicus
‘Manhattan’, or Manhattan euonymus. Of
course, it is also the most widely sold of all.
The last two winters have taken their toll on
these plants, and although it is possible that
we will not see this kind of damage again for
several years, when it is cold enough we will
see this damage repeated. (Damage did,
indeed, occur to this cultivar in October, 1991,
after this article was written. — J.F.)
The genus Mahonia also has two species
for us to consider. The first is the dwarf grape
holly, or dwarf Oregon grape, Mahonia
repens. Native to the Rocky Mountains, in the
wild it is seldom seen taller than 1 foot; how¬
ever, in some Denver gardens I have seen it 2
to 3 feet tall. It spreads by underground stems
0)
a:
*
Q)
C
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and makes a very dense ground cover. The
foliage of this mahonia is not as glossy as that
of M. aquifolium (which I will discuss next)
yet of good solid green in summer. Its new
leaves emerge with a purple and bronze
tinge, then turn purple and bronze again in
the fall. Its yellow flowers are followed by
blue fruit. This is one of our most reliable
broad-leaved evergreens.
The other species, Mahonia aquifolium,
will grow slowly to 8 feet tall. It also has
leaves that are bronze, copper or reddish
when they unfold. Then they turn shiny
green, to regain their spring color in the fall.
Fruits of these plants are similar to those of
the dwarf grape hollies. Because they are
usually grown from seed they vary greatly in
height. A selection of this species, grown from
cuttings, is Mahonia aquifolium ‘Compacta’.
Plants of this grow uniformly to 4 feet. All
mahonias should be planted in sheltered posi¬
tions, at least out of winter wind and sun.
The fire thorns (genus Pyracantha) also
hold some promise for our use. They have
white flowers which, late in summer, turn
into orange or red fruit. They are a vigorously
growing group and can get a bit unwieldy if
not pruned regularly; I think they should be
considered 4- to 10-feet-tall plants.
Although they are not very shade-toler¬
ant they should be planted where they
receive protection from winter wind. They
Erica hederacea
Daphne x Somerset
10
a
Euonymous fortunei 'Vegetus'
Cytissus x Kewensis
also require a moist soil, especially in winter.
The species P. coccinea has been used here
more than others, the varieties ‘Wyattii’,
‘Kasan’ and ‘Pauciflora’ being offered most
often. Although Monrovia Nurseries in Cali¬
fornia lists P angustifolia "Yukon Belle’ as the
hardiest, and it has been sold in Denver for
many years, I still cannot verify its hardiness.
Books list P. angustifolia (as a species) as less
hardy than P coccinea.
Over the years most of our broad-leaved
evergreens have come from these three
groups of plants. In the past five years or so,
some other plants have come to our attention.
Experimental plantings at Denver Botanic
Gardens and some nurseries in the area sug¬
gest a few more recommendations.
It was long thought that none of the true
hollies (in the genus Ilex) could be grown
here. That was before we knew about the
‘"blue” hollies, Ilex x meserveae. As their
names imply, these have very distinctive,
bluish foliage. They have small white flowers
in the spring, and the female plants bear
fruit. You must always plant both male and
female plants in order to get fruit: Male and
female flowers are on separate plants.
This group of hollies came about through
a series of crosses between I. rugosa and I.
aquifolium by Mrs. Kathleen K. Meserve of
New York. We tried the first of these in the
mid-1970s. They have proven to be very
hardy and have performed quite well here.
There are now many selections available from
these original crosses. All appear to be very
slow-growing and may take a long time to
reach the sizes cited in references.
Another holly for our area is the ink
berry, Ilex glabra. Ink berries have lustrous,
smooth, dark green leaves without the spiny
margins characteristic of many hollies. The
fruits on female plants are black. I was first
introduced to this holly at Denver Botanic
Gardens; it has been a pleasant surprise to
watch these plants do well. The Gardens
grows the cultivar ‘Nordic’. Rated by the
USDA as a zone 3 plant, it can be expected to
grow to 3 or 4 feet. It does best in moist soil.
As with the true hollies, rhododendrons,
too, were thought to be difficult — if not impos¬
sible — in Colorado. However, a hybrid named
‘PJM’, developed by the Weston Nurseries in
Massachusetts, has proven to be among the
hardiest of rhododendrons and quite reliable
here. These evergreen shrubs flower in May
with loose trusses of tubular, hot lavender-
pink blossoms. There are similar selections
now available with compact shapes or with pink
or white flowers. ‘PJM’ rhododendrons flower
better if they are protected from winter sun.
Several species and cultivars of the genus
Daphne do surprisingly well in the Denver
area. They are mostly small- to medium-sized
shrubs with compact growth habit. Typically, 1 1
they grow to about 3 feet high, slightly more
across. Sweetly scented flowers appear pro¬
fusely in the spring and, occasionally, in the
fall. One of the most ornamental is Daphne x
burkwoodii ‘Carol Mackie’. whose dark green
leaves have narrow margins of creamy white.
Daphnes grow best in moist but well-drained
soils where they receive light shade.
Hardy clones of boxwood, or “box,” in the
genus Buxus, are becoming more common in
local gardens. Most do best in shady locations
protected from drying winds. Few broad¬
leaved shrubs can compete with these plants’
dense shape and ability to withstand heavy
pruning and shaping. Denver Botanic Gar¬
dens has grown a variety of common box, B.
sempervirens ‘Vardar Valley’, for a number of
years. The little-leaf box, B. microphylla var.
koreana, although hardier than the common
box, is considered inferior by some horticul¬
turists because of their lighter green foliage
that has a tendency to discolor during cold
weather. Hardy cultivars are Winter Gem’
and ‘Wintergreen’. Hybridization between
these two species has resulted in improved
cold hardiness and better foliage color in such
varieties as ‘Green Gem’, ‘Green Mountain’
and ‘Green Mound’.
The previously discussed broad-leaved
evergreens originated in climates generally
milder than ours, with richer soils and
greater rainfall. However, native plant enthu¬
siasts and xeriscape gardeners will be happy
to learn of some broad-leaved evergreens
from our own region that are better adapted
to our temperatures, rainfall and soils.
Sticky laurel, Ceanothus velutinus, is one
of these. It is a spreading shrub to 3 feet tall,
commonly found on dry slopes in the Colorado
foothills. Its leathery leaves are medium green,
oval shaped, about 3a inch long. It has small
clusters of creamy white flowers in spring.
Also, two similar species of mountain
mahogany, native to western Colorado, have
evergreen foliage. Confusingly, both are
referred to as western mountain mahogany.
Cercocarpus ledifolius is the larger of the
two, eventually reaching 15 feet or more. Its
green leaves can vary from inch to slightly
more than an inch long. Plants have a mostly
upright form. Their general appearance is
typical of western dryland trees and shrubs,
that is, less densely foliated than eastern
species. Cercocarpus intricatus is smaller,
growing 4 to 6 feet tall. Its intricately
branched, light gray twigs show effectively
through its narrow leaves, which are about
half the size of the other species.
Although broad-leaved evergreens, in
general, are rather poorly adapted to horticul¬
ture in our region, they include some of the
most dramatic and beloved plants in our
landscapes. Many do surprisingly well when
their locations are carefully chosen and our
soils are adequately amended. Those broad¬
leaved evergreens native to our region, espe¬
cially, deserve wider use in our landscapes. **■
12
Ground Covers
James E. Klett
Ground covers that are evergreen provide
desirable year-around color and texture. They
are especially valuable in areas that are high¬
ly visible, such as near driveways, sidewalks
and entryways.
Broad-leaved evergreen ground covers
often have flattened, leathery leaves resem¬
bling those of deciduous plants. There are
vining forms, low spreading types, and low
clump-formers.
Where you plant broad-leaved evergreen
ground covers is especially important in the
Rocky Mountain and Plains states. These
plants are susceptible to wind desiccation and
normally should not be planted in direct win¬
ter sun or wind. Often they need to be pro¬
tected in winter with temporary screens,
mulches or anti-transpirants to help prevent
\ the wind from drying their leaves.
The narrow-leaved evergreen ground cov¬
ers have fine textured, scale-like or awl-shaped
! needle-like leaves which are generally a little
■ - - — - -
A life member of the Colorado Nurserymen's Asso¬
ciation, James E. Klett is associate professor in the
Department of Horticulture at Colorado State Uni¬
versity, where he has won the Alumni Faculty
Award, 1985; the CSU Horticulture Club Out¬
standing Horticulture Professor Award, 1982, '83
and '85; and the Shepardson Faculty Teaching Award,
1 988. He is widely published in technical and trade
journals, such as The Journal of Arboriculture, Amer¬
ican Nurseryman, The Journal of Environmental
Horticulture and Horticulture Science.
less susceptible to the drying effects of winter
sun and wind than the broad-leaved ones.
This group includes the low-growing and
spreading junipers that are very popular in
this region.
Broad-Leaved Ground Covers
Bearberry, or kinnikinick, Arctostaphylos
uva-ursi, is a creeping ground cover that
grows approximately 6 inches to 1 foot tall
and 2 feet or more across. Often the branches
root as they spread. They grow fairly slowly
after transplanting, but more rapidly once
they are established. The leaves are small,
between k to l-lA inches long, glossy, dark
green above and a lighter green beneath.
They often turn reddish bronze in the fall.
The clusters of white or pink urn-shaped
flowers are borne in the spring and are fol¬
lowed in late summer by red fruits that often
persist through the winter. Bearberry is salt
tolerant, but it needs an acid, well-drained
soil. It also grows best in a partially shaded
site, but can tolerate some wind. Bearberry is
often slow to become established after plant¬
ing, but mulching helps.
Lowfast cotoneaster, Cotoneaster
dammeri ‘Lowfast’, is another low-growing,
mat-like ground cover. It reaches 12 to 18
inches in height. The ‘Lowfast’ cultivar is
hardier than the species and has very dark,
glossy, green foliage that is only semi ever¬
green in colder areas. Its white flowers open
in May, on into June, and are followed by
13
Panayoti Kelaidis
\
Ice plant, Delosperma cooperi, is a succulent evergreen
ground cover.
scarlet fruits. This plant performs best in a
protected area and would be ideal where
there is prolonged snow cover to protect it
from winter wind.
Purpleleaf wintercreeper, Euonymus for-
tunei ‘Coloratus’ is a very dense and vigorous
trailing semi evergreen to evergreen ground
cover that grows approximately 6 to 18 inches
tall. As the stems creep along the ground
they root wherever they touch the soil. It may
also climb to over 20 feet by means of aerial
rootlets. Wintercreeper is mildly invasive and
has a rapid growth habit once established.
When grown as a ground cover the plant does
not produce any flowers or fruit.
During the summer the leaves are deep,
glossy green but as the weather cools they
turn dark red-purple on the upper side,
lighter on the underside. If the plant is grown
in an unprotected area it may lose some
leaves in winter. The plant does well in most
landscapes and can be used to stabilize slopes.
There are other cultivars of Euonymus
fortunei that are sold along the Front Range.
The variegated-leaved Euonymus fortunei are
often planted but they seem to be a little less
hardy than the green forms. One cultivar,
‘Variegatus’, available in both a trailing and
climbing form, can grow 15 to 24 inches tall.
1 4 The leaves are grayish-green with white mar¬
gins. Other variegated cultivars that often
get taller than ‘Coloratus’ are ‘Emerald Gai¬
ety’, ‘Emerald ‘n Gold’, and ‘Silver Queen’.
English ivy, Hedera helix, is a low-grow¬
ing, high climbing, evergreen ground cover
that normally gets about 10 inches tall and
spreads very rapidly, rooting as it goes. The
plant also has the ability to climb by means
of special “hold-fasts” along its stems. Both
juvenile and mature growth forms may occur.
In its juvenile stage the plant has a trailing,
far-reaching, ground-covering growth habit
and does not flower or fruit. The mature form
occurs when the climber reaches approxi¬
mately 15 feet and produces flowers and
fruit. Leaves of the juvenile stage are lobed;
those of the mature, flowering stage are
unlobed. English ivy grows best in a rich,
well-drained soil with fairly large amounts of
organic matter. In our area it should be
planted in shade and protected from winter
sun and wind which dry and bum the leaves.
English ivy is easy to establish after planting.
Annual pruning is usually needed to keep it
in bounds.
Creeping mahonia, Mahonia repens , is
an evergreen that grows approximately 1 foot
high and spreads by underground stems. The
leaves, bluish-green on their upper surfaces,
are pinnately compound with holly-like
leaflets. The yellow flowers in April and May
are followed by bluish-black berries from
mid- to late summer. The plant grows best in
moist, well-drained soils. A proper site is very
important. Creeping mahonia must be pro¬
tected from winter wind and sun. Survival by
stock collected from the wild or handled bare-
root is often poor, but container-grown plants
survive transplanting well.
Common periwinkle, Vinca minor, is a
trailing, mat-forming, evergreen ground
cover that grows approximately 6 inches in
height and spreads widely. The branches root
as they creep. The dark, glossy green leaves
are simple and generally less than an inch
long. Its lilac-blue flowers peak in April and
then appear sporadically until midsummer.
Periwinkle does best in moist organic soil but
cannot tolerate an extremely wet site. It usu¬
ally covers well in relatively dry shade.
Narrow-leaved Ground Covers
The trailing Chinese juniper, Juniperus
chinensis ‘Procumbens’, is a dense evergreen
that grows to 2 feet in height and can spread
10 to 12 feet. The leaves are all needle-like,
with spiny tips, bluish to gray-green. Fruits
rarely occur on cultivated plants. It tolerates
most well-drained soils, from slightly acid to
alkaline, and it grows best in full sun. The
cultivar ‘Nana’ is an outstanding plant that
grows to just 12 inches and spreads to 5 feet.
The awl-shaped leaves, a little shorter and
wider than that of the species, are also more
densely arranged on the stem. The new
foliage is bright green, becoming bluish-green
during the summer, then purplish in winter.
Creeping junipers, Juniperus horizontal-
is, are widely grown. Two good cultivars are
‘Plumosa’ and Wiltonii’. The Andorra creep¬
ing juniper, J. h. ‘Plumosa’, has a distinctive,
flat-topped, spreading growth habit. It grows
18 to 24 inches high and 8 feet or more wide,
with plume-like branches growing from the
center in all directions. The needles are gray¬
ish-green, becoming purplish in winter. The
plant is not as dense as some of the other cul¬
tivars of J. horizontal is.
The blue rug creeping juniper, also
known as the blue Wilton, Wilton carpet and
Wilton’s creeping juniper, has a very dense,
flat growth habit, reaches 6 to 8 inches high
and spreads 6 to 8 feet. It is one of the lowest
growing juniper cultivars. Branches often
take root where they come in contact with
moist soil. The leaves are very small and
closely pressed to the stem, silver-blue in
summer and grayish-blue to slightly purple
in winter. The blue-gray color is enhanced by
its abundant blue fruit. It is a very adaptable
ground cover for the Rocky Mountain and
Plains states.
The savin juniper, Juniperus sabina, is
usually a stiffly upright plant not suitable as
a ground cover. Certain cultivars of the
species, however, are very useful. The Broad¬
moor savin juniper, J. sabina ‘Broadmoor’, is
a ground cover that grows 12 to 24 inches and
can spread to 1 0 feet. The horizontal branch¬
es have short upturned branchlets. As the
Top, 'Broadmoor' juniper; above, 'Blue Star' juniper
plant matures it seems to mound higher in
the center. The leaves are grayish-green.
‘Buffalo’ is a cultivar with very feathery
branches and bright green foliage which
retains its bright color even in winter. The
plant matures about 12 inches high and 6 to
8 feet wide. Being female, it sets fruit. The
plant is very hardy and adaptable to both
partial shade and full sun.
Russian arborvitae, Thuja orientalis, is a
beautiful evergreen ground cover, worth try¬
ing but not entirely proven in this region. It
grows approximately 15 inches tall and
spreads almost indefinitely. The leafy branch-
lets are arranged in flattened sprays like true
arborvitae. Foliage is bright green in summer
and turns bronzy purple to brown in winter.
It is vigorous even in hot summers. (This
plant is also listed by some as T. microbiota
var. decussata but is more likely a juvenile
form of Thuja orientalis.) 1 5
I
Are You Confused ...
Diane Ipsen
‘W Gymnosperms are seed-bearing plants
in which the seeds are naked and free rather
than encased in fruit. This includes the
group called conifers (scientifically:
Coniferales).
W Conifers are plants
that bear their seeds
in cones. They
‘W The pine family (Pinaceae) includes
spruces, pines, firs, larches, yews, cedars,
hemlocks and Douglas-firs. Junipers, arborvi-
taes and false cypresses are members of the
cypress family (Cupressaceae). All are
conifers. While these plants are usually
“evergreen,” there are exceptions. The larch
tree is a deciduous conifer; its needles turn
yellow in the fall and then drop entirely. Don’t
chop one down thinking it’s a dead spruce!
W “Evergreen” refers to plants which
customarily retain their foliage over the
winter. The term is not interchangeable
with “conifer” because not all conifers are
evergreen, nor are all ever-green plants
conifers. Many evergreens are broad-leaved
angiosperms, seed-bearing plants in which
the seeds are enclosed within a fruit.
We may even speak of an evergreen vine
(English ivy), evergreen ground cover (myr¬
tle) or an evergreen flowering perennial
. (coralbells). Broad-leaved evergreens are
valuable in landscape plantings. But
remember, also, that because of climatic
differences whatever is evergreen in, say,
Seattle or Washington
D.C. may not be ever¬
green in Colorado.
...by some of the terms? When is a conifer
not an evergreen? What is a conifer? Is it a pine?
Read on....
include the pine and cypress families.
Though it may seem odd, juniper and yew
“berries” are technically cones.
Bristlecone pine tree
Doris Peacock
Insect Pests Associated with Conifers
Whitney Cranshaw
A large variety of insects, both native and
introduced, are associated with conifers in
Colorado. For the most part their activities
cause little or no serious injury to the plants.
However, damaging outbreaks can occur,
particularly with species that have developed
a local track record as a serious pest (for
example, the pine needle scale, the spruce
spider mite and the Douglas-fir tussock
moth). Persons interested in landscape plant¬
ing should be aware of these potential pests
so that they can be managed, even avoided.
Scale Insects
In most landscape settings scale insects
are the most damaging associated with ever¬
greens. The major pest is the pine needle
scale, Chionaspis pinifoliae, a small, white
hard scale that feeds on the needles. In high
populations pine needle scales cause needle
yellowing and drop. Spruces and mugo pines
are particularly susceptible to this species,
although it may be found on any pine species.
Pine needle scales spend the winter as
eggs under the cover of the mother scales.
During mild winters some females may sur-
Whitney Cranshaw is extension entomologist in the
Department of Entomology at Colorado State Uni¬
versity. He wrote or co-wrote over 50 fact sheets on
insects for the university's extension service and has
written for many scientific and trade journals,
including he Journal of Arboriculture, American Nursr
eryman and Colorado Green.
vive and lay eggs again in spring. Overwin¬
tered eggs hatch as early as late April or the
first week of May and the newly emerged
crawlers settle on nearby needles. This first
generation becomes full grown in early sum¬
mer and a second generation, which attacks
the new needles, hatches in mid- to late July.
Pine needle scales have several natural
enemies, notably small lady beetles which
prey on the species. Also, extreme winter con¬
ditions can kill many of the overwintering
eggs. These often act to provide adequate con¬
trol. However, applied controls are sometimes
necessary. Crawler sprays, which target the
newly hatched insects, can be highly effective
although they are somewhat tricky to time
correctly. Several insecticides are available
which can provide control of crawlers, e.g.,
Sevin, Talstar, Dursban, Tempo, Orthene.
Horticultural oils also are highly effective for
controlling crawlers or young, relatively
unarmored nymphs, although these treat¬
ments will temporarily remove the bluish
waxy bloom from spruces.
In recent years the pine tortoise scale,
Toumyella parvicornis, has increased as a
problem in some areas, notably parts of
metropolitan Denver. This is a fairly large
“soft scale” most commonly observed when
the fertilized females on twigs swell in size
during late spring. Unlike pine needle scales,
pine tortoise scales also excrete large amounts
of sticky honeydew.
Pine tortoise scales spend the winter as
17
partially developed insects on the twigs. Eggs
are produced in June, with crawlers emerg¬
ing during late June and early July. The
young scales first settle on the needles, later
moving to the twigs at the end of summer.
There is only one generation per year. Dor¬
mant applications of horticultural oils are
probably the easiest control of the species.
Insecticide treatments directed at newly
emerged crawlers or early summer oil sprays
should also provide protection.
An infrequent, but sometimes damaging
species associated with native pinyon pine is
the pinyon needle scale, Matsococcus acalyptus.
This scale spends the winter on trunks and
large branches. It becomes active very early
in the season, as overwintered females pro¬
duce conspicuous cottony egg sacks in early
April. During the growing season the devel¬
oping scales feed on the needles, occurring as
“bean stage” nymphs on the needles by sum¬
mer. If control is necessary the overwintered
females on the lower part of the tree in early
spring are most effectively targeted.
Scattered problems with the juniper
scale, Carulaspis juniperi, also occur in the
state, primarily in the Boulder area. This is a
hard scale, most commonly associated with
upright junipers.
Spruce Spider Mite
The spruce spider mite, Oligonychus
ununguis, can be extremely destructive to
spruces and junipers. Outbreaks are fre¬
quent, encouraged by our arid climate. Prob¬
lems can also be exacerbated by use of certain
non-selective pesticides, such as carbaryl,
that are highly destructive to their natural
enemies. Spruce spider mites damage the
plant by rasping the needle surface and suck¬
ing the plant sap. Heavily infested plants
have an unthrifty, grayish appearance and
often lose needles.
The spruce spider mite spends the win¬
ter in the egg stage on its host plant. Eggs
hatch in early spring and the mites develop
rapidly, typically with generations at inter¬
vals of two to three weeks. Some webbing is
1 8 produced by these mites, although not as much
as by the two-spotted spider mite, the common
species found in gardens and greenhouses.
Increasing the humidity around a plant-
, ing can retard the development of spruce spi¬
der mite problems, and regularly spraying
susceptible plants with a jet of water may be
feasible in small plantings for mechanical
control. Relatively few pesticides are effective
against this mite, including Vendex, Dursban
or Kelthane, although insecticidal soaps have
been successfully used in some research.
Borers
Two species of related caterpillars have
emerged as the most serious trunk- and
branch-boring insect pests associated with
pines in Colorado. Pinyon (and rarely pon-
derosa) pines can be attacked by the pinyon
pitch mass borer, Dioryctria ponderosae. The
young caterpillars make deep gouging
wounds in the bark and cambium, resulting
in copious amounts of sticky pitch at the
wound. Attacks are often concentrated at
branch crotches and near previous wounds.
This results in structural weakening of the
tree and serious dieback.
The pinyon pitch mass borer apparently
has a life cycle that may extend beyond one
year. Most emerge as adult moths during late
June and July; they fly and lay eggs through¬
out the summer. Once the eggs hatch and the
larvae enter the bark they are very difficult to
control with insecticides. Repeated applications
of Mavrik or Dursban during the egg laying
period have provided only about 50 per cent
control. Individual larvae in pitch masses can
be dug out or killed by inserting moth crystals
into the wound site. Since susceptibility
appears to be associated with succulent growth
and bark cracking, pinyon pines should not
be planted where they will be over-watered.
Recently the Zimmerman pine moth,
Dioryctria zimmermani, has become a prob¬
lem on Austrian and Scots pines, spreading
from some original infestations in the south¬
ern Denver area. Larvae of this insect also
concentrate their attacks at crotches, making
the trees susceptible to branch-breaking dur¬
ing heavy wind storms or snows. Wounds are
ss of pitch oozing from holes of
/on pitch mass borer
Pitch flowing from damage by mountain
pine beetle
Larva of tip moth on pinyon pine
also characterized by light-colored popcorn-
like sap flowing from the injury.
Zimmerman pine moths have a one-year
life cycle. Adults emerge in late June and
July and lay eggs in midsummer. Newly
hatched larvae do not immediately tunnel
into the tree, but feed externally on the bark
for a while and spend the winter in bark
cracks. They continue to feed on the bark in
spring until they enter the tree to finish their
development. Preventive insecticidal sprays
can be applied in either August or early May,
the latter timing reportedly more effective in
the Midwest.
Both Zimmerman pine moth and pinyon
pitch mass borers appear to be fairly “aggres¬
sive” species, capable of attacking healthy
trees. Other borers associated with conifers
limit their attacks to recently dead or dying
wood, sometimes attacking pines under
severe transplant stress. Perhaps the most
conspicuous of these are the pine sawyers,
large (%-l inch) gray beetles with very long
antennae. Commonly, the adults emerge from
pine logs and may sometimes be seen feeding
on twigs during midsummer. One additional
species, Atimia huachucae, is of occasional
concern on junipers. Scattered outbreaks of
this borer occur in older junipers throughout
the state, sometimes causing dieback.
Tip Moths and the White Pine Weevil
Tip moths are insects which, in the
caterpillar stage, tunnel under the bark of
the terminal growth and produce dieback
symptoms. In Colorado pines are attacked by
either of two groups of tip moths. Most pines
are hosts of Rhyacionia species, primarily the
southwestern pine tip moth, R. neomexicana.
Pinyon pines are attacked by their own com¬
plex of insects. Damage by all tip moths is
quite conspicuous but does not cause serious,
long-term injury unless a high percentage of
the terminals are regularly killed.
Southwestern pine tip moths spend the
winter as pupae protected within cocoons
around the bases of previously infested trees.
The adult moths emerge and fly in mid¬
spring. However, they are most attracted to
pines when the new needles start to form in
spring, the candle stage of pine growth. They
lay their eggs at this time. The young larvae
then enter the developing shoots. Tip die¬
back becomes obvious on the pines about one
and a half months later, as the hill-grown
caterpillars girdle the shoot.
Two types of tip moths commonly attack
pinyons. The pinyon tip moth, Dioryctria
albovitella, is the most common species; it
enters the pinyon branch tips in late May and
June. The pitch nodule maker, Petrova arizo-
nensis, also damages tips but its presence is
characterized by a large purple or pink nodule
of pitch. Both species emerge as adult moths
in midsummer. However, the pitch nodule
makers immediately enter the tips after
hatching, while the pinyon tip moths remain
on the outside until the following spring.
Tip moths are best controlled with insec¬
ticides when the eggs are laid or when the 1 9
Galls of spruce gall adelgid on Col¬
orado spruce
Adult spindle gall midge on pinyon,
and its gall
The frothy defense of spittlebug is suspi
ciously unattractive, but harmless.
larvae are still present on the external bark,
before they tunnel. This occurs during early
candling stage by the southwestern pine tip
moth, during late July and early August by
the pitch nodule moth and in either August
or early May by the pinyon tip moth. In Col¬
orado State University trials, insecticides
with systemic activity (Orthene, Cygon) have
given the best control of these insects.
Another type of terminal injury is pro¬
duced on spruce trees by the white pine wee¬
vil, Pissodes strobi. This insect develops to
the larval (grub) stage under the bark of the
main leader, causing it to die back in the
form of a shepherd’s crook during late spring.
This type of injury can seriously affect the
form of a tree, as competing side shoots will
then form multiple leaders, resulting in the
tree developing a bushy profile. If damage
has occurred, the form can be salvaged by
purposely retraining one of the surviving side
leaders to become the dominant terminal.
Damage, however, is primarily limited to
higher elevations in the state.
The adult weevils spend the winter
under cover of debris. They move into the
trees very early in the season, usually April,
chew small pits in the terminal buds and lay
eggs. The developing larvae feed under the
bark, ultimately girdling their tree. They then
form distinctive “chip cocoons” under the bark.
Later they emerge through small holes. Pre¬
venting damage involves treatment with insec¬
ticides timed to kill the adult weevils return¬
ing to the trees in early spring. Dursban and
2 0 Sevin should be effective for this purpose.
Gall-making insects
A few of the insects associated with
conifers make distinctive distortions, called
galls, in developing new growth. These galls
are often quite conspicuous because of their
peculiarity and they tend to raise concern.
However, rarely are large areas of the trees
involved by this injury.
Perhaps the best known gall-maker is
the Cooley spruce gall adelgid, Adelges coo-
leyi. This insect produces a prominent cone¬
like gall on the tips of blue spruces. Galling is
concentrated on the protected sides of the
trees (usually on the north and east). Some
individual trees seem particularly prone to
infestation.
The Cooley spruce gall adelgid has a
rather unusual life cycle, involving two host
trees, spruces and Douglas-firs. Infestations
start on the spruces by wingless females,
which spend the winter on the undersides of
twigs. In spring they resume growth and pro¬
duce a large egg sack. Eggs hatch when the
new spruce needles emerge and the small
nymphs settle at the bases of the developing
needles. Feeding by the insects at this time
causes the shoots to thicken and form a series
of chambers, in which the Cooley spruce gall
adelgids grow.
By late June or July the galls dry and
open, appearing to be “cones.” The insects
then emerge, transform into a winged stage
and leave their trees. Their normal migration
is to Douglas-firs, the alternate hosts. Howev¬
er, it seems likely that some are able to repeat
\A/Lu.
James reucht
1 i T99?
S0O9 Vori a FoWler ue.'
Defl^f. Colo,
Tussock moth damage on small spruce Mature larva of Douglas-fir tussock moth Giant juniper aphids on pine
the cycle on spruces. Regardless, new, winged
Cooley spruce gall adelgids return to spruces
in late summer to produce an overwintering
form.
Cooley spruce gall adelgids succumb to
many natural forces. The overwintering
females are very susceptible to late spring
frosts that occur after they have emerged
from their winter dormancy. Blowing winds
and brushing needles dislodge others, partic¬
ularly on more waxy-needled (that is, blue)
trees. Several insecticides can also control
them; treatments are best applied in mid- to
late April before they form their large egg sacks.
Gall midges distort the developing nee¬
dles of certain pines, producing swollen pock¬
ets along the base of the needle in which the
developing midge larvae live. Stunt midges,
Contarinia coloradensis, or Janetiella sp.,
associated, respectively, with ponderosa and
pinyon pines, cause the needles to be greatly
shortened. Needles attacked by the pinyon
spindle gall midge, Pinyonia edulicolia, are
normal length. However, all needles damaged
by gall midges die prematurely, within a year.
Serious infestations resulting in signi¬
ficant defoliation by gall-forming insects are
rare. In most instances natural enemies
attack the young midges in the gall and pro¬
vide adequate biological control. If chemical
controls are considered, they should be applied
during the period when new needles are emer¬
ging and galls are forming. Only the insecti¬
cide dimethoate (Cygon) has been consistent¬
ly effective against gall midges on pines.
Defoliators
Several insects chew on the needles of
coniferous evergreens, occasionally causing
severe defoliation. Most important is the
Douglas-fir tussock moth, Hemerocampa
pseudotsugata, a serious pest of spruces, firs,
and Douglas-firs in several Front Range com¬
munities, notably Denver and Colorado
Springs.
These Douglas-fir tussock moths spend
the winter as eggs in masses covered with the
body hairs of their mothers. Egg masses are
commonly on twigs and trunks, but may be
in the vicinity of the previously infested tree.
Human movement of the egg masses may be
an important factor in spread of the insect.
The eggs hatch in spring, typically late
May and early June. The larvae prefer to feed
on the tender, developing needles. As the nee¬
dles are chewed, infested trees take on a
brownish cast, typically concentrated in the
upper parts. During large outbreaks older
needles also will be destroyed, seriously
stressing the tree. Dieback from the top is the
most typical symptom resulting from a severe
infestation.
Feeding is often finished by late June or
early July, although it can continue into mid¬
summer in some locations. The caterpillars
pupate in a cocoon on or around the infested
tree, and adults later emerge in 10 to 14
days. Female moths are wingless and lay
eggs near the point where they pupated.
In the forested areas of Colorado, budworms
are the most serious defoliators. This includes 2 1
I
the western spruce budworms, Choristoneura
occidentalis, on Douglas-firs and spruces, and
pine budworm, Choristoneura C. lambertiana,
on lodgepole and ponderosa pines. Both of
these species occur periodically in massive
outbreaks, causing extensive defoliation
which can kill trees or weaken them so that
they are susceptible to later bark beetle
attack.
Other caterpillars that invade Colorado
conifers are the larvae of the pine butterfly
and of the tiger moth. In addition, early sea¬
son injury, before new growth emerges, is
sometimes sustained due to sawflies.
Most caterpillars are susceptible to Bacillus
thuringeinsis products (e.g., Dipel, Thuricide,
Biobit), although control of Douglas-fir tus¬
sock moth caterpillars with these materials
has often not been satisfactory. Sawflies are
not susceptible to B. thuringiensis. Carbaryl
(Sevin), Dursban, Orthene, Tempo, Mavrik,
and Talstar are also quite effective against
both caterpillars and sawflies.
Aphids
Several types of aphids can be found on
needled evergreens, although they rarely
cause much injury. Among them are the giant
conifer aphids, Cinara species, which are
quite large brown or black aphids that super¬
ficially resemble ticks. These can be found on
spruces, pines and junipers. Woolly aphids,
Pineus species, produce waxy threads which
cover their bodies; they are sometimes com¬
mon in spring on pines. In addition, the alter¬
nate stage of the Cooley spruce gall adelgid
occurs as a woolly aphid on Douglas-fir trees.
Aphids associated with conifers spend
the winter as eggs on the old needles. Largest
populations are typically found in spring, and
the woolly aphids leave the pines by late
spring to feed on summer host plants. Con¬
trols are almost never warranted for plant
protection. Minor needle bending can occur
on Douglas-firs due to the Cooley spruce gall
adelgid and occasional needle shed on
junipers and spruces results from outbreaks
of giant conifer aphids.
Bark Beetles
As their name implies, bark beetles
develop by feeding on the cambium layer
under the bark. Often this activity is aided by
the concurrent presence of blue stain fungi,
Ceratocystis species, which helps to kill the
plant and thus provide the dying wood on
which the bark beetles thrive. This is a mutu-
alistic relationship; the bark beetles are the
main carrier of this fungus to new trees.
Many different genera of bark beetles
occur. Most infamous are members of the
genus Dendroctonus, including the mountain
pine beetle, D. ponderosae, and the Douglas-
fir beetle, D. pseudotsugae. Both these species
occur in mountainous areas, particularly fol¬
lowing stressful events, such as budworm
defoliation. Trees killed by these beetles
“fade” rapidly, turning reddish-brown, then
dying within a year after they have been suc¬
cessfully attacked.
In landscape settings, the engraver or
ips beetles, Ips species, predominate. These
are less aggressive pests, rarely attacking
trees in good health. However, newly trans¬
planted trees or trees that have suffered root
injury Eire at high risk and can support large
populations of these beetles, which can then
threaten other nearby conifers.
Fundamental to controlling bark beetles,
including Dendroctonus species, is maintain¬
ing and promoting vigor in your plants. Vig¬
orously growing trees have natural defenses
that usually can ward off attacking beetles.
Sanitation, removing infested trees and dead
wood before beetles emerge, is also part of a
good management program.
Individual trees can be protected from
attack by appropriately timed insecticide
sprays to kill the adult beetles when they
first visit a tree. Dursban, Lindane, and
Sevin are standard insecticides for this.
These sprays can be easily timed for species
such as mountain pine beetles and Douglas-
fir beetles which each have one generation
per year. However, ips beetles typically have
multiple, often overlapping, generations so
control measures need to be continued over a
longer period when high risk exists.
Dwarf Conifers for
Rocky Mountain Gardeners
Kelly D. Grummons
Tromping through the crusty snow look¬
ing for the perfect Christmas tree was always
a delight for me as a child. Usually, the old
juniper that we selected didn’t look so perfect
when we got it home — kind of amber brown
with empty spots that required branches to
be wired into them. Of course, the tree was
always bigger than we had figured.
It was on these outings that I first noticed
the miniature “trees” growing right out from a
branch of a normal tree. The witches’ brooms
were little dense duplicates of the original pine
or juniper caused by some mutation, perhaps
genetic or pathogenic. More than one of these
little trees through the years came home to
be my own special Christmas tree, sitting on
our pine toy box.
It wasn’t until I worked at Brooklyn
Botanic Gardens that I learned from a friend
about how pieces of these brooms are grafted
onto a normal seedling stock to create dwarf
conifers. Other dwarf conifer selections are
found as seedlings with a genetic dwarfness
not caused by a mutation on a normal tree.
Iseli Nursery in Oregon is responsible for
most of the commercial dwarf conifer produc¬
tion in the United States. I understand, also,
that some local enthusiasts are active in
Kelly D. Grummons, the head grower at Paulino Gar¬
dens in Denver, received his B.S. in horticulture at
Colorado State University and was an intern at Brook¬
lyn Botanic Gardens. He grew up in the Black Hills
of Wyoming. Native prairie plants are his passion.
finding potentially valuable clones from
nature here in our region.
A dwarf blue clone of Colorado spruce
that is very dear to me is Picea pungens var.
glauca ‘R. H. Montgomery’. It is a powder-
blue, pyramidal little fellow that grows slow¬
ly, eventually reaching 5 to 8 feet high and
wide. Under dry culture, the plant grows 2 to
3 inches per season. Under moist, shadier
conditions, I’ve seen it progress at 4 to 6 inch¬
es per year. What a handsome plant it would
be as a specimen in a confined city garden
where a normal-sized spruce wouldn’t fit!
Imagine it underplanted with dwarf winter-
creeper, Euonymus fortunei ‘Kewensis’, and
spring heather, Erica carnea.
A favorite ‘"bird nest spruce” for this area
is Picea abies ‘Pumila’. It isn’t quite as nest¬
forming as P a. ‘Nidiformis’, but it forms a
rather nice globe that sometimes forms a
leader, which gives it a teardrop shape.
Unlike many other Norway spruce selections
this one will stand full sun, even at our high
elevation, providing that enough moisture is
constantly available. Its bright color and
dense habit make it valuable for a rock gar¬
den or a low hedge. The little red flowers of
dwarf twinbeard, Diascia ‘RubyFields’, look
very cheerful in front of this dwarf tree.
If you’ve been looking for a truly dwarf
mugo pine, consider Pinus mugo ‘Iseli’s
White Bud’. It has dense, very short, dark
green needles and resinous white buds in
winter and early spring. At 2 -!$ feet high and
3 to 5 feet wide, this jewel is one of the best
selections ever to be introduced. Plant it in
full sun for optimum dwarfness and grow it
comparatively dry.
One of the first dwarf trees used in our
landscapes was the Alberta spruce, Picea
glauca ‘Conica’. Its narrow, pyramidal shape
and bright green color make it very desirable
in formal gardens. Also available is Picea
glauca ‘Saunder’s Blue’, with the same habit
as ‘Conica’ but with a steel-blue color. Grow it
in partial shade to discourage its reversion to
green, and cut out any green branchlets that
develop. Perhaps with further selection this
reversionary trait will be eliminated. These
dwarf varieties get 7 to 10 feet high and 6 to
7 feet wide after many decades.
Unlike its lacy, 80-foot-tall counterpart —
the eastern white pine — the dwarf, blue Pinus
strobus ‘Blue Shag’ is diminutive. Its long, soft
needles are deep blue-green with nearly white
striations. What a gem! Its 3- to 5-foot informal,
sometimes leaning stature can be highlighted
by planting it near a compact, silver snow-in¬
summer, Cerastium tomentosum, or royal blue
Veronica prostrata. Either sun or shade suit
this clone but it needs plenty of moisture.
If you need an upright dwarf conifer for a
special effect, try a dwarf Swiss stone pine,
Pinus cembra ‘Nana’. This is considered very
choice. Its soft green needles shimmer with a
touch of silver. It thrives in sun or shade and
likes moderate moisture. The plush gray-green
of Veronica pectinata, with sky-blue flowers
and evergreen mossy foliage, make it one of
my favorite ground covers to use with this tree.
You could add clumps of dwarf wild yellow
tulips, Tulipa tarda , for an super combination.
One of the few junipers small enough to
welcome into a rock garden is Juniperus squa-
mata ‘Blue Star’. It has crisp blue foliage and
a pudgy, rounded shape. It tolerates full sun
but finds its glory in shade or partial shade. I
have it planted in my parents’ rock garden
with a big clump of hen-and-chicks, Semper-
viuum ciliosum ‘Borisii’, and woolly thyme —
in shade!
Picea pungens ‘Saint Mary’s Broom’, a
very slow growing, globose blue spruce, thrives
in sun or shade. At about 2 inches of growth
per year, this one won’t outgrow even the
smallest garden. I have mine planted with
Veronica spicata ‘Red Fox’ and hardy ice
plant, Delosperma nubigenum.
Dwarf Serbian spruce, Picea omorika
‘Nana’, is gaining popularity here as a tough
plant in conifer collections. It is broadly pyra¬
midal with a strong leader. The waxy green
branchlets are bluish-silver beneath. For best
appearance you should avoid growing it
under dry conditions. Its 4- to 6-foot height is
ideal for many situations. In a shady garden
dwarf blue hostas and Bethlehem sage, Pul-
monaria ‘Roy Davidson’ are useful compan¬
ions to this plant.
The real pearl in my garden, though, is a
micro-miniature mugo pine called Pinus mugo
‘Mitsch Mini’. It was planted from a 2-k inch
pot into a shallow depression in a moss rock
five years ago and is now only the size of a
baseball! I think that its companion Semper-
vivum ‘Cebenese’ shelters its roots from heat
and cold and helps to absorb excess moisture
during rainy spells.
Dwarf conifers have a place in almost every
garden. Try them; you won’t be disappointed. **
There are dwarf forms of almost any conifer you can imagine. Mr. Grummons also recom¬
mends these tried-and-true selections:
White spruce
Black pine
Scots pine
Balsam fir
Colorado spruce
Norway spruce
Norway spruce
White spruce
Picea glauca 'Echinoformis'
Pinus nigra 'Hornibrookiana'
Pinus sylvestris 'Beuvronensis'
Abies balsamea 'Nana'
Picea pungens 'Mrs. Cessarini'
Picea abies 'Clansbrassiliana'
Picea abies 'Elegans'
Picea glauca 'Pixie'
Pines and Spruces for Colorado Landscapes
Jim O'Shea
Pines and spruces are, with some excep¬
tions, among the largest, stateliest ever¬
greens available for our landscapes. Among
deciduous trees and other evergreens they
provide stability and are useful as back¬
grounds for structures and other plants.
Their forms, however, differ, as do their cul¬
tural requirements.
Pines show great diversity in growth
habit. Their needles are bundled in groups of
two to five and are an identifying characteris¬
tic. They also contribute to the texture and
appearance of individual species.
Pines are generally tolerant of exposed
and relatively “poor” growing sites. However,
over-watering or poor drainage, particularly
in heavy clay soils, may lead to oxygen star¬
vation (root suffocation). They are intolerant
of shade, performing best in full sunlight and
with sufficient space to allow them to develop
fully — some species grow over 40 feet across.
Features that allow them to survive hot,
dry sites, high winds, frozen soil and
extremely low temperatures include a thick
cuticle (wax on the needles), a hypodermis
consisting of a layer or two of thick-walled
cells below the epidermis and recessed stom-
ates. All these reduce water loss from the
plant.
Jim O'Shea is horticulture instructor at Front Range
Community College, where he teaches plant iden¬
tification, plant science and garden management.
For seven years he was a grower in Ohio and Kansas.
Spruces, on the other hand, are more
adaptive to moist, organically rich soils. They
can tolerate some shade and are less resis¬
tant to drought than most pines.
Resin canals in the needles and through¬
out other parts of pines and spruces secrete
resin. This is aromatic and antiseptic; it pre¬
vents the development of fungi and discour¬
ages some insect pests. Note: It is natural for
the oldest (innermost) needles on all the pines
we grow to yellow and drop each autumn.
How to Plant Pines and Spruces
Move and plant either pines or spruces
as balled and burlapped (B&B) or container¬
ized plants. Only small seedlings can be
transplanted bare root. Trees should be
planted in holes that allow 6 to 12 inches all
around the ball for fill soil. To improve aera¬
tion, amend the fill soil with up to one-third
organic matter. I prefer to wait until the tree
is rooted out before fertilizing.
The proper planting depth varies some¬
what with the soil texture. In sandy soils
place the top of the ball at grade level and in
clay soils 1 to 2 inches above grade. In clay
the root ball should rest on firm soil at the
bottom of the hole rather than the fill, other¬
wise the plant may settle too deeply. Immedi¬
ately after planting a tree water it well, then
allow the soil to get slightly dry before the
next thorough watering, particularly for
pines. Do not add small amounts of water on 25
a frequent basis, as this promotes shallow
roots. When checking soil moisture, dig down
into the soil several inches to get a sample.
Close your hand in a fist around some soil
and if it remains in a ball after opening your
hand, hold off watering until the soil sample
you get is slightly crumbly.
When you test the fill soil for moisture
also check to see whether the root ball is
moist or dry. It is possible for the fill soil to be
moist while the ball is dry, particularly if the
ball was on the dry side when you planted it.
Containerized plants should be watered and
allowed to drain prior to planting. For B&B
stock it is important to prevent the ball from
drying out, and the tree becoming stressed,
prior to planting.
It is best to plant pines and spruces
spring through summer, even into early fall.
While fall-dug and fall-planted material can
sometimes succeed, there appears to be a
greater chance of loss, due to little time for
root regeneration before winter.
Finally, many nursery-grown evergreens
have been sheared and have a compact form.
This allows little opportunity for wind to pass
through the plant. Therefore, you should
stake tall specimens after you’ve planted
them. Use 2-inch to 3-inch-wide grommeted
canvas plant straps around the trunk. Thread
wire or strong twine through the grommets
and secure it to stakes in the ground. Flag the
wire or cover it with white plastic so it is visi¬
ble and people won’t trip on it. Allow a little
play in the wire and inspect it periodically.
Wires and stakes should be removed after one
to two years.
Selected Pines
Bristlecone pine, Pinus aristata, is a valu¬
able native tree, tolerant of dry, rocky soils,
whether alkaline or acid. Its mature size
varies from 8 to 20 feet in height, with an
irregular spread. It is extremely slow grow¬
ing; use it as an accent plant. Its leaves are
dark green with white resinous exudations.
This species is among the oldest living plants
on earth. A tree in eastern Nevada has been
documented to be 4,900 years old. Foxtail
pine, P. balfouriana, is related but does not
develop the resinous exudations.
Limber pine, P. flexilis, is another native.
Its young stems can actually be tied in knots,
thus the name. Its mature size varies from 30
to 50 feet in height and 15 to 35 feet in
spread. Conical in its youth, it matures as a
broad, flat-topped tree. Its needles are often
an attractive blue-green, especially in young
plants. In short, the limber pine is a hand¬
some tree, adaptable to fast-draining soils
and a good choice for a large yard. Several
cultivars are available in the trade.
Above, young pine tips in early spring
Right, native pinyons and artemisias on
a south-facing slope near DBG's
Boettcher Memorial Conservatory
Uiane Ipsen
Blue (left), white
(front) and Black
Hills (back)
spruces
Mugo pine, P mugo, is thought of, usual¬
ly erroneously, as a low, broad-spreading,
bushy plant suitable for foundation plantings,
borders, and groupings. However, most are
seed-grown and they vary greatly in size and
growth habit. This species includes a number
of varieties or geographical forms, some of
which can grow 20 to 25 feet tall, or taller. All
tolerate transplanting and adapt to calcareous
(high calcium) soils. If you are seeking a com¬
pact spreader select a plant with small
growth increments between nodes. Although
a number of “dwarf’ cultivars are listed by
nurseries, they are almost impossible to dis¬
tinguish.
Austrian pine, P nigra, is a tree 50 to 60
feet in height with a 20- to 40-foot spread.
Conical as a young tree, it becomes large, broad,
flat-topped and spreading. It’s a hardy pine
that withstands city conditions and tolerates
heat, some dryness and clay and alkaline soils.
Excellent for screen or windbreak, it is a supe¬
rior tree — but only if it has room to develop.
lished. Its squat, resinous cones contain edi¬
ble seeds. Valuable in ornamental plantings,
its popularity has led to some overuse. As a
consequence, several natural pests, including
pinyon needle gall midge, aphids and pinyon
pitch mass borer are becoming increasingly
common, especially on stressed plants. This
tree is subject to oxygen starvation and it is
recommended that it not be planted at the
comer of a building where the downspout can
empty on the tree’s roots, or in any poorly
drained location.
The eastern white pine, P. strobus, is a
fine-textured, graceful, fast-growing pine
which can easily grow 2 feet (or more) per
year after it is established, becoming 50 to 75
feet tall with a spread of 15 to 20 feet. The
tree adapts to transplanting readily but may
become chlorotic in soils with high pH. Its
needles are usually light blue-green and
attractive all year around, but some forms
turn yellowish in winter. A columnar form is
available.
Pinyon pine, P edulis, is a small, bushy,
native tree, slowly growing to 20 feet high,
tolerant of dry situations once it is estab-
Ponderosa pine, P ponderosa, is a native
useful in areas up to 7,500 to 8,000 feet eleva¬
tion. Its needles vary from medium green to
27
yellowish green. Resistant to drought and tol¬
erant of alkaline soils, it is a useful forest and
shelter belt tree that can grow over 75 feet in
height and 50 feet in spread. Perhaps it is
best left in its native habitat; it’s not general¬
ly recommended otherwise.
The Scot’s, or Scotch, pine, P sylvestris,
has needles that are variable in length and
often attractively twisted. While popular and
widely used as a Christmas tree, it is often
passed by in the nursery, which is unfortu¬
nate. As this tree matures it becomes open
and somewhat irregular in spread, creating a
picturesque, Oriental effect. The orange-
brown bark is also interesting. Scot’s pines
will grow in a variety of soils, including poor
and relatively dry sites. As with all pines,
though, good drainage is a must. Average
landscape height is 30 to 50 feet with a spread
of 25 to 35 feet. Various color forms exist;
some are bluish green while others are yel¬
lowish, particularly during the winter. A
fastigiate (narrowly upright) form is available.
Recommended Spruces
Spruce trees are usually tall, symmetri¬
cal, and formal in appearance. Its genus Picea
includes nearly 40 species. (Pix, the Latin
word for pitch, is the origin of the generic
name.) The needles are usually four-angled,
attached singularly to the stem, and borne on
a short peg-like stalk.
Like the pines, spruces should also be
moved balled and burlapped. They are shal¬
low-rooted and prefer a more moist soil than
pines. I have seen spruce roots growing along
the soil surface when in compacted clay soil
or when their roots are covered with black
plastic.
Because of their strong vertical lines and
large size, careful consideration must be
given to site selection. Many landscape archi¬
tects warn against placing these trees toward
the front of the property or too close to houses
or walkways because they consume the prop¬
erty or grow to block access.
White spruce, Picea glauca, has glaucous
28 or pale green needles and grows 30 to 40 feet
in height and 10 to 15 feet in spread. Pyrami¬
dal in habit as a young tree, it becomes tall,
narrow and compact as an older tree. Dwarf
Alberta spruce, P glauca ‘Conica’, is a com¬
mon dwarf conifer and grows only a couple of
inches per year. P glauca ‘Densata’, the
Black Hills spruce, is a slow-growing tree
much denser and sometimes preferred over
the species.
Serbian spruce, P omorika, is less well
known and generally not as readily available
as some of the other spruce species. However,
it is a graceful tree, recommended because of
its excellent foliage, narrow pyramidal shape
and adaptability.
The Oriental spruce, P orientalis, is dis¬
tinctive for its very short needles, which are
bright, dark green. Its graceful, attractive
growth habit makes it a superior choice.
Finally, a few words about the most pop¬
ular spruce tree of all, the Colorado spruce,
Picea pungens. It is also called the Colorado
‘blue” spruce, but, surprisingly, it is often not
blue. Since most trees are propagated by
seed, genetic variability accounts for colors
ranging from dull green to green to blue-
green to silvery blue. Most frequently the
seedlings with the finest blue or silver col¬
oration are selected. Because there is a
greater demand for these trees, they com¬
mand a higher price in the nursery. Some of
the bluer types are propagated and perpetu¬
ated by grafting; selected cultivars such as
‘Hoopsii’, ‘Moerheim’, and Thompson’ are
available. Fortunately, the color of a young
tree is the color it will retain throughout its
life. You can choose a young, relatively inex¬
pensive tree with confidence.
When selecting pines or spruces for your
landscape, recognize that many may become
large trees. Some trees can overpower a small
site and interfere with walks, access and
overhead power and cable lines. Over time
they can also restrict air movement, give
unwanted shade in winter and crowd struc¬
tures and other plants. Choose carefully,
especially for a small property.
Growing Evergreens in Containers
Ken Slump
As any nurseryman can tell you, growing
and maintaining plants in containers poses a
number of special problems and considera¬
tions. Nevertheless, in many situations this
may be the best, if not the only, solution for
creating a “living landscape.” Some sites need
the interesting texture, form and year-round
attractiveness that only evergreen plants can
provide, yet growing them in containers is
the only solution.
Successfully growing evergreens in con¬
tainers requires that you first accept realistic
possibilities. It will require extra effort on
your part. Most of the plant’s environmental
needs will be wholly under your control. Also,
it is unrealistic to expect a woody evergreen
plant to thrive indefinitely in a container of
limited size. You will be less disappointed,
too, if you opt to merely maintain the
plants — don’t expect rapid, lush growth from
them. Here are some observations from my
experience growing a variety of evergreens in
a sheltered patio situation.
Containers
Your first consideration is the container.
There are numerous choices available, inclu-
Ken Slump is a horticulturist who undertakes special
projects in the plant collections department at Den¬
ver Botanic Gardens. Evergreens and other plants
grown in containers enliven the small spaces
around his Denver townhouse residence.
ding clay, glazed ceramic, wood, or plastic.
Whichever you prefer, it must have drainage,
that is, holes to let excess water escape.
Glazed ceramic and plastic containers retain
moisture well but lack the “breathability” of
clay pots and wooden containers. Some clay
pots tend to absorb too much moisture so
they crack in freezing weather. My best suc¬
cess has been with large wooden containers.
They resist heat buildup, they have good
drainage and they provide winter insulation.
The wood, of course, should be decay-resis¬
tant such as redwood or teak. In most cases,
the bigger the container, the better.
Soils
Blending the right soil mix for a contain¬
er plant can be tricky. The mix should suit
the container and its location. For example, a
light, rapidly draining soil mix is important
in plastic containers since they tend to retain
moisture longer than clay containers. The
container’s size and site, as well as the
species of evergreen, will also determine the
soil you use. In most cases your goal is a soil
with good moisture holding capacity as well
as good drainage. Add peat moss or other
organic matter to your potting mix for
increased moisture retention and sand or
perlite for faster drainage. Ideally, you will
not have to water more frequently than once
or twice a week in the hottest weather. You
should fertilize container plants judiciously
and sparingly. Any fertilizer designed for
trees and shrubs is satisfactory for ever¬
greens. Remember, your goal is not rapid
growth, as your plants will soon outgrow
their containers. If possible, select a plant of
the size, growth habit and effect you want,
then simply strive to maintain it.
Repotting
Eventually, though, even the best man¬
aged plant will outgrow its container. When
the plant’s decline signals that it has
exhausted the resources in its container you
should either move the plant into the land¬
scape, repot it into a larger container or
remove it, root prune it and repot it back into
the same container.
To rejuvenate a declining specimen, root
prune it during its dormant season. Careful¬
ly dig the plant out of its container. You will
likely find a thick, circling mass of roots lin¬
ing the container. With pruning shears or a
sharp knife carefully cut away at the tangled
root mass until you can re-place the plant
into its old container with a layer of fresh soil
around the root ball. This is also a good time
to prune the top part of the plant. (Essential¬
ly, this is the technique used to create artful
bonsai specimens.) Following repotting,
water your plant thoroughly. Choosing slow¬
er growing, dwarf types of evergeens will
reduce the frequency of this laborious task —
which brings us to plant selection.
I strongly recommend you choose your
evergreen from those known for their cold
hardiness. Colorado winters are brutal on
containerized plants and few home gardeners
have the inclination or resources to bury or
otherwise insulate the containers to protect
the root ball from freezing. For many years
I’ve grown dwarf cultivars of Colorado spruce,
Picea pungens, in containers. A minor disas¬
ter occurred one year when an early fall
snowstorm broke the top out of a weeping
specimen with a weak graft union. A grafted
weeping form of larch, Larix decidua , has
thrived. Cultivars of our native Rocky Moun¬
tain juniper, Juniperus scopulorum, seem to
do well, too. This past year I acquired Pinus
30 banksiana TJncle Fogey’. This is a dwarf con¬
torted form of the hardy jack pine from north¬
eastern North America so I foresee no prob¬
lems for it from winter cold.
Recommended Evergreens
On occasion, an evergreen has survived
one winter only to succumb the next. These
losses are difficult to diagnose, although Col¬
orado never seems to have a “normal” winter;
each winter seems to present its unique ver¬
sion of cold season stresses. Evergreens I
have grown in containers for a season or two,
but lost later, include a Hicks’ yew, Taxus x
media ‘Hicksii’, a dwarf Alberta spruce,
Picea glauca ‘Conica’ and a bird’s nest
spruce, P. abies ‘Nidiformis’. The spruce
should be hardy enough, so other circum¬
stances, such as the difficulty of proper win¬
ter watering, may be responsible.
Watering
Watering is a crucial factor in container
gardening success. Absolute guidelines are
impossible because of the numerous vari¬
ables. You must consider the species of your
evergreen and its particular moisture needs.
The location of the container will partly
determine the rate of evaporation of water
from the soil, and weather, of course, affects
the amount of supplemental irrigation nec¬
essary.
Seasonally, you will need to water more
frequently in the hot summer months than
during spring and fall. In winter infrequent
watering is usually the rule, but don’t forget
to water the container plants during the
warm, dry periods of a typical open winter
season in Colorado. When you water, drench
the soil in the container thoroughly, allowing
the excess water to drain away, then let the
surface soil dry out before watering again.
Once evergreens exhibit symptoms of water
stress, they are often too far gone to recover,
so become familiar with the moisture condi¬
tions in the container by digging down peri¬
odically and feeling the soil a few inches
below the surface. Generally you want to
keep the soil moist, neither soggy nor dry.
The Risky Exotics
Early in my experience with growing
evergreens in containers I optimistically tried
some exotic conifers which have marginal
records of survival through our winters. Con¬
tainer cultivation practically guaranteed
their loss. A weeping Nootka cypress,
Chamaecyparis nootkatensis ‘Pendula’, and a
beautiful blue Atlas cedar, Cedrus atlantica
‘Glauca’,were two of these.
I have tried some broad-leaved ever¬
greens in containers too. Rhododendron
‘P. J.M.’ survived the winter but suffered die-
back. Unfortunately, I cannot recommend
broad-leaved evergreens for container culti¬
vation. We Colorado gardeners have enough
trouble growing them in the open landscape!
Do you have a spot in your yard or patio
where a special container plant could provide
focus and interest? Or a situation where liv¬
ing plant material is needed to soften and
moderate hard architectural features? Con¬
tainer evergreens are useful alternatives that
will provide a refreshing environment every
day of the year. <*■
Pinyon Pine
W Pinyon nuts, one of the few edible “nuts” that can be grown in this region, are the seeds of
Pinus edulis, our native pinyon pine. They are higher in protein and carbohydrates and
lower in fat than pecans. A favorite food of several
cultures of the Southwest, the seeds are also
important to squirrels and pinyon jays.
31
Limber pine cone
Why Not Try Limber Pine ?
William G. Gambill
Despite its widespread distribution in the
Rocky Mountains, from Canada to Mexico,
limber pine, Pinus flexilis, is one of the least
known and most infrequently recognized nee¬
dle-leaved trees of Colorado. Yet, based on
the cultivated specimens seen occasionally in
parks and gardens, this tree deserves more
careful attention from professionals and the
public alike for its horticultural potential.
What does limber pine look like? It
depends on where it grows. In general, it is a
medium-sized tree 25 to 50 feet tall. Individu¬
al trees have been recorded at 125 feet where
the environment is favorable, while in harsh¬
er conditions the tree is very much dwarfed,
resembling a shrub with a rounded crown.
Growing slowly, a 200- to 300- year-old-tree
may have a trunk with a diameter of 3 feet,
although 1 to 2 foot trunks are more com¬
monly seen. An unusually large taproot
anchors these trees growing on rocky
windswept ridges, bluffs and peaks. In such
habitats the trunks tend to be short and
thick, often crooked, gnarled and misshapen.
Under cultivation, though, they tend to be
tall and moderately straight. Young trees
have smooth and grayish-white bark, while
older specimens are dark brown or blackish
and plated.
William G. Gambill, Jr., is director emeritus of
Denver Botanic Gardens, where he continues to teach
and lead botanical field trips. His botanical writing
reveals his affection toward trees of the Northern
32 Hemisphere.
Foliage and cones are the most notewor¬
thy and attractive aspects of the limber pine.
The needles, more slender than those of pon-
derosa pine, appear bluish-green. The color
comes from the white lines of stomates run¬
ning the length of its needles. Three and a
half inches long, they are borne in fascicles
(bundles) of five, and are curved slightly
inward. Thick clusters of the needles extend
back from the tips of the twigs a few inches,
their abundance giving the tree a lush, bushy
appearance.
Cones of the limber pine grow 8 to 10
inches long and are nearly cylindrical in
shape. When they are new they are green.
They become beautifully light yellow-brown
in the autumn. The cone scales are very thick,
lack prickles, and are only slightly reflexed at
the tips. Abundant exudations of white resin
occur on the tips of the cone scales, making it
prudent to handle the cones with care.
The limber pine has already shown its
potential in cultivation along the Front
Range. Like many other conifers, it must
have a fairly gravelly, well-drained soil to
thrive; it does not do well in heavy, clay soils.
The late George Kelly, dean of Colorado hor¬
ticulturists, wrote that limber pine makes a
very valuable ornamental tree. For many
years, he and others have been advocating its
more extensive use.
Why plant limber pine? It is a handsome,
native tree and is exciting because of its rari¬
ty in cultivation.
Southwestern white pine cone
Southwestern White Pine— An
Under-Used Landscape Plant
Robert Cox
Local landscape architects and horticul¬
turists may be familiar with our native lim¬
ber pine, Pinus flexilis, and aware of its great
landscape value. Less familiar is the limber
pine’s close relative, the southwestern white
pine, due to its infrequent occurrence in
remote areas of the southern Rockies.
The southwestern white pine goes by sev¬
eral other common names, including Arizona
pine, border pine, and Mexican white pine.
To add to this confusion, even its scientific
name is not agreed upon. Earlier botanists
named it Pinus strobiformis, referring to its
similarity to P strobus, the eastern white
pine. Others emphasize its close relation to
limber pine by calling it Pinus flexilis var.
reflexa, referring to its reflexed cone scales,
which the limber pine cones do not have. The
best name would appear to be P flexilis var.
reflexa, but when found locally in nurseries it
is sold under the older name, P strobiformis.
Some other differences between this tree and
the limber pine include the southwestern
tree’s generally longer needles and narrower
cones. However, where the distribution of it
and the limber pine overlap, the two may be
very difficult to distinguish.
Robert Cox is the Jefferson County extension agent
for horticulture. He is author or co-author of articles
in numerous publications, including The Green
Thumb, Colorado Green magazine, American
Nurseryman, the Journal of Plant Nutrition and
Plant Propagator.
The southwestern white pine has attrac¬
tive blue-green needles in clusters of five. Its
dense foliage gives it a softer look in the land¬
scape than Austrian, ponderosa, pinyon, and
other two- or three- needled pines.
Like most pines, it prefers well-drained
soils without salinity problems. The heavy
clays prevalent here should be well amended
with organic matter. Full sun is best, partial
shade is acceptable. Newly transplanted
trees need regular watering. Particular atten¬
tion should be given to watering young plants
during the winter, especially during months
when there is little or no snow cover. Mulches
such as wood chips or straw help to conserve
soil moisture and inhibit weeds. About a year
after planting, young trees begin growing
fast. The mature size will vary by site and
soil conditions but will be approximately 35
to 40 feet tall and 15 to 20 feet wide at the
base. After it is established, the southwestern
white pine is quite drought-tolerant and a
good candidate for xeriscapes. It can be used
as a specimen evergreen or in windbreaks.
As a five-needled “white” pine it is sus¬
ceptible to white pine blister rust and should
not be planted near currants or gooseberries,
which are alternate hosts for the rust. How¬
ever, as a five-needled pine, it is resistant to
damage from larvae of the pine tip moth,
which often damage growth tips of two- and
three-needled pines in our area.
There are a few specimens of this tree
scattered around the Denver area in yards 33
and municipal plantings. Grange Creek Park
in Thornton, at 110th and Dahlia, has several
on the east side of the parking lot. Glencoe
Park in Thornton, at 112th and Glencoe, has
examples along the fence on the west end.
Several can be found in the City of Aurora
Arboretum at Alameda and Potomac Streets.
There are a few near the visitor center of
Denver Botanic Gardens’ Chatfield Arbore¬
tum. A beautiful specimen can also be seen in
the xeriscape garden of the Colorado Springs
Water Department. Although its availability
is limited now, with only a few wholesale nur¬
series handling it, the southwestern white pine
deserves to be planted more frequently. Ask
for it — and help stimulate greater supply.
Limber pine cone and Southwestern white pine cone illustrations by Jeanne Janish, courtesy of Southwest Parks & Monument Association
Did you know these facts about evergreens'
Two upright evergreens in Colorado often referred to as red cedars or cedars are actually
junipers. Western red cedar (also called Rocky Mountain juniper) is Juniperus scopulorum;
Eastern red cedar is Juniperus virginiana. On the Western Slope, what is called a cedar is
usually Juniperus osteosperma (also known as J. utahensis). True cedars are unusual in this
region. They belong to the genus Cedrus and are hardy only in very protected sites in Colorado.
W Bristlecone pines have white specks dotting their needles, giving the branches a slightly
“sugared” appearance that is, usually, entirely normal. In fact, the presence of these resin
specks is a good way to identify this native pine.
W Bristlecone pines are also the oldest living trees on earth. Some of them have been alive for
up to 4,900 years.
« What makes the blue Colorado spruces so blue is not the color of their needles, but rather
a wax, or ‘bloom,” on the needles; it can be scraped off with a fingernail. Some pesticides may
also remove the blue color. The Colorado spruce’s natural color ranges from blue-green to sil¬
ver-blue.
«’ Douglas-fir, a beautiful conifer native to our state, is not a true fir (genus Abies) like white
fir or alpine fir. It belongs to the genus Pseudotsuga. Even more confusing, the name “Pseu-
dotsuga” means false hemlock, still another genus of conifer.
W There is a simple identification trick when you’re looking at evergreen trees: Roll a needle
between two of your fingers. Needles of Spruces will feel Square in cross-section (S-S); Fir
needles will be FI at ( F-F ); and pine needles will always be arranged in bundles of two or more.
W The beverage gin gets its characteristic flavor from the fleshy, berry-like cones of junipers.
W Due to its resonant qualities, spruce is the wood of choice for musical instruments. Gui¬
tars, organ pipes, piano sound boards and violin bellies are usually made of spruce.
W There are deciduous species of hollies with simple, untoothed foliage. It is an extremely
variable genus.
W An easy way to maintain the size of or prune many pines is to simply snap off part of the
“candles” — the new shoots that elongate in spring.
« The fruits of grape hollies, Mahonia species, are edible and make good jelly. However, the
fruits of true hollies, Ilex species, are quite poisonous and the plants should be considered as
dangerously attractive to children.
W The state trees of New Mexico and Colorado are, respectively, the pinyon pine and the Col¬
orado spruce.
The Blue Hollies: Tough New Hybrids
for Our Climate
Ken Slump
Until the introduction of the hardy “blue
hollies” (selections of the hybrid Ilex x
meserveae ) gardeners in our area had to plant
“holly substitutes,” such as Oregon grape
holly, Mahonia aquifolium — not a true
holly — or we could briefly enjoy sprigs of the
real McCoy from our local florists during the
Christmas season. However, the blue holly
cultivars have sharply pointed, dark ever¬
green foliage and the female plants bear shiny
red berries that typify true holly.
They are hybrids between the hardy
prostrate holly, I. rugosa, and English holly,
I. aquifolium. This cross has pro¬
vided numerous named introduc¬
tions that began appearing in the
mid-1960s. Among the many culti¬
vars are ‘Blue Angel’, ‘Blue Boy’,
‘Blue Girl’, ‘Blue Maid’ ‘Blue Prince’
and ‘Blue Princess’. Similar hybrids
resulting from a cross between 7.
rugosa and 7. cornuta are
‘China Boy’ and ‘China
Girl’. All of these hollies
are dioecious; that is, the
male and female flowers
occur on separate
plants. Therefore,
plants of both sexes are
necessary for production
of red berries. ‘Blue
Angel’ is a female culti-
var, and the genders of the other cultivars are
implicit in their names.
k*
y//
/&
Glenda Newton
Denver Botanic Gardens acquired its first
plants of these hollies in 1975. They vary
somewhat in ultimate size, foliage color,
growth rate, cold hardiness and flowering and
fruiting characteristics.
In the Denver area the blue hollies seem
to grow best in protected, partial¬
ly shaded locations. Even
though tolerant of full shade,
growing without some sun¬
light leads to a weak,
spreading habit. Heavy
clay soils should be
amended with
peat or other
organic matter
before planting
these humus-loving
plants. Their average growth is 3 to 6
inches per year. Descriptions claim
ultimate heights of 8 to 12 feet,
but I have not seen any plants
in our area above 5 feet tall.
Their inconspicuous white
flowers appear in mid-spring.
The fruits measure about lA
inch and ripen to bright red in late
summer, persisting into the winter
months. Late spring freezes typical to
our climate occasionally spoil a year’s fruit
production.
These relative newcomers to local land¬
scapes offer refreshing options for year-round
evergreen attractiveness.
35
Manzanitas
Andrew Pierce
With oval leaves that range from deep
forest green to bright apple, the manzanitas
are a group of evergreen shrubs that locally
deserve greater attention, both from nurs¬
eries, who must propagate them for sale, and
from homeowners. Their leathery foliage,
twiggy form and colorful bark are interesting
additions to the summer garden. In winter
they are outstanding.
From cold, often dry, boreal areas of the
Northern Hemisphere, many of them could be
used in dryland scapes to brighten their win¬
ter color and relieve the prickly aspect that
many of them have. Their smallish white,
bright pink or rose-colored, bell-shaped flow¬
ers are welcome in any springtime garden.
There are two, possibly three, species of
the genus Arctostaphylos native to Colorado.
Each has characteristics that make it a desir¬
able landscape shrub.
The well-known bearberry, or kinnikin-
ick, Arctostaphylos uva-ursi, grows through¬
out the higher forest regions of Colorado.
Ground-hugging in character and with small
oval leaves, it is an interesting ground cover
in partially shaded locations. I have seen it
growing in the sun where it receives adequate
moisture, in acid soil. Its small flower clusters
are followed by spectacular k inch scarlet fruits.
Andrew Pierce is senior horticulture advisor at Den¬
ver Botanic Gardens. He received his horticultural
training in England and now lectures and teaches.
His home garden in Evergreen has been featured
36 in several national magazine articles.
In its natural habitat these are eaten by
bears — hence the common name. You may
wish to emulate the pioneers, who used the
berries for cider and jelly.
From the Western Slope, principally on
the Uncompahgre Plateau, comes the green¬
leaved manzanita, A. patula. A larger bush,
up to 4 feet, with rich mahogany-red trunks,
in the wild it forms interlocking thickets sev¬
eral miles in extent. The fruit is creamy white
or yellow and is eaten by several kinds of
birds and animals. At Denver’s “low” altitude
it should be planted in a partly shaded loca¬
tion, in an improved, acid soil.
Intermediate in growth habit between
these two species is the pine-mat manzanita,
A. nevadensis var. coloradensis. In fact the
pine-mat may be a remnant hybrid between
them. (The Colorado subspecies seems to be
very stable and is found nowhere but on the
Uncompahgre Plateau. Some experts elevate
its rank to A. coloradensis. The nearest other
plants of A. nevadensis are in dry, cold places
in California.) Whatever the scientists decide,
it’s a colorful, low — about 2 feet tall — shrub
with red fruit and reddish bark, with sprawl¬
ing trunks that occasionally root at the nodes.
Bearberry is readily available every
spring in many nurseries around Denver. As
interesting as they are, the other manzanitas
are not reliably available, though local nurs¬
eries have propagated them sporadically. It is
a testament to their usefulness that commer¬
cial landscapers buy them up quickly when¬
ever they appear on the market.
ruui iv\ubiui
Top right, Yucca glauca, sometimes
classified as a shrub, augments its ever¬
green foliage with late spring flowers.
Above, Opuntia compressa
Left, Kinnikinick, Arctostaphylos uva-ursi
37
Below, green-leaf manzanita from the
Uncompaghre Plateau
Andrew Pierce
A Few False Cypresses
For Your Landscape
Kelly D. Grummons
Over the past five years we’ve tested sev¬
eral species and varieties of false cypress
{Chamaecyparis) at Paulino Gardens. Three
species and their cultivars have proven to be
tough enough for the Rocky Mountain region.
The real trooper is in Grandmother
Paulino’s garden. It is a weeping Nootka false
cypress, C. nootkatensis ‘Pendula’, planted 10
years ago and now graced with long, pendu¬
lous branches. Planted fully exposed to the
elements, this handsome specimen tree has
survived several 30-below-zero winters with
virtually no damage and indicates that this
variety is a sure bet for any gardener. In its
native habitat, the coast of Alaska southward
into Oregon, this species can reach nearly
100 feet in height. In Denver, though, it may
grow to only 20 to 30 feet.
The Sawara false cypress, C. pisifera,
native to Japan, is also as hardy as they come.
Provided with decent soil, this evergreen
should thrive in our area. The cultivar ‘Filif-
era Sungold’ grew from 15 inches high and
wide to 3 -'a feet high by 4 feet wide in five
years of testing, never exhibiting any winter
desiccation even in full exposure. ‘Sungold’
has pendulous branches and thin, wiry
branchlets of gold. It is a fascinating accent
plant for your garden. This year we’ll be try-
38 ing C. p. ‘Boulevard’, an upright blue form.
The other species of false cypress that
we’ve had some success with is C. obtusa
from Japan. With constant moisture (espe¬
cially during winter) and rich, well-drained
soil, the Hinoki false cypress has performed
well, but it is happiest with protection from
winter sun. It has an upright, irregular form.
At 6 to 8 inches of growth per year in Denver,
I would expect a maximum height of 12 to 15
feet. The dwarf cultivar ‘Nana Gracilis’ is less
tolerant of our dry winters and may need
extra protection.
False cypresses are not for curators of
low-water plants. I’ve seen Phomopsis blight
on stressed plants. Hollow, dry centers and
sparse tip growth often indicate winter
drought stress, so mulch the roots generously
and provide deep, rich, well-drained soils. If
you, too, are successftd with false cypresses,
there are hundreds of cultivars available. You
may become a collector.
Note: False cypresses are beautiful conifers
whose scaled branchlets arrange themselves
in flat, usually vertical fans, so the small trees
have a pleated, “arranged” appearance. They
have received a less-than-desirable reputation
in this region because most examples look
brown or “burned” during the winter. This is
almost always due to an absence of winter
watering. — L.L.
Bibliography
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QK 494.5 P66 S848.
Top-rated evergreen shrubs and how to use them in your gar¬
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Van Gelderen, D.M. 1 986. Conifers. Timber Press, Portland,
Ore. QK 494.5 C75 V35.
Welch, H. 1 966. Dwarf conifers, a complete guide. C.T.
Branford Co., Newton, Mass. SB 428 W456.
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— Solange Gignac, horticultural librarian, Denver Botanic Gardens 3 9
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Mountain, Plain
and Garden
Denver Botanic Gardens
909 York Street
Denver, CO 80206-3799
Printed on
recycled paper
Non Profit Org.
U.S. Postage
PAID '
Permit No. 205
Denver, Colorado
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Dedication: To
George Kelly
This issue of Mountain, Plain and Gar¬
den has been written with the special memo¬
ry of George Whitfield Kelly in mind. George
was a pioneer who came to Colorado not to
dig gold and silver . . . but to dig plants and
shrubs, always reminding us of the fragile
and arid environment in which we live. His
life-long work was geared toward the distinc¬
tion of a Rocky Mountain horticulture.
When George died on August 10, 1991, at
the age of 97, people mourned the passing of
a man known as “the Father of Rocky Moun¬
tain Horticulture.” George was also a founder
and the first acting director of the Denver
Botanic Gardens, the author of countless arti¬
cles and ten different books, the originator of
the Green Thumb radio show, the first editor
of the Green Thumb Magazine (now called
Mountain, Plain and Garden), a successful
nurseryman, and the first full-time horticul¬
turist with the Colorado Forestry and Horti¬
culture Association.
What is not often remembered is that
most of this occured when the average gar¬
dener is contemplating retirement.
These articles represent a tangible result
of George Kelly’s work and love. The unmea-
sureable, however, is the knowledge and
beauty that he passed on to other gardeners,
who join his dream of sustaining the jewel¬
like qualities of the Rocky Mountain West.
— George Kreiger
© 1992, Denver Botanic Gardens, Inc.
909 York Street • Denver, Colorado 80206-3799
Newell M. Grant, president
Richard H. Daley, executive director
Larry Latta, managing editor
Anna Thurston, consulting editor
A continuation of The Green Thumb • Produced by the Marketing and
Special Events Department of the Denver Botanic Gardens
Denver Botanic Gardens and Chatfield Arboretum are established and main¬
tained by Denver Botanic Gardens, Inc., for the people of the City and Coun¬
ty of Denver and for the general public in cooperation with the Denver Parks
and Recreation Department. Denver Botanic Gardens is grateful for funds
from the Scientific & Cultural Facilities District (SCFD), which enable the
Gardens to expand services and enhance the quality of programs and exhibits.
Mountain, Plain -88-
and Garden "v*
The Magazine of the Denver Botanic Gardens
\blume 49 W 1992 W Water-Wise Gardening
Contents
Dedication: To George Kelly . 2
Why the Fuss Over Water? . 3
Designing a Useful Landscape . 5
The Larger Landscape . 8
Entering the ‘Plant Zone’ . 11
Building Your Soil — Carefully . 13
Designing with Water Use in Mind .... 15
The Dry Cottage Garden . 18
Favorite Water-Wise Trees & Shrubs .22
Lawns & Water Conservation . 25
Making the Switch — A Personal
Story . 28
A Prairie for Your Thoughts . 31
How to Water a Lawn . 34
The No Front Lawn Front Lawn . 36
No Maintenance? . 37
Do You Really Need an Automatic
Irrigation System? . 39
An Irrigation System on Your Own .... 42
A NO-Water Garden? . 46
Soil — The Living Sponge . 49
Composting — Ultimate Recycling . 51
Much About Mulch . 52
Mulch . . . More Pros & Cons . 55
How the Fit Survive . 58
Resources . 60
Bibliography . 62
Cover photos, front and back, are by Charles
Mann, Santa Fe, New Mexico. Mann photographs
plants and gardens throughout the Rocky Moun¬
tain West, and his work has been published in
leading American horticultural periodicals. He is
constantly seeking new subjects for his art; he may
be reached at (505) 983-71 67.
The term XERISCAPE and the XERISCAPE logo are
trademarks of the National Xeriscape Council, Inc.
Why the Fuss Over Water 9
Anna Thurston
• Do you know how much water you
alone use every day?
If you are an average citizen of a metro¬
politan area like Denver you probably use
between 150 and 300 gallons of water a day.
That’s a pyramid of one-gallon jugs taller
than a basketball player.
• On average, how much of the water
that you use every day is applied to your
landscape? (We hope you have a landscape, if
you’re reading this magazine.)
An average of half of the water delivered
to residential homes is used to maintain
green landscapes.
• Do you know where your tap water
comes from?
If you live on the Eastern Slope, your
drinking water might travel a tortuous path
up to 200 miles long, starting somewhere on
the Western Slope of the Rocky Mountains,
piping beneath the Continental Divide, and
pumping across vast stretches of countryside.
• Do you know where water goes after it
leaves your sink, toilet or gutter? And then,
where does it go after it leaves the water
treatment plant?
Anna Thurston works as a landscape designer
and water conservation specialist. Whether
dressed as "Sarah the Snowflake" or just as her¬
self, her interest in water and the environment is
shared with schoolchildren, home owners and
industry professionals. Anna has a Bachelor of
Science degree in Landscape Horticulture Design
from Colorado State University. She has taught
landscape design at the Denver Botanic Gardens
and throughout the Front Range for over ten years.
Each one of us is a part of the greater
water cycle. The water that was in your
orange juice or milk at breakfast this morn¬
ing may next week be used as drinking water
in Nebraska. The same is true for the water
that flows down the gutter, with all the
leaves, oil and other litter and chemicals that
might happen to wash in the same direction.
The week after that, the water you used may
be in someone else’s glass in Mississippi, and
later in Europe, or China or back across the
Rocky Mountains, where it will again become
your water once more.
• What happens when there isn’t enough
water to go around? Who makes the decision
about who gets water and who doesn’t? And,
if one group of people doesn’t get water for
their needs (whether here or way out there)
do you think that will affect any other groups
of people, like us?
• What is the most important resource
that you can’t work, play or live without?
• Why bother with water conservation?
The conservation world has been howling
like the wind lately — howling that we live in
an era of dwindling resources. In Colorado
water is plentiful. But getting that water to
us, when we want it — and at a reasonable
price — has become a monumental task.
In other states and other countries, water
issues are underlying tinder for war, just
waiting to be ignited, building up the longer
we ignore the problems of population, over¬
use, pollution and our tendency to think we
can buy our way out of our water resource
problems, hoping they’ll go away.
Most of us don’t want to ignore the prob¬
lem, but we are uncertain what responsible
3
action we can take. Or, we trust that someone
else will “take care of it.” This issue of Moun¬
tain Plain and Garden is devoted to all gar¬
deners in an effort to help each of us under¬
stand, not only the why’s, but also the how’s
of water conservation in our landscapes.
The articles compiled herein are written
by knowledgeable landscapers and gardeners
in our region. They have been asked to share
with you their wisdom and ideals. What you’ll
find is a tapestry of thoughts and gardening
methods that will not only make your garden¬
ing efforts more efficient, but quite likely,
more enjoyable.
Allowing yourself greater involvement
with your landscape will also heighten your
senses. I will always remember watching as
the garlic flowers unfurled and twisted about
in the morning sunlight. They moved before
my eyes! And I will never forget the wonder I
discovered as a child, of seeds turning into
plants, that turned into flowers, that turned
into seeds again; all of this in seeds blowing
from a common dandelion, or in a crunchy
pea fresh from its pod.
We do not need to know everything about
horticulture to be good gardeners. Certainly
classes will help us, but it is ultimately one’s
attentiveness to the natural world that teach¬
es us the most. Water is a part of the natural
world, as are our lovely high plains and Rocky
Mountain environments. If we can visit our
closest surroundings and become aware of
their unique and wondrous properties, we
will be able to complement them in our own
gardens, rather than controlling and confi¬
ning these special microclimates with so
many mechanisms. This isn’t to suggest that
we all “go native.” It is instead a way of gar¬
dening that acknowledges the part of the
country in which we live. It will benefit both
ourselves and our environment, an environ¬
ment that we ultimately depend upon.
Here and there you will encounter the
word “xeriscape,” (pronounced zee-ri-scape).
This trademarked (by the National Xeriscape
Council) concept is not meant to scare anyone
away from gardening. The term itself means
4 “dry vista,” but the concept has been devel¬
oped to follow the thoughts above, of garden¬
ing harmoniously with our environment.
Xeriscape is more simply, good, water-
wise gardening theory put to practice. It is a
whole picture of the landscape in the mind’s
eye of the gardener. In the end, these prac¬
tices not only provide you with a landscape
that gets used, but also one that won’t die at
the first sign of an extended drought.
Droughts have come before, they will certain¬
ly come again.
If you have been developing your garden
for many years, you may already incorporate
water-wise methods. Newer gardeners will
find plenty to digest here. For both we hope
that the water-wise garden is not seen as lim¬
iting, but rather an enjoyable way to meet
and work with the limited resources available
to us all.
Designing a Useful Landscape
Gail Barry and Cathe Mitchell
Today, with renewed emphasis on conser¬
vation, especially of water, landscapes need to
be planned carefully. In considering your own
landscape ask yourself some of the following
questions: Do I need all the high-water-
demand turf area I presently have or could
less be used to better advantage? Are plants of
similar water need grouped together? Have I
taken measures to enrich the soil to reduce
the need for water and fertilizer and improve
the general health of the plants? Is my cur¬
rent method of watering efficient?
Renovating an existing landscape to save
water can seem an overwhelming task. One
starting point is to analyze how you use your
lawn area. There are variations in peoples’
perception of the term “use” Some obvious
uses are activities or games such as croquet.
Some people use their lawn to stretch out
upon or to bury their bare toes into. Others
regard the lawn as an area of green upon
which their eyes can rest, and don’t really
“use” it at all.
How much lawn does it take to satisfy
your requirements? Can you get by with less?
How many funny little pieces of lawn do you
have in your yard that serve no real purpose
other than to occupy time and money in
maintenance and water? What else could you
do with that space?
Gail Barry and Cathe Mitchell share a partner¬
ship in Land Mark Design, Inc. Land Mark
Design, Inc. does a wide variety of small- and
medium-scale landscape projects including resi¬
dential work and is particularly interested in
designing appropriately for our environment.
“Xeriscape” vs. “Zero-scape”
The common perception of the Xeriscape
concept seems to be of a landscape consisting
of rocks and cacti. In the Rocky Mountain
region, generations of settlers have altered
their environment to mimic that of coastal or
Midwestern cities. The attitude has been to
conquer the environment rather than to work
with it. In the natural environment, rocks
and cacti are not as prominent as city
dwellers often visualize. Expansive areas of
stone mulch and sparse, uncoordinated plant¬
ings constitute “zero-scape.” Yet properly
planned, these elements can be the basis of a
very attractive landscape.
In reality, our native landscapes contain
an interesting and broad variety of grasses,
shrubs, annuals and perennials. Naturally
occurring trees are usually found in creek
beds. In many rural parts of Colorado, or in
the larger landscape, it may be more appro¬
priate to encourage or renovate the natural
landscape. For the small urban landscape,
however, naturalizing might be considered a
form of “zero-scape” because these sites don’t
blend with the manicured and water-thirsty
lawns around them.
Xeriscape is not limited to rocks and
cacti, or to naturalization of the landscape. A
true xeriscape is one that provides for its own¬
ers needs, both physically and visually. The
only difference is in how plants are selected,
arranged and irrigated so as to conserve
water.
There are few limits to xeric landscaping
other than those imposed by our climate.
Your yard may reflect the character and style
of many cultures or parts of the world and
still be an efficient landscape. The design,
however, must be carefully considered in
order to save water and reduce maintenance.
Not only will a well-designed landscape
reduce water and maintenance costs (up to 60
percent), it can also add beauty to your home,
enhancing its value up to 15 percent. If the
landscape is planned with your needs in mind
it will be used and appreciated.
Things to consider:
Before deciding on a landscape style con¬
sider what is really important to you. How do
you, or would you, like to use your outdoor
spaces?
Also, consider the practical aspects of
your landscape. Where are the paths you or
your pets tend to follow in your yard? Are you
dying to have a vegetable garden or berry
patch? Are your plants overgrown? Is your
patio or deck large enough?
Other things may be on your wish list.
You may want to consider outdoor lighting, a
sculptural element, a water feature, a bird
feeding area or gazebo. Note unsightly views
both from your yard, and into your yard, as
well as privacy and security.
Check magazines for pictures of land¬
scapes you like. Look around your neighbor¬
hood for places you find appealing. Keep in
mind that many of these ideas may not be
directly transferable to your property. They
are, however, places to begin your planning
process.
Short- and long-term considerations:
Monetary considerations are always im¬
portant. One reason many landscapes include
large expanses of lawn is because it’s an easy
way to cover large areas with an “instant
landscape” for a low cost per square-foot. How¬
ever, the long-term costs of water and main¬
tenance make it a more expensive solution.
Your installation can also be phased in
over time to spread out the initial costs of a
landscape that includes more plantings. Usu¬
ally it is less expensive to install paving, deck-
6 ing and other ‘hard-scape” items at one time.
What have you got?
What does your property have to offer?
Do you have a flat space or steep hillsides?
Lots of existing plants or just a few? A large
space or small? Interesting views or eyesores?
Any of these extremes can be dealt with
in your future landscape. Problem areas may
become potential amenities. For example, a
steep hillside, covered with grass, difficult to
water and mow, can be terraced and planted
with water-conserving ground covers, peren¬
nials and shrubs. Another option is to start a
rock garden in this same area. Both ideas can
enhance your property and provide interest in
all seasons.
Developing the design:
After you have considered what you have
and what you want, it’s time to develop a
plan. Your site needs to be measured and
drawn to scale on a sheet of paper (1”
equalling 8' or 4' is a convenient scale). Make
sure you note the scale on your plan. Mark
which way is north and where the utilities
are. This is your base map of existing condi¬
tions (see diagram A).
Use tracing paper to cover and draw upon
your base map. Using colored pencils outline
and make notes about the areas you are con¬
cerned about. Use arrows to show the direc¬
tion of the prevailing wind and/or harsh sun.
Note where your areas of heavy shade occur
and/or where the soil is constantly wet or dry.
Show unsightly areas you wish to improve, or
pleasing areas that you’d like to enhance. If
you have a problem with noise or neighbors’
windows looking into your bedroom, get it
down on paper. These drawings make up
your site analysis.
From this information you can proceed to
a concept design on another sheet of tracing
paper. Here, you will want to make “bubbles”
showing areas for improvement or develop¬
ment (see diagram B). Think of the ‘"bubbles”
as rooms in a house defining areas that you
will use. Arrows can show where you want
connections between the spaces and hard
lines can indicate walls, screens or barriers.
On yet another sheet of paper, final drawings
can be made detailing the remainder of the
design (see diagram C).
Water-Conserving Considerations:
Reducing turf areas, adding patio or deck
space, arranging plants with similar water
needs together, separating turf from other
plantings, and using retaining walls or other
terracing devices on slopes are all water-wise
ideas to consider. If you want special, exotic
or high water-using plants in your landscape
group them in areas where you will appreci¬
ate them (i.e.: as focal points near your patio
or entry) instead of spreading them indiscrim¬
inately throughout the site. This also will help
reduce the need for maintenance later on.
Need Help?
Landscape architects and designers ser¬
vices range in price from approximately $35
to $100 per hour depending on how experi¬
enced they are, how much education they’ve
had and the size of their firm. Sometimes you
can get the advice you need from an hour-long
consultation at your property. You may also
have a designer come and analyze what you
need and give you a proposal for a complete
design. Some firms provide both design and
construction. You may wish to have several
bids on the design and then select the best
person for your needs. The important thing is
to ask for what you want and find out exactly
what you are buying.
7
»
The Larger Landscape
Don Godi
Large landscapes provide an exciting
opportunity to be water-wise. There are sev¬
eral reasons: 1) The price of water can make
even the most indulgent landowner think
about green money rather than acres of green
sod. Many larger landscapes (over one acre in
size) are owned or managed by corporations
or associations, which are more profit- and
expense-oriented. 2) “Tradition” is “out” and
the environment is “in” ... well, if not yet the
norm, at least to the point of being noticeable.
3) Large landscapes have a difference of scale
and can be looked at and enjoyed from a dis¬
tance rather than walked through and scruti¬
nized. Consequently, they may not require
the precision of finish that may be expected of
smaller landscapes, which tend to have a
more intimate feel and a high water-use and
high-maintenance refinement.
Designing water- wise landscapes is more
demanding than traditional landscapes. It
requires a broader understanding of the ele¬
ments of design and the design’s relationship
to the natural sciences in order to complete a
comprehensive, high quality, water-wise
landscape. This prerequisite and the relative
newness of the concept of applied water- wise
design tend to limit the quantity and quality
of existing water- wise models.
What should be considered when design¬
ing a larger water-wise landscape? First, eval¬
uate whether or not a green-lawn, finished
landscape is required for the entire site. Is
Don Godi is principal of Donald H. Godi &
Associates, Inc., which emphasizes water-wise
landscape design. He also has extensive educa-
8 tion and experience in horticulture.
there a natural area worth protecting? Are
there remote areas not receiving foot traffic or
not requiring a high-impact design? Are there
built-in high-maintenance areas on the site
such as parking lot medians; steep, south¬
facing slopes; poor drainage or poor soil? Or
perhaps most important, what is the con¬
struction budget and how can it be reduced
through the application of water- wise land¬
scape design techniques?
Estimated construction costs for develop¬
ing one acre of landscape:
• Seeding with soil preparation:
$ .13 per square foot, $ 5,663/acre
• Sodding with soil preparation:
$ .25 per square foot, $ 10,890/acre
• Irrigation by automatic, underground system:
$ .40 per square foot, $17, 424/acre
• Mulching, including underlying landscape
fabric:
$ .55 per square foot, $23, 958/acre
• Juniper, ground cover (five feet apart, on
center) with landscape fabric and mulch:
$1.50 per square foot, $65, 340/acre
And last, but not least, the cost of mainte¬
nance:
• “Traditional” full service maintenance for a
normal seven month period per year:
$ .02 per square foot per month for turf
and planting (x 7 months) = $ 6,098/acre
For a large site even the minimum devel¬
opment of traditional turf and its inherent
maintenance is going to be expensive.
Other considerations may encourage the
use of water-wise concepts. The plan should
include scheduling of the design and construe-
The larger landscape: perimeter of naturalized grasses and
flowering perennials
High-water planting zone near building entry where visitors
and employees enjoy the landscape first-hand; also the small¬
est but most maintenance-intensive zone of the entire landscape
mm
fillip
Intermediate
watering zone
showing plant¬
ings of buffalo
grass among
ponderosa pine
9
tion, supplying water to all landscape areas
that need it and determining the availability
of compatible low-water-demand plants.
Scheduling planting is important in
establishing the landscape. Avoid late fall
planting to prevent possible winter damage to
non-established plants. Install major plants,
such as trees and shrubs, first to achieve a
visual impact; then supplement with other
planned planting in the future. Seed turf
grass at the proper season to match its cool or
warm season character of growth.
Design phasing is the only way to effec¬
tively deal with limited construction budgets.
In such instances it is essential to design
functional aspects that are closely attuned to
construction practices. Phased design places a
priority on infrastructure such as grading,
soil preparation, irrigation systems, turf,
hard-scapes (walls, walks, water features,
etc.) and large plant installation. These items
need to be completed first so that future work
does not disrupt previously completed areas.
The availability of water is an essential
element of the design analysis and conceptual
planning. It must be evaluated in the very
early stages of the design. Municipalities, such
as Castle Rock, Colorado, have begun limiting
“traditional” landscape development. They
require every project supported by city funds
to be designed with water-wise concepts to
limit total water use in a site. Higher applica¬
tions of water to some areas of a site must be
matched with lower applications elsewhere to
achieve an average application rate.
Plants suitable for use in the water-wise
landscape may not be readily available. Cer¬
tain natives, especially, take time to cultivate
and make available to the public. Nursery¬
men won’t grow anything they can’t readily
sell at a profit. With advance planning and
communication, ground covers and native
plants, among others, may become available
for phased designs.
Although it may seem complicated, alter¬
natives exist for developing larger water-wise
landscapes. Design is a subjective process
that may produce a nearly infinite number of
1 0 high quality results for any one site. With
that thought in mind, consider the following
alternatives for design:
1. Develop a concept which divides the
landscape into zones of low-water and higher-
water irrigation and plantings that are com¬
patible with site use and the desired visual
character. For instance, areas closer to build¬
ings may be designed with turf for higher
traffic and water use, floral displays and tra¬
ditional landscaping. Service areas, natural
areas and larger remote areas can balance
the site.
Think of the landscape as a golf course
with the “green” being the building, the “fringe”
being the transition zone, the “fairway” being
the water-wise developed area, and the “rough”
being an undisturbed or rehabilitated natural
area that uses little water.
2. Work within the natural contours of
the site so disturbance and overlot grading
are minimized. The powerful desire to over¬
whelm nature can no longer be tolerated,
even in urbanized locations. Less disturbance
means less costly development and rehabilita¬
tion. Indigenous or adaptable exotic plants
can be added to mountain, foothill or plains
landscapes to renovate them.
3. Use a design that specifies low mainte¬
nance as a major element of the design. Build
in low maintenance with a combination of
site, landscape and irrigation system design
that works to limit water use, while providing
for the green look that you desire.
These are the landscapes that will not
require major renovation in the future and
are not a financial drain on their owners or
managers. They also are the landscapes that
will become classics and will mature into
beautiful examples of water-wise design,
installation and maintenance.
Entering the ‘Plant Zone’
Anna Thurston
Even though choosing the right plants is
one of the most important — and easily the most
obvious — decisions in designing a successful
water-wise landscape you should examine
other aspects during your planning phase.
First, you should consider “zoning,” or
positioning together plants which have simi¬
lar needs. This will not only save a great deal
of water in the years to come, but will reduce
long-term maintenance as well.
Take a look at nature’s own examples. In
mountainous regions you can see the land¬
scape segregated into zones, or microclimates,
related to exposure to the sun. Firs and spruces
grow on northern slopes. Aspens grow among
them, not interspersed, but in groves, usually
along drainage ways where the soil is loose
and nearly always wet. This is a zone of shade
where snow may not melt all winter long.
Along a river you will find water-loving
shrubs such as river birches, alders, dogwoods
and willows, and riparian plants such as cat¬
tails, rushes and sedges. Even though this is
a wet zone, note that the river is always mov¬
ing. Therefore, the water is highly oxygenated.
On either side of the river bed may be flat
bluffs that support grasses and low-growing
shrubs. If these are in the sun, this microcli¬
mate may resemble an open, grassy prairie.
In the shade, or where snowmelt is consistent,
the shrubs will predominate.
Slopes opposite the northern exposure
may have easterly, westerly or southerly
faces, depending on geological movement and
erosion in the past. Each exposure and its
associated drainage may host entirely differ¬
ent plant populations.
You can emulate these natural divisions
in your landscape by zoning it. Having given
due consideration to how you will be using
the different parts of your landscape, decide
how much of it you will devote to high, moder¬
ate and low water zones.
If you consolidate the high water zones,
such as lawns and perennial plantings, into
areas that will be seen and used often, then
devote the remainder of your landscape to
lower water zones, you will realize significant
savings in water.
Maintenance needs, too, should be zoned
before you choose your plants. It is especially
important to separate lawn areas from plant¬
ings of trees, shrubs, perennials or annuals.
Unless your lawn will consist of native turf-
grasses, such as buffalo grass or blue grama,
and will be allowed to go dormant during
summer’s heat, it must be considered a high
water zone. Trees or shrubs planted within
turf zones are not only subjected to over¬
watering and “lawn-mower-itis,” but these
islands amid lawn are difficult to irrigate
efficiently and make it harder to maintain
(mow) your turf.
Only after you have established your
water zones should you move on to choosing
the plants for each zone.
There is some debate in the industry
about how much water certain plants need
and into which zone they should fit. Numer¬
ous lists have been compiled, but the varia¬
tion among landscape sites suggests we
should use these lists only as general guides.
Spend some time learning about the
plants you want to use. Talk to local nursery 1 1
salespeople. Most veteran nursery staff mem¬
bers will have grown the plants they sell.
Look around your own neighborhood.
Note where and how each plant is growing. Is
it in full sun? Partial shade? Is it protected
from drying winter winds? How long has it
been growing in its particular location? Does
it appear to be healthy?
Your county’s Colorado State University
extension horticulturist and the staff mem¬
bers of the Denver Botanic Gardens are other
good sources of information. There are also
numerous books about plants for this region.
Most useful are ones by local authors about
indigenous plants or non-natives that are well
suited to our soils and climate. Books about
wild plants of the region, though very valu¬
able, will mention many plants not yet avail¬
able in our nuseries. Your requests for these
plants, however, may encourage nursery peo¬
ple to stock them.
1 2 Above, cottonwoods near Chatfield Arboretum growing near a stream
Above, although more maintenance-intensive, this parking
strip is pleasingly designed to provide year-round interest and
save water.
Building Your Soil— Carefully
Tony Koski
Most Colorado soils are notorious for
making home gardening and lawn care diffi-
Icult. It seems that few gardeners experience
the joy of inheriting a “good” soil here. We
have to work at producing that ideal garden
soil, one with about five percent organic mat¬
ter and an equal distribution of large air
pores — to supply oxygen to roots and to pro¬
mote drainage — and smaller open pores — to
hold precious moisture.
Most Colorado soils are high in clay and
I low in organic matter. We must irrigate more
frequently than we would like, especially if
we are growing less drought-resistant plants.
What can be done to these typical Colorado
soils to increase the availability of water to
our plants and reduce the frequency of irriga¬
tion? One solution is to add organic matter.
Choosing an Organic Source
Before buying organic material you should
determine what you want to accomplish with
your soil.
If you have a heavy clay that drains poor¬
ly, is like cement when it dries and doesn’t
seem to encourage healthy roots, then it is
best to add an organic material that is coarse
I or fibrous and not highly decomposed. Try
partially composted leaves and grass clippings,
pine needles, composted and aged manure
Tony Koski is an assistant professor in the horti¬
culture department at Colorado State University
and the CSU extension turfgrass specialist. His
research investigates methods for more efficient
irrigation of turf and the evaluation of turfgrasses
for use in the Rocky Mountain region.
or — best of all — nitrolized aspen wood. When
these materials are decomposed by soil mi¬
crobes, “glues” (actually sugars) are produced
that help to stick small soil particles together
into larger aggregates, creating the friable,
crumbly soil structure in which plants thrive.
If you are dealing with sandy soil, organic
matter that is finely divided or well-decomposed
is preferred. The finer particles create smaller
pore spaces which retain more water for your
plants. Some suggestions are well composted
plant residues, well composted manures and
processed sewage sludge.
Many organic materials work equally well
in clay or sandy soils; they have a good mix of
fine and large particles. Composted plants —
including bark, leaves, grass chppings and
food wastes — well-composted animal manures
and processed sludge are all effective amend¬
ments for a variety of soil types.
How Much Do I Use?
At first, a general rule of thumb in the
Rocky Mountain region is to spread about
three cubic yards of material over each 1,000
square feet of soil surface (that’s about 2"
deep), then incorporate it to a depth of about
6". This can be done every year in a vegetable
garden or other areas that can be cultivated
often.
On established lawns, a light topdressing
(V 2" - 3/4"), once or twice a year, is beneficial,
especially if you apply it after core aeration,
using a well-composted material. Avoid top¬
dressing with sphagnum moss or peat; they
can repel water and cause irrigation problems. 1 3
Other Benefits of Organics
Besides their effect on soil structure,
organic materials provide other benefits to
your plants. Many provide substantial levels
of micronutrients, such as iron, manganese
and copper. Organic matter also protects
these micronutrients from being tied up by
other chemicals in high-pH soils. Additional¬
ly, adding organic matter can lower the pH of
soil, though it will take many years.
Finally, the use of organics can expand
the number of beneficial microorganisms in
your soil. Scientists have found that the use of
composted plant and animal by-products
results in significant reduction of disease
problems for garden plants and lawn grasses.
For example, hardwood and pine bark
composts, municipal sludge compost and well-
composted dairy manure, as either soil
amendments or mulches, can reduce or elimi¬
nate problems with Rhizoctonia and Pythium
diseases. And using a feather/bone/ grain
meal fertilizer; a dehydrated turkey waste
product; or a dehydrated poultry waste fertil¬
izer, may reduce the severity of necrotic ring
spot disease in Kentucky bluegrass lawns, a
major disease problem in Colorado.
But Be Careful!
Just because a product is labelled as an
“organic soil amendment” does not mean that
it is a good-quality soil amendment.
What should you look for? One concern is
weed seed and pathogen content. Long-term
composting will kill harmful organisms and
increase populations of beneficial organisms.
Weed seeds are often a problem in manure
products, especially if they are not aged or
fully composted.
Another dangerous element of some
organics is salt. Improperly composted
manures are often high in soluble salts; they
can damage sensitive plants. Some peat,
especially that mined in Colorado, also con¬
tains high levels of salts. The salt level of
high-quality products will be on their labels.
This level should be less than one mmho (the
14 practical unit of conductance equal to the reci¬
procal of the ohm; one mmho = Viooo ohm), but
one to five mmhos is acceptable if you incor¬
porate it into the soil thoroughly and seldom
use it.
Also, mining fens for peat is destroying
habitats. Informed gardeners should select
other materials for amendments to soil. Some
sewage sludge composts contain heavy metals
— cadmium or lead. While they are rarely
harmful to plants, they may build up in soils
where vegetables are grown, presenting a
hazard to humans. Municipal sewage sludge
should have less than 500 parts per million of
cadmium.
Finally, make sure that you are buying
organic matter. Some products may contain
only 10 percent, the rest being clay, silt or
“topsoil.”
So read the label. Be suspicious of prod¬
ucts priced much lower than their competi¬
tors. Good quality costs more — you get what
you pay for.
Designing With Water Use In Mind
Jim Knopf
When developing a truly water-efficient
design, it is very useful to calculate the total
amount of water that each zone in the design
is likely to need in a typical season. The
accompanying worksheet offers a convenient
way to do this.
Estimating water bills, however, is some¬
what more difficult, because cities use many
different methods for calculating water use,
and because water rates change frequently.
The following three plans, created for the
same property, illustrate how significantly
water use, and resulting water bills, are
affected by different designs. A hypothetical
water rate has been applied to illustrate the
use of the worksheet. Construction costs in
this study were based on estimates provided
by two landscape contractors who were asked
to review the designs and prepare bids.
Example #1: Water-Wise Foothills Style
Design
This design would look similar to the
local foothills landscape. Maintenance would
be very easy; the small watered lawn would
require only about five minutes to mow, and
the rest of the yard would not require regular
weekly maintenance. Because the only areas
that require regular watering are small, the
need for an expensive automatic sprinkler
system is eliminated. Adequate water can be
supplied by two settings of a manual hose-
end sprinkler, plus a simple do-it-yourself
Jim Knopf is a Boulder landscape designer. This
article is adapted from his book, The Xeriscape
Flower Gardener — a Water-Wise Guide for the
Rocky Mountain Region, Johnson Publishing Co.,
Boulder, Colorado.
drip system that hooks into the end of the
hose that is left in place in the garden.
Construction of the design would be rela¬
tively inexpensive because much of the site is
seeded, rather than sodded. Many of the
shrubs and flowers can also be installed in
small sizes.
What it costs and what it saves:
Original installation cost: $.93/sq. foot
Water use (20-week season) 18,168 gallons
Water Cost (20-week season)
Boulder $35.
Lafayette (minimum charge) $133.
Pine Brook Hills $400.
= iwi^At ed nrm>
Example #2: Suburban Style Design
This water-wise design looks like a typi¬
cal manicured and clipped suburban subdivi¬
sion landscape. It illustrates that the xeri-
scape approach to design provides the possi¬
bility of creating almost any appearance that
might be desired. Maintenance would be
somewhat more than Example #1, but would
be considerably less than for Example #3,
because the buffalo/blue grama grass lawn
and other areas require far less regular main¬
tenance than Kentucky bluegrass.
What it costs and what it saves:
Original installation cost: $1.09/sq. foot
Water use (20-week season) 19,316 gallons
Water Cost (20-week season)
Boulder $36.
Lafayette (minimum charge) $133.
Pine Brook Hills $425.
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Example #3: Hydroscape Style Design
This design is dominated by watered,
manicured lawn. The large lawn would
require several hours of mowing and trim¬
ming, at least once per week, for up to five
months. Missing a mowing for even a few
days, would be immediately apparent. The
design would require an expensive and exten¬
sive automatic irrigation system because of
the complexity and extent of the areas requir¬
ing water up to three times a week.
What it costs and what it saves:
Original installation cost: $1.14/sq. foot
Water use (20-week season) 137,016 gallons
Water Cost (20-week season)
Boulder $248.
Lafayette (minimum charge) $998.
Pine Brook Hills $3,014.
16
Threeleaf sumac
Worksheet for Estimating Landscape Water Use
1. High Watering Zones (18-20 gallons/sq. foot/season)
Lawn (Kentucky bluegrass)
sq. feet
Shrubs
sq. feet
Ground covers
sq. feet
Flowers
sq. feet
Other
sq. feet
TOTAL SQ. FT. for High Watering Zone
sq. feet x
1 8 gallons/sq. ft.
TOTAL 20-week water use for High Watering Zones
gallons
2. Moderate Watering Zones (10+/- gallons/sq. foot/season)
Lawn (Turf-type tall fescue)
sq. feet
Shrubs
sq. feet
Ground covers
sq. feet
Flowers
sq. feet
Other
sq. feet
TOTAL SQ. FT. for Moderate Watering Zones
sq. feet x
10 gallons/sq. ft.
TOTAL 20-week water use for Moderate Watering Zones
gallons
3. Low Watering Zones (0 to 3 gallons/sq. foot/season)
Lawn (buffalo/blue grama grass)
sq. feet
Shrubs
sq. feet
Ground covers
sq. feet
Flowers
sq. feet
Other
sq. feet
TOTAL SQ. FT. for Low Watering Zones
sq. feet x
3 gallons/sq. ft.
TOTAL 20-week water use for Low Watering Zones
gallons
TOTAL 20- week Landscape Water Use (1 +2+3)
gallons
The Dry Cottage Garden
Lise Mahnke
You’ve been drooling over those English
gardening books again, wondering how you’ll
ever pull it off. You know it takes time, money,
ample space and precious resources to garden
like that. Short of a full-time professional gar¬
dener and a mammoth humidifier, odds are
against the grand border gardens of England
surviving Colorado’s cold, dry winters and
sun-baked soils. So why not consider combin¬
ing the root of the border garden — the cottage
garden — with our unique environment? You
could develop a thoroughly modem, old-style
English garden.
Cottage gardens had their humble begin¬
nings centuries ago around the lower-class
cottages of rural England. Out of necessity, to
supplement their diet, people began growing
vegetables, herbs and a few flowers on the
small patches of land adjacent to their cot¬
tages. Through the exchange of seeds and
cuttings among friends and neighbors these
gardens grew in variety and beauty. Later,
around the turn of the twentieth century, cot¬
tage gardens became very fashionable among
the more affluent landholders who uprooted
great expanses of formal gardens to install
the trendy new style.
The element which defines a classic cot¬
tage garden is a small site, which may appear
quite unruly — in a natural sort of way. The
lack of space has driven the gardeners to use
Lise Mahnke is a "refugee" from the interior
design and architecture field. An advanced mas¬
ter gardener, she now runs her own garden
design and maintenance business, Earth Mamas,
which emphasizes water-wise and ecological
18 gardening techniques.
every inch of what is available as efficiently
as possible, spending more effort coordinating
bloom times than using any predefined for¬
mula. The plant combinations that result are
personal experiments in a constantly chang¬
ing palette of color and texture. Plants that
have become classics of the English cottage
style are inexpensive, easy to grow and prop¬
agate, or are useful as food or medicine. They
satisfied the desire for the beauty of blossoms
amidst the blackened cities of industrial Eng¬
land.
What, you ask, does this have to do with
your garden, baking in our infamous sun,
with little rainfall or humidity to nurture
those English darlings?
The essence of a cottage garden is the
expression of your likes, needs and ingenuity.
It is also a product of the opportunities and
limitations unique to your site, resources and
time. Often the most limiting elements can
provide the best potential for creative solu¬
tions to a design problem.
Colorado offers opportunity galore for the
modem gardener seeking to recall the gar¬
dens of our pasts. Because of our sparse mois¬
ture we have few diseases and pests. Our
determination to water efficiently will intro¬
duce us to new plants from around the world.
Eventually we will develop a new style of our
own, rich because of the anomalies of our
location.
Take time to evaluate your specific site,
needs, and preferences, and ponder the fol¬
lowing:
Consider the source. The more closely a
plant’s natural needs match your planting sit-
uation the happier the plant will be. You
won’t have to make heroic efforts to keep that
plant in its prime. Use annuals that self-seed,
such as California poppy ( Eschscholzia cali-
fornica). Don’t put a certified low- water plant,
such as ice plant ( Delosperma nubigenum ) or
paperflower ( Psilostrophe tagetina), in your
best soil with frequent watering. If your soil is
clay, find plants that thrive in clay, such as
wild four-o’clock ( Mirabilis multiflora) or the
decorative grass, sideoats grama ( Bouteloua
curtipendula).
Dry shade presents a challenge to the
water-wise gardener; most shade plants love
moisture. Experiment with plants that grow
in dry semi-shade. For example periwinkle
(Vinca minor), similar to the classic cottage
plant, Vinca major, tolerates dry shade. If the
area can support no other plant, try goutweed
(Aegopodium podagraria ‘Variegatum’) or
sweet woodruff ( Galium odoratum). Both
plants can be invasive if they receive extra
water. It is important to remember, though,
that any plant will need extra water to
become established after being planted. This
establishment period can last any where from
one to three years depending upon the initial
size and health of the plant.
On steep slopes utilize plants with aggres¬
sive root systems to prevent erosion, such as
pussytoes (Antennaria spp.), snow-in-summer
( Cerastium tomentosum) and fleece flower
(Polygonum cuspidatum ‘Compaction’) —
watch this one — it can take over your yard!
For best results match the plant to the
site: reversing this logic leads to the next
point.
Every task takes longer than it should.
Underestimate the time you have available to
garden. A traditional perennial garden can
require much maintenance — deadheading,
, dividing, fertilizing and other nurturing
tasks. Consider plants that are copious
bloomers without the need to deadhead, such
as chocolate flower (Berlandiera lyrata), or
specimens that have interesting seed pods
after they finish blooming, such as butterfly
' weed (Asclepias tuberosa). Choose plants that
bloom for extended periods of time, such as
poppy mallow (Callirhoe involucrata). Leave
plants in their natural form: Shearing and
pruning a plant that is too big for its allotted
space takes a lot of time, and may expose the
plant to disease and insects.
Plan ahead for the whole year. Remem¬
ber how awful the sand and dirty snow looks
come February? You can plan to have texture,
color and interest all year. Choose an archi¬
tectural feature — a fence, walkway or sculp¬
ture — that provides interest in winter. Include
deciduous woody plants that have colored or
textured bark or evergreen foliage plants.
Warminster broom (Cytisus x praecox) has an
interesting evergreen spiky form that com¬
bines well with ornamental grasses. Blue
mist spirea (Caryopteris x clandonensis) with
it’s frothy seedheads looks good against an
evergreen background of Oregon grape holly
(Mahonia aquifolium) or against other ever¬
greens.
In the warm season a water feature can
actually save water, compared to an equal
area of lawn, while providing a “steaming” or
frozen focal point in winter. You can even
have flowers blooming in late winter from
plants such as Christmas rose, (Helleborus
niger) or wooly veronica, (Veronica pectinata).
Or consider selecting a plant as a focal point
that has four-season appeal. Serviceberry
(Amelanchier alnifolia) has white, fragrant
flowers in the spring which develop into blue
fruit for summer. Come fall, the small tree
bursts into flame-red, exposing it’s berries
against the grey bark and attracting birds for
a winter feast.
Plan before you start. Have a general
theme based on color, texture, favorite flow¬
ers, edible landscaping or any other idea that
will give you a starting point in your design.
Try not to labor over this plan; instead, use it
as the beginning.
Experiment. Combine odd textures like
the yuccas with creeping baby’s breath (Gyp-
sophila repens) or red hot poker (Kniphofia
uvaria) with the detailed foliage and
chartreuse blooms of lady’s mantle (Alchemil-
la mollis). Verbascum undulatum, a biennial
bearing a faint resemblance to saguaro cac- 1 9
Right, this shaded garden designed
by Alan Rolinger includes hostas
under the weeping birch ( Betula pen-
dula ), purple carpet bugler (Ajuga
reptans), and coral bells ( Heuchera
sanguined ) in bloom.
Below, border jewel ( Polygonum
affine ) and wooly thyme (Thymus
pseudolanuginosus) serve as an ero¬
sion controlling ground cover that also
smells good when walked upon.
Austrian pine ( Pinus nigra) makes for
a stately guide along the walk to the
front entry.
Anno Thurston
tus, provides a candelabrum quality and
blooms yellow in late summer. You can also
make use of variegated, silver and colored
foliage, with finely cut patterns against bold,
solid backgrounds. Mix vegetables and other
edibles with decoratives. Try an English atti¬
tude. In a cottage garden nothing is improper.
After all of your adjustments and your
horticultural experiments, you may want to
include some of the old cottage favorites.
Plants that require less water
Bulbs:
Daffodils, Narcissus spp.
Tulips, Tulipa spp. and cvs.
Ornamental onion, Allium spp.
Windflower, Anemone spp.
Sweet pea, Lathrys latifolius
Hollyhock, Alcea rosea
Bearded iris, Iris x germanica
Cottage pink, Dianthus plumarius
Cranesbill, Geranium spp.
Borage, Borago officinalis
Michaelmas daisy, Aster novae-angliae
Lavender, Lavandula angustifolia
Plants which make great substitutes for
original cottage plants
Foxglove, Digitalis lanata
Evening primrose, Oenothera caespitosa
Lupine, Lupinus argenteus
Daylily, Hemerocallis cvs.
Bluebell, Campanula rotundifolia
Cornflower, Centaurea montana
Wild rose, Rosa woodsii
Clematis, Clematis orientals
Natives or well adapted exotics that
belong in the dry cottage garden
Blue flax, Linum perenne subsp. lewisii
Perennial sage, Artemisia spp.
Oriental poppy, Papaver orientale
Beebalm, Monarda fistulosa
Turtle's head, Physostegia virginiana
Blanket flower, Gaillardia artistata
Prairie coneflower, Ratibida columnifera
Russian sage, Perovskia atriplicifolia
Purple coneflower, Echinacea purpurea
Prairie zinnia, Zinnia grandiflora
Spiderwort, Tradescantia occidentals
California fuchsia, Zauschneria californica
Gayfeather, Liatris punctata
Annuals that require little water
Cosmos, Cosmos cvs.
Nasturtium, Tropaeolum majus
California poppy, Eschscholzia californica
Strawflower, Helichrysum bracteatum
Flowering tobacco, Nicotiana alata
Rock rose, Portulaca grandiflora
Statice, Limonium spp. and cvs.
Spider flower, Cleome hasslerana
Blackfoot Daisy, Melampodium leucanthum
Love-in-a-mist, Nigella damascena
Fruits, grains, vegetables and herbs that do
not need as much water as a bluegrass
lawn include
Apple, Malus sylvestris
Sour cherry, Prunus cerasus
Wild strawberry, Fragaria vesca
Amaranth, Amaranthus spp.
Dry beans, Phaseolus spp.
Sunflower, Helianthus spp.
Cucumber, Cucumis sativus
Muskmelon, Cucumis melo
Okra, Abelmoschus esculentus
Squash, Curcurbita cvs.
Tomato, Lycopersicon cvs.
Watermelon, Citrullus cvs.
Dill, Anethum graveolens
Onion, Allium spp.
Oregano, Origanum vulgare
Sorrel, Rumex spp.
Basil, Ocimum spp.
Parsley, Petroselinum crispum
Sage, Salvia spp.
Favorite Water-Wise Trees & Shrubs
Larry E. Watson
Shade Trees
Shade trees are the backbone of a land¬
scape, and should come first when you think
of any new planting. Think about shade trees
as those plants in the landscape that you
walk under like an outdoor ceiling. They will
take the longest time to develop and will usu¬
ally consume a large part of your landscape
budget. When properly selected and placed,
the value of these trees will increase year
after year. If you make a mistake, it will cost
a lot more to have them moved or removed
than it does to purchase them in the first
place. Extra dollars spent on the right tree
initially will be rewarded years later.
Selecting trees for a water-wise landscape
presents a challenge in our Rocky Mountain
environment. Drive outside of urban areas
and you will observe that the High Plains
landscapes of lower elevations do not support
many tree species. Basically, the only places
we see trees growing are in areas where there
is extra water: water courses, ponds and
arroyos. This should give some direction to
the kinds of trees you will want to select, and
what you will have to do to make them pros¬
per in your landscape.
Remember, nearly all newly placed
plants must receive additional water in order
to become established, which takes three to
four years. When you attempt to create a
landscape with little additional water, consid¬
er these four trees.
Larry Watson is a native to the Denver area who
has been working in the nursery industry for the
last thirty years. He has his own horticultural ser-
22 vices company, Plants for Today and Tomorrow.
Bur oaks ( Quercus macrocarpa ) are native
to North America. However they do not occur
naturally as far west as Colorado. The bur
oak is a stately tree growing 80 to 100 feet. It
is often fisted as being slow-growing but this
is not always a detriment.
The tree exhibits a deeply furrowed bark
and very corky young branches. It is tolerant
of many different soil conditions and of urban
atmospheres. Its large leaves are dark green
in summer and turn yellow or yellow-brown
in the fall.
English oaks ( Quercus robur) were intro¬
duced to the United States in the late 1700s.
The first of this species were probably brought
to Colorado in 1890. The English oak is a
round-headed tree growing 60 to 80 feet. Its
leaves are small (2" to 6" long and 1" to 3" wide),
dark green and frequently persisting into the
winter. When falls are long, the leaves will
turn yellow, but usually they freeze and turn
brown. Some reference books list the foliage
as being susceptible to powdery mildew,
rarely a problem in our dry climate.
There are named selections of this species.
The most common is the fastigiate or very
narrow form. This form will eventually be 10
to 15 feet wide. It can be grown with branches
to the ground or with its branches pruned up.
Another selection is Quercus robur ‘Pyramich’
or skymaster English oak. This has an excel¬
lent pyramidal form.
Kentucky coffee trees ( Gymnocladus
dioica ) are natives of the eastern and central
United States. Like the English oak, the Ken¬
tucky coffee tree is listed as hardy in zone 4.
The coffee tree is an open, stark looking
tree in the winter. In the summer it has a
lush, almost tropical appearance. Its leaves
are doubly compound and are bright green in
summer. In the fall the foliage turns golden
yellow. One advantage of this tree is that it
gives nice filtered shade in the summer, but
will allow a lot of sun into your yard in the
winter. Coffee trees have pinkish flowers in
late spring. These are later replaced by fat,
dark-brown seed pods, which stay on the tree
well into winter. This interesting tree does
not have much “sales appeal” when young,
but is a tree that “just gets better each year.”
Hackberry ( Celtis occidentalis ) is another
tree native to the northern United States, list¬
ed as hardy to zone 2. Although this tree is
always listed as drought-tolerant (which is
true), it will also live in very wet soil (it must,
however, be well-drained). Hackberries will
increase in size in proportion to the amount of
water they receive. The foliage is a medium
green in the summer and a bright yellow in
the fall. It is another tree that does not have
much sales appeal when it is young, but
grows more beautiful each year.
Shrubs
As trees are the ceiling of a landscape,
shrubs are the walls. Shrubs are used as
screens or for dividing spaces. Normally, for a
screen you will need plants that grow taller
than eye level. To divide your landscape into
areas, you may wish to use smaller shrubs.
One general observation is that almost all
shrubs will grow as wide as they do tall.
Another general rule is: When you are using
the same kind of shrub, you will want to place
the plants close together. With different
types, they should be spaced farther apart.
Here are some of my favorite shrubs,
which will live with very little additional
water after they are established.
Curlleaf mountain mahogany ( Cercocar -
pus ledifolius ) is native to Utah and Colorado.
This large shrub has many interesting fea¬
tures, but its evergreen foliage is one of the
best. This plant has grey bark and small very
dark green leaves. Curlleaf mountain maho¬
gany will grow to 30 feet, although I have
never seen one much larger than 15 feet. It
could be trimmed into a very fine small tree
and responds very nicely to training. There¬
fore, it could be made into a nice hedge as
well.
New Mexican privet ( Forestiera neomexi-
cana) is native in Southwestern Colorado and
New Mexico, where landscapers trim this
plant to form a small tree. It has yellow flow¬
ers in spring before its bright green leaves
appear. Forestiera grows very dense and is
quite twiggy, so that even in the winter it
does a great job of screening.
Threeleaf sumac ( Rhus trilobata ) is a 4' to
5' shrub that can be used as a specimen or as
a medium-sized divider. If given enough space
this plant will spread wider than its 4' to 5'
height, but it can be pruned to fit a smaller
space if necessary.
Threeleaf sumac has yellow flowers in the
spring before the leaves appear. These flowers
then form hairy red fruit which last late into
the winter. The three-lobed, dark, shiny green
leaves turn a rich red or mahogany color in
the fall. Reportedly, some people receive a skin
rash from working with this plant.
Red-leaf rose ( Rosa rubrifolia ) is one of
my favorite shrub roses. Usually seen as a 4'
to 5' plant, it may grow to 10' tall in favorable
locations. The foliage is purple-red, fading to
reddish green in the summer or in shade; its
best color is in hill sun. Its single, pink flow¬
ers are followed in summer by bright orange
rose hips that stay on the plant almost all
winter. In the fall it puts on a brilliant display
of yellow-orange foliage.
When landscaping with little additional
water the shrub list can be much larger than
the tree list. This is only a small sampling of
my favorites.
23
Right, threeleaf sumac
Left, hackberry (Celtis occidentals ) clothed in autumn yellow
Below, Red-leaf rose ( Rosa rubrifolia ) in bloom
Lawns & Water Conservation
Dorothy Borland
Now that we are becoming increasingly
aware of water use in our landscapes, our
first thoughts for saving water in our semi-
arid climate are directed toward our lawns.
Generally, a lawn is the largest plant group¬
ing in a landscape, the one requiring the
highest degree of maintenance and — to keep
it green — water.
Nevertheless, when we consider our
lawns as high-water-using and high mainte¬
nance creatures, we must also remember the
additional benefits that these turf areas
provide.
It has been shown that lawns help reduce
soil erosion and pesticide leaching, stabilize
dust, cool the surrounding air, reduce runoff
from rain and help replenish groundwater.
Lawns also provide a pleasant area to rest
and play.
However, to reap these benefits — and still
conserve water — consider carefully during the
design process where you will plant your
lawn to get the most benefit. Place your lawn
area where it will be used the most, or where
it will receive runoff from other areas.
The most commonly used turf in Colorado
is Kentucky bluegrass. Because of its ability
to produce a dense lawn, it is considered the
premier lawn grass. The newer varieties of
Kentucky bluegrass are dark green and fine¬
leaved. A cool season grass that spreads by
underground rhizomes, it grows best with
high levels of water, mowing and fertilization.
Dorothy Borland is the water conservation ana¬
lyst for the Denver Department of Parks and
Recreation and a widely recognized turf grass
consultant.
Bluegrass can be a good lower mainte¬
nance turfgrass if we water and maintain it
wisely. Also, it wears well and recuperates
from damage fairly readily because of its rhi-
zomatous growth habit. Although its disease
resistance has been improved with additional
plant breeding, bluegrass can suffer from
disfiguring diseases which are generally relat¬
ed to improper maintenance such as irregular
or over- watering and over-fertilizing.
Just as we have many options for our
landscapes in the kinds of trees, shrubs and
flowers from which to choose, now we have
alternatives to bluegrass. But it is important
to understand why you want to change your
lawn and how you want it to appear. Each
alternative grass will produce a different
appearance, just as different species and vari¬
eties of trees have different flower color,
growth habit or leaf color.
The next most commonly used turfgrass
is tall fescue. The newer cultivars have leaf
blades that are as fine as bluegrass and are
commonly called “turf-type tall fescue” to dis¬
tinguish them from the older, wide-leaved
pasture fescues.
Tall fescue, like bluegrass, is a cool sea¬
son grass but, unlike bluegrass, it is a bunch-
grass. It has very good shade tolerance, better
salt tolerance than bluegrass and good wear
tolerance. Also, it germinates faster and
establishes more quickly than bluegrass.
For most uses, this is quite an acceptable
turfgrass. Its appearance, an issue often
raised with alternative turfgrasses, is so simi¬
lar to bluegrass that most people cannot tell
the difference between the two when grown
on opposite sides of a sidewalk. The newer 25
cultivars are “barefootable ,” an attribute not
true with the older cultivars.
It is estimated that tall fescue produces an
attractive turf with approximately 20 percent
less applied irrigation than bluegrass requires.
For warm season grass enthusiasts, the
native buffalo grass is the favored choice. It
spreads by stolons, (shoots that grow like
strawberry plants) forming a dense sod that
rarely grows any taller than six inches. This
Turf grass Options:
Grass
Characteristics
Special Features
Kentucky bluegrass, Poa pratensis
C,S,I
Familiar lawn grass that spreads by rhizomes;
good cold and wear tolerance;
requires approximately 1 moisture/week
during hot season (35"/season).
Perennial ryegrass, Lolium perenne
C,B,I
Often included in mixes with bluegrass; quick
germination; good shade and disease tolerance;
maintenance needs similar to bluegrass.
Buffalo grass, Buchloe dactyloides
W,S,N
Spreads by stolons; turns tan in fall;
greens up three weeks after bluegrass;
rapid germination with treated seed; mowing
optional as normal height is 6" or less; adapted
to 15" to 25" annual moisture; poor shade
tolerance; excellent heat and drought tolerance.
Blue grama, Bouteloua gracilis
W,B,N
Generally found with buffalograss; excellent heat
and drought tolerance; poor shade tolerance;
adapted to 12" to 25" annual moisture;
normal foliage height 8 - 1 2".
Smooth brome, Bromus inermis
C,S,I
Pasture grass now being used in turf settings;
leaves ]/4" to V2" wide; seasonal water
requirement approximately 1 8".
Tall fescue, Festuca elatior
C,B,I
Improved varieties planted in pure stands;
improved varieties have fine texture similar to
bluegrass; good drought tolerance with deep
root system; approximately 28" annual water
requirement.
Wheatgrasses
Characteristics
Special Features
Desert/Siberian, Agropyron sibiricum
C,B,I
Excellent drought tolerance; goes dormant under
heat and drought stress; good cold tolerance;
tolerate a 3" to 4" mowing height; produces
a better turf appearance; leaves about !/4"
wide; adapted to 12" to 20" annual moisture.
Western, Agropyron smithii
C,S,N
Bluish foliage; can be an aggressive spreader;
good drought and cold tolerance;
adapted to 14" to 25" annual moisture.
KEY:
C = cool season; W = warm season grass; B = bunch grass.
S = sod-forming grass, 1 = introduced species; N =
native species
26
feature cam reduce the necessity for mowing
to as seldom as once or twice a year.
Sometimes blue grama, another native
warm season grass, is mixed with buffalo
grass. Blue grama is a taller bunchgrass with
slightly wider leaves than buffalo grass. It can
be added to a buffalo grass mix for diversity,
to reduce the cost of seeding, or to replicate
the natural mix found on the prairies.
Because these two grasses are both warm
season grasses, they go dormant and off-color
in the fall with the advent of shorter days and
cooler temperatures. They usually don’t green
up again until mid-May, depending on the
spring temperatures and weather. The dor¬
mant color is a very even tarn, compared to the
mottled green and brown colors of cool season
grasses during the winter.
Local turf farms have responded to the
demand for sod of alternative grasses and
now offer tall fescue sod. It can be purchased
either as a pure stand and grown with net¬
ting to hold the sod together, or as a mixture
with bluegrass. If the percentage of bluegrass
on a seeded weight basis exceeds 10 percent,
the sod you purchase will likely be over 50
percent bluegrass. Buffalo grass will be avail¬
able as sod in spring 1993 and also from a few
nurseries as plugs that are planted like annu¬
als, but grow perennially.
At this time these are the most likely
choices for turfgrasses. Crested wheatgrass
has been promoted occasionally as a turf-
grass, but, in my experience and at Colorado
State University, this grass has not per¬
formed well, even with heavy irrigation.
There is considerable research and breeding
being performed on additional grasses for
more specialized uses.
27
Making the Switch ... A Personal Story
Sandy Snyder
Residents of hot, dry areas like eastern
Colorado are becoming very interested in
warm season grasses. The question comes up,
‘"What is the best way to convert a lawn of
cool season grass, such as Kentucky blue-
grass, to warm season grasses such as buffalo
grass or blue grama?”
The warm season grasses require less
water, fertilizer and mowing. If you have a
large open area that does not get much traffic,
native grasses will give you an acceptable
suburban lawn. And small, difficult-to-main-
tain, open, sunny areas such as parking
strips, cul-de-sacs and south-facing slopes are
also good candidates for warm season grasses.
These grasses thrive in hot, dry locations and
seem to enjoy being planted between reflec¬
tive surfaces.
An excellent warm season turf is buffalo
grass ( Buchloe dactyloides). It is dioecious,
meaning that the male and female flowers
are on separate plants. The male flowers look
like small wheat heads if they are allowed to
grow to their full height, 4" to 6". I like these
little flowers because they make my grass
area more interesting with texture. Others
prefer planting only the female grass because
it has a less ragged appearance when it is
allowed to grow long. The female plants’ seed
heads are not readily visible because they
snuggle down around the crown and can be
found only if you are looking for them.
Blue grama, ( Bouteloua gracilis ) is a
warm season grass that I like very much
because it sports a cute “eyelash” seedhead
Sandy Snyder, rock alpine gardener at DBG,
lives in Littleton where she maintains an exten-
28 sive, xeriscaped home garden.
atop its wiry stem. It is a clump grass but it
can be broadcast-seeded and treated as turf.
There is a broadcast area of blue grama grass
planted in the Xeriscape Demonstration Gar¬
den at the Denver Botanic Gardens. You’re
invited to see if you could live with it as part
of your home landscape.
Keep in mind that most home lawns have
several areas. The different areas do not have
to be planted with the same kind of grass.
Different sections of your yard can be planted
with grasses that will do the best in each area.
I have converted my own suburban Ken¬
tucky bluegrass lawn to buffalo grass three
different ways. Ten years ago in May and
June I had an open area that I tilled and
seeded with ‘Sharp’s Improved’ buffalo grass
seed. I cared for the newly seeded lawn the
same as for newly seeded bluegrass. I kept it
damp and the seed sprouted in ten days.
During the summer weeds grew faster
than the new grass. I felt that I could not
apply chemical weed killer to the young grass
blades, so I hand-weeded the large area four
times to keep the weeds from crowding out
the new grass. This was not much fun. I don’t
think I will seed a buffalo grass lawn again.
I have since discovered that two inch pre¬
rooted plugs work better. Pre-rooted plugs are
grown from seed in pots or aeration-like plugs
of grass that are pulled from a sod area, put
into pots, watered and fed to develop new roots.
Last year I graded an open soil area and
hand planted two-inch plugs in early July. I
neglected, however, to apply a pre-emergent
herbicide. Purslane quickly appeared and had
to be hand- weeded at least once a week during
Above left, Iris reticulata and Crocus chrysan-
thus 'Snow Bunting' appear before the buffalo
grass comes out of dormancy.
Above right, recently plugged buffalo grass
lawn in area previously covered by Kentucky
bluegrass. Notice the color difference between
the two species.
Left, Xeriscape Demonstration Garden at the
Denver Botanic Gardens showing mowed and
unmowed blue grama
Bulbs and Conns in the Grass!
Species and variety
Flower color
Season of Bloom
Crocus ancyrensis 'Golden Bunch'
Yellow
Mid- to late Feb., last a month.
C. chrysanthus 'Princess Beatrix'
Blue-white
Late Feb. to mid-March, last a month
C. chrysanthus 'Snow Bunting'
White
Late Feb. to mid-March, last a month
C. sieberi 'Firefly'
Lilac
Late Feb., continue into March.
Calanthus elwesii
White
Jan. or Feb., continue into March.
Iris reticulata 'Harmony'
Deep blue
March, last almost a full month.
/. reticulata 'J.S. Dijt'
Dark purple
March, last almost a full month.
Narcissus asturiensis
Yellow
Early to late March, last a short time.
Tulipa humilus
Rose
Mid- to late April, last two weeks.
T. kolpakowskiana
Yellow
Mid- to late April, last two weeks.
T. lini folia
Red
Mid- to late April, last two weeks.
T. tarda
Yellow-white
Late April, last two weeks.
T. urumiensis
Yellow
Mid- to late April, last two weeks.
29
the first part of the summer until the plugs
filled in the area.
My most successful renovation was seven
hundred square feet of healthy Kentucky
bluegrass lawn that I converted to buffalo
grass. I started killing the bluegrass with a
glyphosate-based herbicide in the fall. The fol¬
lowing spring I finished killing it. It took four
applications, in all. I did not, however, remove
the dead sod.
I had contracted with a friend to have
buffalo grass plugs grown in 2 V4" pots which
were ready in July. These were healthy,
robust plugs that were not root-bound. If the
plugs are root-bound the roots must be loos¬
ened before planting, otherwise the plug will
just sit in the ground and fail to grow outside
of the rooted boundary.
We planted the 2" plugs 8" on center.
This was too close, but I wanted to make sure
the lawn filled in within one growing season.
The two-inch plugs took hold very quickly,
and because they were placed in the dead
bluegrass sod there was no open soil to
encourage weeds. As the plugs were filling in
during the summer, only three large mallow
weeds grew. I hand-pulled them, easily.
Buffalo grass does well with little water
but it will also adapt to moderate water lev¬
els. The trick is to give it enough water to
thrive and grow quickly, but not so much that
weeds and bluegrass will settle and compete.
Planting a buffalo grass lawn is a do-it-
yourself project. The seed is available but not
in every garden center.
Plugging is very successful but machines
that plug a large area or convert small areas
are not readily available. We had to design
our own tool to plug buffalo grass into the
dead sod: four blocks of wood shaped like a
2 V4" pot placed in the comers of a 12" square
of plywood with a broom stick for a handle.
We watered the ground so it would be soft but
not mucky, then stepped on the plywood
square to make the holes. This compacted the
soil but it worked anyway. I don’t think a
commercial grass installer would put up with
this primitive tool. It was slow and would be
30 too exhausting to use on more than one lawn.
If a small aerator type machine could be fitted
to pull the correct size plugs I think that
would work beautifully.
The disadvantage of buffalo grass is the
high cost of seed, but this can be defrayed
over the years as you save on water and main¬
tenance. Its light green color is not noticeable
when it is not growing beside bluegrass.
I think the longer dormant period of buf¬
falo grass is very advantageous, because it
provides a time when bulbs can explode with
color on the beige canvas that this grass pro¬
vides. I chose small species bulbs that have
narrow leaves and bloom early throughout
the spring to give color to my buffalo grass
lawn.
I am very satisfied with my buffalo grass
lawn because it now saves me time, work,
water and money. I love my buffalo grass bulb
garden because every spring it inspires an
excitement around our house that even the
best manicured “ordinary” lawn could not
match.
A Prairie for Your Thoughts
Rick Brune
When the first pioneers homesteaded in
eastern Colorado they began to radically
change our prairie ecosystem — an ecosystem
that had evolved over thousands of years into
a landscape perfect for our semi-arid climate.
Prairie gardens allow us to adopt parts of
that ecosystem for our home landscapes.
They also allow a fresh look at the wealth of
beautifully adapted plants our prairies offer.
Using prairie as a landscape element pro¬
vides savings in water, fertilizer, mowing and
weed control. As with any other type of gar¬
den, it isn’t accomplished without work, but
. other expenses are relatively low. No expen¬
sive irrigation system is needed. The lawn
mower will be used perhaps once a year. And
after the first year or two, your prairie garden
will survive with minimal attention.
More importantly, it will give you a new
appreciation of Colorado east of the foothills.
You will enjoy the delicate fragrance of
evening-blooming plants such as scarlet gaura
( Gaura coccinea). Your neighbors may com¬
ment on the gardenia-like scent of sand ver¬
bena (. Abronia fragrans ) permeating the night
air. Spectacular night bloomers like giant
evening star (. Mentzelia decapetala) and even¬
ing primroses ( Oenothera spp.) can also be
enjoyed, without a camping trip to the prairie.
Rick Brune is a botanical consultant. He leads
prairie field trips and teaches prairie gardening.
He wrote a 1 5-page guide to prairie gardening,
The Prairie Garden, published by the Colorado
Native Plant Society. This step-by-step guide to
creating a shortgrass prairie garden is available
for $3 at local chapter meetings or from the Den¬
ver Botanic Gardens Gift Shop.
Of course, most prairie wildflowers are
day bloomers. But when I began prairie gar¬
dening, I had no idea how much exploring
with a flashlight I would do! You may spend
significant time sitting by plants in the evening
as their flowers unfurl before your eyes.
Although some of the common flowers
are available commercially, you may have to
propagate many yourself. That’s part of the
fun and education of prairie plants. Although
we’ve used and abused the prairie for over a
century, we know little about how species are
propagated or other aspects of their life histo¬
ries. Simple backyard observations can pro¬
vide new discoveries.
What type of prairie is adaptable to the
home landscape? Eastern Colorado evolved
with over twenty different kinds. Given the
rather conservative attitudes about landscap¬
ing in Colorado and ordinances governing the
height of unmowed grass, a form of shortgrass
prairie is the best starting point. Rest assured
it will not look like the overgrazed putting
green found in parts of eastern Colorado.
A shortgrass prairie garden is only one
imaginative step from planting a buffalo
grass ( Buchloe dactyloides) lawn. Did I hear
someone say they didn’t want their yard to
turn brown in winter?! A prairie garden with
a mixture of buffalo grass, blue grama
(. Bouteloua gracilis), sideoats grama (B. cur-
tipendula ) and perhaps other grasses doesn’t
just turn brown. It becomes a delightful mix
of warm shades of yellow, bronze and gold.
It’s an infinitely cheerier aspect of winter
than a dingy bluegrass lawn.
Why do we plant a prairie garden? Why
not plant one of the canned wildflower mixes 31
or install sod and be done? Plant a “wildflow-
er” mix and you’ll get everything from Califor¬
nia poppies and cornflowers to blue flax and
field clover. This, however, is not a prairie.
Reading the labels of mixes will usually show
that very few indigenous or genuine wildflow-
ers are in them. “Native” species may be
native to other parts of the country, not to
Colorado. Even if you find genus and species
on the label native to Colorado, it may not be
genetically adapted to our semi-arid prairie
climate or droughts.
There are no shortcuts to a prairie gar¬
den. But success will mean a delightful and
educational garden to explore, and also the
opportunity to educate others about the use of
Above left, Guara coccinea
Above right, shortgrass prairie
garden
Right, a view along the West
boundary ot the Denver Botan¬
ic Gardens' Laura Smith Porter
Plains Garden
32
How To Water a Lawn
Marcia Tatroe
Okay, you’ve added organic matter to
your soil, you’ve chosen the best turf for your
location, you’re following a sensible regimen
for fertilizing, weed control and aeration. So,
now you just add water and — presto — a beau¬
tiful lawn. Well . . . no, it’s not quite that sim¬
ple, especially if you don’t have an automatic
irrigation system.
Turf that is not getting enough water
loses its vigor and becomes prone to insect
damage, diseases and weak, thin growth.
Weeds then move in to compete with grass
roots for any available moisture. Thinning
also leaves soil surfaces exposed and results
in increased evaporation, loss of soil moisture
and erosion.
On the other hand, too much water can
lead to a swamp-like environment, especially
in low spots on heavy, poorly drained clay.
Water fills in all of the air spaces in the soil
and the grass roots are left “gasping” for air.
Ideally, soils should contain equal amounts of
water and air for best root growth.
Overwatering also leaches nutrients from
the soil, creating an increased demand for
costly fertilizer. Additionally, water draining
from lawns collects in sewers, providing ideal
breeding sites for mosquitoes, and problems
with water quality. Run-off also undermines
sidewalks and roadways, adding greatly to
the cost of their repair and upkeep.
How do you decide when to water and
how much? The trick is to strike a balance,
Marcia Tatroe is a master gardener for Arapa¬
hoe County, volunteer in the Denver Botanic Gar¬
dens' Rock Alpine Garden, and chairs the
xeriscape division of Denver Botanic Gardens
34 annual plant sale.
allowing the soil to dry partially between
waterings but watering before the grass
shows signs of stress.
Different grass types have different water
needs. Native buffalo grass and blue grama
will survive without irrigation after they’re
established. Tall fescue and bluegrass turfs
need approximately 1" to 2" of water per week
during hot, dry weather. The first irrigation of
the year should be held off until May to
encourage the grass roots to grow deeply in
search of sub-soil moisture.
Many environmental factors can affect a
lawn’s need for water. Grass that is sheltered
from drying winds and intense sunlight will
usually need less water than lawn on
exposed, south-facing sites. But if trees are
providing this shade, their roots will compete
with the grass for moisture and nutrients.
It’s also important to know your soil type.
Sandy soils allow water to penetrate very fast
and deep, but dry out quickly. Our more com¬
mon clay soils hold water very well, but absorb
it slowly and are terribly prone to puddling
and run-off problems. For both soils, water
may need to be applied in short repeated
intervals for water infiltration that benefits
the turf and not the aquifer or the gutter.
Reflected heat from sidewalks or struc¬
tures, extremely high temperatures, heavy
foot traffic, mowing height under 2 V2", over¬
fertilizing, insect pests, disease and thatch
can all increase a lawn’s need for water.
The best way to decide when to water is
to regularly monitor soil moisture and to
water only when the soil begins to dry out. A
simple gauge is a soil coring tube that pulls a
plug of sod and soil which allows you to see
and feel the moisture — or use a screwdriver.
It will push into the soil easily only to the
depth that the soil is moist. Or several times
a season, 24 hours after watering, dig out a
one foot square of turf and examine the soil
and root depth (you can then replace it with¬
out damage to the lawn). Check the depth the
water has penetrated. The soil should not be
soggy. The water should have penetrated 8"
to 12"; ideally this is about 2" below the root
zone.
Rainfall should be measured and sub¬
tracted from the lawn’s weekly water require¬
ment. A rain gauge is a simple device avail¬
able from most garden centers. A vertical¬
sided food container will also suffice. Measure
the depth of accumulated rain water in the
container with a ruler. Keep in mind that a
light sprinkle will quickly evaporate from the
lawn and that a real gully-washer may run
off before it has time to soak in.
To check the water output and distribu¬
tion of your sprinkler, place a dozen vertical¬
sided containers (all containers should be the
same size and shape) in parallel rows extend¬
ing from the sprinkler. One row should be
placed next to the line of sprinkler heads,
another at the outer reach of the heads and a
third directly between the two. Set the sprin¬
kler system to run for a 15 minute period of
time and then measure the water in each con¬
tainer. Compare applications in each can
before you determine the average amount of
water applied. Then figure out how long it
takes to apply one inch of water. This will
indicate whether the sprinkler pattern is
uneven and where it will be necessary to com¬
pensate by enlarging or overlapping the spray
patterns. Be sure to check the water output
at the same time of the day that you plan to
use the sprinkler as water pressure can vary
greatly at different times of the day.
The best time to water is from 1 to 6 a.m.,
when winds are quiet and evaporation is low.
Use a sprinkler head or unit that throws
large water drops low to the ground to reduce
drift and evaporation. Even in clay soils that
are properly amended, water may run off
before it has a chance to soak in. If this is a
problem, water in cycles: for example, 15 min¬
utes on, 30 minutes off, and repeat the cycle,
experimenting until you find the right combi¬
nation that works. Whatever you do, don’t
forget to turn the sprinkler off. You can buy
am inexpensive faucet timer to do the job for
you, or you might use a timer as a reminder.
Come winter, you may welcome a break
from lawn care, but just because the lawn is
dormant, doesn’t mean it’s without a need for
water. In dry winters the lawn will benefit
from one inch of water once a month. Choose
a warm, windless day and water early enough
in the day so that the water will have a chance
to soak in before the soil freezes at night. Be
sure to pay particular attention to slopes,
especially on south- or west-facing exposures.
You’ll be handsomely repaid for the few
hours it takes to become familiar with your
lawn’s water needs. You’ll reap savings on
your water bills and have a much healthier
lawn.
35
VC
<3
The No Front Lawn Front Lawn
Chet Grabowski
The times sure are changin’
and people are changin’ too,
the ways they approach the lives they lead,
and their environmental attitudes.
We’ve all got to know our place in this world,
and deal with troubles on our own,
so my contribution to the fate of the planet
will be to eliminate my front lawn.
Now I ain’t got that much against
a nice front lawn you see,
’cept you’ve got to aerate it and fertilize it,
and rake it to keep it neat.
Then, you’ve got to move ’round all those hoses
to keep the edges lookin’ fine,
to say nothing of all the cutting it takes
in the middle of summertime.
And after you’ve completed all that work
and managed to keep the weeds at bay,
you’ve used up half the water in the reservoirs.
What’s it good for anyway?
Well, I’m still one of those who likes to wet their toes
in the dew on a new summer day,
and dash across naked in the full moonlight,
or play a friendly game of cutthroat croquet.
But speakin’ just for me, I’d rather see
pretty flowers where my lawn now grows,
and native plants n’ grasses n’ shrubs n’ trees,
that put on a continuous show.
Instead of manicured green for half of the year
and brown the rest of the time,
I’d have bright colors in spring, sweet smells in summer,
and texture for the wintertime.
So all things considered, I’ll make that trade,
and bid my lawn adieu without a sigh. /
That being the case, I’ll put flowers in its place,
and you can kiss my grass . . . goodbye.
36
No Maintenence?
Pat Montane
One of my favorite clients started our
interaction by pleading for a no-maintenance
landscape. At the time he had two-plus acres
hip deep in thistles, clover and bindweed.
“There isn’t such a thing,” I retorted, “even if
you cover the whole lot with weed barrier fab¬
ric and gravel”. If you agree with the need for
maintenance in any landscape, congratula¬
tions, you have just invested in the value of
your home!
You have a great degree of control over
the amount of maintenance that a landscape
will require. It begins with good design or ren¬
ovation layout where the landscape has been
divided into water-use zones, as mentioned in
other articles. This includes the consolidation
of high-maintenance (usually high-water also)
plantings such as perennial and vegetable
beds and lawn areas into easily accessed
zones, choosing plants that “fit” those zones
and planting shrubs and groundcovers so
they will grow to cover the soil completely
within a three year period. If you choose
plantings that require irrigation, all of the
details outlined in the irrigation articles with¬
in will also be helpful. And, depending upon
the plant material you choose, you will most
likely want to prepare your soil when instal¬
ling plants or improve it over time. Mulching
can help reduce maintenance as suggested in
other articles. These techniques, and others
that follow, will also reduce the amount of
water used or wasted in your landscape.
But first let’s examine some important
considerations. Do you want or need the
Pat Montane is a hobby gardener and naturalist
residing in Silt, Colorado.
assistance from a professional landscape ser¬
vice or can you get by on your own? There’s
obviously a financial trade-off here, but you
may also want to consider how much horticul¬
tural knowledge you have. The world of horti¬
culture has disproved many a “wive’s tale”
and some practices work well on the East or
West coast but are very different in the Rocky
Mountains. Do you have access to the right
tools? And most important of all, do you have
the time and energy to commit to your land¬
scape? Newly installed landscapes will
require more maintenance during the first
three years than a mature landscape, primar¬
ily because new plantings must be weaned of
water slowly, and disturbed soils are more
likely to host weeds.
The most important point, however, is
that you enjoy your landscape! If you are
spending more time pulling weeds than you
are sitting in the sun or strolling through
your garden, consider having a professional
do the work.
Lawn Care On Your Own
Maintenance for established bluegrass
lawns includes watering two times or, at
most, three times a week. Other grasses will
usually require less water than bluegrass, but
only if the soil has been appropriately pre¬
pared. This is especially true of tall fescue
lawns. You can tell when any grass is water-
stressed if foot prints remain after walking
across your lawn, or if it develops a dull, blue-
grey color.
Do you have thatch? This is an accumula¬
tion of living and dead plant matter on the
soil surface below the greenery of your lawn. 37
If it’s deeper than V2", your waterings may be
running off the surface of the thatch, rather
than penetrating the soil. And of course, deep
thatch is a great place where bugs and dis¬
ease will make their homes. Thatch can be a
benefit, however, because it serves as mulch.
It also tells you how healthy your soil is. Com¬
pacted soils usually develop thatch problems.
Thatch and many other lawn problems
can be reduced with one to two aerations per
season, in the spring and early fall, and espe¬
cially in areas that are used heavily. Aeration
is the pulling of soil plugs, or introduction of
slits into your lawn. It is the next best thing
to actually tearing out your lawn and starting
over to incorporate air into the soil. Following
a top dressing of V2" layer of a fine grade
organic matter and fertilizer, aerations will
make your lawn noticeably healthier over time.
Mowing to a height of 3" during warm
months, and to 2" during cooler months will
enhance the establishment of deeper roots,
which makes for increased drought tolerance.
Consider leaving your grass clipping on the
lawn as this returns nutrients to the soil and
maintains a consistent thatch reservoir for
soil microorganisms to “eat,” a long term ben¬
efit to the overall health of any soil. If your
clippings are piling up you may be watering
or fertilizing too much, not mowing often
enough, or a combination of all three. There
are numerous fertilization recommendations
available. Follow the one that suits you, but
remember that over-fertilization will force
you to water and mow more often.
Finally, a sharp mower blade will also
reduce water loss through ragged leaves that
have otherwise been flailed by an unsharp¬
ened blade. A ragged lawn is susceptible to
more disease as well.
Maintaining Established Trees & Shrubs
Plants that are bug infested or diseased
are indicators that we are doing something
wrong. About 85 percent of the time, it is seen
that the problem is over- watering! They may
die quickly or over a number of years, but a
stressed plant is an open invitation for insects
38 and disease. They are also susceptible to envi¬
ronmental damage from early or late freezes,
or heavy snows.
Water needs for trees and shrubs are gen¬
erally going to be less than that of a green
lawn area, although some trees will need win¬
ter water applications to prevent die-back of
twigs and branches from our cold, dry winter
winds. Late-fall installations are especially
susceptible to winter-kill because they may
not have adequate root development, as are
birch, and poplar trees.
Trees and shrubs have different watering
needs than lawns, and tree roots always grow
far beyond the “drip line” of the parent plant.
Remember too that 90 percent of a tree’s feed¬
er roots grow within the top 18" of soil. These
can be easily damaged by compaction or trench¬
ing for paths and construction, addition or
removal of soil where roots grow, deep tilling
or cultivation, applications of weed controls or
soil sterilants.
Naturalized landscapes, in general,
require less maintenance overall and five
longer than heavily pruned formal land¬
scapes. This is because plants are allowed to
grow to their natural size and shape. Are you
pruning because your plant won’t let you in
the front door, or because it’s eating your
mailbox? This is a sign of poor design and
plant placement. Tree and shrub pruning
should only be performed to promote healthy
growing conditions, minimal watering, to cor¬
rect irregular growth and remove dead or
dying branches and limbs. Improper pruning
leads to plant stress, which invites insects
and or disease, and all the rest.
Final Recommendations
The best recommendation that can be
made for any landscape effort is, “Keep it sim¬
ple.” This includes design, irrigation, and
maintenance. The more naturally your land¬
scape can be allowed to grow the more main¬
tenance free it will ultimately be. Why fight
nature, (especially when she’s unbeatable)? It
is to your best advantage to work with her so
that she will work for you.
Do You Really Need an Automatic
Irrigation System ?
Jim Clark
While dragging a hose around and mov¬
ing the sprinkler on a summer evening — for
what seems like the thousandth time — do
your thoughts ever wander to the time-saving
pleasures of an automatic irrigation system?
There are several points to consider, including
time-savings, in the decision-making of
whether or not to install an automatic irriga¬
tion system for your landscape.
A residential automatic irrigation system
typically consists of pop-up sprinklers that
are supplied with water through plastic pipe
buried underground.
A controller — also referred to as a timer
or clock — is programmed to electrically open
and close the control valves at desired times
and for desired durations among the system’s
zones. To conserve water each zone should
have uniform solar exposure and be com¬
prised of plants with similar water require¬
ments. A small yard may only require four or
five zones, whereas a larger yard may require
twelve or more.
An automatic irrigation system might
also include drip irrigation. Drip irrigation is
an appropriate method of irrigating individu¬
al trees, shrubs, or flowers, such as in a plant¬
ing bed, when the plants are not densely
spaced.
Jim Clark is the water conservation specialist for
the City of Fort Collins, and has a background in
horticulture, agricultural engineering and commu¬
nity education. As a personal voluntary endeavor,
he is spearheading an effort to establish a Com¬
munity Horticultural Center in Fort Collins.
An automatic system compared to manu¬
al irrigation saves the time involved in mov¬
ing hoses and sprinklers, and in turning the
water on and off. For most homeowners with
an automatic system this is seen as it’s prima¬
ry advantage.
Do Irrigation Systems Save Water?
A properly designed, installed and main¬
tained automatic system will deliver a more
uniform application of water to the landscape
than is realistically possible with manual irri¬
gation. This results in two potential benefits.
First, there is the horticultural benefit of a
uniform application of water that will not
leave one portion of the irrigation zone under¬
watered and another portion over- watered.
Second, an irrigation system with uniform
delivery is more water-efficient, thereby sav¬
ing money. Both of these benefits are qualified
with the word potential, because neither will
occur if the homeowner does not regularly
and properly attend to setting the irrigation
schedule on the controller. A great deal of
water is wasted by homeowners with auto¬
matic systems that are set to irrigate accord¬
ing to the water requirements of a hot, dry
week in July, whether it is May, September or
raining.
Another advantage of an automatic sys¬
tem is that it can easily be programmed to
irrigate during the early morning hours before
sunrise, which would be inconvenient for those
who are irrigating manually . This is the best
time to irrigate, since the least amount of
water is lost to evaporation from the sun’s
39
heat. Yet another benefit of an automatic sys¬
tem is the fact that it can be relied upon to
irrigate your landscape while you are away
from your home for extended periods.
The cost of an automatic irrigation system
is its major drawback. The price for a typical
system with eight zones on a 7,500 square
foot lot is in the approximate range of $2,000
to $2,500. This is for a high quality, contrac¬
tor-installed system.
If you install an irrigation system your¬
self (see An Irrigation System on Your Own,
page 42), you could save 50 percent or more of
the above cost. If you sell your home, you will
likely recoup some of the cost of the system.
Real estate appraisers currently value a typi¬
cal-sized irrigation system at anywhere
between $500 and $1,500.
After your automatic system is properly
designed and installed, whether by you or by
a contractor, there are several things that you
can do to assure yourself of its efficient opera¬
tion and water-savings ability. Good mainte¬
nance of an irrigation system involves being
observant of its operation. The system should
be routinely monitored for proper operation,
checking for such things as: 1) broken, clogged,
or maladjusted sprinklers; 2) pipe leaks; and
3) zones not coming on at the expected time or
for the expected duration. If your system typi¬
cally comes on while you are asleep or away,
you should run it through a test cycle (with
one or two minutes per zone) every few weeks
so you can observe its operation. If you find
any problem with the system, see that it is
repaired by a qualified person. Also, the sys¬
tem should be properly winterized during the
fall, to prevent the water in the system from
freezing and causing damage.
The most essential determinant to an
irrigation system’s water efficiency is the
scheduling. At the very least, your irrigation
schedule should be adjusted monthly, based
upon the water requirement of your lawn.
Water needs gradually increase in the first
half of the growing season and then decrease
in the second half. Better yet, adjust your irri¬
gation schedule on a weekly basis, using your
40 landscape as a visual guide.
In all cases, you should turn off your sys¬
tem when you have received adequate mois¬
ture by rainfall. There are inexpensive rain
sensors available that will perform this task
automatically. Additional information on
lawn watering is available from water utili¬
ties and from CSU Extension. If you do not
understand how to program your controller,
get assistance from an irrigation system con¬
tractor or other knowledgeable source.
Granted, all of this maintenance requires
time (or money, if you pay someone to do it),
which is what you were trying to save by get¬
ting the system in the first place. However,
once you establish an efficient maintenance
routine, it will take only a minimal amount of
time; certainly less than that required for
manual irrigation. Furthermore, you will be
compensated with a better-looking landscape
and water savings. The decision that you
must make is whether or not these benefits
are worth the financial cost of the system.
Left, sculpture adds
interest to this natural¬
ized planting of rye¬
grass.
Below, at the same
residence, the buffalo
grass meets the rye¬
grass border for a
natural but well-
manicured effect.
An Irrigation System on Your Own
John Stinson
Today we see all manner of landscape
sprinkler systems, even at the most modest
homesites. While many people still consider a
sprinkler system to be a luxury item, most
will agree that it represents both a time sav¬
ings and a convenience, two increasingly val¬
ued commodities.
For many homeowners, the substantial
investment of a sprinkler system is practical
only if they undertake to install it themselves.
As a general rule you may expect to save 40
to 50 percent of the cost of a professionally
installed system when you do it on your own.
Such a do-it-yourself project also offers the
benefits of complete quality control and per¬
sonalization. The major expense, of course, is
personal time. Bear in mind that a complete
automatic sprinkler system for an average
urban residential lot will take 60 to 80 hours
to install. Plan your schedule (and gather
your friends, good neighbors and family)
accordingly.
Assuming you have decided to stop drag¬
ging a garden hose around, and you are will¬
ing and able to undertake this project on your
own, you will have to prepare a plan.
First, consider the areas to be watered.
Small areas may be designed to be activated
manually and may include above-ground pip¬
ing and sprinkler heads. Drip systems can
John Stinson is a graduate of the CSU Landscape
Horticulture Design program. He owns and oper¬
ates Colorado Design Group. John is president
of the Denver Chapter of the Associated Land¬
scape Contractors of Colorado, is first vice-presi¬
dent of its state board and is on the board of
42 Xeriscape! Colorado
even be tied into an existing outside hose bib
for water supply (like old-fashioned hose
watering, except the hose, or pipe, is fixed in
place.) Drip systems can also utilize drip or
bubbler emitters placed along small-diameter
plastic pipes that are routed near each plant.
Each emitter delivers V2 to 2 gallons per
hour. Because of this precisely delivered, low
flow of water, drip irrigation has the advan¬
tages of: 1) being more water-conserving than
sprinklers (less water lost to evaporation,
wind, and runoff); 2) encouraging fewer weeds
in the planting bed (water is only delivered to
the desired plants), and 3) lower cost than an
underground sprinkler irrigation. It is not a
panacea, though. The primary drawback is
that drip irrigation requires more concerted
maintenance in keeping emitters unclogged,
especially since the emitters are less visible.
More complete systems may include
below-ground piping, permanent plumbing,
advanced multi-use controllers (timers), and
automatic rain and soil sensors. There is, of
course, a whole range of options in between
these types of systems. You will customize
yours according to your specific desires. Be
aware that any outside irrigation that is con¬
nected to your potable water supply must
have a properly installed backflow prevention
device to protect your drinking water from
contamination.
Do not hesitate to consider modifying
existing or planned landscape areas to better
accommodate an irrigation system. All sprin¬
kler heads and emitters have a specific opti¬
mum distribution radius (head spacing) that
will maximize their performance and mini¬
mize water waste. In general, try to avoid
narrow strips, small angles and small island
areas which are completely surrounded by
plants with different watering needs.
Look particularly closely at any turf areas
you wish to include. Existing lawns that are
hard to water, have lots of run-off onto paved
areas or continually show stress or wear will
not be significantly improved by a sprinkler
system. These areas are prime candidates for
planting conversions or renovations. Consider
how each area might be better utilized. Easy-
to-water areas tend to be relatively flat, large
(8' or wider) and simply shaped. Many times,
small changes in lawn areas or planting beds
will allow for great water economy, improved
appearance and lower maintenance.
After you have decided on a workable lay¬
out for your plantings, you will need to record
it in a scale drawing. Then you will need to
develop a detailed irrigation plan that relates
to it. This work can be accomplished, also,
with the aid of a professional irrigation de¬
signer who can determine the best use of the
myriad irrigation products available for your
specific needs. By accurately zoning your sys¬
tem in relation to planted areas you or a pro¬
fessional designer can ensure the most efficient
and cost-effective layout for your irrigation.
Most designs will include an itemized
parts list for your shopping convenience.
Some design outlets even offer helpful instal¬
lation classes.
Information resources for design services
include local hardware stores and building
centers, plant nurseries, garden centers and
your local landscape contractor association. In
addition to your scale drawing your designer
will request information on the size of the
water line to your house and the static line
pressure (city water service) or holding tank
size, pressure and recovery rate (well water
service). Have them explain this to you.
If you should decide to design your own
system, be sure to have it checked over by a
professional. The most common error in do-it-
yourself systems is to give in to the urge to
economize by “stretching” the system, that is,
by spacing the sprinkler heads too far apart
or adding too many heads to a zone. This is
false economy and will result in a poor substi¬
tute for a professionally designed sprinkler
system. Don’t hesitate to ask for help at your
sprinkler parts supplier. If they are unwilling
or unable to help, find another who’s willing to
spend the necessary time.
Before you begin construction of your sys¬
tem, make sure you have carefully scheduled
the work on paper. Allow for delivery or pick¬
up of all the parts and for any portion of the
work that is being contracted to be completed
well in advance of your own work dates.
Make sure that any rental equipment is
reserved and ready to go. Also, allow for rain
delays and late arrival of parts or helpers.
The parts for an average complete auto¬
matic residential sprinkler system will fit into
a compact pick-up truck and will take approx¬
imately 30 minutes to load and unload.
The work that you may want to consider
contracting includes installation of a tap (cop¬
per pipe and brass fittings), the manifold
(PVC pipe, gluing and valves), the controller
(electrical wiring connected to valves) and the
trenching.
The previously mentioned sources of infor¬
mation will be able to refer you to reputable
contractors for these jobs. Require proof of lia¬
bility and workman’s compensation insurance
before allowing any paid workers of these con¬
tractors on your property.
Rental equipment may include a trencher.
A hydraulic, walk-behind model rents for
about $150 a day. You may also rent cleaning
shovels, a torch and boring tools for reaching
areas that are accessible only by going under
pavement.
With careful planning and use of readily
available resources a do-it-yourself irrigation
system can become a delightful reality. While
not for the feeble or faint of heart, this seem¬
ingly daunting challenge can become a week¬
end project that is surprisingly simple. It will
provide years of benefit to your landscape.
Just be sure to take advantage of professional
services available, remain calm and patient
and be open to a great learning experience.
43
Right, Kentucky coffee tree
(Gymnocladus dioica )
showing its yellow fall
foliage and light grey bark
Below, left and right,
before and after photos
show a septic field installa¬
tion that has been reseeded
with plant species collected
from the surrounding site.
(See story p 46.)
A NO-Water Garden ?
Connie Ellefson
Water-wise gardeners are frequently cau¬
tioned that they will need to water their
newly installed landscape plants with some
regularity until they are established. While
this is usually true, dryland gardeners will be
delighted to learn that, even in Colorado, it is
possible to establish a no-water native plant
garden right from the start.
Owners of a vacation cabin in the foot¬
hills west of Denver faced the unique oppor¬
tunity of putting in a new landscape with no
water supply available whatsoever. With the
help of their landscape architect they were
able to fashion a beautiful foothills landscape
featuring native plants such as ponderosa
pine, chokecherries, currants, gaillardias,
penstemon, liatris, linaria and native grasses.
However, a combination of know-how, excel¬
lent timing and patience was necessary.
Grass and flower seeds collected from the
site or purchased to replicate the indigenous
vegetation were sown in late fall and mulched
with straw to control erosion and conserve
moisture.
Other materials that have been used are
jute netting, excelsior blankets and other bio¬
degradable fabrics that decompose after the
first or second season. (Fine plastic netting is
not recommended because animals can get
tangled in the material.) In the spring, seeds
germinated when the weather was warm
enough, taking advantage of the accumulated
winter moisture retained by the mulch.
Connie Ellefson is co-author of Xeriscape Gar¬
dening, Water Conservation for the American
Landscape. She is also a partner in Western
46 Polyacrylamide.
Shrubs, including some natives propagat¬
ed in nurseries and some transplanted from a
condemned section of the property, were plant¬
ed as soon as the soil could be worked in early
spring. In this way they had a high soil mois¬
ture content to draw upon, and the longest
possible to establish themselves before the
next winter.
The resulting landscape fits unobtrusive¬
ly with its surroundings. Despite the difficult
planting conditions only 25 percent of the
plants died, an acceptable percentage for
these conditions.
Gardeners interested in taking up the
challenge of establishing a no-water land¬
scape need to be aware of the risks involved.
Patience is not only a virtue, it’s a necessity!
It may take two or three years for the land¬
scape to become fully established. Weather
may blow, wash away or dry up the plants
before they are established. Some native grass
seeds are also extremely slow to germinate.
This is part of their survival mechanism;
nature reserves some of the seeds to germi¬
nate later, in case the first wave of seedlings
fails to survive a summer with little or no rain.
In working to develop a no-water garden
it’s essential to use species that grow on or
near the site. For maximum establishment,
native plant experts recommend the use of
plant genotypes that grow within a hundred
miles of the site’s locale. In this way we also
encourage the continuation of truly native
species. It is otherwise unethical to remove
plants from the wild unless the area has been
condemned. And, of course, it is necessary to
get permission from the landowner before
removing plants, even on condemned land.
Seeds may be gathered from existing
native plants, but this takes considerable
planning, good timing and a familiarity, with
the seed-setting cycle of each plant. The Col¬
orado Native Plant Society recommends that
unless one is an expert, it’s better to purchase
seed from reputable local dealers.
Soil preparation for native plants in no¬
water landscapes is simpler than tilling the
soil and incorporating maximum amounts of
organic matter, as is nearly always recom¬
mended in traditional gardening. Many native
plants are adapted to very poor soil, and put¬
ting them in an enriched soil environment
will most likely encourage leggy, spindly
growth that is prone to insect infestation and
disease. In the case of the two most prevalent
native grasses used for seeding in Colorado,
buffalo and blue grama, fertilizer is not rec¬
ommended.
Tilling also brings out the bane of all gar¬
deners, weeds! Tinning over the soil exposes
thousands of weed seeds to the warmth and
sunlight they have been waiting for to germi¬
nate. To establish stands of either wildflowers
or native grasses it is worthwhile to disturb
the soil as little as possible. Instead it is rec¬
ommended to merely scratch the surface,
spread the seeds, scratch it again, mulch, and
water (if possible) or wait for rain to enhance
germination.
For trees and shrubs, water-thrifty gar¬
deners will again forego traditional advice to
work in as much organic matter as possible
into limited planting holes. Considerable
research now shows that this technique serves
to limit the growth of the plants, because the
roots tend to remain in the planting hole
instead of growing into the surrounding soil.
It is now advised to simply loosen the soil in a
fairly wide circle around the plant, up to five
times the diameter of the root ball.
The challenge of establishing a no-water
garden is that it requires much more thought
than establishing a traditional landscape.
One must also be willing to abandon tradi¬
tional methods of installing plants. But less
can be more. For many of us, this is what
makes water-wise gardening so much fun!
47
Soil — The Living Sponge
Gary Finstad
Unless you’re a devoted gardener, mud
wrestler or child under six, you probably don’t
consider soil a major factor in your life. But, of
course ... it is! Soil is the ‘living sponge” that
supports much of the life on our planet.
Landscape design and management tends
to focus on above-the-ground aesthetics: the
sizes, shapes, colors, textures and arrange¬
ment of plant materials in the landscape. Yet,
what happens underground — silently, out of
sight — really determines how healthy, vigor¬
ous and water-efficient our plants and land¬
scapes are.
Good soil literally “breathes” life into our
plants and makes efficient water manage¬
ment for lawns and landscapes possible, sav¬
ing not only water and money, but time and
energy, as well. A small investment in the
health of the soil should be regarded as an
irresistibly lucrative business deal.
How do you ensure your soil is “healthy?”
First, dig a hole into the soil and get to know
it. You can dig anywhere on a new home site.
If your home is already landscaped, select a
spot in your lawn. Grab a spade and dig a
hole at least 18" deep. Make observations as
you dig.
If your first observation is that you’ve hit
concrete, don’t despair; you’re learning! You’ve
just discovered something about “soil depth.”
Once you get deeper, look closely at the
upper 6" to 8". Much of your applied water
and plant nutrients are stored and used in
Gary Finstad is Lakewood Field Office district
conservationist for the Soil Conservation Service
of the United States Department of Agriculture.
this zone. The healthier the soil, the greater
the depth of root growth and soil water stor¬
age.
On a new home site, there probably is no
“topsoil.” Topsoil is not always “whatever it is
on top.” Topsoil is, strictly speaking, the
uppermost, organically enriched and biologi¬
cally active layer of a natural soil. It’s home to
billions of living organisms, most of which are
busy recycling organic matter like dead leaves
and lawn clippings into nutrients, eventually
making them available to your plants.
With only a few exceptions, Colorado soils
lack organic matter and have, naturally, only
2" to 6" of topsoil. A new home site will nearly
always need additional organic matter. Ignor¬
ing this fact is foolhardy, for the return on a
dollar invested in soil improvement is greater
than anywhere else in the landscape — and
the penalty for omission can be severe. A
property owner will forever be cursing him¬
self, or his predecessors, for the time, money
and trouble required to care for half-hardy
plants in an unhealthy soil.
Organic matter, as it is converted into
humus by soil microorganisms, improves “soil
structure.” Structure is the way individual
soil particles group themselves. Good struc¬
ture promotes efficient circulation of water
and air within soil. This is important because
an average soil is about 50 percent pore
space — sometimes occupied by water and air,
(see chart). Creating and maintaining good
soil structure is the most important key to
successful landscape maintenance.
Most clay soils lack good structure and,
even though they have more total pore space
than sandy soils, the pores are tiny and it’s
49
difficult to get water to soak in. It’s also diffi¬
cult to dry clays out once they are wet. This
isn’t good because plants suffocate or drown
in waterlogged soil.
Your soil examination will reveal infor¬
mation about another important characteris¬
tic: soil texture. “Texture” refers to the rela¬
tive proportion of sand, silt and clay particles
in a soil. Sand particles are easily seen. Silts
are so tiny they feel like flour. Clays are even
smaller — microscopic — and they lay flat
against one another like matted leaves.
When we refer to soils as “sandy,”
“loamy” or “clayey,” we’re actually talking
about texture. Different textures “feel” differ¬
ently. They also possess different chemical
and physical properties. Sands are easy to
work, but are nearly sterile and drain quickly.
Clays are difficult to work, but are very chem¬
ically reactive. Clays can lock up nutrients
and water in mineral bonds, holding them
against a plant’s needs.
Soil texture can help you determine how
often to irrigate and how much water to
apply. Sands accept water readily, but don’t
store much. Clays accept water slowly, but
hold it tightly.
To test for texture, simply moisten a small
amount of soil and squeeze it in your hand.
Sandy soil is noticeably gritty. It won’t hold
together very well. Clayey soil is very sticky
and smooth. It will form a ribbon that won’t
break apart. Loamy soils are in between.
Loams possess some clay, but are domi¬
nated by roughly equal proportions of sand
and silt particles. They are slightly sticky
(clay), yet slick (silt.) You’ll be able to feel
some sand, too, and they hold together
pretty well. Loams are the soils which
tend to be best for most plant growth
as they are generally fertile, accept
and hold large amounts of water and
air and are easily worked.
This doesn’t mean, though, that
you should add sand to a clay soil to
achieve a better texture. Remember,
clay and a little bit of sand are the ingre¬
dients for bricks, only slightly harder than
50 what you might already have. The addition of
organic matter at a rate of three cubic yards
per 1,000 square feet is recommended in Col¬
orado to improve any soil’s texture and
water/air holding capacity.
Soil under existing landscape plants can¬
not be easily improved. It may take a long
time, but it can be done! Good landscape
management practices — regular core aera¬
tion, appropriate fertilization, proper lawn
mowing and watering, top dressing with
organic matter — will, over time, encourage
deeper and better root systems. As organic
matter — living roots or decomposing tissues —
increases, so will biological activity. Soil struc¬
ture and the pore space network will gradual¬
ly improve, making irrigation and yard care
easier.
It’s important to remember that the health
and vigor of our plants is largely determined
by what’s happening underground. Dig a hole
once in a while to see where the roots are grow¬
ing and how deeply the water penetrates.
Also remember how important microor¬
ganisms and earthworms are in the recycling
of organic matter and nutrients in soil. Indis¬
criminate or repeated use of pesticides and
concentrated fertilizers may decrease or even
eliminate this life. Use them sparingly and —
always — according to the directions on the
label.
Mud Pie
Composition of a healthy soil
Composting— Ultimate Recycling
Cal Kuska
People who know the value of compost in
their gardens and on their crops have for
years made it in a comer of their yard or
beside the feedlot. Compost is most often val¬
ued for its ability to enhance root development.
Research supports this thinking, showing
growth up to 1,000 times more efficient than
plants grown in depleted or chemically treat¬
ed soils. Other benefits of compost include
reduced need for irrigation, greater availabil¬
ity of essential nutrients, neutralization of
toxins and enhanced soil warm-up in spring.
Other advantages include enhanced plant
color, longer shelf-life of vegetables, reduced
levels of nitrates in root crops, conservation of
petroleum products used to produce fertilizers
and reduced use of a non-renewable resource,
peat moss. Using compost replaces the need
for imported peat moss or local wetlands peat
which is non-renewable because it is 4,000 to
10,000 years old. And, more recently, we have
become aware that 80 percent of the U.S.
landfills will be full by the year 2010. A home
composting program can divert from 400 to
650 pounds of waste per household per year
from going to a landfill.
Mother Nature has been our composter
for centuries, but this natural process is too
slow to be effective in our rapid-paced society.
Raw compost, such as whole leaves, grass,
food scraps and raw manures should be
Cal Kuska is the owner of Kuska/Associates,
Denver, Colorado. He has been involved interna¬
tionally in home and large-scale composting for
20 years.
avoided as soil builders. Such materials rob
nitrogen and other necessary nutrients from
plants and soil while it is undergoing its slow
decomposition process. Finished compost, on
the other hand, is rich in humus, and readily
available for use by plants.
Normally anything organic can be com¬
posted. If your neighborhood has rodent con¬
trol measures, back yard compost units can
accept food scraps (minus bones, meat, dairy
and fatty foods) leaves, coffee and tea grind¬
ings, dead grass or green grass in thin layers,
small pieces of paper without biodegradable
printing inks, and wastes from the garden.
Home built composters and compost piles
are more and more being replaced by factory-
built, controlled atmosphere bins. These bins
usually come with complete instructions,
guarantees, aeration tools, rodent-proof sides
and lids, and colors that absorb the sun’s
heat. These bins, with research and experi¬
ence behind them, produce a product using
either a “batch” or “continuous flow” process
that takes only four to eight weeks, rather
than a year or more.
There isn’t another home-generated waste
that has a better chance of being recycled than
yard wastes. And by keeping kitchen waste
from the sink disposal we save not only water
but energy at the wastewater treatment plant.
The balance stays out of the landfill, saving
truck fuel, landfill space and potential ground-
water pollution.
So take up the challenge: Think globally,
compost locally!
51
Much About Mulch
Robert Cox
Mulch is a material placed on top of soil
to inhibit weeds, reduce evaporation of soil
moisture, moderate soil temperature, outline
shrub beds and other planting areas, and pro¬
vide color and texture.
Take notice on your next mountain hike
of all the pine or spruce needles and aspen
leaves layered on the forest floor. These natu¬
ral mulches keep soil conditions under the
mulch optimal for the plants growing there.
The soil is moist and loose, air and water
freely enter the soil, erosion is reduced and
weed competition is minimized.
We can imitate natural forest conditions
in the urban landscape by using mulches.
Along with proper planting and watering
practices, mulching is one of the most benefi¬
cial things we can do because it retards evap¬
oration from the soil beneath, so watering is
needed less frequently. It is an especially
water- wise practice!
The ideal mulch permits air and water to
penetrate into the underlying soil. It is non¬
toxic to plants, attractive, easy to apply, and
free of weed seeds and disease organisms. It
doesn’t wash away easily in heavy rains or blow
away in high winds and it doesn’t ferment or
bum easily. Mulches are either organic or
inert (inorganic).
The most commonly available organic
mulches in our region are grass clippings,
leaves, pine needles, chunk bark, pole peel¬
ings, straw, hay, wood chips and shredded
wood. Some areas have other materials such
Robert Cox is the Jefferson county extension
agent, horticulture, for the Colorado State Univer-
52 sity Cooperative Extension.
as apple pomace, spent brewery hops or
cmshed corncobs as by-products of local agri¬
cultural processing industries.
Note that aged manure, sawdust, peat
moss and compost aren’t listed. These materi¬
als are better used as soil amendments,
mixed into existing soil to improve its texture,
rather than as surface mulches.
Grass clippings can mat down and fer¬
ment if applied too thickly while fresh. They
should be used in thin layers and allowed to
dry before adding more. They are often better
when mixed with another organic mulch. If
mowing is sufficiently frequent, clippings are
best left on the lawn, to decompose and release
nutrients back to the lawn.
Leaves can similarly become matted into
a slimy mass if used fresh in thick layers. If
dried and shredded, they make a good mulch.
If a shredder is not available, a power mower
run over small piles of dry leaves will work.
Pine needles make an attractive mulch,
but one which can be a fire hazard. Some peo¬
ple worry they will make the soil “too acid.”
Pine needles may be acidic, but Rocky Moun¬
tain soils are generally alkaline and resistant
to drastic or quick change. Pine needles may
be difficult to obtain in large quantities. One
should not attempt to collect pine needles
from public or private lands. Remember, they
are mulch for the trees that dropped them.
However, if you have friends who rake up
pine needles and bag them for landfill dispos¬
al, why not intercept them?
Chunk bark of various sizes is sold by the
bag at garden centers. It is usually ponderosa
pine bark, a by-product of logging. A lumber
Left, close-up of bur oak leaves
Below, prairie zinnia ( Zinnia grandi-
flora ), Verbena tenuisecta and sage¬
brush ( Artemisia )
>• 'i
mill might have bark for sale, but it may be in
larger chunks or strips.
Pole peelings appear bke whittlings, and
are the left-over result of trees harvested for
exposed beams or construction logs. They
interlock nicely and make good informal
pathways, but they will compact and with
time rot.
Straw or hay bales can be broken up and
applied as a mulch. However, they may con¬
tain weed seeds. Wet or moldy bales may be
less expensive and are still fine for mulch.
Straw or hay mulch becomes flammable and
easily windblown if it dries out. They can also
be dusty to apply; a nuisance dust mask helps
avoid inhalation of the fine particles.
Wood chips or grindings can be obtained
from tree services or municipalities with a
chipping operation. Pruned branches and
“treecycled” Christmas trees are run through
a chipper, shredding them into various sizes,
mostly V2" to 3" in diameter. They make a
very good mulch that doesn’t readily blow or
compact. Appearance, though, varies.
Newspapers can be an effective mulch
when laid down about ten sheets thick in over¬
lapping fashion. To prevent blowing, cover the
paper with three to four inches of one of the
other mulches, such as wood chips. This is a
very effective method for eliminating unwant¬
ed turfgrass or weeds. The newspaper smoth¬
ers them and decomposes, leaving the overly¬
ing mulch in place. After two or three months,
trees, shrubs or perennials can be planted in
the area.
the soil. To prevent this, surface fertilize with
a half pound of ammonium sulfate (21-0-0)
per 100 square feet of mulched area. Top lay¬
ers of organic mulch may weather to a grey¬
ish color; this and decomposition of lower lay¬
ers may necessitate adding a thin topdressing
of the mulch every two or three years.
Inert and inorganic mulches include stone
and gravel, often used in conjunction with
plastic sheets or various weed barrier fabrics.
The use of plastic sheeting alone, or under
other mulches is not recommended. Unperfo¬
rated plastic does not allow water or air to
enter the soil beneath it. Plant roots covered
by plastic tend to develop in a thin layer just
underneath the plastic on the soil surface, in
an attempt to get sufficient oxygen. In the
summer, these shallow roots are exposed to
excess heat and to cold in the winter. Such
shallow-rooted plants may blow over in high
winds.
Think of the soil as a living, breathing
organism. Don’t cover large areas of soil with
sheet plastic. A good alternative to plastic is a
weed barrier fabric or “geotextile.” While
more expensive, these allow water and air
into the soil and still reduce weed growth.
However, most weed barrier fabrics must be
covered with a mulch, as they degrade in sun¬
light. On steep slopes, mulches other than
rock may not hold well on the fabric surface,
especially during heavy rains.
The bottom layer of organic mulches, in
contact with the soil, slowly decomposes. Be¬
cause most organic mulches are low in nitrogen,
the decomposers may take up nitrogen from
Approximate quantity of various nitrogen fertilizers required to counter¬
act the nitrogen-depleting effect of a bushel of average fresh, dry sawdust.
Nitrogen source
Nitrogen content (percent)
Quantity required per bushel (pounds)
Ammonium sulfate
21.0
1.2
Ammonium nitrate
33.5
.8
10-6-4 fertilizer
16.5
2.7
5-1 0-5 fertilizer
5.0
5.0
Mulch — More Pros & Cons
Curt Swift
Organic mulches have been reported to
reduce problems with soil compaction and
fluctuating soil moisture content. Also, they
have been shown to reduce soil pH, (by in¬
creasing acidity, reducing alkalinity) a benefit
most of our plants appreciate. A mulch of
chips is even used as a “soft surface” to pre¬
vent personal injury in playgrounds.
The development of fine absorbing roots
and the number of roots infected with benefi¬
cial symbiotic mycorrhizae increases in and
under organic mulch, allowing plants increased
access to nutrients and water. When organic
mulch has been used to replace turfgrass,
iron deficiency problems can also be reduced.
The benefits of organic mulch are many,
yet disadvantages do exist, notably the in¬
crease in garden pests. Slugs, earwigs, pillbugs
and sowbugs, cutworms and other plant feed¬
ers take refuge in the moist conditions found
in and under organic mulch. While a mulch of
sand usually does not provide a good habitat
for these critters, gardeners who use rock
mulches find these pests to be a problem.
Allowing turf to grow under trees or
shrubs has proven detrimental to root growth
of these woody plants, and can speed the
decline of plants already suffering from iron
chlorosis. Replacing this turf with an organic
mulch increases root development and top
growth and often reverses chlorosis problems.
This also prevents what is called “lawn-mower-
itis,” mechanical damage to tree and shrub
bases.
Curt Swift is an area extension agent specializ¬
ing in Horticulture for the Colorado State Univer¬
sity Cooperative Extension, Tri River Area.
Yet the replacement of turf with mulch is
sometimes more harmful to the tree or shrub
than if the grass was left in place. Using a
shovel, sod cutter or hoe to remove the turf
can damage the shallow roots of woody plants
and result in root rot or death. Eliminating
the grass by suffocating it with sheets of black
plastic or multiple layers of newspaper can
also increase root diseases of trees and shrubs
and is likewise not recommended.
It is better to spray the turf with an her¬
bicide designed to kill grasses, being careful
to avoid direct contact with trees or shrubs,
then allow the grass to partially decompose
before installing the mulch. Placing a thick,
loose layer of mulch over the grass also will
kill turf, apparently without the problem of
suffocation. Oxygen is still be able to reach
the soil and roots. If this layer is insufficient,
though, the grass may be even more difficult
to remove.
Most tree and shrub feeder roots grow
within the top 18" of the soil surface. Growth
of these roots is inhibited by compacted soil,
low oxygen levels and extreme moisture and
temperature fluctuations. Once a tree, shrub
or other perennial is established in the ground,
little can be done to amend the soil without
damaging roots.
A layer of organic mulch can improve this
rooting environment by increasing infiltra¬
tion, reducing evaporation and increasing soil
organic matter. Mulch can also act as an insu¬
lator, buffering the soil from rapid tempera¬
ture changes and extremes.
This improvement of the soil environ¬
ment has been shown to increase top growth
of trees, as compared to trees grown in bare
56 Gaillardia in a wildflower plot at the Denver Botanic Gardens
soil. Many new tree roots grow into the
mulch, sometimes in higher density than in
the soil itself. Silver maples and crabapples,
especially, take advantage of mulch. Thus,
these two species would benefit most readily
from the mulch and would suffer the most
severely if the mulch were removed for any
reason.
Gardeners in areas where the snow cover
disappears quickly find that their spring flow¬
ering bulbs emerge early and the flower buds
get nipped by frost. A layer of loose organic
mulch, applied after the ground freezes in the
fall, keeps the soil cold thus slowing emergence.
This same layer will help reduce soil moisture
loss during the winter and early spring months.
Dry soil in early spring can result in the pre¬
mature budding of woody plants as well.
Reduced plant growth that generally fol¬
lows an application of uncomposted sawdust
has caused some gardeners to suspect that
wood wastes contain toxic materials. Studies
show, however, that except in rare cases,
wood- waste (such as black walnut and oak)
mulches are not toxic to plants when used in
usual quantities and with supplemental
nitrogen.
The oxygen that roots require must enter
through the soil surface; any material cover¬
ing the soil can interfere with that supply of
oxygen. If applied too thickly, organic mulches
can keep oxygen from reaching the underly¬
ing roots of trees and shrubs and cause suffo¬
cation. Researchers recommend that mulches
be carefully selected to assure adequate air
and water penetration anytime it is to be
used more than four inches deep. Mulch
should not be in contact with the bark of trees
because decay and rodent damage can result.
Some homeowners opt to cover the entire
landscape with gravel. Usually, the hoped-for
savings on water bills and maintenance time
is offset by higher cooling bills and other prob¬
lems. Vast expanses of gravel also promote
heat gain, which can be beneficial if appropri¬
ately placed. Such “rock-scapes,” however, are
generally monotonous and can reduce the
value of your home. Some judicious use of
rock can be very effective. Cobblestones, for
example, can be used to create an attractive
“dry streambed.”
Turfgrasses near hot rock mulch areas
dry out quickly and are more susceptible to
attack by Ascochyta and dollar spot fungi.
Mites are also a serious problem on turf next
to rock mulch, and turf areas that warm up
early in the spring are more prone to damage
from white grubs, sod webworm and other
turf insect pests.
Soil under rock mulch can be five degrees
warmer than under wood chips, and seven
degrees warmer than soil under a mulch of
corncobs. This increase in soil temperature
can be beneficial in areas where a quicker
spring warm-up is desired, but in the warmer
areas of the Rocky Mountains such an increase
can restrict root development and reduce
water and nutrient uptake.
Types of Mulches
Mulch Type
Cocoa-bean hulls
Crushed corncobs
Grass clippings
Leaves
Peat (sphagnum)
Pine needles
Sawdust
Advantages
Long-lasting, dark color.
Uniform in color.
Readily available.
Readily available.
Attractive.
Attractive, often available, do not compact.
Attractive.
Shredded bark Long-lasting and attractive.
Straw Readily available.
Wood chips Long-lasting.
Gravel & stone Readily available.
Disadvantages
Tendency to compact, expensive.
Retains too much moisture, compacts.
Must be applied loosely, may mat.
Not very attractive.
May crust, expensive.
Fire hazard.
May crust if uncomposted,
needs nitrogen supplement.
Often expensive.
Blows easily, flammable, can contain
weed seeds.
Not uniform in size or color.
Traps/reflects heat.
57
How the Fit Survive
Ray Daugherty
Plants have become adapted to living
nearly everywhere on earth. The myriad
forms we see, enjoy and use in our gardens
are their unique methods of adapting to the
challenges of their every environment. This
adaptation, through evolution, is responsible
for some of the most curious and beautiful
attributes that endear plants to gardeners.
Evolutionary strategies for surviving
periodic or prolonged drought are among the
most interesting — and important — plant
adaptations. Most such plants are placed in
the broad ecological category of xeriphytes:
literally, dry plants.
“Xeriphyte” and “xeriscape” are not synon¬
ymous. A xeriphyte is a plant that has, through
evolution, modified its structure or life cycle to
survive, endure or escape drought until mois¬
ture becomes available. Xeriscape, on the
other hand, is the use of good, water-conscious
gardening practices that reduce the amount
of water used in a landscape. Xeriscape does
not require the use of xeriphytes.
As a gardener, take up the challenge.
After a fresh look at xeriphytes, their water¬
saving and ornamental value, you will begin
to incorporate them into your landscape.
Perhaps the most common way plants
conserve water is by the modification of their
leaf surfaces. Some, such as lamb’s-ears
(. Stachys byzantina ) or silver sage ( Salvia
argentea) have evolved hairy leaves. This
pubescence reduces water loss in two ways. It
shades the leaf surface, reducing heat load on
the leaf and a consequent need for cooling by
Ray Daugherty is plant propagator at Green
58 Acres Nursery in Golden, CO.
transpiration. Also, the hairs act as baffles,
reducing the drying effect of winds.
Such hairy-leaved plants usually appear
grey, blue-green or silvery. In addition to their
water-saving abilities, they break up the usual
sea of garden green and accentuate flower col¬
ors such as pink, red and deep blue.
Other leaf surface adaptations also con¬
serve water. Our native Smith’s buckthorn
( Rhamnus smithii ) and needled evergreens
have developed a waxy coating that acts like
a breathable plastic, allowing the plant to
take in air but inhibiting water loss. Needled
evergreens also have fewer stomata (openings
for the passage of gases, through which the
leaf transpires, losing water) in relation to
their size than plants which need more water.
In the garden these plants provide beau¬
tiful, dark backgrounds for silver plants, such
as sages, and for straw-colored, late-summer
grasses.
Still other plants, such as roundleaf buffa-
loberry ( Shepherdia rotundifolia ) have evolved
a combination of these two coverings, scales.
Many plants have even modified the size
and shape of their leaves. The closer in shape
to a cylinder or sphere a leaf is, the less area
it has in relation to its volume. And, all other
things being equal, the smaller the surface
area of a leaf is, the less water it loses. Many
dryland shrubs, such as brooms, have nearly
cylindrical or spherical leaves, as do sedums.
Leafy succulents, such as stonecrops and
aloes (not hardy here), have taken the oppo¬
site tack, increasing leaf volume in relation to
leaf area. Their greater volume of interior tis¬
sue allows for storage water.
Some plants have the best of both worlds,
wet and dry . They burst into leaf within hours
after a good rainfall, then make and store food
while the moisture is available in the soil.
When their water supply dwindles, they quick¬
ly drop their leaves to avoid transpiration.
Several of our native mountain mahoga¬
nies have adapted another strategy, partial
wilting. The leaves of Cercocarpus ledifolius
and C. intricatus curl under during dry spells.
This reduces water loss from the bottom sur¬
face of their leaves, where the stomata are
arranged. The longer the drought persists,
the farther the leaves roll under.
Stem succulents such as cacti and tropi¬
cal euphorbias have evolved to delegate to
their stems the usual functions of leaves.
Leaves, where present, are ephemeral, drop¬
ping at the first hint of drought. This necessi¬
tates special morphologies and a completely
different way of performing the major process
of a leaf, photosynthesis.
Simply put, during normal photosynthe¬
sis, air (including carbon dioxide) enters the
leaf through its stomata; carbohydrates are
manufactured; and excess water molecules,
oxygen and other gases exit. This usually
takes place in sunshine, just when dryland
plants can least afford to open their stomata.
In the heat of the day they risk losing not only
excess water but tissue moisture as well. But
by a process called crassulacean acid meta¬
bolism, some plants are able to delay photo¬
synthesis until nighttime, when it’s cooler.
During the day the sun’s energy is stored in
acid molecules, while the leafs stomata are
closed. The stomata open at night to permit
the requisite transfer of gases and, through
chemical change, the acid molecules release
the stored energy, facilitating photosynthesis.
Nearly all gardeners are familiar with
plants that store the bulk of their water sup¬
ply away from sun and wind in swollen, more
or less underground root, leaf or stem systems
known as bulbs, conns, tubers or rhizomes.
The stored water and carbohydrates support
the plant in its natural period of “dormancy,”
which coincides with annual drought. Tulips,
crocuses, cyclamens and our native sandlilies
(. Leucocrinum montanum ) and sego lilies
( Calochortus spp.) are examples.
Other plants store water and nutrients
underground in a structure called a caudex, a
combination of stem and roots. So large and
efficient is this structure that the leafy stems,
leaves and flowers that rise from the top of
the caudex may be found flourishing even in
years when all the surrounding vegetation is
parched from lack of rain. It is not unusual
for a caudex to attain the size of a person’s leg
and extend 10' to 15' underground. Native
examples, excellent for dryland plantings, are
bush morning glory ilpomea leptophylla )
desert four-o’clock ( Mirabilis multiflora) and
buffalo gourd ( Cucurbita foetidissima) .
The most common adaptation for surviv¬
ing drought is also the least recognized: pro¬
duction of an overabundance of seed. Plants
who take advantage of this phemonenon are
called teliophytes.
59
Resources
Chris Call
Demonstration Xeriscape Gardens
Arvada: City of Arvada Public Works Center
(303) 420-0984, 6161 Olde Wadsworth Boule¬
vard, east side of building. One acre, featur¬
ing two turf types and 50 labelled plant species.
Boulder: Boulder Creek Xeriscape Garden
(303) 441-3416, West of the Justice Center at
6th and Canyon streets. Quarter acre, featur¬
ing six turf types and 75 species of plants,
including herbs. Interpretive signs with iden¬
tified plants.
Boulder: Chataqua Park Ranger Station
(303) 441-3416, 9th Street and Baseline, west
of the paved road. 300 square feet of labelled
native perennial flowers and shrubs.
Castle Rock: Douglas County Executive
Building (303) 688-3096, 101 Third Street.
1,500 square feet, featuring one turf area and
about 75 labelled plant species.
Chatfield Arboretum: Xeriscape Demonstra¬
tion Garden (303) 973-3705, P2 mile west of
Wadsworth Boulevard on Deer Creek Canyon
Road. Two and one-half acres, with over 150
labelled plant species. Emphasis is on wildlife
habitat, residential design and readily avail¬
able plants.
Colorado Springs: Mesa Water Treatment
Plant (719) 636-5407, 2855 Mesa Road. One
and three-quarters acres, with over 150
species of plants, including 71 species of
natives. Interpretive signs and plant labels.
Denver: Denver Botanic Gardens (303) 331-
4000, 1005 York Street. Quarter-acre garden
Cris Call is conservation specialist with Denver
Water and the voice of Denver Water's conser-
60 vation hotline.
featuring two turf types and about 150 species
of labelled plants.
Denver: Denver Water Department (303)
628-6343, 1660 West 12th Avenue. Quarter
acre, featuring six turf types and 90 species of
plants. Interpretive signs and plant labels.
Different plant regions are zoned and
equipped with water meters to show different
water requirements.
Fort Collins: Fort Collins City Hall (303) 221-
6681, 300 LaPorte Avenue. One-third acre,
including three turf types and over 100
labelled plant species. Different plant regions
are zoned and equipped with water meters
for comparative purposes.
Longmont: Longmont Public Library (303)
651-8348, 3rd and Kimbark, south side. 400
square feet, with two turf types and about 50
labelled plant species.
Westminster: Semper Water Treatment
Plant (303) 430-2400, 2 acres, featuring 6 turf
types and 75 plant species with labels.
Other Resources
Organizations
American Society of Landscape Architects,
Colorado Chapter (303) 830-0094
Associated Landscape Contractors of
Colorado (303) 425-4862
Colorado State University Cooperative
Extension Service:
Adams County
Arapahoe County
Boulder County
Denver Comity
Douglas County
(303) 659-4150
(303) 730-1920
(303) 776-4865
(303) 692-5600
(303) 688-3096
Jefferson County (303)
Denver Botanic Gardens (303)
Denver Water Conservation
Hotline (303)
The Irrigation Association (303)
Metro Water Conservation, Inc.
(303)
Videos
Beautiful Gardens With Less Water.
32 minutes.
Produced by: Sunset Films and Television
Lane Publishing Company
Menlo Park, CA 94025
Sunset Waterwise Gardening,
Western Edition.
32 minutes.
Produced by: Sunset Video
Lane Publishing Company
Menlo Park, CA 94025
Xeriscape — Appropriate Landscaping To
Conserve Water.
Approximately 30 minutes.
Produced by: San Luis Video
P.O. Box 4604
San Luis Obispo, CA 93403
Xeriscape — A Quiet Revolution
28 minutes.
Produced jointly by: Denver Water Depart¬
ment and Denver Museum of Natural History
1600 W. 12th Avenue, Denver, CO 80205
2001 Colorado Boulevard, Denver, CO 80254
Xeriscape — Landscaping to Save Water, Time
and Money
18 minutes.
Produced by:Virginia Jensen and Fred
Liljegren
Department of Natural Resources
Division of Water Resources
1636 West North Temple, Suite 310
Salt Lake City, Utah 84116
271-8980
331-4010
628-6343
695-7711
979-2359
i
i i
1
Bibliography
Solange Gignac
All about lawns. 1985. Ortho. San Ramon, CA.
Bailey, Liberty Hyde. 1949. Manual of culti¬
vated plants. Macmillan. New York.
Ball, Ken. 1990. Xeriscape programs for
water utilities. American Water Works Asso¬
ciation. Denver.
Borland, James N. 1987. Native plants of
Genesee and how to use them in foothills res¬
idential landscape design. Genesee Founda¬
tion. Golden, CO.
CSU Cooperative Extension Office. 1989.
Flowering Herbaceous Perennials for the
High Plains. Technical Bulletin LTB 89-5.
Editors of Sunset Magazine. 1988. Sunset
Western garden book, 5th ed. Lane. Menlo
Park, CA.
Ellefson, Connie Lockhart, Thomas L. Ste¬
phens and Doug Welsh. 1988. Xeriscaping
gardening: water conservation for the Ameri¬
can landscape. Macmillan. New York.
Feucht, James R. 1978. Trail of trees. Fair-
mount Cemetery Association. Denver.
Front Range Xeriscape Task Force. 1987.
Source directory for un-thirsty plants. Denver
Water Department. Denver.
Genders, Roy. 1986. The cottage garden year.
Croom Helm. London.
How to xeriscape. 1986. National Xeriscape
Council, Inc. Denver.
Knopf, James. 1991. The xeriscape flower
gardener: a waterwise guide for the rocky
mountain region. Johnson Books. Boulder, CO.
Solange Gignac is the horticultural librarian in
62 the Helen Fowler Library.
Knox, Kimberly, ed. 1989. Landscaping for
water conservation: xeriscape! City of Aurora
Utilities Department and Denver Water
Department. Aurora, CO.
Landscaping for water conservation:
xeriscape. 1989. City of Aurora and Denver
Water Department. Aurora, CO.
Lean, Geoffeiy. 1990. Atlas of the environ¬
ment. Prentice Hall. New York.
MacFayden, David. 1982. A cottage flora.
Webb & Bower. Great Britain.
Morter, Peter. 1982. A cottage flora. Webb &
Bower. Exeter, Great Britain.
Phillips, Judith. 1987. Southwestern land¬
scaping with native plants. Museum of New
Mexico Press. Sante Fe.
Robinette, Gary O. 1984. Water conservation
in landscape design and management. Van
Nostrand. New York.
Taylor’s guide to water-saving gardening.
1990. Houghton Mifflin. Boston.
Thorpe, Patricia. 1990. America’s cottage gar¬
dens. Random House. New York.
Waterwise gardening: beautiful gardens with
less water. 1989. Lane. Menlo Park, CA.
Whitson, Tom D. 1991. Weeds of the West.
The Western Society of Weed Science in coop¬
eration with the Western U. S. Land Grant
Universities Cooperative Extension Services.
Laramie, WY.
Many pamphlets on xeriscaping and
water conservation also are available at your
local library or in the Helen Fowler Library of
the Denver Botanic Gardens.
Give a DBG Membership!
General Benefits for All Members
• Free admission to York Street and Chatfield facilities
• Green Thumb News and Mountain, Plain & Garden magazine
• Discounts on classes and field trips
• 10% discount at Gift Shop and at the Plant & Used Book Sale
• Early admission and special check-out line at the Plant & Used Book Sale
• Free plant upon joining and yearly plant dividend
• Borrowing privileges at Helen Fowler Library
□ The Gardener - $25 — Admits one. One guest pass.
□ The Landscaper - $35 - One card. Admits two. Two guest passes.
□ The Arbor Circle - $50 - Two cards. Each admits one adult, two children; summer concert dis¬
counts; greenhouse tours. Four guest passes.
□ The Botanist Club - $120 - Two cards. Each admits one adult, two children; four individual
summer concert tickets; ticket and merchant discounts; greenhouse tours. Ten guest passes.
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Denver Botanic Gardens
909 York Street
Denver, CO 80206-3799
Non Profit Org.
U.S. Postage
PAID '
Permit No. 205
Denver, Colorado
Mountain, Plain
and Garden
Through our
investigation of
landscape we can
express our sense
of the connected¬
ness of things,
where we stand in
relation to them.
Above all, we come
in touch with
those over-arching
abstractions that
govern our percep¬
tions: the great
and the small,
near and far, up
and down, sharp
and soft, smooth
and rough.
—Wolf Kahn
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Printed on
recycled paper
using soy-based inks
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Dedication:
To Pete Petersen
If you need to find “Pete,” everyone knows
who you are looking for. More formally known
as Bernice Petersen from her bylines in innu¬
merable Green Thumb Magazine articles, she
has been a volun¬
teer mainstay of the
Denver Botanic
Gardens since
before its founding.
She often intro¬
duces herself mod¬
estly as “Populus
tremuloides” but —
to the delight and
enrichment of all
who meet her — her
friendliness and mental brilliance overshad¬
ow her timidity. Dispensing wisdom on native
plants at the Plant & Used Book Sale or
extending a welcome at Chatfield Arbore¬
tum’s visitor center, Pete’s generous smile
encourages questions and exudes friendliness.
Her love of alpine plants long pre-dates
the completion of DBG’s Rock Alpine Garden.
In 1956 she and “Mr. Pete” built a two-story
home on a steep triangular lot at the comer of
Ridge Road and South Windemere in Little¬
ton. Into every crevice and bed the Petersens
tucked exquisite species of native plants,
wildflowers and ground covers. Their yard
abounds with unusual, horticulturally
neglected, Colorado natives.
She was a natural choice three decades
ago to chair the first native plant booth at
DBG’s annual sale. Pete’s knowledge and
enthusiasm have won an avid following of
loyal customers. Her special interest has been
shade-loving plants. Now, to take Pete out of
the shade, the editors dedicate this issue of
Mountain, Plain and Garden to her and
salute our native star!
— Mary Washburne, Chatfield Arboretum
volunteer and former DBG Trustee
Mountain, Plain -gc-
and Garden 'ir
The Magazine of the Denver Botanic Gardens
Volume 50 No. 1 W 1993 m Rock Gardening
Contents
Prelude: The Chamber Music
of Gardening . 3
Thirty Something . 5
Rockwork . 8
Building a Screen Garden . 11
A Garden in Paradise . 16
Urban Alpines . 22
Introducing Alpines into
an Established Garden . 25
Jerry Morris: Colorado ‘Broomer’ . 28
Alpines from Scratch . 31
Prairie Smoke . 34
Stone Faces Well Chilled . 35
Rock Gardening . 36
Bibliography . 39
Front Cover: Lilacs in the next garden echo the laven¬
der color of Phlox bifida in Sandy Snyder's Littleton
rock garden (see page 1 1 ) photo: Sandy Snyder
Back cover: An outstanding marriage of artistic rock
garden design and choice plants is the garden of Ted
Berginc in West Allis, Wisconsin, seen here blooming
in May.
© 1993, Denver Botanic Gardens, Inc.
909 York Street • Denver, Colorado 80206-3799
Richard P. Koeppe, Ph.D., president
Richard H. Daley, executive director
Larry Latta, managing editor
Panayoti Kelaidis, consulting editor
Tom Witte, art director
A continuation of The Green Thumb Magazine • Produced by the Mar¬
keting and Special Events Department of the Denver Botanic Gardens
Denver Botanic Gardens and Chatfield Arboretum are established and main¬
tained by Denver Botanic Gardens, Inc., for the people of the City and Coun¬
ty of Denver and for the general public in cooperation with the Denver Parks
and Recreation Department. Denver Botanic Gardens is grateful for funds
from the Scientific & Cultural Facilities District (SCFD), which enable the
Gardens to expand services and enhance the quality of programs and exhibits.
Prelude: The Chamber Music of Gardening
Norman Singer
Whenever I am asked what the great
attraction of alpine and rock garden plants is,
compared to the pleasures of growing border
perennials and other garden subjects, I fall
back on my past as a producer of concerts and
I make this analogy: Alpines are to perenni¬
als as chamber music is to symphonic music.
The latter is big and noisy and brassy and
highly emotional — good in its place. The
other, the world of alpines and rock garden
plants, is small and quiet and sophisticated
and arouses the emotions by intellect.
For eight years in the ’50s and ’60s, I was
the Executive Director of the Aspen Music
Festival and Dean of its Music School where
we were devoted to chamber music, albeit with
a symphony orchestra on hand as well. It is
the blight of my life that those eight years had
passed before I became interested in, or was
even conscious of, the individual plants of the
tundra and subalpine areas where we would
go for picnics among the “pretty flowers.”
You can imagine what it feels like to
return to Colorado, now thirty years later, as
President of the American Rock Garden Soci¬
ety with its 29 chapters in Canada and the
United States and with members devoted to
chamber music plants in thirty countries
> around the world, and to have one of our flag¬
ship Chapters, the Rocky Mountain Chapter,
hosting our fifty-ninth annual meeting this
year in Vail.
- - - - -
Norman Singer is president of the American Rock
Gardening Society. He gardens in counterpoint
with Geoffrey Charlesworth in Sandisfield, Mas-
sachussetts. The resulting work is a classical con¬
certo of choice alpine plants.
If I was unlucky in my first encounters,
or rather, non-encounters with alpine and
rock garden plants, I have had no such mis¬
fortune with my association with Denver
Botanic Gardens’ Rock Alpine Garden. I first
visited it in 1982, two years after planting
had begun. The area was new and raw and
the rocks were bold in their austerity. Every
few years since, I have re-visited the garden,
and it has been a repeated pleasure and an
education to see the plants increase in size
and number and variety, softening the back¬
ground and asserting their presence against
the now welcoming rocks.
It is not only local visitors who can be
grateful to the garden. In it, plants from all
over the world are tested. The promising sub¬
jects — through seeds, seedlings and cut¬
tings — find their way into the nursery trade,
then into the gardens of avid local and inter¬
national gardeners. Thus the influence of the
garden and its curatorial staff, their expertise
and their generosity are experienced well
beyond its borders. “Hardy in Denver” is a
frequent imprimatur in plant and seed cata¬
logs and it is immediately understood as
referring to Denver Botanic Gardens’ Rock
Alpine Garden.
Many, many gardeners have been in¬
spired to try all kinds of plants, even beyond
the chamber music kind: perennials, ground
covers, conifers too, which they might not oth¬
erwise have been brave enough or adventure¬
some enough to try if it had not been for Den¬
ver Botanic Gardens’ Rock Alpine Garden. We
are grateful to it. Long may it flourish! 3
Below: Heapes'
brilliant arrange¬
ment of Phlox
mesoleuca
'Arroyo', P.
'Chameleon' and
Zauschneria gar-
rettii ushers in a
Colorado
autumn.
Right: In late May
Allium karata-
viense, Delosper-
ma nubigenum,
Dianthus del-
toides and purple
and (rare) white
forms of Aster
alpinus enliven
the outstanding
garden of Robert
Heapes in Park¬
er, Colorado.
Robert E. Heanes
Thirty Something:
People & Plants of the Denver Botanic Gardens Annual Sale
Bernice E. Petersen
Give a man the secure possession of a
bleak rock and he will turn it into a garden;
give him a nine years’ lease of a garden and he
will convert it into a desert.
— Arthur Young
For almost 30 years members of the plant
sale committee at Denver Botanic Gardens
have been striving to deter that man with the
nine-year lease; in addition, those who sell
rock garden plants and ground covers at the
sale have been guiding the man with the
bleak rock.
“The Flowering of Denver,” an appealing
name for DBG’s annual Plant & Used Book
Sale, began as a plant auction on an October
afternoon in 1949 in the Greek Theatre in
Denver’s Civic Center. It was a benefit for the
Colorado Forestry and Horticulture Associa¬
tion, the organization that preceded and even¬
tually merged with the Denver Botanic Gar¬
dens. About 60 individuals and firms donated
trees, shrubs, perennials, supplies and services.
Charlotte (Mrs. Alexander) Barbour and
John Swingle originated the idea. At some
point in his career Swingle, a respected
arborist, had picked up the hobby of auction¬
ing, and, using the approved patter, he
Bernice "Pete" Petersen and her husband "Big
Pete" have been champions of rock garden and
native plants for Colorado gardens for decades,
and invaluable supporters of Denver Botanic
Gardens. Their Littleton home is a testament to
their horticultural passion. "Little Pete" was once
co-editor of DBG's Green Thumb Magazine, pre¬
cursor to Mountain, Plain and Garden.
delighted the patrons, who laughed at him
and with him as he sold the wares. Profits
were $500; donations boosted the total to $850.
Over the years a variety of schemes and
gimmicks were tried. Auctions were staged
behind Horticulture House (CF&HA’s Victori¬
an headquarters at 1355 Bannock St.), at
Cherry Creek Shopping Center, as part of
garden fairs and shows, and finally at Botanic
Gardens House at 909 York St. Profits fluctu¬
ated, but great fun and good fellowship
always prevailed.
Native trees, shrubs and ground covers
were offered for sale for the first time in 1962
at Cherry Creek, but volunteers groaned as
choice unsold plants were auctioned at a frac¬
tion of their value.
In 1964 the sale turned “big time.” Plants
were chosen for their performance in test
plots at DBG and in Denver’s parks. Growers
agreed to grow plants from seed especially for
the sale, then held in the parking lot behind
Botanic Gardens House.
Temporary shade was erected — the previ¬
ous year plants and people had wilted in the
intense sunlight. Volunteers were recruited
from every possible source — garden clubs,
study clubs, Boy Scouts. A panel of experts
helped train the volunteers. A plant sale issue
of The Green Thumb Magazine trumpeted the
virtues of “the best by test” of annuals, peren¬
nials, gladioli and dahlias, and described the
merits of using natives in our semiarid land¬
scapes. Advance orders were accepted, but
once of that proved enough.
Customers came from near and far. The
Gardens were at their blooming best, with
7,000 bulbs in full flower. The event was a
sellout. The auction had been eliminated!
A native plant division that year included
such rock garden standbys as Mahonia
repens, kinnikinnick, pussy-toes, sulphur
flower, Yucca glauca, Y. baccata and Y. harri-
maniae, all from Western Evergreens, a Gold¬
en nursery, and all on consignment.
Our big break came the following year
when Evelyn Johnson, a gardener in the
English tradition and owner of Wheatridge
Nursery, referred us to Alf Jensen. Alf was a
grower whose specialty was cacti but who
could grow any plant for which seeds or cut¬
tings were available. He must have had an
acre of Phlox subulata in various colors, and
he delivered his boxes by the truckload, trip
after trip.
Best of all, when asked for Campanula
garganica and C. muralis, he understood and
later grew C. poscharkyana, C. collina, C.
cochleariifolia and C. turbinata as well. Alf
provided such gems as androsaces, saxifrages,
Carlina acaulis and an assortment of thymes.
By 1966 we boasted 50 kinds of rock gar¬
den plants suitable for a variety of conditions,
from sun-parched slope to a protected shady
nook. The following year, to our horror, the
shade and the enthusiasm of everyone col¬
lapsed with the arrival of a typical spring
snowstorm. Still, the sale grossed $13,000.
During these early years, a few nursery¬
men had protested the DBG plant sale. They
thought it competed unfairly with their sales.
Among them was Mr. Paul Hoy of Iliff Gar¬
dens Nursery. He later became one of our
closest allies, and rock gardeners are forever
indebted to him: he sold us our start of the
charming native Aquilegia saximontana, the
Rocky Mountain dwarf columbine.
Meanwhile, Colorado carnation growers,
whose flowers were then deemed the best in
the world, were experiencing disastrous com¬
petition from Colombia, S.A., where growing
conditions were equally advantageous, with¬
out the necessity for costly heating and air
6 conditioning.
Eager to diversify, Homer Hill was one
grower who had an intense interest in propa¬
gating wildflowers and unreliably hardy
exotics. We found him through Harry Swift
and Larry Watson of Western Evergreens. He
was responsible for propagating the Rocky
Mountain dwarf columbine — until rock gar¬
deners now probably have more of them
growing in their gardens than can be found in
our mountains. Among the many other trea¬
sures he propagated were shooting stars, rock
ferns, Easter daisy, monkey flower, Penste-
mon pinifolius and Potentilla thurberi.
SaBell’s Hillside Gardens, just breaking
into commercial landscaping, proved to be
another helpful supporter in offering many
plants for rock gardens and the perennials
division of the sale. Growing in their home
planting was pink plumes, Geum triflorum, a
jewel I first noticed in a meadow near our
favorite fishing hole in South Park. Sabell’s
Euphorbia polychroma was always in flower
at sale time. (Any plant that flaunted a blos¬
som at sale time was a quick sale; retaining a
plant as an example was the trick.)
Colorado blue columbine, Aquilegia
caerulea, it seems, was one of the most
difficult plants for growers to produce. Final¬
ly, Mr. Buck at Buck’s Gardens agreed to try,
if we guaranteed him fresh seed.
We knew Emma (Mrs. Edward) Mixa of
Boulder had a lovely mass of columbines
growing outside her picture window. A dedi¬
cated member of the Denver Botanic Gardens,
she was happy to respond to our request.
Paradoxically, she and Kathryn Kalmbach,
for whom DBG’s herbarium is named, made
annual pilgrimages to the mountains where
they carefully planted Emma’s seed by pat¬
ting it into the soil. They theorized that when
columbine seed fell to the ground, it often
failed to germinate without this extra pat. In
her 80s, Emma telephoned me one summer,
frantic, “Petie, we’re in trouble! I found a yel¬
low columbine in my garden — if anyone com¬
plains, I’ll refund their money.”
By 1973 our inventory included 100 kinds
of rock garden plants. Contemporary, a Sun¬
day section of The Denver Post, rejected a
The annual
Plant & Used
Book Sale has
become a pre¬
mier event for
Colorado gar¬
deners.
story on our plant sale. However the editor of
Roundup, The Post’s preweekend section,
offered us its cover in living color: Katharine
Bruderlin Crisp, one of the Gardens’ oldest
volunteers, had been the current plant sale
chairman’s teacher. Mrs. Crisp was pictured
with Gloria Falkenberg’s daughter as they
surveyed DBG’s little red wagon filled with
columbines, pussy toes and other jewels. The
caption: “Botanic Plant Sale: Where Natives
Meet.” Rock gardening had arrived in Colorado!
Usually, when new groups of plants were
introduced to the sale, the rock garden section
was chosen to introduce them. Trees and
shrubs were shed early on. We sold wild
strawberries and runnerless strawberries;
then domestic strawberries landed on our
tables. The next year the berry basket section
was bom. To increase revenues we opted for
miniature roses. The rose division followed.
Within the past two years, drought-tolerant
plants for dry landscapes was the latest splin¬
ter booth. It now offers 200 kinds of plants.
Often at plant sales we found patrons
more knowledgeable than we, so we asked
them to join our fun, selling plants and dis¬
pensing cultural information. One was
Panayoti Kelaidis — very knowledgeable and
enthusiastic. Then, when the Rock Alpine
Garden at Denver Botanic Gardens was
under construction, Panayoti, a dedicated
rock gardener since childhood, was chosen to
be its curator. Suddenly, with his work and
the experience of Andrew Pierce and Jim Bor¬
land, other staffers of DBG, the number of
new introductions, both to the garden and to
the sale, exploded.
The spectacular success of the Rock
Alpine Garden has inspired many commercial
growers. In 1992, 18 growers supplied more
than 500 kinds of rock garden plants, includ¬
ing 15 varieties of columbine, 15 asters, 36
dianthus, 25 saxifrages, 18 veronicas, 14 pen-
stemons — to name only a few.
Is it any wonder “The Flowering of Den¬
ver” is the biggest and most successful sale of
its kind in the world? For some, customers
and volunteers alike, the sale has forfeited
much of its charm and personal contact, but
for serious gardeners, novice or seasoned —
especially rock gardeners — it’s still an extra¬
ordinary opportunity to explore and expand
our world of cultivated plants — in a festive
atmosphere. 7
Rockwork
Steve Cohen
The recent surge of interest in boulder
and rock alpine gardening in Colorado has
been overwhelming. This gardening art form
has fascinated and reached new heights of
creative outlets for individuals varying in age,
economic and professional backgrounds.
Seemingly, the only hurdle that enthusiasts
have to overcome is their physical and mental
capabilities to move boulders and rocks into
their gardens — the bigger the better.
So what attracts gardeners to aggressive¬
ly seek out this high form of creativity?
Each of us has a unique relationship and
understanding of nature. For the rock alpine
enthusiast the integration of rock formations
and plant varieties are ingrained by involun¬
tary study and thoughts brought on by such
experiences as nature walks and camping,
fishing and raft trips through steep mountain
gorges, canyons and valleys. Something
strikes and sticks in our memory when gazing
upon a formation of rock adorned by bluish-
gray, rust-speckled lichen housing random
but systematic patterns of sulfur flowers,
antennaria and kinnikinnick. This thought or
mental photograph is logged into our memory
banks to be retrieved at home while sitting in
the backyard. The photo is contemplated and
then implemented.
But hold on — not so fast! What about the
utility box and power pole? In order to look
natural the swing set, sandbox and redwood
hot tub need somehow to be incorporated.
Steve Cohen, with his wife Robin, owns and
operates Evergreen Nursery in Kittredge, Colo¬
rado. He is also a designer and builder of
8 naturalistic rock gardens.
Planning
This is about the time when you should con¬
sider sitting down with pencil and paper to
sketch your rock garden fantasy. If you feel
you need more information, consider a profes¬
sional landscape designer/architect to address
these issues and to identify drainage, site
obstacles, accessibility to yard, plant vari¬
eties, irrigation methods and soil types.
Be sure to integrate sound soil manage¬
ment techniques in your rock garden. Back¬
filling rocks with poor soils will only lead to
long-term frustration when it comes time to
plant. Use soil media that are compatible to
the plants’ needs, be it a purely xerophytic
type plant setting, to zoning out more water
loving plants away from the latter. The
investment you spend on plant materials will
pay off if the properly enriched soil is used.
Selecting the Rocks
Depending on the scale of your garden, choose
rocks native to the area. For example, when
considering a large project when major terrac¬
ing and retaining banks are in order with
two- to five-ton boulders, inquire with local
quarries or excavators. Due to an increase in
demand in my mountain community, some
excavators have inventoried boulders and are
glad to oblige in delivering these boulders at a
reduced price. City dwellers can choose from
nearby stone suppliers on the outskirts of
Denver or take the time to drive between
Boulder and Lyons where several stone yards
are located.
More budget-conscious hobbyists have
been observed picking through the large rock
piles left at the new mountain highway con-
Left: The "lower meadow" of Denver Botanic Gardens' Rock
Alpine Garden in its mid-June bounty
Below: The "limestone cliffs" in late May with lavender Veroni¬
ca spicata in the foreground, Salvia x superba 'May Night' in
the background and yellow Genista tinctoria var. flore-pleno
Bottom: A close-up of the "limestone cliffs," with Helianthe-
mum canum var. scardicum and Veronica cinerea
struction projects. Just be careful to ask for
permission. Keep in mind that whatever the
size of the project, rock and boulders properly
installed are there to enhance and comple¬
ment your future plantings.
The Art of Setting Rocks
The most difficult part of installing rocks
and boulders is to explain or even show how it
is done. This is where creativity and the
power of visualization skills are tested. How¬
ever, there are some dos and don’ts.
Don’t set rock on top of the ground. Dig
them into the ground to make them appear as
if they have been there for quite some time.
Feature the more interesting side or comer of
the rock. On occasions I have been known to
bury a five to eight ton boulder one-half to
three-quarters of the way into the ground or
hill to achieve or justify a certain angle or look.
Clustering rocks into formations, using
eight to fifteen rocks, can achieve a very effec¬
tive “natural” rock outcropping. While setting
some of the rocks into the ground, others can
be used to overlap or sit on top of the ones
buried. This technique can be used to form
small to large planting pockets for low-grow¬
ing blooming perennials.
Try not to ovemse long, narrow rocks
placed vertically. Rocks like these in large
quantities tend to appear to be tombstones.
Occasional use, though, can be attractive.
The trick to learning about this art form
is to observe what Mother Nature or others
have already accomplished. Take pho¬
tographs of projects or rock outcroppings that
are intriguing. When installing rock, sense
with your mind’s eye what looks natural. If
you have to use a lot of props to make it
appear natural (i.e. old stumps or wagon
wheels) you probably missed the mark. The
rock placement should look natural by itself
before any props or plantings are considered.
I have learned getting to this stage takes
some practice, so start with smaller projects.
But, unlike putting together a jigsaw puzzle,
whatever the outcome, it is the personal
interpretation of the artist within all of us
that comes out in the field.
Potentilla fragarieformis
illustrated by Lynn Janicki
10
Building a Screen Garden
Sandy Snyder
Of the several kinds of gardens around
my house, the rock garden in my front yard is
the one I enjoy most. It is located near the
front door, and it is impossible not to see what
is happening in it every day. I can pull a weed
. or straighten some stones early in the morn¬
ing on my way out the door. And there is no
extra effort required just to stand and enjoy
the flowers and plants one last time before
the day is finished. The garden’s location
makes it easy to keep in touch. It is part of
J my every day.
My nearly circular garden is six feet high
and thirty feet in diameter. It was built
because I wanted to block the road from
view — and to gently circumvent the commu¬
nity’s zoning laws. These allow only a short
see-through fence in front yards. Such a fence
would not have blocked the view of the road
from my front windows. A privacy fence that
gave no privacy? It would not have been
worth the effort or cost. But when I found out
there was no restriction on building a high
pile of dirt and planting anything on it, even
sixty foot trees, I was ecstatic. I perceived a
way to beat the system.
Reality set in. I did not want huge trees
and shrubs surrounding the front of my house,
to make the north-facing sidewalk and drive¬
way colder and even icier in winter. I did want
whatever I constructed to look presentable
and fit into the neighborhood. I thought
maybe I can even improve it by making it a
more interesting and attractive landscape.
Sandy Snyder, horticulturist in the DBG rock
alpine garden, lives in Littleton where she main¬
tains an extensive, xeriscaped home garden.
First, the mountain
After building a French drain so the soil
would not wash onto the driveway or the side¬
walk, and removing all the plants except a
few from around the edges, such as Arctosta-
phylos uva-ursi and Genista sagittalis, that
would look good in a rock garden, I started
out by dumping a big pile of dirt.
But it wasn’t just dirt. It was a special
soil mix. I had the gravel company mix six
cubic yards of top soil, six yards of peat and
eight yards of a stone mixture that consisted
of two yards of squeegee (a grade between
sand and pea gravel), two yards of pea gravel
and four yards of crushed river rock ranging
from fine to three-quarter-inch. This was
mixed into the soil for drainage. This stone
mixture was later used also as the mulch
because it looked more natural than uniform
sized stones. This was the recipe for the soil
mix on the south side of my mountain —
sunny, hot beds with excellent drainage — a
bit of Wyoming and a perfect home for the lit¬
tle mat and cushion plants I like.
My vision for the north side of the garden
was to develop a cool peaty woodland, the
kind of landscape you might find in Scotland.
I have very few north-facing gardens in my
yard; this garden would be perfect for ericas
and dwarf conifers.
For this side the gravel company mixed
five yards of sharp sand, five yards of rich top
soil and five yards of rotted sawdust. This
would be the foundation for planting dwarf
conifers and ericas. Small bulbs and other
plants would be added to provide color, and
interest. Thirty-five yards of custom-mixed
soil cost $850.
I did not put a heavy plastic barrier
between the two different mixes because it
had been my experience that such soil barri¬
ers are not necessary.
For the watering system I buried a hose
to the top of the mound. It ends in a spike hold¬
ing two sprinkler heads. One head is a full cir¬
cle of coarse jets that waters the whole garden;
the other head is a half-circle that sprays extra
mist just on the north side. The north side,
therefore, gets more water than the south.
Having plants with two very different
water requirements back to back does present
some problems. Iris gatesii, a magnificent
desert iris from Iraq, rotted because it got too
much water, even though it was located on
the hot dry side with excellent drainage. But
after much experimenting with nozzles and
schedules I think that both the wet north side
and the dry south side now are coexisting in
harmony. I learned that some ericas are sur¬
prisingly drought- and cold-tolerant based on
my experience in this garden. However, I do
water the ericas every day during very hot
dry spells to keep them from drying too much.
My six-foot-high mound was dubbed
1 2 Mount Snyder by my gardening friends. I
didn’t particularly like this — I had dreams for
my rock garden. It was supposed to provide
an interesting sculpture/painting for my front
entrance. However, the name was appropri¬
ate because the pile of settling soil did look
like a hill in front of the Snyder house.
I let the soil settle for a couple of months
before ordering and placing ten tons of large,
light-colored, lichen covered sandstone rocks.
It was a mistake not to allow for more set¬
tling. The soil should have been piled even
higher. Now the mound is almost three feet
lower than its original height. And, once the
rocks were set, it was impossible to add more
soil to increase the height of the hill. I hope
over the years the plants will grow enough to
compensate for this.
Five years have passed since I began this
garden. It is no longer referred to as Mount
Snyder. People who walk and drive by have
forgotten that it was once just a big pile of
dirt. Instead of fretting, neighbors, joggers,
motorists and bicyclers seem pleased with
what they see. Often they stop to ask about
the garden and its plants. The garden is slow¬
ly developing the interesting colors and tex¬
tures I had hoped it would have.
Hot yellow
Genista lydia
spills from the top
of Snyder's unusu¬
al screen garden
in June.
Sandy Snyder
The Plants for “Scotland”
My first batch of plants came from Heath
and Heathers Nursery in Elma, Washington —
one hundred small pots of ericas. My husband
and I drove them to Colorado in a cartop car¬
rier. Plants grown in Colorado must be able to
tolerate some winter drought stress during
years when there is no snow cover. They may
also have to tolerate summer drought when
the sprinkler system malfunctions, or when I
go away and do not plan on hot weather.
My ericas are a wonderful ground cover
for a fairly steep area. They help knit the
north face of the rock garden together. And
when Fritillaria meleagris, the checkered-lily
grows up through the ericas in the spring to
show off its purple and white checkerboard
petals, the erica makes a wonderful back¬
ground. The ones I planted also make a per¬
fect underplanting for dwarf conifers and they
do a great job of keeping something in bloom
in the garden all year.
In five years, I have not fertilized,
trimmed, or re-propagated my heaths. Most
of them are still alive and growing well in the
conditions provided for them. The USDA zone
evaluations don’t seem to mean much for
heaths planted in Colorado even though we
don’t have reliable snow cover in Denver and
the winter temperature has reached lower
than minus 20°F. Some years they suffered a
little winter damage but they recovered
quickly. However, I must confess we make
use of all the snow we get by directing the
snow onto this garden when we clear the
driveway with the snow blower.
In general, our part of Colorado has a dry
climate. It is difficult to over-water. The eric¬
as have never had any sort of fungal or other
disease problems. I love the way these care¬
free, reliable, good-looking ground covers
bring color and interest to the winter garden
as handily as they provide a dependable
flowering mat in summer.
The other major group of plants on the
Scottish side of my rock garden is the dwarf
conifers. I tried to choose these evergreen
miniatures so that their shapes, (tight cush¬
ions, conical or splaying) their various shades
of green and their various textures comple¬
ment each other and the plants surrounding
them.
I have noticed dwarf conifers take about
two years to establish their roots before they
are rugged enough to tolerate our Colorado
winters. It is not the cold temperatures, but
the bright winter sun that desiccates a plant
that is unprotected or does not have a well
established root system.
I protected small trees by planting them
in the protection of a rock where the low win¬
ter sun cannot hit them directly. When the
trees grow taller and the winter sun can
reach them, they will be well enough estab¬
lished to withstand winter desiccation.
Tucked into rock crevices, and mixed in
among the heaths and between the little trees
on the north slope of my garden are at least a
hundred more kinds of plants. Lewisia cotyle¬
don shows its pink flowers from the highest
rock’s crevice. Arum italicum sports several
big arrow-shaped leaves along the sidewalk.
Astilbe chinensis ‘Pumila’ regularly shows a
wonderful soft pink spike every summer, a
nice surprise since I seem to always forget
it — the plant spends most of its time hiding in
the green tapestry. When Gentiana paradoxa
blooms its best blue in the late summer, I am
very impressed with what Colorado garden¬
ing can be. Cotoneaster microphyllus f. thymi-
folius, C. horizontalis ‘Little Gem’, and C.
apiculata ‘Tom Thumb’ usually show good red
fall color. Their little branches provide winter
interest, struggling to grow up and over rocks.
In the summer they look like a tiny elf should
be standing by.
Daphne cneorum var. pygmaea Alba
shows a mass of little white flowers each sum¬
mer. D. pontica, has not done very much —
perhaps it will after it has had enough time to
develop. Its ultimate size should be one foot
tall and one foot across. Big daphnes like D. x
burkwoodii and D.x b. ‘Carol Mackie’ do very
well in Colorado. Is there any reason why lit¬
tle D. pontica should just sit there?
All of my phloxes grow close to the
ground — like a carpet surrounding the large
furniture of rocks. During April the phloxes 1 3
Genista (top), phloxes (left), pinks and columbines in the
Snyder garden.
bloom and decorate the entrance for Easter
better than I ever could. Purple- lavender-
and pink-bloomers, they fill the southwest
section of the garden. Last year a row of
lilacs, Syringa vulgaris, just east in another
garden was in bloom at the same time. It was
possible to stand and look at the phlox cover¬
ing the hill and, at the same time, the lilacs in
the background. What a lively color combina¬
tion they made. Each year species crocus and
tulips add shades of yellow and white to the
picture. Having it all backlit by the morning
sun really announces the arrival of spring.
The south side of the garden is planted
with cushion- and mat-forming plants.
Among the ones I find especially delightful is
Dianthus anatolicus. This favorite usually
grows in a nice tight green mound. But as the
plants get old and so large they cannot sup¬
port themselves, they collapse in the center
and take on other forms. One of my D. ana-
14 tolicus has managed to position itself around
a rock so that it looks like a snail with the
rock as its shell. I have at least ten of these
plants and each one has taken on its own per¬
sonality. They never flower much, although I
have seen pictures of them growing in pots in
England with the cushion covered with so
many tiny light pink flowers that the green
cannot be seen.
I try to stuff the rock cracks and holes
with sempervivums, sedums, rosularias and
orostachys. Each year there are new favorites.
But I never can give up any of the old
favorites — such as the hens and chicks cov¬
ered with cobwebs, Sempervivum arachnoi-
deum or the round and soft S. ciliosum ‘Mali
Hat’. I have several little chasmophyte plants
that try to help me turn the rocks into gar¬
dens. Viola Corsica blooms ten months a year.
It seems to spread everywhere but never
takes over and looks like a small aristocratic
purple pansy. Talinum calycinum sends its
dark pink flowers up to sway on thin wirelike
stalks and hops around, to grow in different
cracks each year.
I love my garden because I don’t feel that
I must work in it. Small amounts of mulch
applied twice a year eliminate endless hours
of weeding: Pine needles, as many as I can
get, mulch the north side; a top dressing of
mixed squeegee, pea gravel and river stones
covers the south side. The two mulches swing
around the mound and meet each other and
eventually they all mix together and blend.
My mountain garden is fiill of wonderful,
small magical happenings all year and every
year. But it reserves two shows big enough to
stop people who usually drive by at 30 miles
an hour. The Genista lydia on top of the hill is
a large splaying plant every inch of whose
low, arching, green branches is covered with
sunny yellow flowers every spring. It makes
Mount Snyder look like a volcano with hot
yellow lava beginning to flow down the sides.
In the fall the bright red Zauschneria arizoni-
ca, also planted near the top, makes the
Mount Snyder volcano look as if it is explod¬
ing fire for a month. Come to think of it, this
year I will plant more zauschnerias to make
my fall volcano shoot even more fire.
Heaths for a Scottish garden in Colorado
Erica carnea 'Pink Spangles' flowers deep pink, January to April. Foliage bright green. Likes
lime. The only true alpine. USDA Zone 6.
Erica carnea 'Sherwoodii' blooms rose-ruby January to April. Foliage light green. Likes lime.
Zone 6.
Erica cinerea 'Alba' flowers white June to September. Foliage light green. Zone 6.
Erica cinerea 'Atrorubens' blossoms red-pink June to September. Foliage dark green. Zone 6.
Erica cinerea 'PS Patrick' blooms purple June to October. Foliage deep glossy green. Zone 6.
Erica x darleyensis 'Darley Dale' flowers pale lilac-pink November to April. Foliage deep
green. Zone 6.
Erica x darleyensis 'Furzey' blossoms deep lilac-pink November to May. Foliage dark green.
Zone 6.
Erica x darleyensis 'George Randall' blooms deep pink November to April. Foliage fresh
green. Zone 6.
Erica x darleyensis 'Jenny Porter' blooms white November to April. Zone 6.
Erica vagans 'Alba' blooms white July-September. Foliage vivid green. Zone 7.
Erica vagans 'Birch Glow' blooms deep rose-pink August to September. Zone 7.
Erica vagans 'Miss Waterer' blooms deep shell pink August to September. Zone 7.
Note: The USDA Zone numbers are those usually recommended for these plants. The
author has grown these in her Littleton, Colorado, garden, USDA Zone 4, for five years.
Dwarf Conifers for a Scottish Garden in Colorado
Chamaecyparis obtusa 'Densa', Zone 5.
Chamaecyparis obtusa 'Nana Gracilis', Zone5.
Chamaecyparis pisifera minima 'Golden Pincushion', Zone 5.
Chamaecyparis pisifera 'Plumosa Compressa', Zone 5.
Chamaecyparis pisifera 'Tsukumo', Zone 5.
Juniperus communis 'Echiniformis'.
Juniperus communis 'Pencil Point'.
Picea abies 'Clanbrasiliana', Zone 3.
Picea glauca 'Echiniformis', Zone 3.
Picea mariana 'Nana', Zone 2.
Picea abies 'Maxwellii', Zone 3.
Pinus mugo 'Valley Cushion'.
Tsuga canadensis 'Gentsch White', Zone 3.
Tsuga canadensis 'Husii', Zone 3.
Phloxes
Phlox bifida 'Betty Blake'
Phlox x 'Coral Eye'
Phlox 'Sneewittchen'
Phlox stolonifera 'Blue Ridge'
Phlox subulata 'Emerald Blue'
Phlox subulata 'Emerald Pink'
Phlox subulata 'Tardy Pink'
Phlox subulata 'Daniels Cushion'
Phlox bryoides, illustrated by Rebecca Day-Skowron
A Garden in Paradise
Bob Nold
Gardening in Colorado has the reputa¬
tion of being a one-way trip to suffering and
despair. The relative scarcity of ornamental
gardens in and around Denver and the obvi¬
ously abject surrender to high-maintenance
lawn- worship seem to be symptomatic of the
hopelessness with which most Rocky Moun¬
tain residents view gardening. After all, you
can pay someone to mow a lawn and apply
the various chemicals it needs, and watering
can be done automatically.
Some hundred years after the fact, we
still see our climate with the same agricultur¬
al perspective of 19th-century white settlers.
We still think we’re farmers waiting for rain
that almost never comes. We still react with
strongly positive, atavistic feelings to images
of lush greenery originating from rainy parts
of the world. This model of an “ideal world” of
agriculture and, by extension, of gardening,
has such a grip on our consciousness that the
impossibility of achieving this ideal has
robbed neighborhoods of considerable poten¬
tial for color other than green — endless,
unvarying and faceless green.
Preconceptions die hard, but they can be
killed. Suppose that instead of stubbornly
maintaining an “ideal” horticultural standard
you change the standard’s premises to allow
the regional climate to formulate the model
for you. Instead of having to water every
other day to simulate rainfall, you experi-
Lakewood, Colorado, gardener Bob Nold
grows, with no supplemental water, one of the
finest collections of dryland plants in the region.
An employee of US West, he writes extensively
16 for horticultural magazines.
ment with drought-tolerant plants. Instead of
staking gigantic perennials, you choose plants
that like wind. Instead of pining for shade,
you choose plants adapted to our intense sun¬
light. Instead of watering during a dry win¬
ter, you choose plants that prefer dry winters.
A Nietzschean argument maybe, but garden¬
ing becomes much less anguish in the dirt
and much more joyful discovery . . . and even
happiness.
It was practically love at first sight when
I unsuspectingly walked into the Rock Alpine
Garden at the Denver Botanic Gardens. Ex¬
pecting to find a large representation of typi¬
cal rock plants, I found an amazing collection
of mostly unfamiliar plants, and, especially
exciting, dozens of familiar plants which
weren’t even supposed to grow in Denver. My
mind immediately saw visions of superhuman
efforts by the gardeners there, of mysterious
horticultural practices carried out behind
large rocks, and of having the extraordinary
luck of building a public rock garden on the
only spot in the state with a perfect climate.
Of course a model garden devoid of the
usual deaths and blunders would be useless
to everyday gardeners; they need experiences
and practices which can be duplicated in their
own gardens, even if on a smaller scale.
When I saw dead plants in the Rock Alpine
Garden I was relieved; when I saw these
replaced with more unusual and possibly
more suitable plants I was inspired. A static
garden is a monument to boredom. To be
interesting, a garden scheme needs to
change, if not yearly, then at least gradually,
so that we can see some thought is behind it
all. A garden in which the same plants are
Panayoti Kelaidis Panayoti Kelaidis
Top: Magenta
Erinus alpinus,
salmon Papaver
armeniacum and
pink Aethionema
pulchellum in
DBG's "lower
meadow"
Bottom: In DBG's "limestone cliffs," left
to right: lavender Thymus camphoratus,
white Chrysanthemum hosmariense,
magenta Erinus alpinus, Ptilotrichum
spinosum 'Purpureum' and x Celsiover-
bascum 'Golden Wings'
continually replanted is already dead. There
was something going on here; the plant labels
detailing country of origin were a hint.
What was happening in this garden, I
think, was an attempt to realize the horticul¬
tural possibilities of our unique and mostly
delightful climate, partly by seeing just how
many plants could be grown and, partly, by
exploring the largely unknown flora of global
regions with a similar climate. As “tradition¬
al” rock garden plants inevitably died from
the vagaries of our climate, they were replaced
by natives and other exotics. As these plants
thrived, more uncommon genera appeared,
gradually altering the garden’s overall cast.
It’s difficult to describe the way a garden,
or a certain part of a garden, impinges on the
senses, especially since everyone experiences
a garden in different ways. Some people will
walk right past a planting others find en¬
trancing; taste, orientation, knowledge and
levels of interest vary. It’s possible to suggest
that the native shrubs, for instance, that dot
the Rock Alpine Garden lend a distinctive
Western feel to the garden, but only if they’re
recognized as natives. Even so, these shrubs
(little leaf mountain mahogany, one-seed
juniper, etc.) are odd enough to make very
noticeable impressions on anyone who takes
the time to really look at them. The woodland
17
walk under the aspens has a feel vaguely
reminiscent of Eastern woodland, but the feel
of the “Tethyan” garden is something new.
Altogether new and a bit intimidating,
here is a perennial border without the sense
of artificiality and strain most borders have,
the result of anachronistic ideas about the
taming of nature, full as they are of the same
old tried, true and tired high-water-demand
plants. Most Colorado perennial gardens (I
speak with the experience of ownership) look
about as natural as hot dog stands on
Mars: out of place, forced and full
of grotesquely inappropriate
plants. Here, though, is a t
perennial border where the
plants have been chosen because
they have their origins in homolo¬
gous climates and their ability to with¬
stand sun, drought, and wind are inbred —
not because every gardener since the
Dawn of Gardening has grown them.
The idea that you can actually
have a garden in Colorado that rep¬
resent mankind’s perpetual struggle
with the forces of nature may be a minor
philosophical revelation, or maybe not. What
is important is that at last you can have a
garden without tears, without having to rush
outside every half hour with a watering can,
without having to “improve” the soil (the old
19th century creeping in again), without hav¬
ing the Poison Control’s emergency number
programmed into the phone. The essence of
good gardening isn’t in having the best tools,
the most expensive urns on the patio, the fan¬
ciest Bulgarian hand-made hose guides, or
knowing when to spray or prune, or knowing
what color combinations are approved by
authorities using criteria derived from cli¬
mates where the sun shines for three minutes
every fourth year, but in intelligent, practical
plant selection.
Slowly, through the “trickle-down” theory
of institutional horticulture, these Turkish
salvias, exotic cornflowers and other fantastic
plants are becoming available in nurseries
and making Tethyan appearances in the gar¬
dens of the progressive, sophisticated, and
1 8 individualistic.
This garden leads us downward and
inward to the Rock Alpine Garden proper,
where only those free of envy and greed
should tread.
The notion that some plants could be
grown in Colorado despite dire warnings
about instant death probably wasn’t pio¬
neered in the Rock Alpine Garden (advanced
gardeners in the West had been experiment¬
ing with wildly unlikely subjects for many
years prior to the first plantings at DBG), but
at least here is positive proof for all to see.
For example, the books say Corsican helle¬
bore is hardy only to Zone 8, but here it is,
growing in perfect bliss on the
north side of a wall, without any
of the special growing tech¬
niques many people insist
DBG applies in secret.
The little plants, low
and unassuming, form the
core of any serious rock gar¬
den and are typically what other gardeners
imagine when they think of rock gardening.
Plants from high mountain tundra and
windswept cold deserts throughout the world
derive their huddled compact forms from liv¬
ing in extreme climates and are ideal for rock
gardens, even though most of them don’t
grow in settings resembling rock gardens.
The “rock garden” as a format for alpine
plants really is a fairly modem idea, and
probably wouldn’t have evolved into the
stylish constmctive art it is today if the origi¬
nal European proponents hadn’t discovered
that their wet climates demanded providing
conditions that kept the foliage of alpines dry
during the winter. Most alpines spend win¬
ters quite dry under a blanket of snow, and
living in parts of the world where it rains in
winter usually means a soggy death for the
minuscule treasures, not to mention the con¬
comitant fungal diseases and other troubles
people forget about when they yearn for rain
and humidity. Many alpines live tucked tight¬
ly into rock crevices in their natural homes,
keeping their foliage and root crowns dry, so
this technique has been replicated for many
decades in Europe and damp parts of the
U.S., but in Colorado, thanks to our dry,
sunny, windy climate this isn’t necessary. In
fact many of these alpines whose cultivation
so troubles other gardeners can be grown in
ordinary soil with very judicious or even no
watering. If the garden is irrigated, as you
would expect any public garden to be, many
of these plants thrive in conditions of the
rapid drainage provided by gritty soil mix¬
tures and full exposure to the sun, wind, and
other drying factors. Since rain in winter is
nonexistent, the protection devices (a pane of
glass placed over the plants, etc.) used else¬
where are completely unneccesary.
Late spring frosts and the snowstorms
that sweep down the Front Range from Cana¬
da are the bane of many a Colorado garden
but alpines are unaffected by such weather,
blooming through the snow and being none
the worse for it. Like the native-plant garden¬
er who is unbothered by summer drought, the
alpine gardener generally remains in a state
of bliss regardless of the weather. Many of
these tiny plants are, believe it or not, quite
hail-proof (if you think our spring weather in
Denver is awful, try an afternoon hike above
timberline) and, if damaged, usually recover
quickly.
Alpine and tundra plants and cold-
desert plants share many of the same
characteristics; a hike along the south
ridge of Loveland Pass will
demonstrate this. Here are low,
flat mats growing completely
exposed in awful soil, gnarled and)
compacted by wind, sun, cold and
drought. The soil is quite dry; the
plants’ roots go down forever, and
frosts are possible almost any night of the
growing season. Cold-desert plants such as
those found at Pawnee Buttes have nearly
identical features and growing conditions.
They share the ability, in most cases, to con¬
serve moisture with fine hairs on the leaves,
sometimes to such an extent that the leaves
appear silver or gray. These gray- and silver¬
leaved plants tend to rot if moisture collects
in the hairs, so some of them are extremely
sensitive to overhead moisture at any time.
Some sections of the Rock Alpine Garden are
subirrigated to subvert this. And while these
plants are usually relegated to the alpine
house (an unheated greenhouse-type affair)
or to wistful yearning in rainy climates, they
are perfectly growable in Denver.
The inability to grow moisture-sensitive
plants caused European and American rock
gardeners to explore other realms of garden¬
ing and other genera from wetter locales, so
plant catalogs emanating from these areas
feature wider ranges of moisture-tolerant
plants and also some that demand consider¬
able moisture at all times of the year. The
result is that many gardens in wet regions
tend to focus on these plants, and cold-desert
plants from the American West, Turkey and
Central Asia were neglected to the point
where they received at most a footnote in a
text. Many genera were practically unknown
or, at best, represented by only a single species
that happened to make the grand tour of indi¬
vidual gardens thanks to a cutting procured
as a curiosity by an eccentric collector one
morning on a forgotten peak many years ago.
The Darwinian (or was it Lamarckian?)
drama of deaths and survival enacted out in
the first few years of the DBG Rock Alpine
Garden’s existence pointed the way to
these forgotten and ignored cold-
desert plants and soon it was these
genera, not the woodland plants of
America and Japan, that drew attention.
Suddenly the genus Acantholimon, for
example, which heretofore languished
under the rubric “alpine house
only” (in other words, don’t let
them get wet), found itself as the
object of adoration and wonder at
the Denver Botanic Gardens and thence to
local gardens where the many species have
proved superb plants for the dry rock garden.
Suddenly Western American alpines and
plains plants found themselves coveted and
preferred to the traditional rock garden plants
such as primulas and “mossy” saxifrages.
The dry winters that are such a curse to
local tree and shrub owners became a boon to
alpine gardeners; now you could grow South
African iceplants, even if you had to take ten
years to adjust to that idea after having spent
a Southern California childhood joyfully
19
On page 1 8: Daphne arbuscula,
illustrated by Rebecca Day-Skowron
On page 19: Lithodora olei folia,
illustrated by Lynn Janicki
Now much in demand, zauschnerias and
the Mexican phloxes were introduced as
continental-climate plants and popularized
by Colorado rock garden enthusiasts.
Right: Phlox 'Chameleon' and Zauschneria
garrettii in the Heapes garden in August
Below: Phlox mesoleuca 'Arroyo' and
P. 'Vanilla'
squashing them with your toes. The bulbs
that rotted in rainy winters came up year
after year, and we discovered that Denver
had the best climate in the United States for
growing anything like a wide variety of bulbs.
Dianthus and campanulas found an ideal
home, and many Mediterranean plants whose
hardiness was previously questionable flour¬
ished as though they had never read any gar¬
dening books. Our dry autumn weather
allowed plants to stop growing and ripen in
the sun, reinventing conventional notions of
plant hardiness.
In fact, many alpine gardeners around
the world are bitterly jealous of our climate
and the growing abilities superbly demon-
20 strated in the Rock Alpine Garden. (The situ¬
ation is thus completely reversed from that of
gardeners working with traditional plants.)
Many rare and “ungrowable” plants find an
easy life in Denver.
The extent of what we can grow is still
unknown; floristic regions of the world with
similar climates are not fully explored. Visi¬
tors to DBG may leave bewildered at the com¬
plex, multitudinous and unfamilar conglom¬
eration of plants, but surely they can’t fail to
appreciate the glory and not-so-subtle mes¬
sage the Rock Alpine Garden whispers to
local enthusiasts even in the gloomiest days
of winter and even as the hail comes crashing
down and the wind screams in our ears and
the sun dries leaves to a crisp: We are garden¬
ing in paradise.
Sandy Snyder Robert E. Heapes
Achilleas and tulips are but two examples of the amaz¬
ing wealth of plants from the Mediterranean region that
thrive in Colorado's hot, dry continental summers.
Left: Tulipa whitfallii, in the Coe garden
Below: Achillea ageratifolia in the Heapes garden
Bottom: Fritillaria meleagris in the Snyder garden
Urban Alpines
Ken Slump
The decision of two avid gardeners to for¬
sake traditional yard and garden space for
the “convenience” of town house living was
not an easy one. Although we still enjoy what
may be described as a small but typical front
yard, other landscaping opportunities are
restricted since the architectural design
includes no garden area at the rear of the
property. Our rooms surround a small, interi¬
or patio viewed on three sides by windows,
the fourth side being the solid brick wall of
our neighbor’s town house. This intimate
focal area sold us on this townhome’s plan.
Having no yard, yet two large dogs, creat¬
ed an immediate dilemma. The townhome’s
accommodating builder was eager enough for
a sale to sit down with us, the architect, and
the contractor to devise a solution. The front
yard of the complex slopes steeply up to the
building. We determined to excavate an area
for a dog run up near the front of our unit. It
necessitated a retaining wall on the uphill
side and wrought iron fencing on the front —
an over-elaborate response, considering the
area’s purpose!
This construction removed most of the
foundation plantings in front of our unit that
had just recently been installed by the pro¬
ject’s landscape contractor. It was not a
tremendous loss. The plantings, although
adequate, lacked imagination and diversity.
The slate was now cleared to replant to our
own satisfaction.
Ken Slump, a graduate of Colorado State Univer¬
sity, maintains the Denver Botanic Gardens plant
records. A former Denver city arboreal inspector,
22 he holds a special interest in unusual trees.
A prominent flight of steps climbs the hill
to the front of the unit. The landscaper par¬
tially flanked the steps with a few very large
boulders and installed the landscaping about
them. This slope had also been a selling point
for us; we envisioned an opportunity to devel¬
op it into a prime rockery. Two existing trees
spared by the excavation process now became
the backbone of an expansive new planting
area extending across the front of the dog run
and back up to the building.
This steep, dramatic slope challenged us
to visualize a bold, strong design. We were
anxious to maximize the limited space and
realized that including many of our favorite
plants would require an intensively planted
landscape. A common thread was needed to
unify the planting and give some emphasis to
our front entrance.
To screen the dog run as well as create a
landscape attractive in all seasons, we elected
for a planting that relies heavily on the color,
texture and form of dwarf conifers. Among
the conifers we planted groundcovers, a few
perennials and selected deciduous plants.
Additional rocks and boulders were brought
in to expand and enhance that aspect. Bulbs
ranging from the fire engine red Tulipa foster-
iana to the delicate bluish Puschkinia scil-
loides were tucked in to bring spring interest.
About a dozen dwarf conifers compose the
design. Among them, vertical forms of dwarf
Alberta spruce, Picea glauca ‘Conica’ and sen¬
tinel juniper, Juniperus communis ‘Sentinel’,
contrast with the horizontal habit blue chip
juniper, J. horizontalis ‘Blue Chip’. The silver-
blue needles of the blue globe spruce, Picea
pungens ‘Glauca Globosa’ glow against the
rich green shades of bird’s nest spruce, P.
abies ‘Nidiformis’ and the nearby lawn. Fine-
textured juniper foliage plays against the
coarser textured spruce. A most successful
component of the plan is a weeping Norway
spruce, P. a. Pendula which has grown to
reach out from a rock outcrop to “shake
hands” with visitors as they ascend the steps.
We incorporated a few broad-leaved
shrubs into the scheme for seasonal interest.
Dwarf winged euonymus, Euonymus alatus
‘Compactus’ was planted with the hope that
its crimson fall foliage and symmetrical shape
would blend with, yet complement the dwarf
conifers in the autumn months. We situated
two of the hardier evergreen rhododendron
cultivars, ‘Scarlet Wonder’ and ‘Ramapo,’
near some of the large rocks with the expecta¬
tion of exotic floral displays in the spring.
For the cause of “edible landscape” we
planted a couple of Nanking cherry shrubs,
Prunus tomentosa, that also provide some
height and a background for certain conifers.
Thus far robins have been the primary bene¬
ficiaries of the fruit. A grapevine trained onto
the iron fence provides not only fruit but
extra screening of the dog run in the summer.
We removed the landscaper’s wood chip
mulch and planted more than two dozen
species of groundcover and perennial plants
among the shrubs and trees for a more natu¬
ral effect.
Our first filler plants included species and
cultivars of Veronica, Sedum, Phlox, Draba,
Campanula, Aquilegia, Iberis, Thymus and
Dianthus, among others. Irregularly shaped
plantings were executed in drifts between
and around the shrubs and trees. “Filler
plants” is a poor moniker for this group as
they really gave the garden its seasonal spice
and textural depth, especially in its early
years. Spreading carpets of Lotus cornicula-
tus and Sedum kamtschaticum soon reward¬
ed us with their golden summer blossoms.
The silvery foliage of Lamium maculatum
‘Beacon Silver’ and Artemisia stellerana
added contrast that seemed particularly effec¬
tive in the twilight hours. Carpets with subtle
floral interest were also provided courtesy of:
Asperula gussonii, Antennaria parvifolia and
Arenaria hookeri.
Eight years have passed since our initial
plantings, and some observations are pertinent.
(I am always fascinated by the ways plants
and gardens mature and evolve both because
of and in spite of our best plans and efforts.)
The dwarf conifers developed into a
handsome planting and are indeed striking
throughout the entire year. They have grown
and spread as hoped, some to the point of
requiring judicious pruning to keep them
under control. ( Warning : The term “dwarf’, as
applied to conifers, is truly a relative term!)
As the conifers, deciduous trees and shrubs
expanded, many of the herbaceous plants
were crowded out or eliminated. Some, I’m
sure, completed their limited lifespans and
disappeared. They filled spaces and flowered
seasonally as the planting matured. Yet a
number of the original species proved to be
tenacious and long-lived.
Each April one section is still carpeted
with the small blue flowers of Veronica pecti-
nata. Spring also sees the return of a colorful
succession of phloxes. Good performers in¬
clude Phlox x procumbens ‘Millstream,’ P.
subulata ‘Scarlet Flame’ and P. douglasii
‘Boothman’s Variety.’ Another perennial that
still makes an appearance is the cheerful dwarf
Rocky Mountain columbine Aquilegia saxi-
montana, and each fall I look forward to the
violet-blue flowers of Aster novi-belgii.
A couple of the broad-leaved shrubs didn’t
work out. The first dwarf winged euonymus
we planted grew nicely but never developed a
hint of fall color. It seemed every November
found this plant with emerald leaves clinging
stubbornly to the twigs, while the same
species next door had already shed its flame-
red foliage. After several years I reluctantly
removed the healthy, but non-performing
specimen and replaced it with another, which
died. The ‘Scarlet Wonder’ rhododendron also
failed. ‘Ramapo’ is barely surviving. In spite
of the difficulty in selecting and establishing
rhododendrons in this climate, we persevere
and this year added a reputedly super-hardy
evergreen azalea ‘Pot’s Silver Pink’ to the
23
planting in a more protected but less conspic¬
uous location.
Landscaping the patio area offered some
tough challenges as well as exciting opportu¬
nities. The space, regrettably, is mostly paved
but the architect left an oblong open area
toward the southwest comer, i.e. the north
side of a massive brick wall. The bed is large
for an ornamental tree and a few carefully
selected shrubs and herbaceous plants. Seek¬
ing an inviting scene appropriate to the shady
site led us to use a woodland theme.
The protection offered by the building on
all sides encouraged us to consider some
species that tend to be marginally hardy in
Colorado. At the same time, the plants had to
be able to tolerate extra heat in summer that
is reflected from the expansive concrete area.
For a small, flowering tree, we considered
the usual options of crabapple cultivars,
hawthorns, mountain ash and even flowering
dogwood. We selected the interesting yet reli¬
able redbud, Cercis canadensis. If I were mak¬
ing the choice today, I might opt for a more
unusual species. Would the protected site sus¬
tain a Japanese snowbell, Styrax japonicus,
perhaps a single-trunked fringe tree, Chio-
nanthus virginicus, or possibly a Japanese
stewartia, Stewartia pseudocamellia ? Each
would offer a variation of an exotic white
inflorescence and are intriguing alternatives.
Beneath and near the redbud grows a
curious selection of shmbs chosen for their
variety of evergreen textures. Dwarf Hinoki
false cypress, Chamaecyparis obtusa ‘Nana’;
‘Blue Prince’ and ‘Blue Princess’ hollies, Ilex x
meserveae cvs.; and Rhododendron ‘P.J.M.’,
though hardly rare plants, display an unordi¬
nary visual melange. A specimen of redleaf
Japanese maple, Acer palmatum ‘Atropur-
pureum’ is a personal favorite.
European wild ginger, Asarum europaeum,
provides evergreen ground cover near the foot
of the redbud. Two hosta cultivars, a hardy
fern, a blue-flowered spiderwort hybrid, and
violets mingle among the shmbs during the
summer months. A few years ago, we cau¬
tiously added the much maligned bishop’s
24 weed, Aegopodium podagraria ‘Variegatum’,
and thus far I am pleased with the way it fills
between shmbs and appreciate the lightness
its variegated foliage brings to an otherwise
dark, shady bed. I rip out any parts that seem
to be heading vigorously in the wrong direc¬
tion. This restricted planting area provides
the opportunity for using this invasive plant
as the “right plant in the right place.”
Lacking sufficient planting space in our
“outdoor room,” we turned to container gar¬
dening for additional greenery and color. Sev¬
eral large teak planters display deciduous
and evergreen shrub and small tree specimens.
I regretfully admit that over the years, numer¬
ous woody plants have succumbed as we
attempted to cultivate “interesting” plants in
these containers. Two of the container speci¬
mens continue the dwarf conifer theme of the
front yard planting. A weeping Colorado blue
spmce, Picea pungens ‘Glauca Pendula’, and
weeping larch, Larix decidua ‘Pendula’, have
survived in the wooden planters for years.
Recently, we added two deciduous woody
plants: Amur maple, Acer ginnala, for its
orange and fiery scarlet autumn tints and
Canada red cherry, Prunus virginiana ‘Cana¬
da Red’, for its burgundy summer hue.
Our rock garden bent is partially satisfied
by a couple of trough gardens that augment
the patio plantings. The troughs are great
conversation items, especially during the
summer months. One that includes several
species of the genus Sempervivum was partic¬
ularly effective last season. We usually add a
few pots of annuals for summer display.
Our plantings have created desire among
our fellow town house dwellers to augment
and replant their landscapes with more dis¬
tinctive species. Both of our adjacent neigh¬
bors have developed their public yard space
into unique plantings that reflect their per¬
sonal preferences, yet the shared elements
among all the gardens result in a unified site.
We prize our small garden and appreciate
the consideration we must give to each addi¬
tion. We strive for selections that are not only
the most effective in meeting the demands of
design, but are also uniquely personal expres¬
sions of the beauty and diversity of plants.
Introducing Alpines Into
an Established Garden
Clark Coe
As longtime members of the Denver
Botanic Gardens, my wife and I have enjoyed
following its gardens through the seasons,
making use of its outstanding library and
taking wintertime classes. Through all this, I
became interested in rock alpine plants.
These plants were all new to me. One
thing I liked was that their botanical names,
rather than common names, were used so
once these were learned, one could speak the
language of rock gardeners.
In early 1988 I decided to grow them in
our garden. Joy and I have been gardening in
Denver for forty years. But suddenly we
became puzzled how to introduce into the
rather formal design of our perennial garden
a naturalistic rock alpine garden, a miniature
reflection of Denver Botanic Gardens’ impres¬
sive Rock Alpine Garden.
I was particularly impressed with the
plants that seemed very appropriate for small
gardens. And I was drawn to the plants natu¬
rally suited to Colorado’s climate, plants
native to the mountains and high plains of
our latitude around the world.
Many of these plants have long periods of
bloom in addition to attractive foliage and
growth habit. Most are evergreen or “ever-sil-
ver”, providing four-season appeal.
A native of North Dakota, Clark Coe wanted to
be a landscape architect, but he earned a busi¬
ness degree from the University of Colorado at
Boulder and devoted his career to the late Fron¬
tier Airlines. His devotion to gardening is accom¬
panied by interests in photography, travel and
classical music.
Our Perennial Garden
Let’s take a look at the southeast-Denver
garden we dreamed to change, then 20 years
old. Our perennial garden lies on the west
side of our house. It has a central elliptical
lawn surrounded by sweeping curves of
perennial borders featuring irises, peonies,
lilies and roses, a few broadleaf evergreens,
flowering shrubs and small trees. A pleasing
backdrop is provided by red oak, Quercus
rubra, and two large Colorado spruces, Picea
pungens, over the back fence. There are no
trees in the lawn, which makes the entire gar¬
den seem larger.
From the living room patio one can survey
the perennial borders, and the simplicity of
design creates a tranquil feeling. But also one’s
interest is piqued to see the plants and flowers
more closely. The view suggests a stroll along
the borders — much to the owners’ delight.
To introduce rock alpine plants into this
scene, we concluded that we should get to
know a goodly palette of them before making
a major change in the character of the peren¬
nial garden. It would be best for a naturalistic
miniature rock garden to come later.
The Wall Garden
The first prospective location for growing
rock alpines in our garden was atop a three-
foot buff sandstone wall that curves 30 feet
out into the lawn to define the separation of
the sloping upper portion on the north from
the level lower portion to the south. The wall
gradually becomes lower and ends where the
two lawns meet. Part way along the wall,
steps provide access between the lawns. 25
We decided to begin by removing a strip
of grass and creating a rock alpine bed atop
the wall, six feet wide at the patio, curving to
three feet at the steps and narrowing gradu¬
ally to the lower end of the wall. In early
spring 1988 we prepared the soil, selected the
plants and planted them.
My new interest in rock garden plants
was paralleled by a new attraction to dwarf
conifers, which I first saw at Paulino Gardens,
a nursery in northern Denver. I became excit¬
ed about them after a rock garden society
slide lecture by the prominent grower of
dwarf conifers from Iseli Nursery of Oregon.
So a few dwarf conifers were included for
variety and interest. Among the ones we now
have, I am most fond of a mugo pine, Pinus
mugo ‘Iseli White Bud’, an Eastern white
pine, P. strobus ‘Macopin’, and a Colorado
spruce, Picea pungens ‘Glauca Globosa’ in the
wall garden, and a Yugoslovian spruce, P. omor-
ika ‘Nana’ and another Colorado spruce, P.
pungens ‘St. Mary5 elsewhere in the garden.
We think the new wall garden is success¬
ful, not only because the plants are thriving
and much enjoyed, but also because, when
you now view the entire perennial garden
from the living room patio, the wall garden
makes a quiet visual impact and arouses your
interest without overwhelming the rest of the
perennial garden and without destroying the
feeling of unity and tranquility of the original
garden design.
The South Garden
Around the comer from the perennial
garden, on the south side of the house, there
was an unwatered area 13 feet wide and 30
feet long, where a large curly leaf mountain
mahogany, Cercocarpus ledifolius, a bigtooth
maple, Acer grandidentatum, and a thornless
honeylocust, Gleditsia triacanthos ‘Inermis’,
grew with underplantings of Vinca minor,
Euonymus fortunei ‘Kewensis’ and volunteer
Oregon grape, Mahonia aquifolium. There,
between a sandstone path and the house, we
built a buff sandstone planter 2 feet wide and
18 feet long with well-draining soil for dry¬
land plants, all to be infrequently hand-
watered. Several eriogonums from the West
are there with acantholimons, drabas and
sempervivums from the eastern Mediter¬
ranean through south-central Asia. Even our
local harebell, Campanula rotundifolia, is a
better garden plant there with less water.
8
u
u
26 Erigeron chrysopsidis 'Grand Ridge'
Veronica thymoides ssp. pseudocinerea
Clark Coe
South of the walk we created a sunny 7
feet by 9 feet bed for phloxes, penstemons,
veronicas, aethionemas, sedums and like
plants that need to be watered more often. A
dwarf Cedar of Lebanon, Cedrus libani
‘Nana’, and miniature mugo pines, Pinus
mugo ‘Paul’s Dwarf, add contrast. And last,
in the dappled shade of the honeylocust, are
two small beds for Lewisia cotyledon and
other plants requiring some shade.
The four beds of the new south garden
are a satisfying addition because they create
a surprise around the comer from the main
perennial garden, while providing a place for
rock alpines that want drier conditions.
Wild Tulips
Both the south garden and the wall gar¬
den spring to life early in the growing season
with several varieties of small, short¬
stemmed wild tulips native to Turkey, Iran
and beyond. This part of the world is the
source of the tulips that the Dutch have
hybridized over centuries to achieve the great
array of large-flowering bulbs so popular today.
But the little wild ones are just the right scale
for the rock garden and are equally delightful.
Among my favorite wild tulips are the
royally magenta Tulipa pulchella ‘Persian
Pearl’, the rich orange and pale buff T. whit-
tallii, the sulfur yellow and orange-edged T.
batalinii ‘Bright Gem’, and T. montana, a rich
red.
Love Affair
Now that we have lived five years with
rock alpine plants and dwarf conifers, I must
admit that I am surely in love with both of
them, but don’t want to turn my back on our
bearded irises, peonies, lilies, roses and other
standards. And I haven’t even mentioned my
recent fascination with small-leafed rhodo¬
dendrons. But I believe that there simply is
no end to the number of plants that dedicated
gardeners can love!
Ten of My Favorite Rock Alpine Plants
Erigeron chrysopsidis var. brevifolius 'Grand Ridge', a gray-green cushion with long-blooming
chrome yellow daisylike flowers, from the Wallowa Mountains of eastern Oregon.
Daphne arbuscula from the Carpathians of Slovakia, a tight little shrub with glossy dark
leaves and fragrant deep pink flowers that appear twice a season.
Veronica caespitosa from Turkey, a tight ever-silver mat covered with tiny blue flowers in
spring.
Two porophylla (Kabschia) saxifrages originally from the Alps to the Himalayas, Saxifraga x
hornibrookii 'Ariel' with miniature wine red trumpets and S. burseriana 'Princess' with
small white cup flowers, both on precise little green cushions.
Dianthus microlepis, a dense green bun with vibrant pink flowers, from the Balkan Mountains of
Bulgaria.
Lithodora oleifolia, with gray-green foliage and clusters of delicate blue trumpets, from the
Pyrenees of Spain.
Asperula gussonii, with clusters of minute pale pink stars on low spreading mats, from the
mountains of Sicily.
Androsace lanuginosa from the Himalayas, soft green dense mats that bear clusters of light
pink flowers with red eyes.
Geranium dalmaticum from the Dalmatian coast of Yugoslavia, with rich pink flowers on a
perfect green mound of small geranium leaves.
Jerry Morris: Colorado ‘Broomer’
Susan Eubank
How far away from the house or the walk
is your Colorado spruce, Picea pungens, plant¬
ed? Mine, a 12 foot specimen, is planted with¬
in three feet of the back porch. A horticultur-
alist told me the cost to move it to a more
appropriate site would be much more expen¬
sive than what the tree is worth. Now I can
only see it as a potential Christmas tree.
The inappropriate use of trees in the resi¬
dential landscape is one of the many reasons
Jerry Morris, Colorado arborist and land¬
scape consultant, developed a passion for
dwarf conifers and witches’ brooms.
His interest began in the 1960s hiking
through the Rockies in search of elk and fish.
He’s not a roadside sportsman, so he has cov¬
ered many miles in the back country. He
became curious about the odd branches he
remembers seeing first in a tree near the old
highway to Evergreen, Colorado.
What were these odd, tightly-compacted
growths? In a 1967 article in Arnoldia, publi¬
cation of Arnold Arboretum, Alfred J. Ford-
ham describes the European origin of folklore
about these unusual growths called witches’
brooms. The term describes various kinds of
stunted growths on woody plants caused by
insects, disease or genetic mutation.
During medieval times these growths
were thought to have protective and healing
powers. Witches, as well as other spirits such
as elves, hobgoblins and “mares” (as in night¬
mares) used them as nests and resting places.
They were also used by witches for transpor-
Susan Eubank, associate librarian in DBG's Helen
Fowler Library, volunteers in the Rock Alpine
28 Garden and enthusiastically gardens at home.
tation. The ‘"broom” appellation comes from
their resemblance to a bundle of twigs used
for sweeping.
With many more wanderings through the
mountains of Colorado, New Mexico and
Wyoming, Morris grew to understand the
natural history of some local conifer witches’
brooms. He has found brooms of every species
of native Colorado conifer.
After many years he began noticing pat¬
terns in the sites in which they are found:
Trees with witches’ brooms are usually in
rocky drainages that run northwest by south¬
east. If the canyon meanders, wherever it
coincides with the northwest to southeast
axis, those slopes are the most likely place to
have brooms. Amazingly, either side of the
canyon is a possible broom site, without any
preference as to north or south slope. They
don’t typically grow on the canyon bottom,
and if the valley is too wide, the canyon sides
are no longer a suitable broom site.
Once he finds a specimen, Morris careftd-
ly documents the site with a map and gives
each individual tree a name. In order to relo¬
cate the specimen, the name usually refer¬
ences a geographic site, such as Picea pun¬
gens ‘Rifle Gap’, which is located north of the
town of Rifle, Colorado, or Pinus flexilis
‘Damfino’, on Damfino Creek near Walden. At
particularily rich sites, trees get metal tags
above the snowline to remind Morris of its
location and name. Even the city of Denver
has its own witches’ broom population, which
Morris has carefully documented.
This sounds like a lot of work, but locat¬
ing the witches’ brooms (and elk) is only part
of the fun. He then collects cuttings (scions)
Clark Coe
Left: Jerry Morris' grafted-conifer nursery
and seeds and uses these to produce hundreds
of progeny of the various forms.
He regularly exchanges scions with about
10 other “broomers” through the American
Conifer Society. The seed goes into the ACS
seed exchange. Does the Colorado nursery
trade need a very slow-growing columnar blue
spruce whose branches shed snow because
they grow horizontally rather than in the
upright fashion of the usual fastigate conifer?
Joe Stupka, broomer and nurseryman in
Pennsylvania, is just starting production of
such a tree. He had previously lost his stock
plant. Then he found a specimen in a front
yard about 30 miles from his home. After the
homeowner generously let him take cuttings,
Joe offered to buy the tree but the owner
refused, saying he liked it very much and had
purchased it from a short, young nurseryman
about 25 years ago at a nursery up the way
about 30 miles. Stupka recognized his own
description of younger days. Jerry Morris
received cuttings (“wood”) of this one too.
With his many years of grafting experi¬
ence, Morris has developed techniques for
grafting all year-round. In the winter the
grafting just moves inside. In July he takes
his specimens up to the mountains and makes
sure they are in the dripline of the north side
of his cabin. He constructs miniature green¬
houses — needed so the graft doesn’t dry out —
encasing the whole plant, pot and all, in a cou¬
ple of plastic bags.
Another source of Morris’ plantings are
seeds. Witches’ brooms sometimes produce
viable seed; wind-swept, tree-line environ¬
ments sometimes produce genetic dwarfs; and
abandoned nurseries of field-grown plants are
always a good source of genetic oddities. He
starts his seeds with 24 hours of light; heat
and within two years the plants have pro¬
duced five or six flushes of new growth.
Morris has some favorite plants: Pinus
ponderosa ‘Stoney’ is 15 feet tall by about 30
feet wide. The trunk is 20 inches in diameter.
It has dropped all its lower branches up to
5 feet and the branches are very twisted. It’s a
beautifiil natural bonsai.
In southern Colorado he found a dwarf
one-seed juniper, Juniperus monosperma. It’s
about 4 feet high by 7 feet long and 4 feet
wide. Unlike the usual one seed juniper the 29
foliage is a very bright green. For many years
Morris tried to get grafts to take but had many
failures. He sent out wood to the other broom-
ers and just this year, he heard that they had
produced some successful grafts. This winter
he finally got some of his to take also.
There’s a Umber pine, Pinus flexilis ‘Saun-
ny’, up in southern Wyoming that is about 16
inches high and 30 inches across. Its needles
are shorter than the species and bright silver-
green. The tree really stands out on the
mountainside. Morris speculates from count¬
ing some rings on a dead branch, that the tree
is over one hundred years old. During the
winter of 1989-90 the elk took 20 or 30 years
of growth for dinner, but in the spring of 1990
the tree had a new flush of growth and
seemed healthy. That fall Morris saw the elk
again and decided to protect the tree with hog
wire. Now its grafted scions are doing well.
He also believes he’s found Colorado’s old¬
est dwarf conifer. At about 11,000 feet in the
Rockies, the 12-foot bristlecone pine, Pinus
aristata, with thick, vigorous, and very attrac¬
tive foliage is a genetic dwarf with a ring
count of 667 years at the four-foot level.
Pinus flexilis ‘Cherokee’ and P. f. ‘Dam-
fino’ are beautiful examples of dwarf conifers.
‘Cherokee’ is a very low bird nest shape with
a very bright blue-green color. It grows about
2 inches a year. He has one that is 5 years old
and is about 14 inches in diameter. ‘Damfino’
is more upright. It’s a very deep, dark green.
His oldest example is 10 years old and about
30 inches tall and 20 inches wide.
What does Morris hope will happen to all
these dwarf and slow-growing Colorado na-
30
Join Us For Fun!
Rocky Mountain Chapter of the
American Rock Garden Society
Membership includes:
• Quarterly bulletin
• Seed exchange
• Educational meetings
• And much more!
$25 national dues, $7.50 local dues
Call 526-0017 for membership information.
fives that he is propagating? One ambition is
to find someone with enough land to plant
100 different forms of a single species. He has
at least that many each of bristlecone pine,
limber pine and Colorado spruce. This unusu¬
al arboretum would be a good testing site to
watch the future growth of the forms. In 10
years it could be a formidable display of
genetic variety. He also believes these many
different varieties should be pushed into the
steppe climate nursery trade.
For those plains and montane areas that
receive less that 20 inches of rain a year, the
dwarf conifers developed in Europe, the east¬
ern United States and the northwestern Unit¬
ed States are challenging to grow. If Morris’
Rocky Mountain witches’ brooms became
standard local nursery stock our gardeners
would have evergreens that require little
water or maintenance. Slow growing, they
would be beautiful accent plants to use along
walks, as foundation plantings and in spaces
too small for standard 100-foot specimens.
Jerry Morris came to pursue his passion
while working his way up through the tree
service industry. While working in the 1970s
for Rocky Mountain Tree Experts (a company
he later owned) Morris showed his dedication
to Colorado native conifer species with his
work on the Denver Botanic Gardens’ Chat-
field Arboretum. The Arboretum was so new
the landscaping existed only in plans. In
order to push the plans into some tangible
reality, Morris suggested that some pon-
derosa pines could be planted at the entrance
gate. The site was not irrigated. He studied
the site at the gate of the Arboretum and situ¬
ated the pines at the low point of a small
slope near the entrance. He then dug chan¬
nels following the contours so that any water
on the slope would be directed to the pines,
six-foot to 12 foot specimen trees were planted
and watered in. Once, in the hottest part of
their first year, he brought the watering truck
and directed some water down the contour
channels. In subsequent years, no irrigation
has been necessary for every tree to survive.
Do you want to help? Call Jerry Morris at
303 234-0780.
Alpines from Scratch
Kirk Fieseler
I first became interested in rock garden¬
ing while visiting the Rock Alpine Garden at
the Denver Botanic Gardens eight years ago.
The curator, Panayoti Kelaidis, was busy
planting some small seedlings, but he took
the time to introduce me to some of his trea¬
sures. For some reason everything clicked at
that moment and I became aware of this
beautiful marriage of rocks, water and plants.
Or in simpler terms, I started to dig rock gar¬
dening.
The best way to enjoy rock gardening is
to take an active role in all its aspects, from
building and planting, to seasonal mainte¬
nance. Unfortunately, I have yet to find the
time to do all this. I am too busy producing
plants to build my own garden. I think my
horticultural background at production-ori¬
ented Colorado State University and my
growing up in crop-dependent Iowa led me to
the nursery (growing) side of rock gardening.
I have this habit of measuring my life in
terms of past crop seasons and my future in
how many I have left.
Patience is probably the greatest virtue of
a plant grower, especially if you are interest¬
ed in propagating dwarf conifers and alpines
of the Rocky Mountains. My first crop of
bristlecone pine, Pinus aristata, was seeded
in 1980, and this year I will harvest and,
hopefully, sell 40 36-inch individuals from
that seedling year. I also grow Picea pungens
‘Montgomery5 by grafting. These grow much
Kirk Fieseler is director of the horticulture program
at Front Range Community College North, Fort
Collins, Colorado. Fie owns and operates LaPorte
Alpines, a mail-order source of choice plants.
faster and I can produce a four-gallon plant in
only eight or 10 years. My mortality rate is
very low, not more than 40 percent. Even
many of the herbaceous perennials and
alpines grow slowly. I have some sego lily,
Calochortus gunnisonii, that consist of a one-
half-inch diameter bulb and a three-inch tall
blade of grass for three months out of the
year. These are four years old now. Many of
my petite alpines ( Primula angustifolia, Sax-
ifraga caespitosa, and Lewisia pygmaea) are
perfectly happy in their 2 V4-inch pots year
after year. Patience and learning from mis¬
takes are important in the world of plant pro¬
duction.
My growing facilities consist of two
unheated greenhouses (30 feet x 50 feet), two
large lath houses and approximately one-half
acre of sand plunge beds. Most seeds are
sown in four-inch pots during the winter
months and placed in an unheated green¬
house to experience natural vernalization
periods. I begin transplanting the seedlings
into 2 V4-inch plastic pots in mid-May. These
transplants are left for one full growing sea¬
son before they are available for sale.
Plants are overwintered in the same
unheated greenhouse on the ground and nes¬
tled in sand. Most alpines seem to do better if
kept on the dry side throughout the winter.
My growing mix is very simple: one-third
each of perlite, sand and sphagnum peat
moss. I fertilize with a general liquid fertilizer
(20-20-20) every four to eight weeks through¬
out the growing season. Pests are always pre¬
sent but seldom harmful. I do seem to have
problems with slugs (liquid slug bait works
great) and fungus gnats (I use Gnatrol, a
31
Bacillus thuringiensis product). Of course,
both problems are due to excess moisture.
Unfortunately, this is a problem that’s
difficult to eliminate in a greenhouse.
Most of the seed I use, I collect in north¬
ern Colorado and Wyoming. I collect very
small amounts of seed which I usually get
cleaned and stored away in empty film canis¬
ters by Halloween of the same year. Seed pots
are kept for two growing seasons before I dis¬
card them, but because I reuse this soil I am
constantly being surprised by some tardy
seedling showing up in the most unexpected
place. I just replant them in their own pot
and put them in a “hodgepodge” flat.
Cuttings and separations are also used to
produce many kinds of plants such as
dianthus, saxifrages, phloxes, veronicas,
silenes and androsaces. Most cuttings are
taken in July and August and placed in a
very simple mist bed until they are rooted.
Close watch must be maintained to remove
cuttings promptly after rooting starts,
because cuttings will rot quickly if left too
long in the mist system. I find rotting a very
common problem in rock garden plants. A
fungicidal drench would probably overcome
32 this problem, applied when the cuttings are
first stuck. I do not use hormonal or fungici¬
dal dips when sticking cuttings, but I may
start soon.
When to take the cuttings, or “timing,” is
probably the most important factor in propa¬
gating difficult-to-root herbaceous plants.
Determining when the physiological condition
of the cutting is prime for rooting to occur
depends on many factors: seasonal growing
environment, light, temperature, photoperiod
and growth phase of the mother plant, active
growth, flowering and dormancy. It takes
some experience to be able to take advantage
of this window of rootability. I don’t care how
green your thumb is or how much rooting
powder you use, if your timing is off, you will
have poor rooting results.
Some successes with growing rock garden
plants have been achieved with benign
neglect. Usually, the more I coddle a plant
species — give extra lime, provide a gravel col¬
lar, give extra water — the less successful I am
at growing it. Generally, I follow these simple
guidelines:
Provide a well-aerated soil.
Provide a well-ventilated site.
Protect plants from direct hot sunlight.
Keep plants on the dry side when not in
active growth.
Use low amounts of fertilizer.
Don’t look at poorly growing plants too
often.
Change the growing conditions of poorly
growing plants the following year.
Listed below are some plants that I have
had some luck in propagating and growing.
All are Colorado natives.
Arenaria hookeri This prickly bun of a
sandwort has a very long blooming period
when cultivated. I propagate this plant by
taking cuttings in early April from stock
plants that have a very tight growth habit.
About 60 percent of the cuttings root and it
takes a long time, usually two to three
months. Seeds are easy to germinate, but
much height variation exists.
Astragalus spatulatus Large flat (three-
inch diameter) pads of grayish-green foliage
characterize this plant. Seeds germinate easi¬
ly if given a quick rub between two sheets of
sandpaper before sowing. Cuttings can also
be rooted if taken early in the spring. This
plant is difficult to grow once transplanted;
plants seem to languish if kept too wet and
hot. They need excellent drainage and good
air movement.
Dryas octopetalata Large, white roselike
flowers and shiny crinkled oaklike leaves give
this alpine great ornamental value. Seeds are
easily germinated if given vernalization and
thoroughly mixed into soil media during sow¬
ing (typically, seed germination percentages
are low). Cuttings will root if stuck in mid¬
summer. Keep on the dry side after active
growth has stopped.
Gentiana affinis Six- to eight-inch stems
bear many dark purple tubular flowers that
remain almost closed throughout their bloom¬
ing period. They are very easy to reproduce by
seeds; germination percentages are usually
high. This is probably the most easily grown
of all the native gentians.
Hymenoxys acaulis This is a dwarf, clump
forming plant with hairy basal foliage and
bright yellow miniature sunflowers. It’s easy
to germinate but difficult to grow once trans¬
planted into 2 V4-inch pots. Keep on the dry
side, cool and well ventilated.
Oxytropis multiceps A xeric bun plant with
fuzzy, gray-green foliage and abundant pur¬
ple flowers both in the spring and fall. Seeds
need a scarification treatment (sandpaper
works well) before sowing. Germination per¬
centages are usually quite high and seedling
growth is rapid. Keep dry after transplanting
or rotting will occur. Give plants full sunlight
and plenty of fresh air.
Phlox bryoides This plant has very con¬
densed, grayish foliage and produces delicate,
fragrant white flowers in early spring. It is
found growing on limestone outcrops. Seeds
germinate, but in low percentages. Seedlings
grow very slowly and resent wet, humid con¬
ditions. I have never been successful in root¬
ing cuttings.
Primula angustifolia This is a dwarf alpine
that grows in the shade of boulders on rocky
peaks. It produces magenta flowers with yel¬
low centers. Small green seeds germinate
readily and in high percentages. Seedlings
grow slowly and should remain in seed pots
one entire growing season before transplant¬
ing. Don’t expect flowers until the second or
third spring after transplanting.
Primula parryi This plant consists of tufts
of narrow, 10-to 12-inch tall leaves with
flowers that are bright reddish purple with
yellow centers. The entire plant has a distinc¬
tive odor to it. Seeds germinate in fairly low
percentages. Resulting seedlings are slow to
establish themselves and should be left in
seed pots for most of the first growing season.
Provide plenty of moisture when growing but
withhold water once the plant starts to go
dormant, and keep on the dry side through¬
out the winter.
Saxifraga flagellaris As its common and
botanical names suggest, this plant spreads
by runners. It is easily propagated by separat¬
ing rosettes in early spring. Older rosettes die
after producing brilliant yellow flowers, but
send out numerous plantlets before doing so.
Provide a gravelly soil and good air move¬
ment. 33
Prairie Smoke
Andrew Pierce
Trios of small, rose-colored, nodding flow¬
ers on foot-high stalks is a deceptively simple
description of prairie smoke. A plant of many
names, it also goes by “pink plumes,” “grand¬
father’s beard” or “Apache plume.” And as with
many geums, its botanical name has varied:
Currently — locally — it is Erythrocoma triflora.
Whatever you call it, it is an attractive
plant to grow in a “wild” garden with little
water. In rock gardens that receive more
moisture it tends to be short-lived.
According to one source, “The Indians
boiled the roots to make a beverage. It tastes
very much like weak sassafras tea.”
DBG plant propagator Andrew Pierce's superb
garden in Evergreen, Colorado, has been the
subject of articles in magazines worldwide.
In the wild, from the foothills to high in
the montane zone, it is sometimes overlooked,
as it often grows among grasses in gravelly
locations. Its finely dissected leaves, some¬
what typical for the geums, appear very early
in the spring as bright green rosettes. The
flower stalks follow in summer.
What we call “smoke” or “whiskers” are
feathery extensions of its seeds, similar to
those of pasque flowers and wild clematis. By
August these rose-pink plumose clusters have
changed to creamy white and are dispersed to
other locations by the wind. At this stage its
leaves are just tinged with red; after the first
light fall frosts they turn bright red, like the
plant’s cousin Acomastylis ( Geum ) rossii, late
in the season the most brilliant color-maker of
our tundra.
Bulbs
Herbs
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Gardening Tools
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Decorative Pottery
Small Fruit
Foliage Plants
Bedding Plants
Patio Tubs & Baskets
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Container Nursery Stock
Bird Baths and Feeders
Fresh, Silk & Dried Flowers
The Botanical Paradise
Hanging Baskets
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Plant Accessories
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Organic Gardening
Supplies
34
Stone Faces Well-Chilled
Mary Ann Heacock
Lithops lesliei,
illustrated by
Lynn Janicki
It was never my intention to test lithops
for winter hardiness. I tumbled into it or, more
accurately, I was pushed into it.
In May 1983 Panayoti Kelaidis gave me a
small plant of Delosperma nubigenum which
had proved to be hardy in the Denver Botanic
Gardens Rock Alpine Garden. It thrived, and
later I received a plant of the purple-flowered
D. cooperi. It too thrived and I gave cuttings
to all who would accept them.
Paul Heiple who lived in Golden had been
growing and testing mesembryanthemums
for winter hardiness with great success. He
shared with me plants of Aloinopsis spathula-
ta, Stomatium suaveolens, S. fulleri, Delosper¬
ma sutherlandii, and Neohenricia sibbettii. All
of these proved to be winter-hardy to a marked
degree.
On August 15, 1990, I was given 60 assort¬
ed mesembryanthemums to test. These had
been grown by Kelly Grummons from seed
purchased from Mesa Gardens. Although it
was late in the season to establish plants, I
planted them in a raised bed with an eastern
exposure using porous soil with plenty of
small gravel for drainage. During the winter
months there was a fair amount of snow cover
and the bed was exposed to the full blast of
north wind. In the spring of 1991 1 found the
survival rate to be better than I had expected.
In June 1991 Grummons gave me 20
more mesembs to test. I shuddered when I
saw eight of these plants were lithops! Sur¬
prisingly six of these came through the 1991-
Sixty years on the horticultural scene, Mary Ann
Heacock is one of Colorado's premier plantswom-
en and the mentor of generations of gardeners.
1992 winter and by the end of December 1992
five were alive and doing well. The sixth
species, Lithops hallii ‘C174’, had been alive
and happy during the early fall so I suspect
birds may have gobbled it up. Too, it could be
the plant had withdrawn into the soil and
could not be seen.
Lithops are great mimicry plants. The
name comes from the Greek “lithos” meaning
stone and “ops” meaning the appearance or
face so the common name of “stone faces” is
appropriate. The plants are attractive to birds
and although I have a top dressing of small
stones and rocks, birds with keen eyesight
and sharp beaks can quickly devour them.
Lithops are South African succulents
which have developed thickened leaves with
windows at the end of or on the face of the
leaves. A thickened taproot with radiating
fibrous roots help the plant to survive under
harsh temperatures and drying winds. When
grown in our gardens or greenhouses a light
misting or spraying of the tops seems to stim¬
ulate root development. The plants absorb
the water through their epidermis. It is not
wise to soak the plants as this could induce
rotting.
Lithops are easy to grow from seed. The
seeds usually germinate in three to five days
and requires good light and air circulation.
Within each species there is a wide variation
in color and markings to the extent it appears
to be several different species growing in each
individual seed flat.
The five species which have survived and
thrived are: Lithops fulviceps ‘C170’, Lithops
lesliei ‘CIO’, Lithops lesliei ‘C14’, Lithops sali-
cola ‘C34’, Lithops salicola v. maculata ‘C86’. 35
Penstemons: Naturals for Colorado
Ann and Dick Bartlett
While gardening can only be an emulation
of the beautiful Colorado natural environment,
we also strive to bring home our memories of
the many wild plants we encounter in the
mountains, foothills and high plains.
Perhaps our most successful achievement
has been growing some of the nearly 250 spe¬
cies of American penstemons. Penstemons,
members of the Scrophulariaceae, are noted
for their large five-lobed, bell-shaped flowers.
Another prominent characteristic is their
sterile stamen, which is fuzzy or hairy —
hence their common name “beardtongue.”
In the wild, most penstemons thrive in
arid, gravelly soils in a sunny locations. This
makes them ideal for the rock and water-
smart gardens that are fast becoming popular
in Colorado. Most penstemons are reasonably
long-lived perennials if given rapid drainage
and limited water. More penstemons have
been lost to too much watering than from too
little. Our rock garden soil is composed of
one-third gravel, one-third sand and one-third
garden soil. It is dressed with a salmon-
colored scree of Pike’s Peak granite.
Penstemons can be easily cultivated from
seed or cuttings. The plants produce large
quantities of seed in brown prickly capsules.
Seed can be sown directly into pots with a soil
mixture of play sand, peat and perlite. The
pots are then placed in a cold frame for a win¬
ter dormancy period to await germination in
the spring. If nothing germinates the first
Ann and Dick Bartlett are champions of native
plants, natural gardening and, in particular, pen¬
stemons. Their Lakewood, Colorado, garden is
36 an exquisite treasure trove of plants.
year, these pots are best held over for at least
another winter.
Gardeners are attracted to penstemons
for their variety of intense colors. Most bloom
in late spring and early summer, deep crim¬
son, pale violet, shell pink, rich blue-purple,
glowing turquoise and, occasionally, yellow.
Penstemons come in all sizes, from five feet
tall to minute mats one inch high. The latter
are ideal for a town house rock garden or in a
miniature stone trough. These uniquely
North American plants are on the forefront of
the latest introductions to the garden and are
a break from the usual European floral domi¬
nation. The following ten penstemons are our
favorites for the rock garden.
Blue-mist penstemon Who could resist
growing a plant with this name? Ruth Ashton
Nelson describes Penstemon virens as cover¬
ing the Colorado foothills along the Palmer
Divide in such abundance as to give the slopes
a misty blue appearance from afar. From a
mat of shiny, green leaves sprout many stems
of deep blue blooms that rise up to a foot tall.
P. virens is long-lived in the garden. It spreads
by putting down lateral roots to establish new
crowns. It can tolerate full sun, but it is also
happy with some shade and a pine needle
mulch similar to that found in its natural pon-
derosa pine environment. In our garden, P.
virens helps us remember picnics held among
vast fields of them along the Front Range.
Penstemon nitidus Imagine a penstemon
with bright robin’s egg blue bells and thick
gray leaves that starts blooming in April. P.
nitidus is a prairie plant hailing from eastern
Wyoming and into Nebraska. This short
stature plant thrives in an arid, alkaline soil
Dick Bartlett Dick Bartlett
y
Q
Clockwise
from far left:
Penstemon
virens, P.
secundi-
florus,
P. barbatus
'Schooley's
Yellow'
P. cardwellii
'Roseus'
with good drainage. In fact if the soil around
it is too acid it will mute its brilliant color. It
has been long-lived in our garden and main¬
tains its bright hue in our poorly nourished
gravelly soil.
Shrubby penstemon Penstemon fruticosus
is one of the most ideal rock garden penste-
mons with its leathery evergreen foliage and
woody stems that drape fetchingly over adja¬
cent stones. Many shrubby penstemons of the
Dasanthera section (as P. fruticosus is) are
native to the northwestern mountains of the
United States. It grows about a foot tall and is
about 18 inches wide, and it is usually cov¬
ered with large lavender flowers although
there are also white and pink forms. We had
marginal success with this plant until we
realized it needed more shade and a bit more
moisture. A cutting of this beautiful plant
came our way at a plant sale and now its
legacy continues on in our eastern sloping
garden slowly creeping over a rock under our
crabapple tree!
Crested penstemon The crested penstemon,
P. eriantherus, is a hairy native of the high
plains and foothills. Its stems and leaves are
fuzzy with hairs and even its protruding
staminode is bearded with yellow hairs. In
spite of this description, P. eriantherus is a
beautiful plant with large fat flowers ranging
in color from pale lavender to pink. Purple
nectar guides lure giant bumblebees to its
tubular interior for pollen. The bees tumble
inside and emerge covered with it. This six- to
10-inch plant prefers the dryland garden and
appears to be a short-lived perennial. Cutting 37
back the stems after blooming may increase
its longevity, however; it is easily grown from
seed. Sometimes a short-lived penstemon
becomes a longer-lived one when the perfect
microclimate is found. This is part of the
intrigue of this genus.
Hall’s penstemon Found at about tree line
P. hallii, an endemic plant of the central Col¬
orado mountains, puts on a spectacular mass
of brilliant violet-purple flowers in late June
and early July at Boreas pass and on the road
to Kite Lake. It has done very well in our Lake-
wood garden in a lean scree of sand and grav¬
el. Every year when it blooms it reminds us of
our favorite outings to these mountain areas.
Pygmy penstemon One of the eastern pen-
stemons, P. hirsutus Pygmaeus’ is a dwarf
four- to six-inch beauty and also is a great
favorite. Its two-tone lavender and white
flowers and dark burgundy foliage are strik¬
ing. Like most eastern penstemons it prefers
dappled shade and abundant moisture. Our
pygmy penstemon droops over flat rocks bor¬
dering a dry stream bed in the backyard por¬
tion of the rock garden. It reseeds well, and it
is fun to see where it will take hold next.
These new young plants are a joy to dig up
and give to friends and visitors, as we feel it is
one of the very best rock garden plants.
Penstemon cardwellii ‘Roseus’ The origins
of P. cardwellii are found in the moderate ele¬
vations of the coastal mountains of Oregon
and Washington. This low shrubby penste¬
mon normally produces wine purple to deep
blue-violet flowers but a naturally occurring
brilliant carmine-rose variant has been dis¬
covered and introduced to the nursery trade.
Like the other species in the Dasanthera
group it prefers some shade, more moisture in
our dry climate and a crevice or rocky slope to
spread across.
Firecracker penstemon The fire engine
red, tubular corolla of P. eatonii is shockingly
bright and is easily grown. However this
plant is a bit too large for a small rock garden
and can be confused with the red forms of P.
barbatus to the uninitiated gardener. Maybe
its place is best in the dryland border or in a
38 large boulder field. A two- to three-foot native
of southwest Colorado, the firecracker penste¬
mon precedes the Fourth of July in Denver
with its bloom in June, but is still lends a lot
of snap to the garden! We have not found it
difficult to grow except that it got badly frost¬
ed one year with a very early cold spell.
Whipple’s penstemon This poor, maligned
plant has been described as dingy, droopy and
shy! Well, for us it is not shy but a frequent
and friendly companion during our mountain
treks as it is widespread in the Rocky Moun¬
tains. Easily found on the road to Mount
Evans, P. whippleanus produces both a dark
purple and a muddy cream-colored form, each
about a foot or more tall. A more spectacular
wine red variety is found south in the San
Juan Mountains. Whipple’s penstemon is an
easy plant to grow with some afternoon shade
and a normal loamy soil at our elevation.
‘Schooley’s Yellow’ penstemon Another
favorite penstemon, more suitable for the
larger rock garden or water-smart border
with an interesting pedigree is a form of P.
barbatus. Its corolla takes on the shape of an
elongated shark’s head. And this species has
served as the sturdy stock for many of todays s
hybrid penstemons. One of these, a natural
occurring hybrid, ‘Schooley’s Yellow’ is a
bright lemon yellow, two to three feet tall. It
was found by Gussie Schooley of New Mexico.
Dr. Dale Lindgren of the University of
Nebraska at North Platte further developed
this penstemon for its disease resistance and
longevity. Like other P. barbatus ‘Schooley’s
Yellow’ is a sturdy upright plant which lasts
for years. It appears to be one of the brightest
of the yellow penstemons and a suitable place
should be found for it in every garden.
We hope this exploration of a few of the
wonderful penstemons has stimulated your
interest in these all-American plants. If so,
you may wish to join the 450 other “penste-
maniacs” who are in the American Penstemon
Society.
Bibliography
Solange Gignac
Barr, Claude A. 1983. Jewels of the plains.
University of Minnesota Press, Minneapolis.
QK 135B3769.
Bloom, Alan. 1980. Alpines for your garden.
Floraprint Ltd., Nottingham, Eng.
SB 421.B536.
Brickell, Christopher and B. Mathew. 1976.
Daphne: the genus in the wild and in cultiva¬
tion. Alpine Garden Society, Woking, Eng.
QK 495.T48B75 1976.
Chalk, Douglas. 1988. Hebes and Parahebes.
Christopher Helm, London. SB 413.H4C48.
Elliott, Roy. 1976. Alpine gardening. Theo¬
phrastus, Little Compton, R.I. SB 459E447.
Farrer, Reginald John. 1932. The rock gar¬
den. T. Nelson & Sons, London.
SB 459F377Ro.
Foerster, Karl. 1987. Rock gardens through
the year: an illustrated guide for beginners
and experts. 7th ed revised by Bernhard Rol-
lich. Sterling Pub. Co., New York.
SB 459.F6 1987.
Foster, H. Lincoln. 1968. Rock gardening: a
guide to growing alpines and other wild
flowers in the American garden. 1968.
Houghton Mifflin, Boston. SB 459F677.
Gabrielson, Ira Noel. 1932. Western Ameri¬
can alpines. Macmillan, New York.
SB 421G13.
Grey-Wilson, C. 1988 The genus Cyclamen.
Timber Press, Portland, OR. SB 413.C9G7.
Halda, Josef J. 1992. The genus Primula in
cultivation and the wild. Tethys Books, Den¬
ver, CO. QK 495.P95H3 1992.
Handbook of rock gardening. 2nd ed. 1988.
Alpine Garden Society, Woking, Eng.
SB 459.H375.
Solange Gignac is the horticultural librarian in
the Denver Botanic Gardens' Helen Fowler
Library.
Kohlein, Fritz. 1991. Gentians. Timber Press,
Portland, OR. SB 413.G3K6 1991.
Kohlein, Fritz. 1984. Saxifrages and related
genera. Batsford, London. SB 413S28K65.
Krussmann, Gerd. 1983. Manual of cultivated
conifers. Timber Press, Portland, OR.
QK 494.5C75K7 1985.
Mathew, Brian. 1973. Dwarf bulbs. Arco
Pub., New York. SB 425M395.
Mathew, Brian. 1989. The genus Lewisia.
Royal Botanic Gardens in association with
Christopher Helm and Timber Press,
Portland, OR. QK495.P8M3 1989.
Mathew, Brian. 1981. The iris. B.T. Batsford,
London. QK495.I75M38 1981.
Payne, Helen E. 1972. Plant jewels of the
high country: sempervivums and sedums.
Pine Cone Publishers, Medford, OR. SB 438P39.
Pennell, Francis Whittier. 1920. Scrophulari-
aceae of the Central Rocky Mountain states.
Govt, print, off., Washington.
QK495 S43P46.
Rocky Mountain Alpines: choice rock garden
plants of the Rocky Mountains in the wild
and in the garden. 1986. Timber Press, Port¬
land, OR. SB 421R62.
Schacht, Wilhelm. 1981. Rock gardens. Uni¬
verse Books, New York. SB 459S352Ro.
Schenk, George Walden. 1964. How to plan,
establish, and maintain rock gardens. Lane
Book Co., Menlo Park, CA. SB459 S3.
Smith, George F. and D. B. Lowe. 1977.
Androsaces. Alpine Garden Society, Woking,
Eng. QK 495P95S6583.
Thomas, Graham Stuart. 1989. The rock gar¬
den and its plants: from grotto to alpine house.
Timber Press, Portland, OR. SB 459.T35.
Titchmarsh, Alan. 1983. The rock gardener’s
handbook. Timber Press, Portland, OR.
SB 459T5734.
39
Denver Botanic Gardens
909 York Street
Denver, CO 80206-3799
Non Profit Org.
U.S. Postage
PAID '
Permit No. 205
Denver, Colorado
Mountain, Plain and Garden
Printed on recycled paper using soy-based inks
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r
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1
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.
*
*
and Garden
The Magazine of Denver Botanic Gardens • Volume 51r No. 1
Mountain, Plain and Garden
The Magazine of Denver Botanic Gardens
Volume 51 No. 1 • 1994 • Deciduous Trees
Contents
Trees — a Denver Tradition . 3
Reading Our Landscape of Trees . 5
Practical Plains Forestry . 9
Barking up the Right Tree . 11
Street Trees . 16
Trees for Small Spaces . 22
Alley Cat Trees . 27
Blossoms Through the Year . 29
Demystifying the Maples . 30
Crabapple Update for the Front Range . 35
The Backyard Orchard . 38
Green Trees Have Colorado Blues . 41
Tree Rings — Reading Between the Lines . 43
How to Plant a Tree . 45
Bibliography . 47
Cover: Eastern river birch (Rollinger); Back cover: Star magnolia (Ipsen)
© 1994, Denver Botanic Gardens, Inc.
909 York Street • Denver, Colorado 80206-3799
Richard P. Koeppe, Ph.D., president
Richard H. Daley, executive director
Larry Latta, managing editor
Diane Ipsen, consulting editor
Tom Witte, graphic designer
A continuation of The Green Thumb Magazine
Produced by the Marketing and Special Events Department of Denver Botanic Gardens.
Denver Botanic Gardens and Chatfield Arboretum are established and maintained by Denver Botanic Gardens, Inc. for
the people of the City and County of Denver and the general public in cooperation with the Denver Parks and Recre¬
ation Department. Denver Botanic Gardens is grateful for funds from the Scientific and Cultural Facilities District
(SCFD) which enable the Gardens to expand services and enhance the quality of programs and exhibits.
Trees — a Denver Tradition
Denver, like other towns and cities on the
Eastern Slope, has evolved into a “green oasis
on the Great American Desert” by virtue of the
men and women who migrated here. Early set¬
tlers began planting trees even before the com¬
pletion of Smith’s Ditch, Denver’s first reliable
source of irrigation. Now, 134 years later, our
streets and gardens are graced with nearly
every species of tree that can possibly grow here.
For the most part, trees were tested and
found appropriate, or not, through the adven¬
turous efforts and experimentation of homeown¬
ers and gardeners. Local horticulturists and
nurserymen contributed to the body of local tree
wisdom so the urban forest grew even more
diverse.
In 1905 the Colorado State Forestry Asso¬
ciation published “The Forests and Exotic Trees
of Colorado” in which W.G.M. Stone fisted 69
different kinds of trees which were then growing
in Denver — all but seven on private grounds!
Denver’s street tree tradition began when roads
were little more than dirt wagon tracks. The
very first trees planted were locally gathered
cottonwoods. Then box elders and soft (silver)
maples were tried. Later, black locusts, ashes
and elms expanded the tree palette, as people
realized other species would actually survive
here.
About 1873, a man named James Richard
planted two rows of black walnuts along a lane
in Edgewater, and bur oaks were starting to be
grown by farsighted pioneers. After that, nurs¬
eryman Hiram Wolff was the first to experiment
with apple trees on his Clear Creek ranch,
where the finest hackberries in the region grew
around his home. William Byers, editor and
owner of the Rocky Mountain News, introduced
dozens of new trees to the area. He grew some
35 varieties on his own property.
According to Mrs. Katharine Bruderlin
Crisp, Denver’s foremost tree chronicler who
wrote her 1933 thesis on trees of the area, other
sites for early tree experimentation were the
cemeteries and the municipal parks. More than
30 species of trees were planted at Fairmount
Cemetery, and 47 varieties of trees grew in
Cheesman Park alone. In one park developed on
former nursery lands a person could see Japan¬
ese pagoda trees, sycamores, horse chestnuts,
sycamore maples, tulip trees, black alders and
several species of oaks.
The public schools became outdoor labora¬
tories in the next phase. Skinner Junior High
became an arboretum of sorts. Byers Junior
High, built on the home grounds of William
Byers, boasted mulberries, chestnuts, Russian
apricots, butternuts, lindens, cutleaf maples,
hawthorns, Kentucky coffeetrees, hackberries
and more.
A group of pioneer men and women who
called themselves the Old Cronies Club land¬
scaped the road from the Denver Museum of
Natural History in City Park to the park’s lily
pond, planting sycamore trees, Kentucky coffee-
trees, English oaks and tulip trees — all at their
own expense. This road is still called Old Crony
Lane.
Finally, the era of Denver’s Mayor Robert
Speer (1904-1912 and 1916-1918) was the Gold¬
en Age of tree planting. Under Speer’s direction
the talents of city landscape architect Saco
Rienk DeBoer were used to best advantage as
the “garden system” of parks and tree-canopied
boulevards flourished. During the City Beauti¬
ful era, the street tree became a symbol of civic 3
pride in a community-wide effort to dignify every
block with trees.
By 1933 Denver was home to 105 different
species of trees. DeBoer and a group of like-
minded citizens pressed for a “botanic gardens”
where additional trees and shrubs could be test¬
ed for hardiness in our unique climate. In 1951
that dream became a reality.
Until recently, Denver’s legacy of trees
had been deteriorating for several decades. Age,
neglect, pollution, disease, severe weather and
the chain saw all contributed to the decline of
the tree plantings along streets and in parks.
However, through a $3 million dollar bond
and citizen groups like Denver Urban Forest,
The Park People, Volunteers for Outdoor Colo¬
rado and numerous neighborhood organizations,
with help from Denver’s Parks and Recreation
Department and the Denver Water Department,
attention has been directed toward restoring
and maintaining one of the city’s finest civic tra-
4 ditions and greatest assets — our trees.
Top: Mayor Robert Speer personally supervised the
distribution of free saplings to Denver homeowners at
annual Arbor Day observances.
Above: Early Denverites often took elaborate mea¬
sures to protect their newly planted trees, scarce and
valuable additions to the prairie landscape.
Reading Our Landscape of Trees
Diane Ipsen
In the 1990s, citizens of towns and cities
on the Colorado Plains take for granted their
lovely, sheltering canopies of “urban forests.”
However, in this locale a century and a half ago,
the poetry of the land was not written in trees,
but in prairie grasslands and creekbottoms and
occasional scrub. Trees, mostly coniferous, grew
only in the foothills and higher. Cottonwoods or
willows were scattered along the watercourses,
but for the most part, trees had no place in a
plains ecosystem.
On the Great American Desert the
appearance of trees announced the pioneers’
arrival. Far from signifying wilderness, trees on
the Great Plains symbolized settlement, human
activity and the interaction of European peoples
with the land. Connections between trees and
the human psyche have always run deep, but
this natural reverence may be intensified in
arid, untimbered country.
The planting of trees and the systems of
irrigation ditches needed to nurture them were
the earliest and most visible signs that people
from the East had come to conquer and impose
order on the land. Even now, we recognize and
perpetuate the simple pattern of the homestead
encircled with sheltering trees, and it speaks of
place-making, protection and settlement. Tbday
on the plains, long after dwellings have crum¬
bled or burned down, one is able to sense the
domestication of places where pioneers had set¬
tled. Groves of trees and other woody vegetation
mark the spot.
Landscape architect Diane Ipsen, consulting edi¬
tor of Deciduous Trees, is a long-time contributor
to DBG. Her professional practice, DDI Design,
specializes in residential landscapes.
In this sense the landscape as modified by
humans is a vast historical record offering clues
to the past. And trees, enduring and visible, are
testimony to past intents and actions on the
land. However, the domesticated landscape is
ultimately mutable, and many features long
since erased are known to us only through leg¬
ends, photographs, maps and names.
For example, persisting “tree” place
names offer clues to local landscape history.
Baggage tags labelled ORD on items destined
for Chicago’s O’Hare Airport are simply expres¬
sive of the place name “Old Orchard,” which has
been given to the region of fruit orchards that
formerly covered the airport site.
The old and the new: A sprinkler system now waters the
banks of City Ditch in Washington Park. Irrigation has
always been necessary for growing trees in Denver.
A line of cottonwoods reveals the course of an old agricultural ditch that still traverses Loretto Heights Park.
Likewise, the local name “Hackberry Hill,”
given to a high bluff north of Arvada, signifies
some of its intriguing history, as revealed in the
“Legend of the Hackbeny Tree”: Once, this oth¬
erwise barren hill was home to a mysterious
lone hackberry tree, conspicuous from a dis¬
tance and a landmark on the treeless plains.
Old photographs show a short, twisted tree with
a kink in its trunk. It was thought to be ex¬
tremely old, having grown very slowly.
The 1843 Fremont Expedition is said to
have noted the tree standing on its lofty site, but
no written record of such has ever been found. It
was a puzzle how a non-native tree came to be
growing in such a dry hostile place, long before
the arrival of the first Eastern settlers. But one
theory supposed that it sprouted from the grave
of an Indian chief, slain in battle and buried on
the hill. Perhaps he had been buried with his fa¬
vorite amulets to ward off evil, which might have
included a pouch of souvenir hackberry seeds
gathered on some distant hunting expedition.
Another folk tale tells of a Sioux medicine
man who planted hackberries on high ground
across the West, as never-to-be-disturbed altars
to the Great Spirit.
Non-romantics among us may prefer the
supposition that the seed was brought to Hack¬
berry Hill by migrating birds from the Missouri
River Valley.
At any rate, government surveyors plan¬
ning a new road over Hackberry Hill in 1936
6 met with citizen outrage when they decided the
aged hackberry would have to be cut down.
Even the State Historical Society became in¬
volved in the battle, so officials agreed to trans¬
plant the tree. On the eve of its journey, with a
big trench dug around the roots, the tree was
cut down by an unknown vandal. According to
one source, in 1974 someone did confess to the
heinous deed, silencing those who suspected the
Great Indian Father had sought revenge on the
white man for building a road on sacred ground!.
The state lost its only native hackberry,
but place names such as Hackberry Hill Ele¬
mentary School and Hackberry Hill Amoco pre¬
serve a bit of local history.
Similarly, the name of Alamo Placita Park
along Speer Boulevard on the north bank of
Cherry Creek means “Little Place of the Cotton¬
woods” and recalls the original tree cover in that
location. A beautiful stand of old cottonwoods
growing in this creek-bottom area had become a
favorite picnic spot and something of a sacred
grove for early Denverites. Original park plans,
as well as the name, preserved the trees.
Those lost tree landmarks are now known
only through photos, place names and legends.
But other trees from the early days of Denver
still survive as evidence, telling us of human
activity long ago.
An observant person sometimes will
notice a line of ancient cottonwoods cutting
across a neighborhood, marching through back¬
yards, or traversing an office complex, golf
course or park. From a distance, especially, this
pattern of giant trees stands out, marking the
route of a 19th-century irrigation ditch — forming
a lineal forest strangely at odds with contempo¬
rary land patterns imposed around it. Painstak¬
ingly carved out on the arid plains from the 1860s
to the 1880s, irrigation ditches coursed through
land that was initially rural in character.
Today this network of ditches still criss¬
crosses Front Range cities and suburbs. But as
neighborhoods and subdivisions have grown up
around them, these little tree-lined acequias
have disappeared, hidden in alleyways, back¬
yards and underbrush, even shunted into pipe.
Only their cottonwood companions reveal their
routes. In their new contexts these giant ditch
trees seem awkward, struggling to fit in with
plots of house and bluegrass and exotic vegeta¬
tion — but this is also their charm.
By their presence we sense the persistent
traditions of frontier Colorado poking through
the urban fabric and we’re reminded of where
we live and of the labors of our predecessors.
Modem horticulturists may think of cotton¬
woods as cheap trees, but once people toiled
mightily to have and preserve them.
Like the ditch cottonwoods, other ancient
trees are historical indicators in the landscape.
Motorists on South Federal Boulevard in the
vicinity of Union, Tufts and Stanford avenues
may notice the arresting, inordinately large bur
oak trees growing along the west side. These are
the historic Sarah Brown Oaks, demarcating
what was once Sam and Sarah Brown’s farm on
this site near the South Platte River. The oaks
are awesome in size, reminiscent of Midwestern
trees. In fact, they look out of place, dominating
yards in a subdivision of modest one-story brick
houses.
In 1870 Sarah Brown had carried home
acorns from a visit to Missouri and Kansas, and
she planted them along the road and boundaries
of the farm. This was a common marking prac¬
tice of the day. Long after these homesteaders
were gone, their trees endured as a living histor¬
ical reminder.
In 1934 our State Forestry Association
reported that 26 of the magnificent trees were
standing. A recent expedition noted only six or
eight burr oaks on the west side with several
more across Federal toward the river, seemingly
from the same planting. As one admires these
magnificent specimens, sensing their indignity
at the doghouses and encroaching chainlink at
their feet, one can only lament that this land
was not preserved as a park to celebrate their
legacy.
Another indicator in our local landscape is
the mature planting of Koster blue spruce and
tall pines along Speer Boulevard on the south
side of Cherry Creek between Logan and Clark¬
son streets. These trees are the most visible
remnant of Mayor Robert Speer’s and S. R.
DeBoer’s elaborate 80-foot wide “forest belt,”
specifically the “evergreen extension,” installed
along Cherry Creek in 1917 and 1918, partly to
screen an unsightly dump from motorists’ view.
Speer had been inspired by “city forests”
while visiting Germany and was eager to create
one in Denver. This portion of the road was
named Forest Drive, and it became one of the
“sights of the city” according to DeBoer. Though
most of the forest belt is gone, even today one is
struck by the abrupt change from deciduous to
evergreen trees east of Logan.
Have you ever noticed two double rows of
European lindens gracing the northwest edge of
Cheesman Park? It seems a rather rigid and lin¬
ear arrangement for a park designed in the tra¬
dition of Frederick Law Olmsted. But in fact the
trees are clues to a vanished landscape: At one
time Franklin Street cut through the western
edge of the park and the lindens were planted
along both sides, in accordance with Reinhard
Schuetze’s 1902 plan. German-bom Schuetze,
the city’s first landscape architect, designed
Franklin Street to be Denver’s version of Unter
den Linden, the famous strasse in Berlin which
had so impressed Mayor Speer. While the street
was removed in the ’20s to ease traffic and elim¬
inate “drag racing” in the park, the surviving
trees still indicate the old route.
As long as the planting of trees remains a
primary endeavor of human beings, trees will
provide a visible record of people’s activity and
intervention, especially in the West. Land uses
may change, but the purposeful assembling of
trees in the landscape can endure for genera¬
tions. If we know what to look for, we can extract
fascinating insight about the past by “reading
the landscape.” 7
Above, left and right:
The magnificent Sarah
Brown Oaks, planted
to mark the boundary
of a 19th-century
homestead, persist
with an urban land¬
scape at their feet.
Right: Polypropylene
mulch has been use¬
ful in reducing
the water needed to
establish windbreak
trees at Chatfield
Arboretum.
Below: The arboretum
serves to meet the
challenge of devel¬
oping new trees for
the High Plains.
Practical Plains Forestry
Chris Hartung
Recent visitors to Denver Botanic Gar¬
dens’ Chatfield Arboretum have noticed a grad¬
ual change among the seeded prairie grasses
that dominate the arboretum’s flat expanses:
Thousands of tree seedlings now poke their tops
above the 4-foot high grasses.
As programs and gardens grow at the
arboretum, perhaps the least noticed but most
significant things to emerge are these trees.
They are an integral part of the first stage in
developing an arboretum on Colorado’s open
High Plains. Their job is to provide a favorable
climate for future plants: to provide protection
from the drying winds and to harvest snow
moisture.
Many visitors recognize these tree zones
as windbreaks or shelter belts: trees and shrubs
planted in several adjacent rows. They influence
the climate in specific ways, depending on their
design.
Why should we even try to plant trees on
the High Plains? Very simply, they make our
communities, farms and ranches more resource
efficient.
Substantial research shows that we bene¬
fit economically if trees are well-placed through¬
out our agricultural and urban settlements. In
fact, windbreaks are still considered the best
defense against soil erosion during periods of
drought, when other types of vegetation will not
persist. Contrary to the belief that they require
additional watering, some types of windbreak
trees can be grown in Colorado without it. In
Chris Hartung. a Denver Botanic Gardens horti¬
culturist for seven years, is Chatfield Arboretum's
supervisor. His interests are in drought-resistant
woody plants and prairie ecosystems.
addition, a diversified windbreak provides food
and shelter for wildlife.
The history behind windbreaks on our
Great Plains reveals their value. The need for
trees on the prairie was demonstrated during
the Dust Bowl Era, when the sky was blackened
with soil blowing off cultivated lands across the
plains from North Dakota to Texas. One result
was the Prairie States Forestry Project from
1934 to 1942, when 222 million trees were
planted in windbreaks and shelter belts. This
was the largest tree planting ever undertaken
in the United States. The first shelter belt of the
project was a 1935 planting in Oklahoma of
Austrian pines; it is still providing protection to
that land today and is a living monument to
man’s perseverance on the prairie.
While some new windbreaks are still being
planted, over the past 15 years many agricultur¬
al enterprises have been cutting down wind¬
breaks to make room for more crops or accommo¬
date center-pivot irrigation systems. Combined
with natural attrition, this has resulted in a dra¬
matic decline in numbers of windbreaks through¬
out the Great Plains. It is a cause of concern.
Recently, the New Farm Bill created
incentives to agricultural enterprises to plant
more windbreaks. A program called “The Center
for Semi-Arid Agroforestry” at the University of
Nebraska-Lincoln is coordinating with federal
and state agencies to conduct research and to
combat the decline in windbreaks by initiating
another massive planting effort comparable to
the 1930s.
Chatfield Arboretum is recognized as a
collaborator and leader in windbreak technolo¬
gy. It offers some of the best examples of wind- 9
breaks in the state. Many of the more than 50
species of trees used in our windbreaks are not
traditional windbreak species nor have ever
been cultivated in Colorado before.
Since our primary objective in planting
windbreaks at the arboretum is practical, I have
tried to anticipate which species are likely to
thrive, and to plant more of those species. Both
failures and successes, though, will be impor¬
tant information for plains forestry and dryland
horticulture in Colorado.
The need to develop and discover addition¬
al trees that can adapt to our environment is
one of the most important challenges for horti¬
cultural researchers in Colorado and on the
High Plains. Long-term tree research is usually
not a high priority for many agencies and uni¬
versities. This is why it is important for every¬
one — citizens, agencies, industry — to cooperate
in making such research possible. And it
emphasizes the need for an institution like Den¬
ver Botanic Gardens’ Chatfield Arboretum
where cooperative efforts can be realized.
10
A few examples of seldom used and
uncommon tree species being grown at Chat-
field are western soapberry ( Sapindus drum-
mondii), Kentucky coffee tree ( Gymnoclados
dioicus), jack oak ( Quercus ellipsoides), Arizona
walnut ( Juglans major), white bark pine ( Pinus
albicaulis), southwestern white pine {Pinus
strobiformis ) and Macedonian pine ( Pinus
peuce ).
Most of our 16 miles of tree rows at Chat-
field Arboretum have been or are being estab¬
lished with water. Some species require no
water to establish, others need it for only one
year, and some we are choosing to water for four
or five years. Some of our windbreaks
do not receive any water, but instead
are established with a polypropylene
material mulch that has proven to be
effective in keeping natural moisture in
the soil. Eventually only weed control
will be necessary to manage these plant!
ngs, and no supplemental water will be
used.
This year three new
windbreaks (500 trees) were
installed as part of a 20-year,
multi-agency, North America¬
wide provenance study of bur
oak {Quercus macrocarpa). Work
ing with Colorado State Forest Ser¬
vice, we are providing a site for 28 dif¬
ferent seed sources of the oak,
which will tell researchers
which seed sources, geo¬
graphically, are best suited
for Colorado. Other source
studies are being conducted on
Scots pine {Pinus sylvestris ) and
western soapberry.
Visitors can observe the
arboretum’s windbreaks from 9
a.m. to 5 p.m. any day; it is
open year-round.
Kentucky coffee tree (.Gymnoclados dioicus)
Barking up the Right Tree
Diane Ipsen and Alan Rollinger
The sorts of trees being planted in our
Front Range landscape are determined by many
different people. Homeowners, designers, land¬
scape architects, urban foresters, park planners,
developers, nurserymen — all contribute to the
tree cover of our locale.
With such a diverse bunch selecting the
trees, the monotony and predictability of what
gets put in the ground is inexplicable. Generally,
we are in a crabapple-and-aspen rut, with a few
thousand honeylocusts, green ashes, suckering
Shubert chokecherries and narrowleaf cotton¬
woods thrown in for the maintenance people. If
screaming boredom isn’t enough of a reason to
try something different, the fact that these four
or five overworked trees have some serious
drawbacks ought to be.
For example, few trees planted on the Col¬
orado plains are more plagued with diseases
than the short-lived aspens. Their habit of suck¬
ering, while not as destructive as that of nar¬
rowleaf cottonwoods or chokecherries, is guar¬
anteed. And at lower elevations they don’t often
display the coveted autumn gold. Crabapples
need almost constant pruning to remove the vig¬
orous suckerwood, and all too often end up
chopped into ugly stumpiness at the hands of
misguided tree trimmers. Also, fire blight is a
problem on many varieties (see “Crabapple
Update”) and rotting apples are a squishy nui¬
sance when they fall on patios, tennis courts,
drives or sidewalks. Neither aspens nor crabap¬
ples do well in shade.
Landscape architect and Colorado State Uni¬
versity graduate Alan Rollinger specializes in
residential planning. A pioneer in water-saving
landscape design, he has more than 800 pro¬
jects to his credit.
Green ashes and honeylocusts have sim¬
ply been used ad nauseum.
Nevertheless, all these trees continue to
be specified repeatedly and planted by the truck-
load. Are we suffering from arboreal anemia?
Transfusions, please!
Infusing some new blood into our pool of
possible choices does not have to be risky busi¬
ness. Happily, there are any number of reliable
trees that qualify as excellent alternative selec¬
tions for our region — trees which are beautiful,
interesting, versatile, durable plants. They just
need more “press.”
To that end we submit to the enterprising
gardener and designer the following short sur¬
vey of trees which we feel deserve greater atten¬
tion and use, and which are in many ways supe¬
rior to those more commonly chosen.
Purple leaf
European
beech
European Beech
A mature specimen of purple-leaf Euro¬
pean beech ( Fagus syluatica purpurea ) is a sight
to behold. The rich purple-bronze foliage, smooth
gray bark and unusual branching structure are
an unsurpassed combination. With maturity,
the bark develops an elephant-hide appearance
which is quite beautiful and unforgettable. Not
the least of its attributes is its stateliness for it
often grows more than 50 feet in height and
tends to branch close to the ground, with a nice,
broadly-oval form. The lustrous leaves turn a
rich russet and bronze color in fall.
While European beeches are rare in this
area, they do grow here — and there are a num¬
ber of grand old specimens around Denver. The
southeast comer of St. John’s Episcopal Cathe¬
dral at 13th Avenue and Clarkson Street in
Denver is virtually screened by the dense pur¬
plish foliage of an enormous European beech
planted decades ago. Between Marion and
Lafayette streets along Third Avenue grows
another magnificent specimen. All the beeches
in our area are the so-called purple-leaf beeches,
selections from the standard green-leafed tree.
Just which selections they are no one can tell.
There are numerous purple beech cultivars;
leaves of a common one in the nursery trade,
‘Riversii’, emerge a deep purple and remain a
purple-green into summer.
Beech trees have always been important
to humans. Beech nuts are still eaten in some
parts of Central Europe, as they were by Stone
Age people. In the Old World, the abundant
beeches provided heating fuel and charcoal for
the iron smelters. Beech was considered the
general utility hardwood of Europe for every
timber need, from furniture to tool handles to
wooden shoes!
While beeches are relatively tolerant of
various soil conditions, along the Front Range
they need a well-drained location. If at all possi¬
ble, you should try a beech, for its attributes
make it one of the finest trees in any landscape.
Perhaps there is none finer.
Asian Whitespire Birch
Birch ( Betula ) is a beautiful and diverse
genus, but one which has not been without its
problems. The scourge of the birch world is the
bronze birch borer, a small opportunistic beetle
that tunnels beneath the bark of trees under
stress. By the time injury has made itself evi¬
dent, it is usually too late to save the tree.
1 2 Consequently, the white-bark birch indus-
Asian
Whitespire
birch
try almost died at one time. But due to its
remarkable resistance to bronze birch borer, and
the purity of its white bark, the Asian White¬
spire birch has taken the lead for landscape use.
It is, however, only moderately resistant to the
less-serious but annoying leaf miner.
This tree has an interesting and fairly
recent landscape history. All plants of Betula
platyphylla japonica Whitespire’ growing in the
United States originated high in an alpine
meadow in Honshu, Japan. In 1956 John
Creech, of the National Arboretum, passed
through this meadow in search of a certain
rhododendron and was attracted to a beautiful
specimen of birch with gleaming white bark. He
brought seed back to the United States. The
resulting trees reside at the Brooklyn Botanic
Gardens and Longenecker Horticultural Gar¬
dens at the University of Wisconsin where in
1983 the name Whitespire’ was made official.
Later, in controlled testing to determine borer
resistance of various birches, Whitespire clearly
outperformed other species.
Whitespire birch is a pyramidal tree reach¬
ing 40 to 50 feet in height. It is loveliest grown
as a clump and displays its chalky-white non¬
exfoliating bark at an early age. Cultural require¬
ments are the same as for Betula nigra. Report¬
ed to be tolerant of heat, this tree will do best in
moist but not wet soil. A periodic winter water¬
ing is important. Two young Asian Whitespires
are planted at the entrance to Wellshire Inn.
Eastern River Birch (Water Birch, Black
Birch)
The eastern river birch ( Betula nigra), not
to be confused with the Colorado river birch
( Betula fontinalis), is a native American tree
found on streambanks and in swampy forest
lowlands.
This beautiful, fast-growing tree is notable
for its distinctive shaggy bark mottled with
tones of cinnamon, salmon pink and cream.
Young limbs have a rusty metallic sheen, which
on mature limbs exfoliates in appealing papery
tatters, giving the tree a wonderful winter value
in the landscape. The leaves are larger than
some birches: up to three inches long, thick, deep
green and lustrous above. Fall color is yellow.
Eastern river birches are reported to have
great resistance to heat and cold. Most sources
state that they prefer acid soil but are adapt¬
able, and observations around Denver would
bear out their ability to adjust to our alkaline
soils. While supposedly tolerating wet places,
they require well-drained soil and need even,
consistent moisture. As with all birches grown
in this area, these require winter watering dur¬
ing dry spells. (When you see a truly healthy,
good-looking birch here, you can be certain it has
remained that way through wise management:
i.e., late fall and winter watering after automat¬
ic sprinkler systems have been turned off.)
Osage
orange fruit
Eastern river birches are graceful in form,
being particularly handsome when grown in
clumps or planted in groups. Stalwart resis¬
tance to the serious pest bronze birch borer has
given eastern river birches new status as orna¬
mental landscape trees. They are big birches,
ultimately growing to 50 or 60 feet.
Birches should be planted with the root
ball 2 to 4 inches above the surrounding soil
level. Underplant them with a sweep of ground-
cover and they will look their best. Diane added
three multi-stem clumps of the faster-growing
variety ‘Heritage’ to her garden several years
ago and is impressed by the woodsy quality they
have created, as well as by their performance.
As lovely as the foliage of Betula nigra is, the
visual treat is in the winter, when the dramatic
bark is set against the snow. This is a perfect tree
to place where it will be viewed from a window.
Osage Orange (Bodark, Bois-d’arc, Bow
Wood)
Almost a horticultural institution in the
United States, Osage oranges ( Maclura pomi-
fera) are found growing throughout most of the
country. Nevertheless, many Coloradans have
overlooked these small, thorny members of the
mulberry family, although the trees are known
for their toughness.
Their most attractive feature is their shiny,
deep-green foliage which contrasts noticeably
with other landscape plants. Their crowns are
rounded, sometimes irregular, on short trunks.
Flowers are not showy, but they are followed by
interesting softball sized fruits with a bumpy
rind vaguely resembling an orange. (As kids we
would have called them “ammunition trees.”)
The mess from these bitter yellow fruits is a
drawback for landscape use, but with the intro¬
duction of the variety ‘Park’, we now have a
fruitless Osage orange tree.
The native habitat for Osage oranges is
the rich bottomland of the Arkansas and Red
rivers in the region inhabited by the Osage Indi¬
ans. There the trees’ suitability for windbreaks
and hedges earned them the name “hedge
apples,” and many a pioneer surrounded farm
land with this “living fence.”
Because the flexible wood is strong and
hard, it was used to make the hubs and rims of
wagon wheels in the horse and buggy days. Few
woods are rot resistant when in contact with the
soil, but this attribute of Osage orange is the
reason the tree was extensively used for fence-
posts, railroad ties and cabin underpinnings.
One of the numerous uses the Osage Indians
made of the wood was for bows and arrows,
hence the French name bois d’arc, “bow wood.”
The vernacular name bodark is simply an angli¬
cized version of bois d’arc. 1 3
Under the 1934-1942 Prairie States
Forestry Project, 18,000 miles of shelterbelts
were established to protect farms and ranches
on the Great Plains — the largest tree-planting
effort in our nation’s history. Osage oranges
were utilized extensively, for they are hardy,
adaptable, drought resistant trees. In fact, the
poorer the site the better these trees like it.
However, they have not been widely
accepted as ornamentals. Now, with the avail¬
ability of the fruitless ‘Park’ variety, Osage
oranges could help ease the dearth of small
trees suitable for landscape work. There is also
a thornless Osage orange, the variety inermis.
In Denver, a beautiful example of the fruit¬
ing species can be seen in a yard near the north¬
west comer of south Jackson Street and Arizona
Avenue. There are also some growing north of
Denver Botanic Gardens’ main parking lot.
Chinese Catalpa
Probably the best of the catalpas are the
trees known as Chinese catalpas ( Catalpa
ovata). Their large leaves have a purple vena¬
tion which gives them an unusual and attrac¬
tive purplish-green color. The pretty flowers in
late June and July are yellowish-white, striped
with orange inside and spotted dark violet.
Even young children are acquainted with
the long and stringy catalpa “beans,” which add
interest to the landscape but which can be a
nuisance in the garden. Fruits of Chinese catal¬
pas are narrow, clustered, and more finely tex¬
tured than those of western catalpas, and there¬
fore less bothersome.
Chinese catalpas grow to 30 feet tall or so,
roughly half the size of their more common
western cousins. No pests or diseases attack
them, although hailstorms can considerably tat¬
ter their big leaves.
Chinese catalpas are often best-used as
specimens because of their eye-catching texture
and flowers. As with several other trees men¬
tioned here, clump forms are particularly appeal¬
ing. Although not widely known, Chinese catalpas
are not new to the Denver area; mature examples
can be seen at the entrance to the Denver Zoo,
1 4 and here and there in the city’s neighborhoods.
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Turkish
filbert
Turkish Filbert (Turkish Hazelnut)
Turkish filberts ( Corylus corluna ) are big
handsome trees suited for use as shade or street
trees but little known or grown. Their form is
symmetrical and pyramidal, and their good-
looking, dark green foliage and striking, corky
bark make an impressive contribution to the
landscape. They are cold-hardy trees that should
be planted more often.
Turkish filberts are also reported to toler¬
ate a certain amount of drought and heat, once
established, and may be a good choice for a site
with little moisture. They will not scorch in city
conditions where maples often do. When the
eastern United States was experiencing severe
drought in recent years, other trees defoliated
while the Turkish filberts remained green and
vigorous. They are pest free and they adapt to
various levels of soil alkalinity. If obtainable, a
multi-stemmed specimen is striking.
Actually, Turkish filberts have been in the
area for a number of years. Alan specified this
tree 20 years ago in his design for the Foothills
Art Center in Golden. It has done very well, as
have other known specimens in the area. At
Denver Botanic Gardens, Turkish filberts can be
seen at the south end of the main perennial path.
Swamp White Oak
In their native American range, swamp
white oaks ( Quercus bicolor) are found on the
borders of streams and swamps and in low,
poorly-drained meadows. They have attractive
foliage: characteristic leathery “white oak”
leaves with rounded lobes. The species name
“bicolor” refers to the two colors of the leaves:
dark green above and whitish and velvety below.
Swamp white oaks are long-lived, and
throughout the United States many centuries-
old trees have become beloved landmarks. Their
wood is used to make wine and whiskey kegs,
among other things.
Swamp white oaks were planted in the
Denver area 50 or 60 years ago and then, for
some reason, dropped out of the nursery trade.
Several specimens in older neighborhoods have
achieved a measure of grandeur over time, one
of the most beautiful being on the old Mary
Chase estate along Circle Drive in Denver.
About 20 years ago interest in this species
was revived, on the theory that a tree which
naturally grows in wet, low-oxygen soils should
do well in our heavy, clay soils. This has proved
to be a good assumption — if the tree is not over¬
watered. Swamp white oaks could be trees that
thrive on neglect.
For many years now Alan has enjoyed
watching the progress of his favorite swamp
white oak, a vigorous specimen that grows in
the bentonite clay soil of Broomfield at the home
of a relative, a neglectful “erstwhile gardener”
who under waters. Interestingly, the key to suc¬
cess seems to be deep but infrequent waterings,
which ensure that proper oxygen levels are main¬
tained in the soil. In fact, swamp white oaks can
be considered xeriscape plants if properly grown.
American Hornbeam (Blue Beech, Water
Beech, Ironwood, Musclewood)
American hornbeams (Carpinus caroliana)
are small, handsome, bushy trees. They should
be in greater demand in our region and deserve
serious consideration for our landscapes. They
are understory trees in the forests, seldom over
40 feet tall, more often reaching only 20 feet.
Their slender trunks are short and somewhat
crooked, often forking low.
Hornbeams are most recognizable by their
distinctive fluted trunks and branches called
“musclewood.” The spiraled and twisted ripples,
to many, resemble a flexed muscular arm. The
bark is gray and smooth and appears to be
swelling inside itself. This trait is seen even in
young trees.
Among the many fine features of Ameri¬
can hornbeams are their extreme shade toler¬
ance and absence of mess. There is no juicy fruit,
so they make excellent patio trees. Slim catkins
appear in spring in conjunction with the emerg¬
ing leaves, which are polished, thin and translu¬
cent. The rather dense foliage turns scarlet and
orange in autumn. A “grove” planting of Ameri¬
can hornbeams at the Ruth Porter Waring Den¬
ver Botanic Gardens House at 909 York Street
illustrates their suitability for naturalizing, and
the trees may be at their best grown in groups.
Wafer Ash (Hop Tree)
Wafer ashes iPtelea trifoliata) are small
patio-type trees that many local tree con-
noiseurs have admired for some time. They con¬
tinue to be difficult to obtain but it is hoped
that — as with all these trees — increased interest
and demand will result in supply! This tree is
one of those “sleepers” that demands wider use;
it is a better tree than many that are more com¬
monly sold.
Wafer ashes are round-headed trees reach¬
ing up to 25 feet tall that perform equally well
in heavy shade or sun. Illustrating how decep¬
tive common names can be, they are not true
ashes ( Fraxinus ) at all. The plants are native to
the East and Midwest but have demonstrated
hardiness and drought tolerance here in Col¬
orado. Local specimens have been around long
enough to have survived several legendary win¬
ters and they have exhibited no problems.
Sources list them as USDAZone 3 plants.
Wafer ashes, of course, also can be grown
with irrigation, and they enhance a garden with
fragrance and beautiful foliage. Corymbs of
small yellowish flowers open in June, releasing
a scent surpassing that of any other hardy tree,
equaling the most fragrant honeysuckle. The
leaves are composed of three dark green, glossy
leaflets that turn yellow-green to yellow in fall.
Their seeds, which have been used as a substi¬
tute for hops, are bom in samaras similar to
elms. Mature trees exhibit attractive reddish-
brown bark. An example of this tree can be
found on Marion Parkway just north of Alameda.
These are but a few of the numerous trees
that deserve more attention in Colorado. All can
be planted with confidence. They will contribute
to the diversity of our urban forest and give
unique character to personal gardens. 1 5
t
Street Trees
Ken Slump
Individuals and civic groups have worked
diligently in recent years to promote tree planti¬
ng throughout metropolitan Denver’s neighbor¬
hoods. Their goal is to replace the thousands of
trees that have been lost in Denver since the
1960s due to a variety of factors such as Dutch
elm disease, street widening projects and old age.
Trees in cities experience a number of
stresses not found in their natural habitats. Often
they are planted in restricted areas with limited
soil surface for water absorption and root devel¬
opment. Soil temperatures are usually higher in
urban sites than in the trees’ natural settings.
Injuries from machines, from lawnmowers to
trucks, tear and injure their trunks. Urban air
pollution, or course, takes its toll, and street trees
in cold climates frequently suffer the additional
insult of road salt splashed onto their root zones.
Although numerous species survive here,
it is important to note that most never attain
the size or the lifespans that they might in their
native habitats. Native trees consisted mostly of
a few cottonwoods and willows growing along
the rivers and creeks.
Denver’s mayor Robert Speer was a great
promoter of planting street trees in the earlier
part of this century. His administration distrib¬
uted hundreds of trees: stately American elms
( Ulmus americana ) the fast growing soft maple
( Acer saccharinum ) and the thirsty cottonwood
(. Populus deltoides). Many of the elms have suc¬
cumbed to Dutch elm disease, and most of the
Ken Slump, plant record keeper of Denver
Botanic Gardens, is a graduate of Colorado
State University, a former arboreal inspector in
the Denver Department of Parks and Recre-
1 6 ation and a dedicated horticulturist.
cottonwoods, being comparatively short-lived,
have died from old age. A large number of the
soft maple trees are still living in some of Den¬
ver’s older neighborhoods; however, many are in
a state of decline. Current guidelines in the City
and County of Denver prohibit the planting of
poplars, aspens and cottonwoods (all of which
are Populas species) or willows ( Salix spp), box-
elders (Acer negundo ) and soft maples in the
public rights-of-way.
New plantings of the thornless honeylo-
cust ( Gleditsia triacanthos inermis cvs), green
ash ( Fraxinus pennsylvanica lanceolata cvs) and
soft maple have dominated urban planting for
the past 30 years. Although these species may
merit some popularity, it is imperative that we
diversify our urban forests to avoid the Dutch
elm disease tragedy which left urban streets
across the country planted as monocultures
nearly treeless.
What makes a good street tree? Most peo¬
ple favor a fast-growing, disease free, single¬
trunk tree with ornamental features, with a
minimum of maintenance and unnecessary
mess or litter. Also desirable in Colorado are
trees that do not leaf out too early in the spring
or hold their leaves too late into the fall as such
trees are prone to breakage in unseasonal snow
storms typical of our climate. Drought tolerance,
too, is important for Colorado trees, although
conclusive data on this characteristic for each
species is not complete.
Of all these, rapid growth seems to be the
main criterium in our “instant” society. We have
been conditioned to wait for nothing. Belying
this, many established communities, public gar¬
dens and arboreta across the country have
plantings or specimens of mature, unusual
Ipsen Ipsen Ipsen
species that are loved and admired by the pub¬
lic. A sensible approach would seem to be to
plant for both the long and the short term,
including fast- as well as slower-growing species
in street plantings. Fast-growing trees generally
have weaker growth and shorter lives than
slow-growing types. It is important to realize
that many tree species believed to be slow-grow¬
ing often have quite satisfactory growth rates,
once established.
It may also be good to reconsider whether
the usually brief periods of litter from tree flow¬
ers and fruit are really so serious. Northern
catalpa ( Catalpa speciosa ) female specimens of
Kentucky coffeetree ( Gymnocladus dioica), Buck¬
eyes ( Aeschulus spp.), Horse chestnuts ( Aesculus
hippocastanum ) and even seed-producing indi¬
viduals of thornless honeylocust are shunned
because of the “mess” their large seeds or pods
produce. Older parks, however, frequently have
mature specimens of thornless honeylocust,
planted before the introduction of seedless
varieties, which in fall and winter are laden
with dramatically long, twisted, mahogany-
colored pods.
Normally, pods will also be found lying on
the ground beneath these trees, giving interest
to the otherwise dormant, monotonous brown
turf and demonstrating nature’s self-perpetua¬
tion. And what child hasn’t delighted in a pock¬
etful of shiny ‘"buckeyes” from beneath a horse
chestnut or buckeye tree? Continuing the prac¬
tice of selecting only cultivars with flowerless or
seedless characteristics not only makes for a
dull landscape with limited seasonal interest, it
drastically limits genetic diversity in each
species and, as well, limits the food supply for
insects, birds and wildlife.
Oaks are considered to be slow-growing
but are unquestionably a long-lived, majestic
choice for street planting. The genus Quercus is
large and diverse. Three species that do well as
street trees are bur oaks (Q. macrocarpa), nor¬
thern red oaks (Q. rubra) and English oaks (Q.
robur ). Other oak species with well established
specimens growing in the area deserve wider
planting. Among these are swamp white oaks
( Q . bicolor) and Mongolian oaks ( Q . mongolica).
Several linden species may be grown in
1 8 this area. Two of the more common are Ameri¬
can lindens (Tilia americana) and littleleaf lin¬
dens (T. cordata). Both are stately trees with
pyramidal growth habits when young. Lindens
grow into sturdy trees that seldom need prun¬
ing. In late June their pale yellow flowers open
beneath the dense, green, heart-shaped foliage
to delight unsuspecting passersby with their
sweetly fragrant scent. ‘Redmond’ linden, a
hybrid of somewhat uncertain origin, has red¬
dish bark in winter.
Seldom-encountered but seemingly well-
adapted trees for our area are the Turkish fil¬
berts ( Corylus colurna). The filberts, or hazel¬
nuts, are members of the birch family. These
trees are reputed to thrive in hot summers and
cold winters, and are very drought tolerant once
established. They have an attractive form
rather like some of the oaks and require little
maintenance.
Birches, among the most beloved of trees,
have varied success in our area. A decade or
more ago it seemed each spring brought the
decline and death of numerous mature speci¬
mens. A combination of dry winters, borer infes¬
tations and old age seemed to be the causes.
Most of these losses were specimens of Betula
pendula, known as European white birch, and
B. papyrifera, or paper birch. Even under the
best of circumstances, most birches cannot be
considered long-lived.
Birches are not a common choice for street
planting, and it should be noted that the City
and County of Denver prohibits the planting of
trees in the public right-of-way with weeping or
pendulous growth habits, as well as multi¬
stemmed trees. These are habits common to sev¬
eral birch species. There is, however, one birch
which tends to be more trouble free than others
and whose growth habit would make it a suit¬
able street tree. This species is the handsome,
widely adaptable Eastern river birch (B. nigra).
Unlike most birches, this rather fast-growing
tree is tolerant of dry periods, particularly in the
summer and fall, and is resistant to birch borer.
Its bark exfoliates into rough, curling plates
that are highly ornamental. The cultivar ‘Her¬
itage’ is an excellent, highly recommended tree.
Now, picture a sound tree with an attrac¬
tive branching pattern, distinctive ornamental
bark and bright green foliage that turns yellow
in autumn. Some authors describe it as one of
the best substitutes for the American elm along
our streets. Yet hackberry ( Celtis occidentalis )
remains underused. It is tolerant of a wide vari¬
ety of soils. It grows well in windy dry sites. And,
although it’s a cousin of the American elm, it is
not susceptible to Dutch elm disease. Perhaps
“nipple gall” on the foliage is a deterrent. It
shouldn’t be, as this insect-caused problem does
little damage to the tree.
Another American tree that is highly
adaptable to Colorado soils
and climate is the Kentucky
coffeetree. Mature specimens
are renowned for their hand¬
some, rugged winter silhouette
and rough, attractive bark.
Female trees produce thick pods
containing large seeds that early set¬
tlers in this country roasted and
ground into a coffee substitute.
Another of the tree’s advantages
in our climate is its tendency to
leaf out rather late in the
spring, avoiding heavy late spring snow
damage. Certainly these are trees that deserve
planting outside of public parks, where they are
frequently found.
Unusual medium-sized trees with poten¬
tial for street planting are Amur corktrees ( Phel -
lodendron amurense). They tend to have a pic¬
turesque, broad spreading habit so they may
need some pruning for street clearance. Among
their many desirable characteristics are ease of
transplanting, ability to grow in a wide variety
of soils, tolerance of drought and urban pollution
and low maintenance requirements. The rough¬
ly ridged, corky bark on older trees is an impor¬
tant ornamental feature. The trees’ tendency to
defoliate early in the fall season is an additional
advantage in this climate.
There are mixed reviews on sycamores
(. Platanus occidentalis ) also known as American
planetrees. They are, nevertheless, worthy candi¬
dates for a varied urban forest. They are among
the taller trees and they grow relatively fast. Most
detractors cite their messiness and susceptibili¬
ty to the disease anthracnose. Anthracnose, how¬
ever, rarely kills the tree and its seriousness in
any year depends on weather conditions. Cool,
moist late spring weather favors its spread, so
Colorado’s usually low relative humidity mini¬
mizes the problem.
Sycamores’ tolerance of adverse city condi¬
tions is one of its greatest assets. The mature
line of sycamores on either side of Marion Street
Parkway just north of Washington Park, plant¬
ed decades ago by S.R. DeBoer, is stunning. Aes¬
thetically they are known for their intriguing
bark, which exfoliates in smooth patterns in
shades of white, gray and brown. Sycamores,
also, leaf out somewhat late in the
spring.
Several mature Japanese pagoda
trees ( Sophora japonica) in the
Denver metropolitan area imply
that these trouble-free, pollution
tolerant trees may be hardier in
Colorado than some references indi¬
cate. Also known as scholar trees,
their creamy white flower clusters
appear unexpectedly late in summer,
followed by lustrous yellow-green seed
pods. Their compound leaves are somewhat sim¬
ilar but not as finely textured as those of honey-
locusts.
Finally, let’s ponder whether we must for¬
ever forsake the planting of American elms,
once the tree-of-choice for streets across much of
the country. Even without the threat of Dutch
elm disease, the species is not lacking in prob¬
lems, further illustrating that there is no perfect
tree. Work on Dutch elm disease-resistant
American elm hybrids and cultivars continues.
Whether currently available cultivars will suc¬
cessfully combine disease resistance with the
graceful and esteemed vase-shape form remains
to be seen. Gamblers may choose from the culti¬
vars Washington’ or the promising ‘Liberty
series.
Trial and error taught early Colorado
plantspeople which trees would survive along
our streets; adventurous Front Range horticul¬
turists continue the experiment as new cultivars
and species become available. A more interest¬
ing, healthier urban forest would result if each
resident could tell those who inquire of their
tree, ‘Yes, it is quite an unusual species, and the
only one I know of in the neighborhood!”
fosen _ Ipsen
Ipsen Rollinger
Top left: Littleleaf
linden in Washing¬
ton Park
Above: European
mountain ash
in fruit
Left: Downy
hawthorn fruit
Below: ‘Autumn
Purple’ ash and
green ash in
the fall
Trees for Small Spaces
Susan Yetter
Ever since losing Eden, people have been
busy creating sacred and magical places, called
gardens, in which to take refuge from the hectic
world. The process of making a garden — from
the first internal vision, through the design
process and, finally, to the tools and sweat — is
about creating a space — ideally one with some
poetry to it.
Of the many materials and design elements
available to make a garden enclosure, trees can
be used as “living architecture” to define the bound¬
aries, form the garden ceiling, frame or screen
views, cast shade, or simply be used as center-
pieces (focal points) placed where we may appre¬
ciate their explosion of blooms, fall colors or
interesting textures and structural forms. Glades
or woodsy groves create a certain mood in a gar¬
den; a formal allee strikes a different mood.
In small gardens where space is at a pre¬
mium, the selection and placement of trees war¬
rant special consideration. More heartbreak has
come from miscalculated placement of trees and
underestimating their ultimate sizes than from
any other element in the garden. After all, the
idea is to create space, places to sit and stroll
and explore and gather — not to fill it with space-
dominating vegetation.
Having at hand a list of appropriate small-
er-scale trees, and understanding their shapes
and unique features, a garden-maker will have
a better chance of arriving at a sanctuary that
functions for its many intended uses and gives
sensory pleasure throughout the seasons.
Susan Yetter is a garden designer specializing
in regional and sustainable landscapes in har¬
mony with the West's semi-arid climate. She is
22 a regular instructor at Denver Botanic Gardens.
Columnar Trees
Trees with a narrow, upright profile create
a strong vertical accent as single specimens;
they are also ideal for screens in small gardens.
Upright European Aspen ( Populus tremula
‘Erecta’)
Also known as Swedish columnar aspens,
these attractive trees are useful for screen plant¬
ing, small groves or planting as a single speci¬
men. Their growth rate is somewhat faster than
that of our native aspens. However, unlike our
natives, these do not put out sucker growth.
Their leaves have crisp, wavy edges and glow
with shades of yellow, orange and red in autumn.
For best growth, plant upright European
aspens in full sun in well-drained soil and ade¬
quate moisture. They will reach 20 to 30 feet
tall, and 8 feet broad. They are useful up to 8,500
feet elevation.
Columnar Norway Maple ( Acer platinoides
‘Columnare’ and A. p. ‘Crimson Sentry’)
The form ‘Columnare’ is a relatively old
cultivar dating back to 1855. It is adorned with
small, shallow-lobed leaves on branches arrayed
at 60 to 90 degree angles from a strong central
trunk. Mature trees are 35 to 40 feet tall with a
spread of 15 feet.
‘Crimson Sentry* is a dense form with dark
purple foliage in spring and early summer. It
grows 25 feet in height and 15 feet in breadth.
Both forms possess characteristics com¬
mon to Norway maples: cold hardiness, soil tol¬
erance, the ability to withstand hot and dry
weather. They also offer a profusion of spring
flowers followed by an abundance of winged
samaras.
Pyramidal European Hornbeam ( Carpinus
betulus ‘Fastigiata’)
This is the most widely planted cultivar of
the European hornbeam, although it still has
not been used much in the Rocky Mountain
West. The trees have a formal appearance that
is highlighted by their sinewy smooth, grey
bark. Of very narrow form when young, they
tend to develop into oval-to fan shape as they
mature. They do not develop a central leader.
Their foliage, evenly distributed along
dense branches, changes from dark green to yel¬
low in late fall. They are remarkably tolerant of
city conditions. Young examples may be seen
along Speer Boulevard in Denver at the new
KUSA-TV building.
They grow approximately 35 feet tall and
15 to 20 feet broad. They thrive up to 6,000 feet
elevation.
Capital Pear ( Pyrus calleryana ‘Capital’)
Introduced to the nursery trade by the
National Arboretum, these are an extremely
narrow, upright form of the callery ornamental
pears. Their branches are graced with heart-
shaped leaves of a lustrous dark green that glow
with a coppery reddish purple fire come
autumn. In sprint they explode with white
flower clusters that produce almost no fruit.
It is reputed to have moderate to good
resistance to fire blight. ‘Capital’ pears reach a
height of 30 to 35 feet and a breadth of only 8 to
10 feet, making them a choice substitution for
the pedestrian and pitifully short-lived Lom¬
bardy poplar. They are hardy up to 6,000 feet.
Columnar English Oak ( Quercus robur
‘Fastigiata’)
The stately magnificence of the immense
English oaks, in a size suitable for even the
smallest garden! Very narrow, upright trees,
they have a distinctive upright branching habit
as well. They grow 40 to 45 feet tall and 10 feet
Their leaves are large, with rounded lobes.
They are smooth dark green above and pale
bluish green beneath, turning rich russet in the
fall. Tending to persist through the winter, the
leaves contrast nicely with the deeply furrowed,
grey-black bark.
Tallhedge Buckthorn ( Rhamnus frangula
‘Columnaris’)
The narrowest of the narrow, these dense
plants grow to 15 feet high and a mere 3 to 4 feet
across.
Their dark, glossy green, oblong leaves
arranged alternately along slender branches
turn rich yellow in fall. In early spring they pro¬
duce a haze of creamy white, nearly inconspicu¬
ous flowers that ripen to pea-sized fruit in mid¬
summer, red first, then glossy black.
Gracefully arching trees are of structural
interest as accents, focal points or an “Oriental”
feeling.
These are broad, dome-shaped trees
prized for stunning foliage of deep purple in
early spring that becomes rich green-purple in
midsummer. In winter their bare branches arch
to the ground in a weeping framework that cre¬
ates a focal point with dramatic impact.
They are slow-growing trees and, like all
beeches, are shallow-rooted. A site in light shade
would be ideal for them, as the dark leaves tend
to bum at high altitudes; protection from the
desiccating effects of winter winds is essential.
Growing to 15 feet tall, they spread to 20 feet.
Weeping Mulberry ( Morns alba ‘Pendula’
or M. a. ‘Chaparral’)
This cultivar of the white mulberry is of
relatively short stature with slender, weeping
branches that form a deep, umbrella shaped
crown. They reach a height of 10 to 15 feet and a
spread up to 20 feet.
The bright green foliage becomes yellow in 23
Weeping or Pendulous Trees
Weeping Purple Beech ( Fagus sylvatica
‘Purpurea Pendula’)
across.
Columnar maple
autumn; when they fall they reveal a gnarled
pattern of naked branches. Generally, these are
fruitless trees.
Camperdown Elm (Ulmus glabra ‘Camper-
downii’)
The scion wood of these grafted trees origi¬
nated from a seedling found outside Camperdown
House near Dundee, Scotland, at the beginning
of the 19th century. From their rounded crowns
emanate pendulous branches of deeply toothed,
dark green leaves, slightly hairy on their under¬
sides. These unusual trees are slow-growing and
difficult to obtain.
Trees for Seasonal and Structural
Interest
Trees with strong structural character are
excellent for intimate spaces; these are highly
ornamental in several seasons.
ing canopy of heart-shaped leaves that are
tinged with orange as they emerge, then darken
to a rich, lustrous green. Their pink flowers are
among the first to awaken in spring and are
often bitten by frost, so these are unreliable fruit
trees. They are, however, no less ornamental.
Warm orange with splashes of red are the
autumn colors of their leaves. As broad as they
are tall, they grow to 25 feet.
Amur Chokecherry ( Prunus maackii )
A vision of shiny, peeling, cinnamon bark
against a pure white blanket of snow — these
trees are winter poems. They have an interest¬
ing, rounded shape, with muscular branches
sporting white flower clusters in spring followed
by small red fruit that matures to black in late
summer. Birds quickly gobble down the fruit!
Cultural considerations are well-drained soil
and a sunny location. They reach a height of 20
to 25 feet and a spread of 15 to 20 feet.
Apricot ( Prunus armeniaca)
This is a drought-tolerant species. The
24 trees, rounded-to-vase-shaped, provide a spread-
European Mountain Ash ( Sorbus aucu-
paria)
For a ferny, somewhat tropical appear¬
ance, plant these small trees with pinnately
Ipsen
Looks are deceptive: Although young Lombardy
poplars seem to be ideal trees tor narrow spaces,
they prove troublesome on the High Plains, and
should not be used.
flowers and ornamental, persistent fruit, then
continue the year with outstanding autumn col¬
oration and craggy winter forms.
Russian Hawthorn ( Crataegus ambigua)
These vase-shaped trees have a character¬
istic crooked or twisted aspect. Their deeply
incised leaves of glossy green turn orange to red
in fall. Their rugged winter form is accented by
small red fruit against a mass of thorny branch¬
es. Quite drought tolerant, they grow 15 to 25
feet tall and nearly as broad. They are suitable
up to 8,000 feet elevation.
Thornless Cockspur Hawthorn ( Crataegus
crus-galli ‘Inermis’)
The spreading crowns of these small trees
have a distinctively horizontal branching habit,
giving them a layered look. Their pea-sized red
fruits hang well into autumn, accenting their
deep purple-red fall foliage. Growable up to
8,000 feet, they are as broad as they are tall —
up to 20 feet. 25
Golden chain tree
compound leaves. Their large, white May flower
clusters give way to clusters of orange or red-
orange berries that persist into winter. Their
bark is a rich, dark coppery skin with a shiny
cast that seems to intensify in fall when the
leaves turn to bright orange-red.
Very well-drained soil is necessary for
these trees to thrive. They are exceptionally
cold-hardy root systems and can be grown up to
9,500 feet elevation. Some of Colorado’s premier
nurserymen suggest they would be suitable
choices for growing in large containers.
The cultivar ‘Cardinal Royal’, an ideal
columnar tree for small gardens and hedging,
grows only 10 to 15 feet broad. ‘Black Hawk’ is
more broadly columnar. Both cultivars grow 20
to 30 feet tall.
Hawthorns
As a group the hawthorns are excellent
hardy small trees for this region. They are
remarkably tolerant of many soils, but prefer
their site to be well-drained and in full sun to
light shade. They produce a profusion of spring
Ipsen
26
Winter King Hawthorn ( Crataegus viridis
‘Winter King’)
Distinguished by a vase-shaped, angular
form, broader than tall, these trees also have
shiny green foliage — changing to simmering
purple to scarlet — and lovely silver-grey bark.
Sparse thorns occur throughout their dense
branches. Up to 6,500 feet they grow 15 to 20
feet in height and spread to 25 feet across.
Magnolias
Yes, three magnolias do bloom in Col¬
orado! The key is preparing the soil well and
putting the plants in the right spot.
Best locations for magnolias are in full sun
or partial shade away from direct winter winds.
Avoid a southern exposure because of the
extreme fluctuations in spring temperatures
that we encounter here: Warm early-spring
weather may encourage magnolias’ flower buds
to open prematurely only to be nipped when
winter reasserts itself.
A well-draining soil amended with com¬
post is also paramount. Magnolias take hold
somewhat slowly, and care must be taken to
water them regularly during dry winter months.
Merrill Magnolia (. Magnolia x Loebneri
‘Merrill’)
These are free-flowering magnolias with
an upright, pyramidal structure, to 20 feet tall
and 15 feet broad. They grow well to 6,000 feet
elevation.
It is breath-taking to see them laden with
15-petaled flowers in early spring like earth-
bound clouds. Each flower is about three and
one-half inches across. The dark green, oval
leaves emerge shortly after this spectacular dis¬
play, then the flower buds for next spring are set
and remain on the tree like giant furry catkins
through the long winter months.
saucers — an incredible 5 to 8 inches in diame¬
ter! They open in early spring, blushed old-rose
on the outside, opening to creamy white. Their
silky silver-grey buds shimmer luminously all
1 winter.
Star Magnolia {Magnolia stellata)
The large (3- to 4-inch) white flowers of
these small trees emerge from their velvety
buds in early spring with an intense, gardenia¬
like fragrance, their wavy petals curling back
into a many-petaled star. The leaves are dark
green and shiny above, light green on their
undersides. The trees grow only 10 to 15 feet
tall and across. They are hardy to 6,000 feet.
Saucer Magnolia {Magnolia x
soulangiana)
Compact, rounded trees to 25 feet in
height and breadth, their flowers are, indeed,
Alley Cat Trees
Rob Proctor
Alley cats have earned reputations for
being tough. The riffraff vegetation known as
“alley trees” shows the same tenacity to survive.
They get by on limited food, space and water,
taking the abuses of weather extremes without
help from us. They are at the mercy of garbage
trucks, power line crews and waste tossed at
their feet.
Few of us pay much attention to our alley
vegetation. We usually have our hands full pam¬
pering the plants in our civilized gardens. Out¬
side our walls or fences, plants must survive on
their own. Most of their roots are buried under
asphalt and concrete, and reflected heat from
pavement and the sides of buildings bakes them
in summer. Yet some survive and even thrive —
while the pampered garden plants may succumb!
My appreciation for alley trees started
years ago in my old backyard. A tree-of-heaven
(Ailanthus altissima ) grew there, as in Brook¬
lyn — its 40-foot trunk rising out of slabs of buck¬
led concrete. A female, it shed abundant seeds
each year that sprouted vigorously around my
garden. Several times I thought of chopping it
down, but I had to consider the consequences.
Now most trees are “messy.” That’s their
job: to make fruits or seeds to propagate them¬
selves. I never understand people who complain
about seeds, leaves, fruit — and even blossoms —
falling on their pristine patios and walks, as if
the producers are misbehaving. That’s nature. I
heard of a couple who chopped down a magnifi-
A prolific writer and former editor of Mountain,
Plain and Garden, Rob Proctor is the author of
a series of books on antique flowers. His "Front
Range Gardeners" column appears regularly
in The Denver Post.
cent redbud near their front door because the
blossoms blew indoors as they came and went.
Surely, there are worse things in life than a gen¬
tle rain of pink blossoms each spring, and I can’t
imagine fussing over a few in the foyer.
My tree-of-heaven offered no gift quite so
lovely, but it served several beneficial functions.
Its arching branches shaded the neighborhood
dumpster, no doubt sparing all of us on the
block the stench of sun-ripened garbage. It also
blocked my view of a particularly unattractive
high-rise apartment. Constructed in the sixties,
a decade that fails to impress me with its archi¬
tectural achievement, this building got my vote
as one of the ugliest structures on Capitol Hill.
The tree-of-heaven blessedly obscured it from
sight as I sat on my patio. Chopping down the
tree would have meant an even bigger task —
dynamiting the apartment building.
So the tree-of-heaven remained, still not
my favorite, seeding itself like mad — but I
began to respect its handsome, pest-free leaves
and appreciate the red tint of its chartreuse
seed heads as summer waned. I’ve moved from
that garden, but my new alley sports a tree-of-
heaven, even bigger than the last. I’m sure I’ll
be pulling up its seedlings until the end of my
days, but there are worse fates — such as having
a Siberian elm in your alley. I have those too.
Siberian elms lack most of the attributes
of a desirable tree. About the best thing I can
say is, that they provide shade. The metropoli¬
tan area discovered a couple of years ago that
they’re not quite as tough as their name implies,
when thousands of them died after the infamous
autumn temperature crash, when 90-degree
weather dropped to nearly zero in 24 hours.
Crews are still taking out the dead Siberians. 27
The leaves of the survivors are chewed each
year by insects and, although this species is not
susceptible to Dutch elm disease, its dead wood
does harbor the beetles that carry the disease to
American elms.
Other alley trees vary from neighbor¬
hood to neighborhood — all of them
more desirable than Siberian elms.
Catalpas are some of my favorite
trees — in the alley or otherwise. I
love their exotic, fragrant flowers
and large, heart-shaped leaves.
There’s still boy enough in me to app
ciate their long, thin pods, so per¬
fect for sword fights.
Box elders, an old native of the
plains, take the rigors of city life in
stride. It’s best to have them far
away from the house, anyway, if
and red box elder bugs disturbs you,
even though the insects are harmless.
Old Russian olives sometime ^
soften our alleys, their silver foliage a
nice contrast to brick and spray paint. Their
fragrance floats on spring breezes, dis¬
guising more pungent alley aromas.
Cottonwoods, too, are sometimes
found, especially the hybrid Populus x acumina
ta, a cross between the narrow-leaf mountain
species ( P angustifolius) and the plains cotton¬
wood (P deltoides). It is a first-rate all
there is such a thing.
Old ashes, honeylocusts and black locusts
shade alleys in older parts of the cities and
towns long the Front Range. They cope relative¬
ly well with the less-than-ideal conditions of
alley life and are an asset. Sometimes I see old
fruit trees living their lives on the edge, their
fruit-laden branches bending across trash cans
and chain link. Chokecherries are around, too,
their autumn leaves turn to maroon and yellow.
Gardeners take great pains in selecting
plants for their gardens, but ignore their alleys.
We visit the dumpster or back out of the garage
almost as often as we collect the mail. Perhaps
we should pay more attention to, and pause to
appreciate, the trees that we pass beneath every
28 day, among the refuse and alley cats.
Blossoms Through the Year
Late Winter
Witch Hazel Hamamelis species
Cornelian Cherry Cornus mas
Goat Willow (Pussy Willow) Salix caprea
Early Spring
Wild Plum
Eastern Redbud
Shadblow Serviceberry
Magnolia
Prunus americana
Cercis canadensis
Amelanchier spp.
Magnolia spp.
Mid-Spring
Newport Plum
Crabapple
Apple
Bradford Flowering Pear
Bird Cherry
Schubert Chokecherry
Prunus cerasifera "Newport’
Malus spp.
Malus spp.
Pyrus ealleryana "Bradford’
Prunus padus ‘Alberti’
Prunus virginiana ‘Schuberti’
Late Spring
Hawthorns
Sour Cherry
Mountain Ash
Yellow-Wood
Golden Chain l¥ee
Crataegus spp.
Prunus cerasus
Sorbus aucuparia
Cladrastis lutea
Laburnum anagyroides
Early Summer
Chinese Catalpa
Western Catalpa
Ohio Buckeye
Yellow Buckeye
Horse Chestnut
Chinese Tree Lilac
Japanese Tree Lilac
Hop Tree, Wafer Ash
American Linden
Littleleaf Linden
Catalpa ovata
Catalpa speciosa
Aesculus glabra
Aesculus octandra
Aesculus hippocastanum
Syringa pekinensis
Syringa reticulata
Ptelea trifoliata
Tilia americana
Tilia cordata
Midsummer
Goldenrain Tree Koelreuteria paniculata
Late Summer
Japanese Pagoda Tree Sophora japonica
Chinese tree lilac
Goldenrain
tree
plum
White
crabapple
Demystifying the Maples
Larry Watson
Among the almost 200 species of the genus
Acer (maple) the only consistent similar feature
is their winged seeds. Most maples are decidu¬
ous and many color brilliantly in autumn. Beyond
that, variety is the theme in the world of maples.
Their beautiful foliage ranges from the
familiar hand-shaped leaf of the big solid North
American species, such as sugar maple, to more
delicate, filigreed foliage of the Eastern Asian
maples. Barks, too, vary, and forms run the gamut
from stately shade trees to shrubby plants.
Maples have been and continue to be of
horticultural importance — some member of this
diversified, hardy and easily cultivated group is
grown nearly everywhere in the United States.
As a general rule, maples are sun lovers
and prefer rich, moist soils. Many are sensitive
to alkaline or heavy, poorly-drained soils. In the
Rocky Mountain West sunny locations are not
hard to find, but rich soils are exceptions and
difficult to manufacture. Silver maple and gin-
nala maple often display the yellowing of chloro¬
sis when they are grown in areas of heavy clay.
A few maples find our climate too severe,
such as the Japanese maple group, although an
individual may grow for a while in a sheltered
location. Despite these selective limitations, the
maple continues to be an important genus in
our region.
The many species within the genus have
had numerous selections developed over the
years and their names can be confusing to the
Larry Watson is a Front Range native and a 30-
year veteran of the local nursery industry. He
has his own horticultural services company,
30 Plants for Today and Tomorrow.
average tree buyer. For example, how does
‘Royal Red’ differ from a ‘Red Sunset’? They are
actually varieties of two different species. One is
a Norway maple and one is a red maple.
Certain selections are better than others
for the Rocky Mountain West. Some old favorites
have been replaced by newer cultivars. Consid¬
ering these confusions, it will be helpful, in the
discussion that follows, to sort out some of the
best cultivars of the various species that can be
grown in our climate.
Shade Tree Maples
Box elder (Acer negundo)
This maple is an extremely hardy North
American species (USDA Hardiness Zone 2). It
is one of the hardiest of all the maples and has
been used for years in shelter belts. It is also
thought of as being a “weed” tree, in the same
class as Siberian elm and tree of heaven. This is
unfortunate. Box elders thrive in adverse condi¬
tions in extremely harsh locations; with irriga¬
tion there are a few selections of this tree well
worth considering.
A negundo ‘Baron’ is a 35- to 40-foot tree with
an upright, oval shape and a spread of about 30
feet. It is a selection from the Morden Station in
Canada and was introduced by the Canadian
Ornamental Plant Foundation. This male selec¬
tion produces no seeds.
A. n. ‘Flamingo’ will attain a height and width of
about 30 feet. It exhibits showy foliage of pink,
white and green variegation.
A. n. ‘Variegatum’ is about 25 feet tall and 20
feet wide and has variegated, creamy white and
green leaves. The fall color is yellow.
Sensation box elder (A. n. ‘Sensation’) grows 30
feet tall and 25 feet wide and has brilliant red
fall color.
Norway maple (A. platanoides)
This European species has been in produc¬
tion since the 1700s. Hundreds of selections
have been made for form, leaf color, size and
adaptability or ease of growth. Many of the
selections are difficult to distinguish, while oth¬
ers are very distinctive. A list of all the selec¬
tions of Norway maple would make for tedious
reading, so the following only hits the highlights:
The Columnar Norway maple (A. pla¬
tanoides ‘Columnare’) will reach a height of 35
feet and will be about 15 feet broad. It has a
narrow upright form with ascending branches.
It can be grown branched to the ground or
pruned to a standard. It has the usual dark
green foliage of the Norway maple and the typi¬
cal yellow fall color.
The Crimson King Norway maple (A. p.
‘Crimson KingO will reach a height of 40 feet
and a width of 35 feet. The leaves of Crimson
King emerge deep purple and remain that color
through the growing season.
Royal Red Norway maple (A. p. ‘Royal
Red’) is a selection of the Crimson King maple.
Some growers say it is no different from Crim¬
son King; others claim it is somewhat hardier.
Crimson Sentry maple (A. p. ‘Crimson
Sentry7) also has deep purple coloration but it
will only reach a height of about 25 feet with a
spread of 15 feet. It can also be grown branched
to the ground or as a standard.
Deborah maple (A p. ‘Deborah’) is the
variety that has replaced the Schwedler maple.
It grows 45 feet tall and 40 feet wide. Its foliage
is reddish purple in the spring and dark bronze-
green in the summer. Deborah maple is actually
a seedling of Schwedler but growers feel it has a
better branching habit and is less susceptible to
leaf tatter than Schwedler.
The silver variegated maple (A. p. ‘Drum-
mondii’) will attain a height of 35 feet and a
width of 25 feet. It has very striking light green
leaves with creamy white margins. The varie¬
gated maple will grow more slowly than some
other forms. It can also show some scorching if
planted in a hot, sunny location.
Globe Norway maple (A. p. ‘Globosum’) is
a nearly perfectly round tree. It is often grown
on a standard, but sometimes is not tall enough
to walk under.
Princeton Gold Norway maple (A. p.
‘Princeton Gold’) has bright yellow foliage
throughout the summer and yellow fall color.
The preceding list represents some of the
unusual forms and leaf colors available in a
Norway maple. In addition, there are the stan¬
dard green-leaf types, all about 40 to 50 feet tall
and 25 to 40 feet wide. The merits of these vari¬
ous forms are debated among tree experts, but it
will make little difference which of these Nor¬
way maples you use: all have dark green foliage
and yellow fall color. The more common, named
selections are:
Cleveland Norway maple (A. platanoides. Cleve¬
land’)
Crystal Norway maple (A. p. ‘Lamis’)
Emerald Queen Norway maple (A. p. ‘Emerald
Queen’)
Emerald Lustre Norway maple (A- p ■ ‘Pond’)
JadeGlen Norway maple (A. p. ‘JadeGlen’)
Parkway Norway maple (A. p. ‘Columnarbroad’)
Summershade Norway maple (A. p. ‘Summer-
shade’)
Superform Norway maple (A p. ‘Superform’)
Sycamore maple, planetree maple (Acer pseudo-
platanus)
This very large tree — to 60 feet — is native
to Europe. Mature, it has an oval to rounded
head 40 to 50 feet wide. The reason for its name
is the resemblance of its leaves to those of the
sycamore ( Platanus occidentalis). This plant has
a hardiness rating of Zone 5, which makes it
slightly risky in some parts of the Rocky Moun¬
tain West, but there are some very old, large
plants in Boulder and Colorado Springs. It
prefers good drainage but is adaptable to most
soils and is salt tolerant. Although there are
many selections listed in reference books, only
the Spaeth sycamore maple (A pseudoplatanus 3 1
I
*
►
»
Sugar maple
Ginnala maple in fall
‘Atropurpureum’) seems to be in the trade. The
Spaeth sycamore maple has foliage which is
dark green above and rich purple beneath.
Red maple, scarlet maple, swamp maple
(A rubrum)
The native range of red maples extends
from Newfoundland to Florida, west to Min¬
nesota, Iowa, Oklahoma and Texas. The red
maple has something red about it in most sea¬
sons. Red winter buds open early in the spring
to a showy display of red flowers against light
gray bark. Emerging leaves are tinted red, and
in fall the fiery leaves almost rival those of
sugar maple, accounting for a large amount of
the orange-red fall color in the East.
Red maples are fast-growing trees that
reach a height in this area of 50 to 60 feet. The
species grows about 35 to 40 feet wide. It is hap¬
piest in moist, well-drained soil; it does not do
well in alkaline soils. Because of its extensive
native range, many selections of red maple have
been made for different parts of the country, as
well as for fall color and form. It is my feeling
that in the Rocky Mountain region, we need to
32 pay particular attention to A. rubrum selections
taken from the colder climates. All three of the
following selections are from Northern Minneso¬
ta. They will grow to about 50 feet tall and 30 to
40 feet wide. All have a good branching habit
and bright red fall color.
Firedance maple (A r. ‘Landsburg’)
Northwood maple (A r. ‘Northwood’)
Northfire maple (A r. ‘Olsen’)
Autumn Spire Red maple
(A r. ‘Autumn Spire’)
Also from Minnesota, this selection will
reach 50 feet with a spread of only 20 to 25 feet
for its growth habit is broadly columnar. It also
exhibits beautifiil red fall color.
Acer x freemanii
I have refrained until now from discussing
this group of plants. Many horticulturists, tax¬
onomists, and dendrologists have found what
they consider to be natural hybrids of red maple
(A. rubrum) and silver maple (A. saccharinum).
The natural ranges of these two species overlap
in many parts of the United States. In addition
to these natural crosses, other crosses have been
made by plant breeders. This entire group has
now been labeled Acer x freemanii.
Since this classification is relatively new,
some varieties will be listed in one reference as
A. x freemanii and in another as A. rubrum or A.
saccharinum selections. These selections may
exhibit characteristics of either or both parents
and may be superior because of the positive
traits of silver maple (A saccharinum). Below
are but a few of the more than 200 identified
selections of this hybrid.
Autumn Blaze maple (A. x freemanii ‘Jef-
fersred’) was selected by Glen Jeffers. This one
will reach a height of 50 feet and a width of 40.
It has an upright-branching, broadly oval habit.
The original tree is believed to be in Ohio. Its
fall color is brilliant orange-red.
Armstrong maple (A. x freemanii ‘Arm¬
strong’) is a fast-growing maple with a spire-like
appearance. It will reach a height of 50 feet and
a width of about 15. The leaf of Armstrong maple
looks more like silver maple than the red maple.
Fall color is not as good as that of the red maple.
Celebration maple (A. x f. ‘Celzam’) is
another fast-growing maple. It looks much more
like the silver maple than the red maple, reach¬
ing a size of about 45 feet by 25 feet. The fall
color of Celebration maple is mostly yellow.
Scarlet Sentinel maple (A. rubrum ‘Scar-
sen’) although listed as a red maple, is now
thought by most to be a hybrid. The form on this
hardy 40-foot by 20-foot tree is broad at the
base, but columnar. Fall color is yellow-orange
to orange-red.
Silver maple, soft maple (Acer saccharinum )
Silver maple is a common North American
species. It grows from Quebec south to Florida,
west to Minnesota, Nebraska, Kansas and Okla¬
homa. It is rated as a Zone 3 plant and normally
reaches a height of 60 feet and a spread of 40 to
50 feet. The silver maple is a very rapidly grow¬
ing tree, making it more brittle and subject to
breakage. It is more tolerant of alkaline soils
than red maple but this does not mean that it is
happy in alkaline soils. The fall color on silver
maple is a lovely yellow. There are only a few
selections of silver maple in general production.
Silver Queen maple (A. saccharinum ‘Sil¬
ver Queen’) is a seedless selection and a more
uniform tree than the species: It will grow 50 feet
tall, with a spread of 40 feet. Fall color is yellow.
Skinner’s Cutleaf maple (A. s. ‘Skinneri’)
is, in form, the same as Silver Queen maple. The
difference is that it has neat, cutleaf foliage. This
makes a very attractive tree, one with a distinc¬
tive texture discernible even from a distance.
Sugar maple, hard maple, rock maple
(Acer saccharum )
Sugar maple is a widely planted North
American tree, rated Zone 3. Its natural range
is from Eastern Canada to Alabama, Mississippi
and Texas. The tree is impressive in size, though
in our area it will probably not reach more than
50 feet. Sugar maple has a dense regular habit,
with dark green leaves that turn yellow-orange
and orange-red in the fall. There are some 25 to
30 known cultivars of sugar maple; only a few
will be listed here.
Bonfire sugar maple (A. saccharum. ‘Bon¬
fire’) is a selection from Princeton Nursery. It is
a vigorous grower with vibrant dark green
foliage and good heat tolerance. It exhibits bril¬
liant carmine red fall color. Bonfire will grow 50
feet tall by 40 feet wide.
Commemoration sugar maple (A. s. ‘Com¬
memoration’) was selected by W. N. Wandell and
patented by Moller’s Nursery in Gresham, Ore¬
gon. It, too, is a rapid, vigorous grower to about
50 feet with a spread of 35 feet. Foliage is glossy,
dark green; it turns orange to orange-red in the
faff.
Green Mountain sugar maple (A. s. ‘Green
Mountain’) was patented by Princeton Nurseries
in 1964. This tree has an upright oval form and
orange-scarlet fall color. The waxy protective
coating on its leaves is more than double the
thickness of that of regular sugar maple, and its
leaves are less likely to tatter in hail and wind.
Legacy sugar maple (A. s. ‘Legacy5) was
introduced by W. N. Wandell. This tree also has
thick leaves resistant to tearing, is fast growing
and is more heavily branched than other sugar
maples. Fall color is red, orange and yellow. 33
Smaller Ornamental Maples
Hedge maple (Acer campestre )
Hedge maple is native to Europe and
western Asia. It can be grown as a large shrub
or small tree. As a tree it can be expected to
reach 25 to 35 feet tall with a spread of about 25
feet. It has a USDA hardiness rating for Zone 4.
Foliage of hedge maple is deep, dark green that
turns yellow in fall. The bark is deeply furrowed
or corky. Hedge maple is very tolerant of alka¬
line and compacted soils. This tree has not been
extensively planted here but there are some
quite old specimens in the area. The hedge maple
demands more attention for our landscapes.
Amur maple, ginnala maple ( Acer ginnala )
The Amur maple is native to China, Man¬
churia and Japan, and was introduced into
Western cultivation in the late 1800s. This is an
extremely hardy Zone 2 plant, grown as a large
shrub or as a small patio or specimen tree. It is
good for massed plantings. As a tree, with either
single or multiple trunks, it will grow 20 to 25
feet tall and about as wide, with an irregular
habit. Amur maple is fast-growing and slightly
brittle.
Its leaf is identified by the dominant long
central lobe. The fruit (seed) is normally con¬
spicuous and red during summer, and fall leaf
color is brilliant orange and orange-red.
This maple is somewhat intolerant of
alkaline and heavy clay soils. It tolerates shade
better than most maples, and it’s a good choice
for higher elevations, growing up to 10,000 feet.
Additionally, it is reported to be one of the best
maples to grow above ground in a container.
Both of the following selections have been made
to ensure a more uniform plant with red fruit
and red fall color: Embers Amur maple (A. gin¬
nala “Embers’), Flame Amur maple (A g. “Flame’).
Rocky Mountain maple (Acer glabrum)
The Rocky Mountain maple is native from
Montana and South Dakota to California and
New Mexico. It grows in the lower foothills of
the Colorado Rocky Mountains, usually in rocky
soil. It is mostly multi-stemmed in the wild but
34 can be trimmed to a single stem. Rocky Moun¬
tain maples reach a height of 20 to 30 feet with
a spread of 15 feet. The petiole or leaf stem of
the Rocky Mountain maple is bright, showy red
and the bark is ash gray. The leaves turn yellow
in the fall.
Bigtooth maple, Wasatch maple ( Acer
grandidentatum )
The bigtooth maple is native to Wyoming,
New Mexico and the Wasatch Range in Utah,
where it is the dominant tree. It usually is low-
branched or has multiple trunks. It will grow to
a height of 20 to 30 feet, with a width of 15 to 20
feet, and is actually more like a large, space-
dominating shrub than a tree.
Bigtooth maple tolerates highly alkaline
soils and has excellent drought tolerance. Its
pretty leaf is like a small version of a sugar
maple leaf, and fall color can also be similar:
brilliant red-orange. However, it should be noted
that fall color is variable within the species.
Some plants display only dull yellow leaf color
and it might be wise to purchase this tree in the
fall when you can see what you’re getting.
Tatarian maple (Acer tataricum)
Tatarian maple comes from southeast
Europe and west Asia. In many ways it looks
like Amur maple. It will reach a height of 30 feet
and a spread of 20 feet. It, too, can be grown as a
tree or a large shrub. The leaves are bright
green in summer and yellow in fall. The red
fruit in summer is very attractive. Tatarian
maple is very tolerant of alkaline soils. At least
one reference book refers to a selection which
has red fall color (Acer tataricum rubrum), but I
have never been able to locate it.
Although there are a few other species of
Acer growing in this area, some may be less
hardy; others are shrub-like. With the wide
range of maples suitable for our conditions,
every homeowner could grow at least one.
Crabapple Update for the Front Range
Gary Epstein
For many people the beauty of full-flow¬
ered crabapples is unrivaled by any other tree or
shrub in Colorado. In streets and yards up and
down the Front Range, the spring arrival of the
pink and white blossoms lifts our spirits.
Earlier attempts to line avenues with
Japanese cherries and other less hardy, spring¬
flowering ornamental trees failed, but the flow¬
ering crabapples ( Malus sp.) stepped right in
and demonstrated their ability to tolerate our
peculiar and harsh climate.
During my more than 20 years in the Col¬
orado nursery business I have learned that
crabapples are a complex and diverse group of
trees. Across the country somewhere between
400 and 600 different types of crabapples are
known. Their diversity is exhibited not only in
blossom and fruit color, but also foliage tint and
even leaf shape. New cultivars are being intro¬
duced all the time.
This, coupled with ongoing disease
research, makes the title of this article some¬
what suspect: Any information you read about
crabapples could be revised at any time. But for
now, this is our most up-to-date assessment.
When choosing a crabapple variety for the
Front Range you must keep in mind that Col¬
orado horticulture is a different breed of cat. In
my early years in the nursery business, I often
had the good fortune to hear the late George
Kelly, former acting director of Denver Botanic
Gardens, speak at the Colorado Nurseryman’s
Association meetings. Long considered the guru
Gary Epstein is principal co-owner and opera¬
tor of Fort Collins Nursery, a 45-acre retail and
wholesale business. He holds a Colorado State
University degree in landscape horticulture.
of Rocky Mountain horticulture, George devoted
his life to understanding the peculiarities and
frustrating disappointments one experiences
gardening in this part of the country.
He once said, “When it comes to reading
about horticulture you might as well throw
away the books written by those Easterners
who live in places with four distinct seasons, 30
inches of annual precipitation, and rich,
humusy, acid soils — because what they are say¬
ing just doesn’t work here.” His prophetic words
stuck. Almost every year since I first heard
George Kelly say Rocky Mountain horticulture
is a maverick science, I have seen it proven in
some way!
A case in point is my recent experience
with crabapples. Our nursery is always looking
for superior woody plants for the Front Range.
About three years ago, we decided we should
introduce some of the newer crabapple varieties
that were purported to show resistance to fire
blight, a bacterial disease that can seriously
affect certain varieties of the tree.
One of the cultivars we selected to observe
was ‘Ormiston Roy5, a pretty white-flowered tree
with small persistent fruit. In the literature, it
received the highest ratings for “disease resis¬
tance.” I observed three 5-year-old specimens at
the Crabapple Trial Garden at Colorado State
University and all showed excellent form with
no fire blight present in the plants. I discussed
attributes of ‘Ormiston Roy5 with fellow plants-
men who had observed this tree in arboretums
and gardens around the country. All looked good.
At least that’s what we thought. But in
our nursery this past summer, ‘Ormiston Roy5
exhibited what I would describe as a severe out¬
break of fire blight: Major branches were infected 35
with the bacterial disease. I revisited CSU’s trial
garden and found, of the three original plants,
two had died and the remaining tree was
severely infected with fire blight.
Well, great. This was the cultivar with all
the high marks for disease resistance!
Perplexed by this development I was
determined to find out more. I learned that the
CSU trial, in which three replications of 50 vari¬
eties of crabapple were planted in 1985, is part
of the National Crabapple Evaluation, a pro¬
gram of the International Ornamental Crabap¬
ple Society in cooperation with Morton Arbore¬
tum near Chicago. Trees growing on 23 sites
throughout the United States are being evaluat¬
ed for their resistance to such diseases as scab,
cedar-apple rust, powdery mildew and fire
blight, as well as their aesthetic value. Ratings
from all the sites are tabulated and averages for
the nation are published.
Here is the surprise: Morton Arboretum
officials visiting the crabapple trial garden at
CSU in summer of 1992 stated, “The incidence
of fire blight is far greater and more severe here
than on any other site in the nation.” However,
in checking the national ratings, I found that
our unique Front Range environment presents
very few problems with scab, cedar-apple rust or
powdery mildew — something that cannot be
said for other parts of the country
Our major disease problem with crabap-
ples is clearly fire blight. For example, ‘Radiant’
crabapple rates close to dead last on the nation¬
al scale because of its susceptibility to scab, yet
along the scab-free Front Range, it is probably
the most widely-used crabapple and shows only
a slight-to-moderate fire blight problem. Nation¬
al crabapple ratings appear to have little appli¬
cation to our region, and George Kelly’s pro¬
nouncements about Rocky Mountain horticul¬
ture are ringing truer than ever.
I knew that Colorado was becoming noto¬
rious in national horticulture circles as the fire
blight capital of the country. In light of our expe¬
riences at Fort Collins Nursery, I could only
agree that our reputation was well-deserved.
Yet we still wanted to offer for sale flower¬
ing crabapples that would live for 20 years or
36 longer without succumbing to fire blight and
that would bear smaller fruit than the varieties
we were currently growing. Toward that end we
were willing to share what we had learned, for
we had valuable information on several vari¬
eties we had grown over the years.
Recognizing that other Front Range grow¬
ers probably had similar experiences, we invited
18 Colorado growers, along with Dr. Jim Klett,
CSU professor and cooperator in the crabapple
trials, to meet in September 1992 for an exchange
of our experiences with the fire blight problem.
Our time together proved very valuable.
One result of the symposium is the follow¬
ing fist of crabapples to be avoided. These are
cultivars which have shown severe to very
severe susceptibility to fire blight (several major
branches infected, considerable die-back or
death of the tree).
Not recommended:
‘American Beaut/, ‘Bechtel’, ‘Flame’, ‘Hopa’,
‘Mary Potter’, ‘Ormiston Ro/, ‘Pink Perfection’,
‘Professor Springer’, ‘Red Jade’, ‘Red Jewel’,
‘Red Splendor’, ‘Royalty’, ‘Sentinel’, ‘Silver Moon’,
‘Snowdrift’, ‘Strathmore’, ‘White Angel’ and ‘Zumi’.
Recommended:
Now, I would like to share a list of trees
which showed none to moderate incidence of fire
blight (numerous branch tips showing symp¬
toms, few major branches infected). This list,
while in no way complete, still might be worthy
of consideration when selecting a crabapple that
would exhibit low fire blight incidence when
grown along the Front Range. Incidentally, it is
my opinion that there does not exist a crabapple
tree which offers complete fire blight resistance.
‘Beverl/ — Rounded and spreading form; small,
light green leaves; pink buds open to single,
white flowers; ^/8-inch red fruit.
‘Bob White’ — Dense rounded form; green foliage;
pink buds open to single, white flowers; 1/2-inch
persistent yellow fruit.
’Brandywine’ — Vigorous growing; vase shaped;
green leaves with a purple tinge (purple in fall);
double rose-pink fragrant flowers; green fruits
to 1 1/4 inches.
‘Centurion’ — Upright when young, becoming
more rounded with maturity; reddish-purple
leaves aging to green; red buds open to rose; 5/8-
inch glossy red persistent (two to three months)
fruits.
‘Coralburst’ — Compact, dense rounded form to
only 10 to 15 feet; green foliage; coral pink buds
open to rose; ^/2-inch red, persistent fruits.
‘David’ — Compact, rounded; green foliage (tends
to conceal fruit); pink buds open to white; 3/8-
inch to 1/2-inch red, persistent fruit.
‘Dolgo’ — Upright, spreading; glossy green
foliage; large white flowers; 1 1/2-inch red edible
fruits; the most cold hardy crab on this list.
‘Indian Magic’ — Rounded and spreading form;
dark green foliage; rose-red buds opening to
pink flowers; glossy red, 1/2-inch fhiits changing
to orange and persisting through the winter.
‘Indian Summer’ — Rounded form; bronze to
green foliage; pink flowers; bright red, 5/8-inch
persistent fruit.
‘Prairifrre’ — Upright spreading becomng round¬
ed; red to maroon foliage aging to reddish green;
crimson buds open to pinkish red flowers; orange-
red, 3/8-inch to 1/2-inch, persistent fruit.
‘Profusion’ — Upright spreading form; purple
foliage fades to bronze; deep pink flowers; maroon,
1/2-inch fruits.
‘Radiant’ — Round spreading; reddish-purple
foliage aging to green; deep red buds open to
pink; bright red, 1/2-inch fhiits ripen in summer.
‘Red Baron’ — Columnar form; reddish-purple
foliage ages to a bronze green; dark red flowers;
dark red, 1/2-inch fruits.
‘Robinson’ — Upright, spreading with age; red¬
dish foliage ages to bronze green; pink flowers
contrast well with foliage; 3/8-inch, dark red
fhiits are well hidden by foliage.
‘Selkirk’ — Rounded; reddish-green foliage ages
to dark greenish bronze; deep pink flowers; very
glossy red, 3/4-inch fhiits.
‘Spring Snow5 — fruitless; white flowers; bright
green foliage; upright, spreading; golden bark.
‘Thunderchild’— Upright spreading form; purple
foliage; pink to rose flowers; 1/2-inch, purplish-
red fhiits.
‘Velvet Pillar’ — Upright form with ascending
branches; purple foliage; single, pink flowers;
sparse, reddish fhiits.
Generally, if you are planting crabapples,
select a spot with good drainage, though the trees
need irrigation. Fire blight, ironically, attacks
vigorous, healthy trees, so avoid locations where
the tree will receive a lot of fertilizer — for exam¬
ple, in the lawn.
Heavy pruning and truncating branches
will only encourage vigorous interior growth
(watersprouts) which are attractive to the dis¬
ease. This factor is illustrated by an old variety
of crabapple once grown here called Vanguard’,
a slow-growing semi-dwarf. Profit-conscious nur¬
serymen stopped producing it because it took a
whole year longer to grow to salable size, but it
never got fire blight!
Considering the tremendous number of
varieties available, you may wonder why there
are only a handful for sale in local garden cen¬
ters. Because assessments of crabapples in dif¬
ferent parts of the country do not apply to Colo¬
rado, we must test each variety for ourselves.
The nursery industry in Colorado comprises
small independent businessmen; we love plants,
but research and development budgets are
limited.
We will learn much from Fort Collins.
Eight years after the inauguration of the CSU
trials, more than one-half of those varieties have
developed disease problems. By consolidating all
our information we have definitely made
progress toward understanding diseases in
crabapples.
Speaking as only one nurseryman, I will
continue to look for superior woody plants to
grow along the Front Range. With persistence,
one may be a crabapple.
37
The Backyard Orchard
Robert Cox
If you enjoy the fruits of your labor, a back¬
yard orchard may be just the project for you.
Pride of ownership, therapeutic value, fresh
fruit picked at the peak of ripeness and orna¬
mental spring blossoms are good reasons for
growing your own fruit trees.
However, fruit trees should only be planted
by homeowners willing to work with them year-
round: Pest control, pruning and other cultural
and maintenance needs must be considered.
Don’t plant fruit trees to save grocery money.
Along the Front Range of the Rockies in
Colorado, apples and pears (“pome fruits”) and
apricots, cherries, peaches and plums (“stone
fruits”) can be grown, some more easily than
others. Our growing conditions and climate are
not as conducive to tree fruit production as the
Grand Junction area of the Western Slope. Your
success with fruit trees in your yard will depend
on good soil preparation, the location you choose
for planting and careful selection of locally
adapted varieties.
Fruit trees prefer full sun and well-drained
soil. To plant a small orchard area, condition
heavy clay soils by rototilling or spading in a 2-
inch layer of coarse organic matter such as com¬
post, sphagnum peat or aged manure (dairy cow,
horse or sheep). The same procedure will improve
texture, fertility and water-holding capability of
sandy soils.
If you are planting just one or two trees
rather than a small orchard area, you can
Robert Cox, Jefferson County extension agent
for horticulture, Colorado State University
Cooperative Extension, has contributed to
numerous publications, including American
38 Nurseryman and the Journal of Plant Nutrition.
improve soil conditions in the planting area by
digging the planting hole at least twice as wide
as the tree’s root ball diameter, but a bit shal¬
lower than the tree’s root ball depth. Mix organ¬
ic materials into excavated soil at up to 25 per¬
cent by volume; then use this improved soil as
back-fill.
Other than a small handful of superphos¬
phate sprinkled in before back-filling, use no fer¬
tilizers in the planting hole. “Root stimulator”
solutions, especially those promoting vitamin B1
as an “active ingredient,” are of questionable
value and are not needed. Organic mulches such
as wood chips or straw applied after planting
will help to keep soil moist and suppress weed
growth.
Because freezing cold air is heavy and will
flow into low-lying areas, avoid planting fruit
trees in the lowest part or your yard; doing this
would subject blossoms or small developing fruit
to cold injury, reducing or ehminating the crop.
Instead, if your yard allows, plant fruit trees on
an east- or north-facing slope. Similarly, if trees
are to be planted near the house, the east or
north sides are best, as long as sunlight is plen¬
tiful during the growing season. Planting on
south and west exposures would promote earli-
er-than-normal blooming, subjecting blossoms
to a longer period of potential frost damage.
Late spring frosts when trees are in flower
present the biggest obstacle to growing fruit in
the Front Range. Our winters are generally
scattered with several unseasonably warm days,
which tend to encourage blooming before the
danger of frost is past. For example, apricots
tend to be the earliest-blooming fruit tree, well
before the danger of frost is past. For this reason
and the fact that winds and cold inhibit bee
pollination of apricot flowers, Front Range apri¬
cots may bear fruit only one year in 10. Howev¬
er, apricot trees are very attractive, with lovely
heart shaped leaves and gold fall color, and are
worthy of planting even if fruit production is not
dependable. Select later-blooming varieties such
as SunGlo, Golden Amber or Chinese. Other
good varieties are Sungold, Moongold, Moorpark
and Goldcot.
The date and severity of late frosts will
determine whether or not fruit will develop in
your backyard orchard. Don’t equate the term
“hardy” in the description of the tree with
“dependable fruit production.” For example, the
peach variety Reliance is “hardy” in that the
tree and its flower buds can survive lower win¬
ter temperatures than most other peach vari¬
eties, but its flowers and developing fruits are
just as susceptible to late spring frost as any
other peach.
Besides selecting later-blooming varieties
(especially important for apricots, pears, plums
and peaches), some other tactics may help delay
blooming by up to two weeks: Mulching trees 3
to 4 inches deep will keep the soil cooler than if
it were bare, and cool soils delay flowering.
Shading the south and west sides of the trunk
with boards or other material may also help.
Wrapping young trees’ trunks with tree wrap in
late October will accomplish the same thing and
prevent winter damage called “sunscald” (Just
remember to unwrap trees around April 1).
Trees planted on a north slope or north
side of a building will bloom later than the same
varieties with western or southern exposures.
The home orchardist can also mist trees with
water on warm days (above 50 degrees) in Feb¬
ruary, March and April to provide “evaporative
cooling” for the blossom buds and, in turn, delay
flowering.
If a fruit tree is in bloom when frost is
expected, cover the tree with a sheet or cloth, if
the tree is small. Some people report that small
Christmas tree lights placed throughout the
tree will give off just enough heat to protect
flowers.
Just as important as delaying bloom and
protecting against frost is choosing varieties
whose fruit will mature before the threat of
early frost in the fall. This is especially impor¬
tant for peaches and apples. For example, late
season apples such as Arkansas Black, Rome
Beauty or Winesap may not ripen fully in our
area before cold weather threatens in late Sep¬
tember or early October. Similarly, Belle of
Georgia peaches would not be a good choice for
our region.
For some homeowners, creating shade or
privacy may be as important as producing fruit.
If so, plant standard-size trees. For most city
yards, with less space available, semi-dwarf and
dwarf trees won’t take up as much room. Also,
they will begin to fruit at an earlier age and are
easier to prune, spray and harvest. Dwarfed
trees bear full-sized fruit, but are budded onto
roots (“rootstock”) which are not as vigorous.
This limits the size the tree can attain. Minia¬
ture (“genetic dwarf’) fruit trees can even be
grown in large pots, attaining a full height of
only 6 to 8 feet.
The pollination needs of fruit trees are
often misunderstood. When a catalog descrip¬
tion says that the tree needs a pollinator, it
means that the tree won’t fruit well unless there
is another tree of a different variety within
about 50 yards, blooming at the same time, so
bees can readily transfer pollen from one tree’s
flowers to the other’s. For example, Golden Deli¬
cious apple is a good pollinator for most other
apple varieties: If your neighbor has a Golden
Delicious and you have almost any other variety
of apple within 50 yards, both trees should bear
good crops. Exceptions include Red Delicious:
Following a mild winter, it may bloom earlier
than Golden Delicious, which would minimize
pollen transfer. Also, Golden Delicious will not
pollinate Jonagold apple. A solution would
appear to be the “three-in-one” or “five-in-one”
multiple-graft trees that have three or five dif¬
ferent apple varieties grafted onto the same
rootstock. Each grafted variety should become a
major branch of the tree and the different vari¬
eties can serve as pollinators for each other.
Locally, what usually happens to these multiple-
graft trees is that one or more of the varieties
are susceptible to fire blight, which may kill sev¬
eral of the branches (varieties). The result is a
lopsided, one- or two-variety tree.
If a tree is “setf-fruitful” or “self-pollinating”
(most apricot, peach and sour cherry varieties
are self-fruitful) it means that the tree can fruit
well without another variety nearby. Most self¬
fruitful trees will, however, produce bigger crops
if another variety is nearby. For example, Red-
haven peach is self-fruitful, but another peach
variety near it will help both varieties develop
bigger crops.
Backyard orchard pest problems include
peach crown borers, which attack stone fruit
trees near the ground line; codling moths, whose
larvae are found in “wormy” apples or pears;
pear “slugs” which feed on leaves of pears, plums,
peaches, apricots and cherries, and every gar¬
dener’s nemesis, aphids, which are found in
clusters primarily on leaves of plums, peaches
and cherries. The apple maggot is an emerging
pest problem. We have seen increased incidence
of it in the past two years. Earher-maturing
apples with thin skins appear to be the most
susceptible. One way to help control these and
other garden pests is to plant a wide variety of
flowering plants in your landscape. This diversi¬
ty is attractive to beneficial insects who will help
control the pest insects.
Diseases include fire blight, a bacterial
disease that severely damages some varieties of
pears, apples and crabapples. Many horticultur¬
ists feel that only apple and pear varieties con¬
sidered resistant to fire blight should be planted
in our area.
Fruit trees need only light fertilization
with nutrients often lacking in Front Range
soils. Zinc and iron may be deficient in soils that
are too alkaline. Spring shoot growth of more
than 12 inches may indicate excess nitrogen fer¬
tilization. Excess nitrogen stimulates excessive
succulent shoot growth, which is very suscepti¬
ble to fire blight in the case of apples and pears.
Fruit trees growing in lawns are often
over-stimulated by lawn fertilizers. The pomes
are then predisposed to fire blight. Stone fruit
trees are often more susceptible to peach crown
borer, which can more easily attack the lower
trunk, as it is “softened” by the regular irriga¬
tion needed by the lawn. Lawn fertilizer in late
summer or early fall can stimulate succulent
new tree growth which will not “harden” (become
40 sufficiently woody) before cold weather arrives,
resulting in cold injury and die-back of new
growth.
Ideally then, a fruit tree’s root system
should be mulched over rather than sodded over.
Putting fruit trees in bed areas rather than lawn
areas and using mulches not only eliminates
tree-lawn competition for water, air and nutri¬
ents, it also prevents lawnmower and weed-
eater damage to the trunk.
Do not fertilize woody plants, including
fruit trees, after mid-July. Cut back on (but do
not stop) watering trees in September to help
alert the tree to harden off for winter. When tree
leaves fall in late October or early November,
water heavily to send trees into winter with a
good moisture level. Water them during dry
spells through winter.
Yes, it’s a challenge here, but home-grown
fruit for preserves, pies and eating ffesh-off-the-
tree is not beyond reach.
Local Best Bets
Choose these for hardiness, fire blight
resistance, and bloom and harvest times.
For more information, visit with your
nurseryman and contact Colorado State
University’s Cooperative Extension office
in your county.
• Apples: Wealthy, Duchess, Haralson,
Golden Delicious, Red Delicious, McIn¬
tosh, Joyce, Northwest Greening, Lodi,
Fameuse, Stayman’s Prairie Spy.
• Apricots: Sunglo, Golden Amber, Chinese,
Sungold, Moongold, Moorpark, Goldcot.
• Sweet cherries (not as dependable as
sour cherries): Stella, Van, Black Tartarian,
Kansas Sweet.
• Sour (pie) cherries: Montmorency,
Meteor, North Star.
• Peaches: July Elberta, Reliance, any
of the “Havens”: RedHaven, HaleHaven,
GloHaven, SunHaven.
• Plums: Santa Rosa, Burbank, Stanley,
Blufre, Damson, Green Gage, Waneta,
Sapalta
Green Trees Have Colorado Blues
James R. Feucht, Ph.D.
Growing trees in Colorado or, for that mat¬
ter, anywhere in the Rocky Mountain West,
offers many challenges: vagaries of climate, gen¬
erally poor soil conditions and assorted pests.
They make growing trees to mature size almost
impossible, especially without a lot of effort.
Perhaps more of a challenge than pests is
the condition of many soils, heavy clays with low
oxygen content. In fact, many pest problems are
aggravated by the poor soils, which weaken
trees and, thus, make them more susceptible to
attack by insects and invasion by disease organ¬
isms. In more than 25 years of field diagnosis
while I was with the Colorado State Cooperative
Extension, I found that up to 80 percent of the
problems are seated in conditions of the soil.
A high percent of these problems are due
to the compacted clays, which bring about “oxy¬
gen starvation” of roots. This one factor really
separates Colorado horticulture from growing
plants in the loamy, well-drained soils of some of
the mid-Westem and Eastern states. Real suc¬
cess here depends to a great extent on good soil
preparation and on sensible site-specific man¬
agement. With trees, of course, this is difficult
because they soon outgrow the loamy mix we
put in the hole — but shouldn’t — as we plant them.
Adding vagaries of climate to our poor soil
problem brings about even more frustration.
Who has forgotten the deep freeze on Halloween
1991? Dead and mostly dead Siberian elms,
some silver maples and introduced varieties of
James R. Feucht, Ph.D., is a consultant in horti¬
culture and landscape management. He is a
former extension professor of Colorado State
University and was the consulting editor of
Mountain, Plain and Garden, Evergreens.
cottonwoods are still scattered across our cities.
Why these trees? One would think, after all,
that trees from Siberia should be able to take
extreme cold. The silver maples had been
around for many decades and, aren’t cotton¬
woods natives?
The answer lies in the fact that all three
are fast-growing types that tend to delay the
normal hardening-off process in order to make
late growth. In addition, none of them is truly
native. What of the cottonwood (poplar) you say?
The cottonwoods that were most severely dam¬
aged were hybrids, not the native plains cotton¬
woods ( Populus sargenti ) the narrowleaf cotton¬
woods iP. angustifolia ) and lanceleaf cottonwoods
(. P. acuminata). In a sense, the hybrids didn’t
know how to get their antifreeze ready.
The most severe damage to silver maple
(Acer saccharinum ) occurred on trees already
stressed by the alkaline condition of our soils,
which leads to iron and manganese deficiency.
Trees in this weakened state have little energy
to divert to hardening-off, a process that
requires a storehouse of sugars and starches.
So plants that go into fall and winter in
either a vigorous condition or a weakened state
become casualties of weather extremes. Frus¬
trating, isn’t it!
Trying to grow some of the more colorful
flowering trees such as crabapples has its frus¬
trations, too. Fire blight, a bacterial disease
(. Erwinia amylovora) that causes new growth —
sometimes the entire tree — to blacken and die
seems to attack most of the crab varieties that
have the showiest flowers, such as ‘Hopa’, ‘Bech¬
tel’ and ‘Strathmore’. Fire blight is usually the
most severe when we have the most favorable
weather in the spring, cool and moist. 41
It also attacks other members of the rose family,
such as the mountain ashes.
Fortunately, Colorado’s weather is not as
conducive to other epidemic diseases commonly
found in the mid- West and East. Treating large
trees for foliage diseases is a rarity. An exception
is Dutch elm disease, which is transmitted pri¬
marily by an insect, the elm bark beetle.
Insects and mites, however, can get the
upper hand but, again, they are more severe
when trees are weakened due to soil and climate.
It has been shown time and again through
research — and has also been my observation —
that severe impact from heavy pest attacks can
often be blamed more on poor tree health to
begin with than on the pest themselves.
I have also observed that yards that are
repeatedly sprayed for no reason other than
“peace-of-mind” tend to have more severe prob¬
lems with some insect and mite pests than those
more-or-less left alone. Loss of the pests’ natural
enemies is likely a factor. For instance, I did a
brief study several years ago of the tiny orange
midge that causes stunted needles in pinion
pines. The study was given further attention by
entomologists at Colorado State University. It
was observed that yards with pinions under reg¬
ular, “contract” spraying generally had more
stunt midge than those not sprayed. It turns out
that a tiny black wasp (not the stinging kind)
was an effective parasite of the midge. Spraying
at the wrong time reduced the wasp population
and multiplied the midges!
There are, of course, insect pests that do
need occasional control. Aphids sometimes build
up rapidly on birch, maple and many other
trees. Chewing “worms” such as the larvae of
elm leaf beetles, tussock moths on spruces and
the more recent invasion from the south of ash
sawflies (the larvae of a kind of wasp!) can do
severe damage.
Even in these cases, though, timely, tar¬
geted sprays or the use of biological controls can
prevent devastation of your trees. The real key
to sound and timely control is in early detection
of the pests, correct identification and good man¬
agement of your trees.
For help, contact Denver Botanic Gardens
42 or the Cooperative Extension office of Colorado
State University in your county. Literature on
the most serious diseases and insect pests is
available free or at a nominal charge. The impor¬
tant thing is to monitor on a regular basis the
health of your trees and take action when need¬
ed — before a pest problem grows out of control.
Some things to avoid:
• Do not assume that what a flagging tree needs
is fertilizer. This is a common assumption, but
can further injure a sick tree. If, for instance,
the plant is weak from drought, lack of soil oxy¬
gen or excess salts in the soil, applying fertilizer
will increase the stress on the tree. Also,
research shows that excess nitrogen can actual¬
ly lead to greater damage from pests such as
aphids and mites.
• Do not water a tree unless you are certain
that it is suffering from dry soil conditions. Wilt¬
ing can be the result of excess water creating
oxygen starvation, a natural gas leak, high soil
salts or a vascular disease such as verticillium
wilt or Dutch elm disease. Adding more water
will likely magnify the problem.
• Do not assume that the presence of “bugs” on
your trees will present a problem or call for
immediate spraying. There are many “good
guys” that may look like pests. For instance, the
larvae of the ladybug are rather suspicious-look¬
ing orange and black “worms,” but they are
worth their weight in gold.
Another common insect that may appear
to be a problem but is, in fact, very beneficial is
the lacewing. This small-bodied, large-winged
green insect devours many aphids and other
soft-bodied pests.
• Avoid applying a “cover spray” over everything
in your yard. This practice is guaranteed to lead
to more problems and is dangerous to your
health and to the health of pets, nesting birds
and neighbors.
Growing trees to maturity in Colorado is a
challenge and, now and then, may give us the
“blues.” But even the worst of conditions and the
most serious pests are offset by the rewards of
those trees that survive, grow, give us shade on
hot days and protection on windy ones and most
of all — inspire us with their beauty.
Tree Rings-Reading Between the Lines
Moras L. Shubert, Ph.D.
Who hasn’t counted the rings on a tree
stump or the end of a log to determine the age of
the tree?
I believe all of us are aware that as a tree
grows, a new layer or “ring” of wood is formed
just under the bark each year. If a stump has 80
rings from its center to the bark, the tree must
have lived for about 80 years. But did you know
that, in addition to a tree’s age, there is a wealth
of information that tree rings can reveal?
As unique as a person’s fingerprint, a
tree’s annual rings contain its whole life story.
They are a permanent record of all the events
that have taken place around the tree — from
the climate and any catastrophic occurrences to
which the tree was subjected to any interference
by animals or humans. These events can be
reconstructed by a close study of the rings’ color,
their form and width.
Initially, we observe that different colors of
the wood create the rings. The light or dark tone
of the ring expresses what time of year that par¬
ticular layer of wood was being made. When the
cambium produces new wood each year, larger
cells are made during the cooler, moister spring¬
time when growth is vigorous and the tree
needs big vessels to carry a greater quantity of
nutrients to its crown. As the season advances,
becoming warmer and drier, the vascular cells
being produced are smaller, as growth slows
down. Therefore, each ring is fighter in color in
the “springwood”and darker in color where cells
are more compact in the “summerwood.” This
alternation of color, no matter how subtle, pro-
Moras Shubert, Ph.D. is professor emeritus of
biology, University of Denver, and a life trustee
of Denver Botanic Gardens.
vides the visible new ring for each year. As one
might expect, the color contrast may be less in
tropical and subtropical climates where season¬
al variations are milder.
Another message which can be deciphered
from tree rings is the story of past climatic con¬
ditions, a possibility that first occurred to the
insightful mind of Leonardo da Vinci. A tree’s
reaction to variations in its environment will be
seen in its growth. The relative widths of a tree’s
rings indicate which years in its lifespan were
the best for growth: if it was a moist warm year
the ring will be wider than if it had been hot and
dry. Technically, it is possible to count tree rings
to determine the exact year, for example, of a
drought. Using bristlecone pines ( Pinus aristata )
due to their sensitivity to rain, scientists have
been able to reconstruct the climatic conditions
from a period 7,100 years ago.
Other past events are recorded in a tree’s
annual rings as well. Their appearance can
reflect the stress of a cold spell that occurred
long ago. And harvesting a tree has sometimes
uncovered a black scar within the tree’s interior,
indicating where and when this tree had been
scorched by a forest fire.
Tree rings also provide a method for learn¬
ing about past civilizations. Using an instru¬
ment called an increment borer, scientists can
take core samples from trees or logs, and study
the ring patterns along the narrow column of
wood. This is how the cliff dwellings of the
Anasazi Indians in such places as Mesa Verde
have been dated back over 1,000 years, for these
ancient dwellings were supported with log
beams. Starting with a log or felled tree whose
age is known, it is possible to cross-match its
oldest rings with an older log from the same 43
Below right:
Native alder
Bottom right:
Seed pods
of golden
rain tree
locale whose most recent (outer) growth rings
are identical. This overlapping match-up
process can be carried back through numerous
“generations” of logs. In this way the construc¬
tion beams of the Anasazi cliff dwellings were
dated. It was comforting to the dendrochronolo-
gists (scientists who use this method for study¬
ing old wood) when carbon dating became avail¬
able and verified the accuracy of their findings.
Besides telling us the ages of trees or logs,
the zones of springwood and summerwood are
responsible for the beautiful grain patterns in
fine furniture, flooring, panelling and wood
sculpture. What is a circular pattern of annual
rings in cross-section becomes a variety of pat¬
terns depending on how the log is sawed. These
patterns are more marked in some species, like
pines and firs, than in others.
The production of veneers, very thin
sheets of wood, has provided all kinds of elegant
patterns for such items as table tops. Selected
logs are cut into proper lengths called bolts, soft¬
ened by steaming and then turned against a
sharp blade, shaving off a thin layer like
unrolling a roll of paper towels. This gives a
grain that is somewhat parallel to the length of
the log with the tree’s variations in growth pro¬
viding the amazing grain patterns. Indeed,
when you consider what an elegant engraving
tree rings are, a recorded natural history of
what went on over a specific period of time in a
given locale, you may never look at your hard-
44 wood floors the same way again.
How to Plant a Tree
Vicky Stinson
There is no simpler act of faith in the
future than planting a tree. A tree is a legacy we
leave to the generations who follow us — if we
plant it right.
Among Colorado tree people, there are
various opinions regarding the depth of plant¬
ing, use of soil amendments, staking and remov¬
ing root ball coverings, so some clear guidelines
might be helpful.
But before we cover some of these
specifics, you must make some initial decisions.
Begin by selecting the most appropriate
location to plant your tree. If you’re not already
working from a plan, consider shade and solar
benefits you might gain or lose from the place¬
ment of a deciduous tree. Consider the screen¬
ing or winter wind protection to be derived from
planting an evergreen tree. Be realistic about
the ultimate size of your tree. Wherever possi¬
ble, plant in bed areas rather than lawn areas
as some trees have different water requirements
from turf. Avoid planting in drainage areas.
Also, know if you’re planting a tree that is
finicky about shade or sun. Select a variety suit¬
ed to your purposes and site.
Ideal weather for planting is cool, cloudy
and humid, but this cannot always be arranged.
Early spring and early fall are the ideal times,
but you can plant most any time providing the
ground is not frozen or the tree is not putting on
new growth.
Vicky Stinson is a registered landscape archi¬
tect with a degree in landscape horticulture
from Colorado State University. She works for
the National Park Service.
Handling Your Tree
Once you have selected a location and are
ready to plant, move your balled and burlapped
(B&B) or container-grown tree near its intended
place.
It is absolutely essential that the root ball
not be broken up. Always handle your tree by its
root ball, rather than its trunk. Depending on
the size of your tree you may need a ball cart,
dolly or wheelbarrow to transport it from your
vehicle to the planting site. Once you have your
tree near its destination, begin to dig the hole.
Note: if weather is hot or you are planting sever¬
al trees, dig the hole(s) prior to bringing the
tree(s) to their planting location. Try to keep
them in a shady location to prevent dessication.
Digging a Planting Pit
Start by measuring the diameter and depth
of the root ball. Your planting pit should be at
least two times the diameter of the root ball. The
larger the diameter of your pit the easier it is to
work around the ball once it is in the hole.
Usually, the pit depth should be about 2
inches shallower than the depth of the tree’s
root ball. If you happen to be planting in sandy
soil, the pit should be equal in depth to the root
ball, but never deeper. Take the time to measure
as you dig, as it is almost impossible to compact
the soil properly should you dig too deeply and
need to replace soil in the hole. It is critical that
the root ball sit on firm, undisturbed soil.
Do not add gravel to the bottom of the pit
for “improved drainage,” as this may actually
hold water under the root ball and drown the
roots. If you are planting in heavy clay soil, make
an effort to roughen up the sides of your planting
pit to assist root penetration beyond the pit walls. 45
Planting Your Tree
If you are planting a tree grown in a plas¬
tic container, carefully remove the container by
sliding it off the root ball, placing as little stress ,
as possible on the trunk. If planting a B&B tree
or tree grown in a fiber pot, carefully roll or rock
the tree into the center of the planting pit. With¬
out disturbing the root ball, cut off the top and
sides of the fiber pot. Next, remove all twine
from around the trunk and root ball of balled
and burlapped trees and cut away at least the
top half of the burlap. If the root ball is in a wire
basket, cut off at least the top two-thirds of the
basket. Twine left in place will girdle and even¬
tually kill the tree. Remove all excess material
from the pit. The tree’s root ball should be about
2 inches higher than the original surrounding
ground level, even higher for some species such
as birch, mountain ash and cherry.
Begin filling the pit with the soil that was
removed, keeping the tree plumb. To support
the tree you may want to add about one-third of
the backfill prior to removing the burlap and
twine from B&B trees.
Though some experts recommend adding
amendments to the soil, I do not. It is possible
that adding organic amendments to the soil
retards growth, as the roots will tend to stay
within their amended planting pit much as they
would in a pot.
Water with a hose as you backfill, to settle
the soil and eliminate air voids. Do not tamp the
soil. Add more backfill if settling occurs over the
next day or so. Build a temporary saucer or rim
of soil around the outside of the pit if your tree is
within a bed area or an unirrigated area.
Mulch with several inches of wood chips,
especially if you are planting in the fall. If your
tree is in a lawn area, remove a two-foot circle of
sod from around the tree and mulch, to prevent
mower or weed-eater damage to the trunk.
Staking Trees
For deciduous trees in very windy areas or
when the root ball is disproportionately small
compared to the size of the tree’s crown, staking
is necessary. But don’t use staking to straighten
46 a crooked tree!
If you need to stake your newly planted
tree, use two steel t-bars or two 2-inch x 6-foot
wooden stakes. Drive them into undisturbed
soil, with one stake on the northwest side of the
tree. Connect stakes to the tree with horizontal
guy wires fastened to the tree with soft carpet
strips or nylon tree straps, but not so tightly as
to prevent some movement of the trunk. Never
place the wire itself around the tree! Attach a
small colored flag or white pvc piping to the
wires so people don’t trip over them. Finally,
after a year, remove all staking and straps to
prevent girdling the tree.
Tree Wrap
An important word about wrapping tree
trunks: wrapping is only a temporary, Novem-
ber-to-April, protective measure against sun-
scald, which occurs in our area on certain
species only in late winter and early spring.
Tree wrap may be used for the first winter or
two after planting to prevent sunscald on thin-
barked newly transplanted trees such as maple,
linden, Japanese pagoda and honeylocust, and
should not remain on trees through the spring
and summer. So often we see trees that have
been in the ground for many years bursting out
of their dilapidated tree wrap, looking pathetic
and neglected.
Wrap young tree trunks in November,
starting from the base, and secure the wrap
with a couple of tacks. Never use tape or twine
for this purpose. Then be sure to remove it
around April 1 by unwinding the wrap, which, if
left on, could harbor opportunistic insects or dis¬
eases. Furthermore, never accept a new tree
that is already wrapped without first removing
the wrap to inspect the trunk; it could be
cracked or otherwise damaged.
By applying sound tree-planting practices,
you will help ensure the health and long life of
your trees — so that they may be appreciated by
future generations.
Bibliography
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Great Plains. Fulcrum. Golden, CO.
SD 409.5 ,B7 1992.
Carr, David. 1991 . Garden trees: step by step to
growing success. Crowood. Swindon, Wiltshire.
SB 435 ,C2770Ga.
Collingwood, George Harris. 1974. Knowing
your trees. American Forestry Association.
Washington. QK 482 C27 1974.
Courtright, Gordon. 1979. Trees and shrubs for
western gardens. Timber Press. Forest Grove,
OR. SB 435.52 P32 C6879.
Dirr, Michael A. 1990. Manual of woody land¬
scape plants: their identification, ornamental
characteristics, culture, propagation and uses.
Stipes Pub. Co. Champaign, IL. SB 435 D577 1990.
Elias, Thomas S. 1981 . Illustrated guide to street
trees. New York Botanical Garden, Cary
Arboretum. Millbrook, NY
Fairchild, D.H. 1993. Woody landscape plants
for the high plains. Colorado State University.
Fort Collins, CO. SB 435.52 ,C6 F3 1993.
Feucht, James. 1987. Landscape manage¬
ment: planting and maintenance of trees,
shrubs and turfgrasses. Van Nostrand Reinhold.
New York. SB 435 ,F4 1987.
Harris, Richard Wilson. 1992. Arboriculture: inte¬
grated management of landscape trees,
shrubs, and vines. Prentice-Hall. Englewood
Cliffs, NJ SB 435.H366 1992.
Hightshoe, Gary L. 1988. Native trees, shrubs,
and vines for urban and rural America: a plant¬
ing design manual for environmental design¬
ers. Van Nostrand Reinhold. New York.
SB 435.5 H5458 Na 1987.
Hillier, Harold G. 1972 Hillier's manual of trees
and shrubs (1st Am. edition). A.S. Barnes, South
Brunswick SB 435 H5554 1972
Kelly, George W. 1976. Trees for the Rocky
Mountains: a manual of the use and care of
trees in the Rocky Mountain area. Rocky
Mountain Horticultural Pub. Co. (s.l.).
SB 435.52 .R62K45 1976.
Knowles, Hugh. 1989. Woody ornamentals for
the prairies. University of Alberta. Edmonton,
Alta. SB 435.6 .C22 P7 K6 1989.
Krussmann, Gerd. 1984. Manual of cultivated
broad-leaved trees and shrubs. Timber Press.
Beaverton, OR. SB 435 K75Ma 1984.
Little, Elbert Luther. 1953. Check list of native
and naturalized trees of the United States
(including Alaska). Forest Service. Washington.
QK 481 L57.
McPherson, E. Gregory. 1984. Ornamental and
shade trees for Utah. Utah State University.
Logan, UT. SB 435 M38 1984.
Mitchell, Alan F. 1987. The trees of North Ameri¬
ca. Facts on File Publications. New York, N.Y.
QK 481 ,M579Tr 1987.
Peattie, Donald Culross. 1953. A natural history
of western trees. Bonanza Books. New York.
QK 481 ,P3 1953 .
Rehder, Alfred. 1940. Manual of cultivated
trees and shrubs hardy in North America, exclu¬
sive of the subtropical and warmer temperate
regions. The Macmillan Company. New York.
QK 481 ,R45 1940 .
Sargent, Charles Sprague. 1961 . Manual of the
trees of North America (exclusive of Mexico).
Dover Publications. New York. QK481 S374 1961.
Shigo, Alex L, 1991 . Modern arboriculture. Shigo
and Trees. Durham, NH. SB 435 .S55 1991 .
Snyder, Leon Carlton. 1980. Trees and shrubs for
northern gardens. University of Minnesota Press.
Minneapolis. SB 435.5 S584.
Taylor's guide to trees. 1987. Houghton Mifflin.
Boston. SB 435 .T434 1987.
Wandell, Willet N. 1989. Handbook of land¬
scape tree cultivars: palms, evergreens, cacti,
nuts, and fruit trees excluded. East Prairie Pub.
Co. Gladstone, IL. SB 435 ,W3 1989.
Wyman, Donald. 1990. Trees for American gar¬
dens. Maxwell Macmillan. New York.
SB 435 .W92 1990. Whitcomb, Carl E. 1987
Zucker, Izabelle. 1990. Flowering shrubs and
small trees, rev. by Fell, Derek. Grove/Atlantic
Monthly Press. New York. ISBN 0-8021-1242-0
Establishment and maintenance of landscape
plants. Lacebark Publications. Stillwater, OK. SB
435 ,W54 1987.
- 1983. Know it and grow it. Lacebark Publi¬
cations. Stillwater, OK. SB 435.5 ,W55 1983.
— Compiled by S. Gignac
Librarian, Helen Fowler Library
Denver Botanic Gardens
909 York Street
Denver, CO 80206-3799
Non Profit Org.
U.S. Postage
PAID '
Permit No. 205
Denver, Colorado
**C034
Mountain, Plain and Garden
Printed on recycled paper using soy-based inks
.
m
ndscape Aesth
Mountain, Plain and Garden
The Magazine of Denver Botanic Gardens
Volume 52 • 1995 • Rocky Mountain Landscape Aesthetics
Contents
Waterwise Gardening, Water-Smart Gardening™, Xeriscape Gardening
Toward Appealing Rocky Mountain Aesthetics . 3
Why Waterwise Gardening?
The Cost of Treating Drinking Water . 6
The Hard Lessons of Rocky Mountain Droughts . 7
The Role of Landscape Design Guidelines
Aesthetic Pursuits — New Lawns and Marvelous Meadows
Beyond Ecstasy in a Can . 11
New Turf-TVpes of Buffalograss & Tall Fescue . 13
Water-Smart Gardening™ at Denver Botanic Gardens
The Laura Smith Porter Plains Garden . 14
The Water-Smart Garden . 15
The Rock Alpine Garden . 18
The Xeriscape Demonstration Garden . 22
The Nature Center Garden . 26
Xeriscape & Wildlife Gardening Principles . 27
The Visitor Center Garden . 28
Sample Plants Rated by Water Needs . 30
Nifty Flowers for Nifty Rocky Mountain Landscapes
The Perfect Perennial for the American West . 31
Floral Fantasies Fulfilled . 32
Sawsepal Penstemon ( Penstemon glaber ) . 34
Weeds We Like . 36
Penstemons to Star in Your Waterwise Garden . 38
Authentic Aesthetics — Landscaping with Rocky Mountain Natives
Native Landscaping for Many Reasons . 40
Going “All the Way” . 42
For More Livable Urban Surroundings . 43
When Is a Native “Native?” . 45
Bibliography . 46
© 1995, Denver Botanic Gardens, Inc.
^09 York Street • Denver, Colorado 80206-3799
Donald J. Kany, president
Richard H. Daley, executive director
Jim Knopf, consulting editor
A continuation of The Green Thumb Magazine
Produced by the Marketing and Special Events Department of Denver Botanic Gardens.
Denver Botanic Gardens and Chatfield Arboretum are established and maintained by Denver Botanic Gardens, Inc.
for the people of the City and County of Denver and the general public in cooperation with the Denver Parks and
Recreation Department. Denver Botanic Gardens is grateful for funds from the Scientific and Cultural Facilities
District (SCFD) which enable the Gardens to expand services and enhance the quality of programs and exhibits.
Waterwise Gardening, Water-Smart Gardening™, Xeriscape Gardening:
Toward Appealing
Rocky Mountain Aesthetics
Jim Knopf
Low- water landscaping, less-water land¬
scaping, water-efficient landscaping — the super¬
abundance of terms gets in the way. But what¬
ever it’s called, gardening in pursuit of water
conservation, especially when combined with
the pursuit of appealing local landscape aesthet¬
ics, is wonderful. It’s fun. It’s pretty. It saves
water. It solves environmental problems. It’s all
good news.
There are many wonderfiil styles to pur¬
sue — ranging from landscapes that appear as if
they were never disturbed, to landscapes that
use native plants in formal fashion, and to land¬
scapes that use wonderful well-adapted intro¬
duced plants. There is room to accommodate
many personal preferences and to address any
landscape situation.
With so many wonderful natural land¬
scapes for inspiration, and so many possibilities
for appealing adaptations to the full range of
modem urban landscape situations, it is sur¬
prising and tragic how far most landscaping has
strayed from sensible, satisfying designs. It is
also tragic how fast the scenic and meaningful
natural landscapes of the vast and varied Rocky
Mountain region are disappearing in the cur¬
rent frenzy of urbanization.
Before it is too late, it is worth reflecting
on some of the evocative natural landscapes that
could lead us to more satisfying and sensible
urban landscape surroundings. Pinon- Juniper,
Jim Knopf, landscape architect and author of
The Xeriscape Flower Gardener, lives and gar¬
dens with lots of native plants and wild critters
in Boulder, Colorado.
and Ponderosa-Oak woodlands, Blue Grama-
Buffalograss prairie, and Aspen-Engelmann
Spruce-Subalpine Fir forests are among the
major image-setting natural landscapes to study.
Each of these natural landscapes is composed of
numerous larger and smaller plants arranged in
meaningful, marvelous patterns. Each land¬
scape type also presents specific visual and hor¬
ticultural challenges to urban translation.
This issue of Mountain, Plain and Garden
is devoted to the challenging and alluring, but
elusive goal of expressing these marvelous nat¬
ural landscapes of the Rocky Mountain region
in meaningful modem landscaping.
The terms Water-Smart Gardening™,
Xeriscape, xeriscape plant, drought-tolerant
plant and aesthetic are worth some special
attention, since they are often used to mean dif¬
ferent things.
Water-Smart Gardening™ (a term used
by Denver Botanic Gardens) and Xeriscape (a
term first promoted by the Denver Water
Department) have always been intended to
refer not only to landscaping that is entirely dry,
but also to landscaping that uses some water
wisely. Entirely dry landscaping is clearly con¬
sistent with the goal, but so are heavily-irrigat¬
ed athletic fields, because they grow faster and
repair themselves faster than non-irrigated ath¬
letic fields. Water-efficiency and wise use of
water are the goals. Also, neither term is intend¬
ed to refer only to rock and gravel landscaping,
though rocks and gravel can be quite attractive.
Likewise, neither term refers only to native
plant landscaping, though native plants are
often part of good waterwise landscaping.
Xeriscape plant: Technically, this is a
meaningless term, since waterwise landscapes
can have highly- and moderately-irrigated, as
well as non-irrigated areas. When referring to
plants that need little or no irrigation, it is bet¬
ter to use the terms “xeric plant” (xeric = dry) or
“totally drought-tolerant plant.”
Drought-tolerant plant: This term is
used in several very different ways. First, it can
refer to plants that never need irrigation. Sec¬
ond, it can refer to plants that simply need little
irrigation. Third, whether a plant needs a lot or
only a little irrigation depends on the local cli¬
mate. For example, Black-eyed Susan ( Rudbeck -
ia hirta) needs no irrigation in Atlanta, Georgia,
but needs regular irrigation in Albuquerque,
New Mexico.
Aesthetic: “Pertaining to the beautiful, as
distinguished from the moral” . . . “Appreciative
of, or responsive to, the beauty in art or nature” . . .
“Expressing good taste” . . .
Dictionary definitions of this evocative
word suggest that the pursuit of a Rocky Moun¬
tain landscape aesthetic is the pursuit of entic¬
ing, artistic and meaningful Rocky Mountain
images. It is on these notions of enticing and
meaningful landscapes that this issue of Moun¬
tain, Plain and Garden focuses special attention.
Facing page, left column: Aspen-Spruce-Fir forests—
some of the early architecture fits well, some of the
newer architecture does not.
Facing page, right column:
Pinon-Juniper woodlands— these visually attractive
landscapes are easy to restore and maintain.
Why cover them with gravel?
This page: Blue Grama-Buffalograss prairie — these
native shortgrass landscapes offer many attractive
variations for urban settings. Who really thinks gravel
is nicer?
_
Why Waterwise Gardening?
The Cost of Treating Drinking Water
Paul Lander
Most utilities in the western U.S. treat
water to drinking-water standards only to have
50percent or more used for landscape irrigation.
To make things worse, the demand for landscape
water occurs during a four to five-month sum¬
mer period, creating a surge in demand which is
often three to four times the demand for water
in the winter.
If a community had a dual-pipe distribu¬
tion system, it would be easy to satisfy the land¬
scaping demands utilizing untreated (raw) water
directly from surface or groundwater sources.
But, with only a single-pipe distribution system,
which is the case for the vast
majority of utilities, the pri¬
mary option for util¬
ities in addressing
this problem is
to reduce over¬
all summer
water demand,
and especially
the summer
peak demand.
It costs
money to treat
water to drinking-
water standards. It costs a lot of money to build
and expand a treatment system’s capacity to
keep up with the growing peak demand. Peak
Paul Lander, water conservation specialist for
the City of Boulder, Colorado, keeps Boulder
residents on their waterwise toes by organizing
an array of services, ranging from waterwise
programs to xeriscape design contests. He is
6 current chair of Metro Water Conservation, Inc.
demand drives the ultimate size, operating cost,
and the rates most utilities charge customers.
Here in the semi-arid West, it is our decades-old
habit of importing and growing water-loving
plants that has created that peak demand.
A portion of the operating costs of any utili¬
ty is fixed — to pay personnel, to maintain equip¬
ment, and so on. As more water is treated, more
money is spent by utilities, so conserving water
helps keep facilities operating at their most effi¬
cient levels. Water conservation is a superior, and
money-saving, alternative both to finding and
developing new water supplies, and to building
and operating new treatment facilities.
As a “supply” of water, conservation can usually
make water available to an exist¬
ing system at one-half to
one-third the cost of buy¬
ing new water. On the
treatment side, conser¬
vation can save money
by extending the time
before new treatment
facilities — increased
capacities — need to be
added. Adding time can add
up to big savings.
In 1988, the Delaware River Basin Com¬
mission estimated that capital costs alone (this
does not include the cost of financing) for water-
supply facilities were about two million dollars
per million gallons per day (MGD) of capacity,
and about four million dollars per MGD units,
which adds up to big money very quickly. So,
save some water, and save your town money for
other (possibly more important) needs of the
community.
Why Waterwise Gardening?
The Hard Lessons of
Rocky Mountain Droughts
Jim Knopf
If nice weather is sunny, dry and warm,
then drought must be wonderful . . . not so! The
early pioneers on the High Plains and in the
Rocky Mountain West, who tried to farm as if
they were still in the East, learned very hard
lessons about the frequency and severity of
droughts in this region. Likewise, today’s subur¬
ban gardeners will also have to learn the hard
way that drought here is both common and very
disruptive, if they continue to pretend that
water for irrigation is unlimited and cheap.
The evidence is clear. The 20- to 22-year
recurrence of droughts in the Great Plains of
North America is well documented. 1892, 1912,
1934, 1953,1976 and (1998?) mark mid-points of
droughts in this pattern. Intriguingly, this coin¬
cides closely with the timing of every other
sunspot minimum, when the magnetic polarity
of the leading sunspots in the sun’s northern
hemisphere changes from north-seeking to
south-seeking. Making this pattern even more
compelling, tree-ring studies indicate that dur¬
ing the 1600’s there was a 70-year drought in
the western U.S. occuring at the same time
sunspots were essentially absent for 70 years.
By comparison, the “Great Drought” of the
1930’s lasted only about 6 to 9 years.
Taking a longer view, vast variation in wet
and dry periods are indicated by geologic studies
covering approximately the 10,000 years of cur¬
rent climatic conditions since the last great
Ice Age. All of this might lead people to wonder
about the severity of a “1,000 year drought.”
Consider California. Beginning about 1,100
years ago, the Golden State has endured two
mega-droughts. The first lasted 220 years and
the second lasted 140 years. These droughts
were not only much longer, they were also
much drier than the modest “dry spells” of the
20th Century.
The message should be clear . . . live
realistically within the limits of local water
supplies or suffer the consequences. Fortunate¬
ly, these climatic conditions have resulted in
some of the most appealing natural landscapes
anywhere, and these wonderful natural land¬
scapes are well suited to urban and suburban
surroundings. 7
Fawn Hayes Bell, designer of the beautiful Col¬
orado Springs Xeriscape Demonstration Gar¬
den (a marvelous companion to nearby Gar¬
den of the Gods) is a professional landscape
architect in Colorado Springs, Colorado.
This page: Ponderosa Pine-Gambel’s Oak
woodlands— buildings often look best in these open
woodlands, with their knee-high grasses, when the
site is disturbed very little.
Bottom left and right: Regrading of hillsides should
be avoided or done very carefully. Poorly graded
hillsides often never recover, while undisturbed
hillsides are often very attractive.
The Role of Landscape
Design Guidelines :
Two Examples from Colorado Springs, Colorado
Fawn Hayes Bell
Example #1:
"Colorado Springs Landscape & Site
Improvements Design Guidelines"
In 1993 the Colorado Springs Water
Resources Department asked me to prepare
design guidelines to facilitate eventual land¬
scape development of some thirty-five sites. The
Water Resources Department has a strong com¬
mitment to promote water-efficient landscapes,
and has conducted an active program, including
the construction of an award-winning Xeriscape
Demonstration Garden, a community- wide ET
program, and numerous research and educa¬
tional programs.
Despite the success of these programs,
there was one question frequently posed by the
xeriscape garden visitors which was difficult to
answer: ‘Where can I see examples of water-effi¬
cient landscapes?” From these inquiries the
direction for a new project was developed — to
landscape the department’s own sites through¬
out the community to illustrate xeriscape design
principles and to create a portfolio of examples
for interested customers.
Initially, the task of writing the guidelines
focused on (1) implementation and management
of the proposed landscape improvements, (2)
communicating the Department’s role in water
conservation, (3) the creation of sustainable
landscapes, and (4) the preservation of indige¬
nous and endangered species. For example, at
the historic 33rd Street Pump Station, the site
will be renovated to
reflect the historic
character and the
urban riparian set¬
ting. At tank sites
located throughout
the community,
from clay foothills to
sandy plains, the
natural setting and
plant communities
provide distinctly
different design
directions. As the
project progressed,
the guidelines’ pur¬
pose was enlarged
to foster local com¬
munity awareness
of landscape design
issues and to encourage similar efforts from oth¬
ers, like universities, developers and public
agencies, whose actions affect the land. The
guidelines became an opportunity to challenge
the community’s ability to create landscapes
that convey a sense of regional context and
reflect man’s commitment to shape a positive,
sustainable future.
Unlike regulatory ordinances, guidelines
serve to show how to achieve a goal, instead of
emphasizing regulatory constraints and/or
requirements. Because they are not regulatory,
one of the problems for landscape guidelines is
— “How do you get people to read them?” It
helps to assume that people are looking for solu¬
tions, and to start with a clear mission state¬
ment. It is also important to define the audi¬
ence — will the document be used by technical or
lay readers? Is it part of a larger effort — or a
stand-alone piece? Finally, define “success” — is
it related to large-scale distribution, education,
compliance or to stimulating new ideas?
The Colorado Springs Water Resources
Department Landscape and Site Improvements
Design Guidelines were published in September
1994. They were the result of a collaborative
process including this consultant, the client and
an enthusiastic and supportive group of volun¬
teers. They will be considered a success if they
gain acceptance by the community, are used by
members of the target audience, result in an
improvement and beautification of the communi¬
ty, increase water conservation, and if they
enhance active partnerships between the Water
Resources Department and the community. The
guidelines received 1994 awards from the Ameri¬
can Society of Landscape Architects, Colorado
Chapter, in the categories of “Research and Com¬
munication,” and “Outstanding Public Entity.”
The following excerpts from the guide¬
lines, with photographic illustrations, show two
examples of ideas which the guidelines are
intended to accomplish.
Identifying an appropriate
landscape character:
Designers are encouraged to develop inno¬
vative and regionally-specific design solutions
which will serve as examples to . . . school dis-
10 tricts, developers, public agencies and commer¬
cial institutions. One of the first design tasks for
a particular site is to identify which image of the
Colorado Springs regional landscapes it should
reflect. Is it the short grass prairie which
bounds the city on the east, or the Pinon-
Juniper plant community on the southern edge,
or the foothills scrub oak and ponderosa pine? Is
it perhaps the cultivated and groomed mix of
indigenous species and adapted exotics intro¬
duced over more than a century of habitation by
the many people who have adopted Colorado
Springs as their home?
Slopes, Grading and Berms:
Where possible, retaining existing vegeta¬
tion will assist with control of erosion by water
and wind ... A slope contoured to look natural
will visually blend with the native terrain . . .
Where berms are used as a buffer, to screen
views and divert sound or for visual interest, it
is important that large, gently rolling landforms
compatible with the landscape be created ... A
rigid berm of constant slope and height is not
typically harmonious with the surrounding nat¬
ural landforms ... A convex slope (at the bot¬
tom) is preferred . . . avoid berms fewer than 10
feet in width.
Example #2:
Kissing Camels Estates
Landscape Guidelines
The landscape and site improvements
design guidelines have served as a catalyst for
other guidelines which are more detailed and
project specific. For this residential develop¬
ment, these brief guidelines stimulate a more
thorough approach to design, as in the following
excerpt :
“One of the key design considerations is
whether to overlay the natural setting with
an alternate landscape style from another
region of the country, or to reveal the setting
by using compatible colors, native plant
materials and patterns of planting which
echo the natural plant communities.”
In our modem urban settings, filled with
constraints, intensity and great expectations, we
long for inspiration, beauty, and a sense of
regional identity. Landscape guidelines, when
structured properly, can fill these needs.
Aesthetic Pursuits — New Lawns and Marvelous Meadows:
Beyond Ecstasy in a Can
Three Native Meadows for Modern Landscaping
Jim Knopf
Mention meadows in landscaping, and
thoughts quickly turn to images of the unbeliev¬
able meadows on pretty seed packages. Unfortu¬
nately, meadow mix marketing, with overly-
pretty pictures of flowers, grasses and beautiful
butterflies, threatens to take meadows out of
reality and into some other realm. In fact, it is
probably only a matter of time before “Ecstasy
in a Can” meadow mix hits the garden market.
The advertisements might read:
Just scatter in the wind, and enjoy
ecstasy beyond your wildest dreams . . .
completely legal . . . only slightly addictive . . .
basically harmless . . . thousands of
ecstatic customers.
Unfortunately, this “euphoric” approach to
meadows is usually disappointing and misses
the real value that meadows offer in addressing
modem landscape needs. Suburban open space
areas, highway right-of-ways, and wildlife gar¬
dens could all benefit from landscaping that is
both much more realistic than most commercial
meadow mixes, and less costly to maintain than
traditional, manicured lawns.
For modem landscaping, a meadow could
be defined simply as a visually-appealing mix¬
ture of flowers and grasses. With this definition,
the tallgrass, midgrass, and shortgrass mead¬
ows native to the Rocky Mountain Region and
Great Plains, are worth serious consideration
for landscaping on sites where each is adapted.
It is important to note that the height of a
meadow is largely determined by the species of
grasses that are selected, and the height of a
meadow is important for the visual impact as
well as the uses of the meadow area. It is easier,
for example, to walk around on a shortgrass
meadow than on a mid or tallgrass meadow, and
it is easier to see across a short or midgrass
meadow than a tallgrass meadow.
Shortgrass meadows tend to grow less
than ankle high and are the dominant grass¬
land of the western high plains, where the
Rocky Mountain rainshadow results in the dri¬
est conditions on the Great Plains. The domi¬
nant grasses are buffalograss ( Buchloe dacty-
loides) and blue grama ( Bouteloua gracilis).
Some of the associated wildflowers are chocolate
flower ( Berlandiera lyrata), blanket flower
( Gaillardia aristata), and mexican hat cone-
flower ( Ratibida columnifera). Buffalograss is
such a vigorous, spreading grass that it can
crowd out many wildflower species. Greatest
success with wildflowers in this grassland type
may come from planting the wildflowers in
areas where only blue grama is planted, because
blue grama is a bunchgrass and won’t crowd out
wildflowers. Alternatively, the entire meadow
area might be planted using only blue grama. It
should also be noted that this grassland type is
best grown on very warm, dry sites. In Colorado,
meadows at elevations above about 6,000 feet
are usually too cool and moist to remain entirely
blue grama and buffalograss, and tend to evolve
toward midgrass meadows. A good example of a
shortgrass meadow can be seen at the Denver
Botanic Gardens. Another extremely photogenic
shortgrass meadow can be seen around the Old
Pecos Office Compound on Old Pecos Trail in
Santa Fe, New Mexico. In this meadow planti¬
ng, blue grama, Paintbrush ( Castilleja sp .) and
blue flax C Linum perenne ) were seeded under
the native pinon pines, and have resulted in a 11
stunningly attractive, low-maintenance setting
for the Santa Fe adobe-style buildings.
Midgrass meadows tend to grow from
knee high to waist high and are common among
ponderosa pines. Boulder, Colorado, for exam¬
ple, has many areas of this grassland type
extending from the mountain backdrop into res¬
idential areas. In many cases these areas have
been stable and attractive for 20 to 30 years
with little or no maintenance. Dominant grass
species are western wheatgrass ( Agropyron
smithii), little bluestem ( Andropogon scoparius,
syn. Schizachyrium s.), and sideoats grama
(. Bouteloua curtipendula). Purple prairie clover
( Dalea purpurea ), pitcher sage (a.k.a. blue sage)
(, Salvia azurea) and Lewis’ flax ( a.k.a. prairie
flax) ( Linum perenne var. lewisii) are three wild-
flowers that grow well in these grasses. During
dry conditions, where fire danger is a concern,
mowing or grazing “defensible” space adjacent
to buildings creates very effective fire breaks.
Narrow, watered lawn areas are also effec¬
tive. The greatest fire danger is actually from
ponderosa pines, junipers and pinon pines that
may grow in this grassland type. The grasses
contain little fuel, but can carry a fire to the
trees and shrubs. Removing lower limbs on pon¬
derosa pines, and maintaining a reasonable dis¬
tance between buildings and the woody plants is
an important consideration. Taking these pre¬
cautions will usually result in fire danger no
greater than in the same type of forest areas
that have watered lawns.
Tallgrass meadows were the dominant
grassland in the eastern Great Plains before
farming and ranching changed everything. Big
bluestem (. Andropogon gerardii), Indian grass
( Sorghastrum nutans), and switch grass (Pan-
icum virgatum) are the dominant grasses. Wild-
flowers include purple coneflower (. Echinacea
purpurea), wild monarda (a.k.a. wild bergamot)
(Monarda fistulosa), and Maximilian’s sun¬
flower ( Helianthus maximilianii). These grasses
and flowers are adapted to relatively moist con¬
ditions, compared with short- and mid-grass
meadows.
Maintenance of tallgrass areas, because
they are wetter than mid- and shortgrass mead¬
ows, is likely to require periodic mowing and/or
burning to keep woody shrubs and trees from
dominating. Midgrass areas, by contrast, often
continue indefinitely without mowing or burn¬
ing. It depends on the site, however. Excessive
moisture is the major factor in favoring woody
plant growth. Shortgrass areas may need occa¬
sional mowing to keep cool season grasses from
growing too tall during cool, wet periods.
A bit of pioneering spirit and a bit of perse¬
verance is very helpful, since meadow landscap¬
ing has been worked with so much less than has
traditional “lawnscaping”. Also, meadows are
dynamic, and change a lot, especially in the first
few years. Real economic and aesthetic rewards,
however, await those who pursue the challenge
of finding more sustainable and satisfying types
of landscaping.
This page: Restored shortgrass meadow with
paintbrush, blue flax, blue grama, and buffalograss.
Opposite left: Turf-type tall fescue.
Opposite right: ‘609’ buffalograss.
Aesthetic Pursuits— New Lawns and Marvelous Meadows:
New Turf-Types of Buffalograss
and Tall Fescue
Jim Knopf
Buffalograss
Buffalograss, a native warm-season grass
from the western Great Plains, shows extraordi¬
nary promise for widespread use as a lawn
grass in hot, sunny dry, locations. Being a
warm-season grass, it tends to start spring
growth about a month later than turf-type tall
fescue or Kentucky bluegrass, and goes dormant
about a month earlier in the fall. However, some
of the new varieties are day-length neutral, and
retain their color a month longer in the fall.
Other new varieties begin spring growth several
weeks earlier in the spring. It remains to be
seen whether the season can be extended in
both spring and fall. The color of most varieties
is a beautiful greenish-blue, but some of the new
kinds are an appealing blue-green. Male forms
of buffalograss have attractive flowers that
stand a little above the 4-6 inch high leaves.
Female forms do not have flowers that are visi¬
ble from a distance. Commercial plant selection
is taking advantage of this by providing all¬
female or mixed male and female varieties.
Because it is so low-growing, buffalograss
does not require mowing, but mowing about
once a month easily maintains a more tradition¬
al lawn appearance. The water and fertilizer
requirements are extremely low. Watering about
once per month in the hottest weather is all that
is needed to maintain the beautiful blue-green
color. Except in the driest desert areas, it needs
no irrigation to survive quite well, and this is
creating enormous interest in places where irri¬
gation is not possible. The new female varieties
are available only as sod or plugs, in order to
maintain the all-female type plants. Mixed
female-male varieties are already available for
seeding lawns and short grass meadows.
Buffalograss is generally not satisfactory in
shade, though some of the new varieties will do
well in light shade. Buffalograss thrives in hot
weather. 90° F, or more during the day, with
very warm nights is when it grows best. Buffalo¬
grass is the “hot” new choice for lawns in hot,
dry, sunny places across much of the western
and south-central U.S.
Finally, there is even sexual instability in
buffalograss. Where growing conditions vary
enormously from year to year, some plants have
evolved to make the most of their precarious sit¬
uation by performing the female sex role of pro¬
ducing seeds when conditions are favorable.
Then, when conditions are less favorable, they
switch to the male sex role of producing pollen.
Apparently it requires less favorable conditions
to produce pollen than to produce fully devel¬
oped seeds. In this way, there is more pollen in
tough times so that some of it can reach the few
female plants that may be located in favorable,
but remote locations. Buffalograss, saltbush
(. Atriplex spp. ), and Jack-in-the-pulpit are exam¬
ples of this intriguing adaptive strategy. In the
buffalograss turfgrass industry, a sexually sta¬
ble, female-only form of Buffalograss is consid¬
ered so commercially important that a bumper
sticker slogan has even been proposed. The pro¬
posed slogan — “it’s 9 p.m. Do you know what
your brand of buffalograss is doing?”
Tall fescue
Turf-type tall fescue is a cool-season grass,
like the familiar Kentucky bluegrass. It has
essentially the same dark green color, but it is
much more shade tolerant. It is also more toler¬
ant of road salt and irrigation water with high
salt content. It competes with tree roots far bet¬
ter than Kentucky bluegrass, and it is doing
very well in the heat of southwestern desert
areas where Kentucky bluegrass won’t survive,
even with unlimited irrigation. There appear to
be no insect problems. The biggest difference,
however, may be how much less nitrogen it
needs. Grown with clover, it might never need
fertilizing, on many soils. In general, turf-type
tall fescue grows in a wider range of conditions
than Kentucky bluegrass. It appears able to use
more water, when it is available, but maintains
a completely satisfactory appearance with much
less water — savings of 30 percent to 50 percent
not uncommon. In fact, turf-type fescue has
been compared with a light on a dimmer type
switch, where growth can be turned up with
more water and more nitrogen, or turned down
with less water and nitrogen. Faster growth is
frequently desirable on athletic fields following
major events, but it is often not desirable on a
home lawn. Kentucky bluegrass, by contrast, is
more like a light on an ordinary switch. It either
grows full tilt, or it goes dormant. In many dry
western areas, Kentucky bluegrass will go
brown in as little as one day, while adjacent turf-
type tall fescue will gradually go less and less
green over 3 to 5 days, or even more. Turf-type
tall fescue is a bunch grass — meaning it does
not spread as Kentucky bluegrass does. This
means it does not invade adjacent gardens — no
need for sharp metal edging. Turf-type tall fes¬
cue is available as sod, or a lawn can be grown
very successfully from seed sown on site. It is
also easy to top-dress and overseed an existing
fescue lawn that needs some renovation.
Water-Smart Gardening™ at Denver Botanic Gardens:
The Laura Smith Porter Plains Garden
This unique recreation of several native The shortgrass prairie of the Plains Gar-
grasslands was thoroughly written up in Mown- den shows special promise for addressing urban
1 4 tain, Plain & Garden , Spring/Summer 1987. landscape needs.
Water-Smart Gardening™ at Denver Botanic Gardens:
The Water-Smart Garden
Lauren Springer
This sunny, south-facing bed showcases
over three hundred species and cultivars of
plants — shrubs, perennials, groundcovers, annu¬
als, biennials, succulents, herbs and bulbs — that
all thrive on little water. Some are well-known
favorites such as basket-of-gold, dianthus, laven¬
der, baby’s breath, blue flax and thyme. A large
number of native plants are included, with spe¬
cial emphasis on the genera Eriogonum and Pen-
stemon. Lastly, a host of recent newcomers to
Rocky Mountain horticulture are featured as
well as both western American natives and those
harking from other regions with similar sunny,
dry, cold-winter climates.
In designing this bed, I emphasized flow¬
ing, curved sweeps of plants whose colors, forms
and textures play off one another through the
months. The groupings needed to be large and
bold, not “cottage” and soft, to stand up to the
large structures and broad views that surround
this garden, yet by staying away from formal
shapes and lines, a less harsh feeling results.
Most drought-tolerant plants work best in infor¬
mal designs, for they tend to be softer-textured
and looser in look, which can appear unkempt
when pushed into a formal framework. I have
strong reservations about the majority of so-
called naturalistic water-conserving plantings.
In a non-naturalistic setting, their sparse spac¬
ing, with no cohesion of groups or contrast of tex¬
ture and color, results in a scruffy, undynamic,
Lauren Springer, through her delightful northern
Colorado flower garden, her book The Un¬
daunted Garden, and many marvelous
programs, is helping to make Rocky Mountain
flower gardening the envy of other regions.
and weak design. One needs to be exceptionally
conscious of contrasting shapes and textures as
well as colors, or a shapeless blob emerges.
I combine plants in seasonal spots of color
— as one grouping of several different blooming
species wanes, another takes center stage. This
way, during the growing season, there is always
something in flower, always something combin¬
ing and contrasting for interest. Winter holds
much visual interest as well: evergreen foliage in
varying muted tones forms a tapestry of texture
and form until the first blossoms of hundreds of
early bulbs once again start the color parade.
Color in this garden changes and pro¬
gresses not only over time but also over space.
As one walks along the planting, one moves
through a “planted rainbow.” Starting on the
east end, one enters an explosion of bright reds,
oranges, and yellows, cooled by blues and pur¬
ples. Harmonious yellow and blue lead into the
purples, magentas and pinks, softened by white
and silver. Pale yellow returns with lavender,
intensifies, and joins purple and finally blue at
the far west end for a bold finale. So, whether
one tends toward the bright, hot colors of the
spectrum or prefers the cooler, more restrained
pastels, there is a part of the garden to inspire.
The site is very hot, sloping south and sur¬
rounded by reflective and radiant concrete
walls, walks and light fixtures. While all the
plants selected are adapted to dry heat, intense
sunlight, and little water, they still vary in their
preferences regarding how much water and
nutrient level and texture of the soil. The planti¬
ng has been divided into three zones to accom¬
modate these differing needs.
The first zone, at the lowest level, encom¬
passes the plants between the walkway and the
south side of the path winding through the gar¬
den. This zone has the richest soil, heavily
amended with organic matter and fertilizer to
simulate the perfect garden loam. This area also
receives more irrigation than the others, but
still considerably less than the typical Kentucky
bluegrass lawn, annual bedding plants, or the
traditional delphinium, shasta daisy, lupine
require. The second, or middle zone, includes
plants on the north side of this path approxi¬
mately halfway to the evergreens at the back.
The soil is leaner here, with adequate nutrient
levels but little organic matter, and receives less
water. The top zone, with the poorest soil and
least irrigation, comprises the plants that reach
up to and between the large evergreens.
Some plants may grow in more than one
zone — these are adaptable enough to make their
home in more variable conditions, making them
highly tractable garden subjects. Some plants
may not grow well in any of the zones, flunking
out and then being removed — this garden is an
experiment, a trial of drought-tolerant plants in
a challenging site. As in all but the simplest gar¬
dens, there will be change over the years, as
young plants replace the older ones losing their
vigor, as promising new introductions replace
the more staid plants. But, throughout the
many changes, the Water-Smart Garden is
intended to show that gardening with less
water can be as full, rich, colorful and flower-
filled as the most over-irrigated cottage garden,
border, or annual bedding display, attractive to
butterfly, bee, hummingbird and human alike.
This page: The Water-Smart Garden
at Denver Botanic Gardens.
Water-Smart Gardening™ at Denver Botanic Gardens:
The Rock Alpine Garden
Panayoti Kelaidis
The Rock Alpine Garden at Denver Botan¬
ic Gardens unofficially celebrated its fifteenth
year of existence this past summer (it was prac¬
tically all constructed in the summer of 1979,
although plantings were only begun in earnest
the summer of 1980). It’s hard to believe that
much of the grounds at DBG were fallow back
then — not exactly fallow — quite a few had
world-class clumps of Canada thistle, ragweed
and veritable Guinness-Book-class clumps of
bindweed. I remember how surprised I was that
nothing was mulched. There were virtually no
perennial plantings anywhere on the grounds at
that time, excepting for thick clumps of daffodils
along the conservatory wall (long gone) and of
course the wonderful Herb Garden which was
then, as now, one of our best and best-main¬
tained gardens. Can you imagine Denver Botan¬
ic Gardens with no perennial borders, no
xeriscape, no plains garden and hardly any
water lilies? We have grown so quickly and so
well that we never seem to take a breather to
look back, and give ourselves a well-deserved
pat on the back.
Not only were there few perennials at
Denver Botanic Gardens, but most local nurs¬
eries had only the smallest selection of the com¬
monest sorts. I described elsewhere, the exhila¬
rating, delightful process we underwent to
Panayoti Kelaidis, curator of the Denver Botan¬
ic Gardens' Rock Alpine Garden, is sometimes
known as "Mr. Ice Plant," for his introductions of
numerous wonderful plants from South Africa
and other semi-arid climates around the world.
Panayoti is greatly appreciated for his infec¬
tious enthusiasm in pioneering our own new
1 8 Rocky Mountain horticulture and design.
obtain seed, cuttings, plants from the leading
local gardeners, then by mail order and finally,
in desperation, by flying here and there. Planti¬
ng an acre of fluffy soil, filled with weed seed,
with tiny plants that don’t even get very big is a
daunting task, I can assure you. In retrospect I
wish we’d experimented more with pre-emer-
gents. I wish the scree and moraine mounds had
been thickly mulched with stone chips from the
start — these not only keep the roots of the high
alpines cooler, they seem to slow the germina¬
tion of weed seed substantially.
Mumbling and grumbling aside, I think
it’s appropriate at this point to sit down and
make some preliminary assessments and obser¬
vations about some of the artistic and botanical
lessons the Rock Alpine Garden has taught us.
Diversity in Terrain
No style of garden epitomizes diversity so
elegantly as a rock garden. First, there is diver¬
sity of habitat — berms and rocks provide a
dizzying variety of niches so that gesneriads
from the Pyrenees ( Ramonda myconi ) needing a
shady, cool crevice can grow just a few feet away
from a high mountain agave from New Mexico
{Agave neomexicana). Rather than creating a
uniform “chocolate cake soil,” as in vegetable or
perennial gardens, rock gardens can be
designed to cater to desert plants, woodlanders,
as well as alpines. Many habitats exist in the
world’s high places, and most are represented in
the laboratory of biodiversity we call the Rock
Alpine Garden.
By incorporating a rock garden in a home
setting, imaginative gardeners are freed from
the constraints and dullness of flat places.
Berms and rocks can be used to mask unattrac¬
tive features, add a focal point near a patio and
just generally rise to a new level of drama and
interest.
Year-round Garden
Many visitors to Colorado comment on
how sterile and uninteresting so many of our
landscapes are much of the calendar year. I sug¬
gest they come first to the Rock Alpine Garden
any time of year, whether there’s snow down
there or not. Such a tremendous wealth of ever¬
green and silver ground covers, shrubs trees
and perennials are available to grow in our cli¬
mate that I have placed greater emphasis on the
pleasing combination and textures of foliage in
this garden than mere, fleeting bloom color.
Even the longest-blooming annual usually lasts
only a few months in our climate — a tiny frac¬
tion of the gardening year. But well over half the
nearly 4,000 plants in the Rock Alpine garden
have beautiful year-round effect.
Most alpines start to bloom much earlier
in the year than do conventional perennials. On
occasion we have kept phenological data on this
garden: by May, when most Colorado gardens
are yet to be planted, there are so many hun¬
dreds of kinds of alpines in bloom we invariably
toss our notebooks up in despair. When I
returned from Africa this past January, I was
stunned to find several dozen kinds of plants —
hellebores, heathers and snowdrops to be sure,
but also cyclamen, eranthis, crocuses, drabas
and a good many more — in full, glorious bloom
in midwinter.
Western and Southwestern
North American Center
Plants native to Colorado form an impor¬
tant core to the Rock Alpine Garden. We find we
must plant Colorado columbines a number of
places around the garden to satisfy that most
common question, “Do you have your state
flower?” Agastache barberi, A. rupestris, Arc-
tostaphylos patula, most eriogonums aside from
E. umbellatum, Melampodium cinereum, Pen-
stemon strictus ‘Bandera, Penstemon digitalis
‘Husker Red’, Verbena canadensis, Zinnia gran-
diflora, and many more nursery classics had
their public garden debut in the Rock Alpine
Garden — at least as far as the Rocky Mountain
region is concerned. Once their utility is proved
here, they are planted elsewhere on the
grounds, and often feature at Denver Botanic
Garden’s annual plant sale a year or two before
spreading into the local and national trade.
Eurasian Semi-arid Climates
Next to our native flora, the area that
seems to have produced the greatest number of
durable, showy garden plants is the vast belt of
hot-summer, cold-winter climates that stretch
from Spain and Morocco in the West all the way
to China in the East. It is no secret that many
Mediterranean plants possess great adaptabili¬
ty — since these form the core of herb garden flo¬
ras. But countless ornamentals from higher and
drier plateaux have largely been overlooked by
gardeners, because they are absent from the
cold, wet gardens of northwest Europe and the
steamy eastern American states.
From Spain we introduced a deep orange
foxglove with evergreen leaves ( Digitalis obscu-
ra) and a variety of sea thrifts. Morocco has pro¬
vided the long-blooming Atlas daisy ( Anacyclus
pyrethrum var. depressus ), Greece an Turkey
have produced an extraordinary variety of orna¬
mentals in many of the same families as are in
the Herb Garden, mints such as the giant yel¬
low Jerusalem sage ( Phlomis russelliana),
thymes and germanders. Much of the summer
garden is enhanced with showy bellflowers,
from the Mediterranean, but the genus that has
stepped to the forefront from this region is
Veronica. Many local gardeners are growing
Veronica liwanensis and V. pectinata — two of the
showiest and most versatile new ground covers.
Both had their regional debut in the Rock
Alpine Garden.
Botanists have divided the Earth’s floristic
regions into a few dozen sections based on the
uniformity and close relationship of plants that
grow there. The largest such division is called
the Irano-Turanian province — the vast steppes
of Central Asia that stretch from Turkey to Chi¬
na. This stretch of nearly 4,000 miles of desert,
grassy plain and a thousand mountain ranges is
neatly dissected by the ancient Silk Route.
Remote, romantic cities such as Ferghana and
Samarkand lie in its heart. Much of this region
is subjected to great summer heat and drought,
as well as searing cold in the winter — a close
climatic parallel to the western United States.
It’s hardly surprising that it has become a trea¬
sure trove of beautiful ornamentals — many of
which have the added bonus of resisting our
native insect pests. The best know exports are
bulbs — especially the bulbous irises and dozens
of species of tulips such as “waterlilies” ( Tulipa
kaufmannia) and ‘Red Emperor’ ( T. fosteriana
Red Emperor’). A genus that was virtually
unknown in horticulture prior to the Rock
Alpine Garden’s development was Acan-
tholimon (prickly thrifts). There are over a hun¬
dred species of these, practically restricted to
the Irano-Turanian region. We grow nearly
twenty of these in this garden — every one of
which has outstanding ornamental merit.
Southern Hemisphere Steppe Plants
Perhaps the greatest excitement the Rock
Alpine Garden has caused is the awareness of
the genetic resources available to our gardens
from the Southern Hemisphere. In 1980, the
only plants from this region grown in local gar¬
dens were hybrid kniphofias. Today we are
experimenting with hundreds of species of
South African succulents, shrubs, bulbs, and a
whole spate of long-blooming, stunningly beauti¬
ful herbaceous perennials. What would our gar¬
dens look like without the hardy yellow and pur¬
ple ice plants? Diascias first made their appear¬
ance in the Rock Alpine Garden in 1982. But
early in this garden’s history I would have never
dreamed that two of our greatest introductions
would turn out to be long-lived, perennial Gaza-
nia krebsiana and a “freeway daisy” Osteosper-
mum jucundum.
We have barely touched the high dry hills
of Patagonia in South America, but the “astro¬
turf plant,” Bolax glebaria, is already a main¬
stay of local gardens. A number of calceolarias
and calandrinias are appearing locally. There
are sure to be many more plants from this
region.
And finally, even New Zealand has con¬
tributed to local gardens. The Canterbury
Plains in the South Island are both winter-cold
and summer-hot. They have contributed three
vigorous ornamental groundcovers to Colorado
Gardens, Roulia australis — a silver scab plant,
Cotula potentillina — a ground-covering daisy
relative, and several hebes, such as Hebe X
youngii, with lustrous evergreen leaves and
purple flowers.
The dramatic structure of a rock garden is
such that plants can mingle informally on its
slopes, allowing for a greater freedom of expres¬
sion and experimentation. There is no doubt
that many more stunning, durable, and unique
plants will find their way to our gardens from
the slopes and berms of the Rock Alpine Garden.
Left: The Nature
Center Garden at
Chatfield Arbore¬
tum — a water-
conserving garden
designed to attract
hummingbirds and
butterflies while
discouraging deer
browsing.
20
Left: The Visitor Center
Garden at Chatfield
Arboretum — a Colorado
native plant garden.
Bottom: The Laura Smith
Porter Plains Garden at
Denver Botanic Gardens
illustrating shortgrass prairie.
■>
i
\
l
- -
Water-Smart Gardening™ at Denver Botanic Gardens:
The Xeriscape Demonstration Garden
A Display of Native Habitat Communities
Gayle Weinstein
Somewhere between the traditional and
natural landscape lies the Xeriscape Demon¬
stration Garden at Denver Botanic Gardens
(DBG). I first conceived the idea for this garden
after attending a dedication of a Xeriscape Gar¬
den at the Denver Water Department. What a
great and timely idea — perhaps we (DBG) could
develop a display of this type in conjunction
with the Water Department. After approaching
and receiving a “go ahead” with the idea from
Merle Moore, Executive Director at that time, I
soon made contact with Ken Ball, Conservation
Officer for the Denver Water Department. He
was equally enthusiastic.
Ken and I felt this garden should demon¬
strate water conservation in the landscape.
However, we also wanted to represent a portion
our western heritage with a design based on
natural plant communities and associations.
This garden would illustrate practical issues of
gardening in dry lands as well as abstract the
essence of arid and semi-arid ecosystems.
Once this philosophy was developed, I
began to lay out design possibilities by research¬
ing photographs of semi-arid and arid regions
Gayle Weinstein designed many of the Denver
Botanic Gardens plantings, including the cut¬
ting garden, the Xeriscape Demonstration Gar¬
den, and the gardens around the Waring
House. She also reorganized the Scripture Gar¬
den and the Laura Smith Porter Plains Garden.
Gayle is now director of education at Bern-
heim Arboretum and Research Forest in Ken¬
tucky, and teaches courses in plant identifica¬
tion and planting design for the landscape
architecture program at the University of Col-
22 orado in Denver.
such as the eastern prairies of Colorado, Nebras¬
ka, and Wyoming, the Colorado Plateau in Col¬
orado, Utah and Arizona, and the Sonora, Great
Basin and Mojave deserts. I also read through
garden and nature periodicals as well as exam¬
ined a variety of books on arid ecosystems.
Selecting models of ecosystems of dryland com¬
munities and geographic areas was difficult
because there were so many from which to
choose. After considerable thought, southern Col¬
orado was chosen as a model for the arid plains.
Many plants for this area in the Xeriscape
Demonstration Garden were collected off Inter¬
state-25, such as James’s frakenia ( Frankenia
jamesii), a compact dwarf shrub that to my
knowledge had not been in cultivation. We went
to the site several times to collect viable seed and
cuttings to no avail, forcing us to dig and trans¬
plant shrubs from the site. This was a difficult
task because the soil was so dry and loose. How¬
ever, a few plants managed to survive. We were
very successful in our collections of many colorful
herbaceous perennials from this area like
Wright’s verbena ( Verbena wrightii ) and Black-
foot daisy ( Melampodium leucanthum).
The desert community on the west side
was patterned after the area near Carlsbad ,
New Mexico. With help from the Colorado Cac¬
tus Society we were able to acquire a variety of
hardy cacti that would, otherwise, have been
difficult to find. Although plants such as little-
leaf sumac (Rhus microphylla), Fremont’s
mahonia ( Mahonia fremontii) and desert peach
( Prunus andersonii) were experimental, they
did remarkably well.
The idea for the open woodlands, or pygmy
forest, was taken from Colorado National Monu-
ment and other places in the Colorado Plateau.
Even the path mimicked the sandstone dry
stream. Utah juniper ( Juniper us osteosperma )
and pihon pine ( Pinus edulis) commanded the
woodland setting along with random plantings of
penstemons, eriogonums, and evening primros¬
es. Wildflowers such as Baker’s paper flower
(. Psilostrophe bakeri) and blanket flower ( Gaillar -
dia pinnatifolia), found their own niches growing
in places other than where we planted them.
The eastern side of the garden was plant¬
ed with “soft” and “hard” chaparral. “Soft” chap¬
arral consisted of artemisias along with
roundleaf buffaloberry ( Shepherdia rotundifo-
lia). an experimental plant that did surprisingly
well. “Hard” chaparral included Arctostaphyllos
patula, A. nevadensis and various mountain
mahogany ( Cercocarpus spp. ) as found on the
Uncompahgre Plateau in western Colorado.
The savanna or parkland community, sim¬
ulating Colorado foothills and intermountain
valleys of California, was carpeted with blue
grama (Bouteloua gracilis ) and other grasses
intermixed with various wildflowers such as epi-
lobiums, rudbeckias, and penstemons. I tried
some live oaks such as southern live oak ( Quer -
cus virginiana) and canyon live oak ( Q .
chrysolepsis), however, few survived.
Because the Laura Smith Porter Plains
Garden, adjacent to the Xeriscape Demonstra¬
tion Garden, included eight different grassland
ecosystems, there was no need to represent the
short or midgrass prairies in the Xeriscape
Demonstration Garden.
After spending evenings drawing the plan
to unify the selected plant communities, Merle
Moore and Ken Ball critiqued it for improve¬
ments. Soon after, the design and budget were
presented to our respective boards, and in a
matter of weeks this new garden was funded by <
the Johnson Foundation and the Denver Water
Department. Without delay, we began to create
the garden. Ken and I went to rock quarries to
select appropriate boulders for the framework.
We methodically numbered boulders on the plan
with those at the quarry, facilitating the rock
placement once on site. In the meantime, Bill
O’Hayre, a talented gardener at DBG shaped
the earth, creating various topographic features
including the mesa, hillside, and plains.
After the final selection of plants for each
community, the garden contained over 350
species. Finding the plants was a real challenge.
Since many native and dryland species were
unavailable through commercial means, we had
to seek them out ourselves. With the help of
staff, volunteers, and plant societies, we collect¬
ed seeds, propagules and plants from the wild,
from plant experiment stations, mail-order
nurseries and native plant organizations. The
Xeriscape Demonstration Garden was begin¬
ning to house numerous botanical and cultural
treasures. Not only did many of these plants
emerge as potential material for landscape use,
they also encouraged public awareness of
species that grow with minimal water and care.
Some plants such as golden columbine
(Aquilegia chrysantha), littleleaf sumac ( Rhus
microphylla), and squaw apple ( Peraphyllum
ramosissimum) established quickly and grew
well. Others like huckleberry oak ( Quercus vac-
ciniifolia) and evergreen chinkapin ( Castanopsis
sempervirens now Chrysolepis sempervirens )
were sluggish and barely grew. Some plants
died within a short period of time, others myste¬
riously disappeared. Today, the Xeriscape
Demonstration Garden is unique in depicting
major types of dryland vegetation in natural
plant communities. Although the areas illustrat¬
ed in the garden are not exact reproductions,
they give the appearance and texture of the dry¬
land gardens more suitable to arid- and semi-
arid regions.
23
This page: Tallgrass
meadow at
Denver Botanic
Gardens.
Below left:
Indian grass
(Sorghastrum
nutans).
Below right:
Maximilian’s
sunflower
( Helianthus
maximilianit).
Opposite left:
Midgrass meadow,
blue sage, and
blue flax.
Opposite right:
Shortgrass
meadow,
chocolate flower,
and poppy
mallow.
Water-Smart Gardening™ at Denver Botanic Gardens:
The Nature Center Garden
A Waterwise Wildlife Garden
Jim Knopf
Speak of wildlife and gardening to a group
of people, and half will immediately imagine
beautiful butterflies, cute little hummingbirds
and sunny “Chamber of Commerce “weather,
while the other half visualizes rakish, raffish,
rambunctious raccoons, and demonic deer in
their roses or smelly skunks under a deck.
Though the combination of wildlife and
gardening raises mixed emotions, it turns out
that putting together waterwise (Xeriscape) gar¬
dening and wildlife gardening is a story of sur¬
prising serendipity. By zoning a landscape into
dry, medium, and wet areas, for example, not
only can lots of water be saved, but delightful
diversity automatically results, and diversity is
one of the key principles in successful wildlife
gardening. Deer browsing, for example, drops
off dramatically when a plant like creeping
mahonia ( Mahonia repens) is not irrigated. So, if
you want to discourage deer damage but still be
able to enjoy watching them, plant this or many
other plants, in your dry zones. Diversity in
plantings is also a primary principle for increas¬
ing the variety of wildlife in a small garden.
Waterwise wildlife gardening is a subject
that is fascinating, frustrating, fun and even
funny. It provokes thoughts about the role of
native, near-native and introduced plants. It
26 unveils our botanical bigotry — is biodiversity
always good? — and how native is native
enough? It involves the perplexing and promis¬
ing world of pollination biology. Why, for exam¬
ple, do some flowers insist on attracting hum¬
mingbirds and repelling crawling critters, while
other plants couldn’t care less?
Waterwise gardening is a journey on
which, “you’ll win for awhile, but never forever.”
It’s about being involved. It’s about connecting
with nature, right at home. It teaches that gar¬
dening is best when thought of as something to
do rather than to be done with, and it can save
lots of water.
With all of this in mind, two old farmhous¬
es at Chatfield Arboretum have been land¬
scaped to illustrate attractive, waterwise
wildlife gardens, as they could be done in ordi¬
nary suburban situations. The traditional-look¬
ing lawns are turf-type tall fescue, requiring
much less irrigation than Kentucky bluegrass.
The garden area near the houses and along the
front fence are dry zones, which get a little extra
water by being near the lawn. The plantings in
the parking lot are totally dry. The plantings
have been selected to attract an array of
wildlife, including birds and butterflies, while
discouraging damage from deer and other cun¬
ning critters.
Water-Smart Gardening™ at Denver Botanic Gardens:
Xeriscape & Wildlife
Gardening Principles
The Seven Water-Saving
Xeriscape Principles
Illustrated at Chatfield Arboretum
1. Plan & design comprehensively from
the start.
2. Create practical turf areas of
manageable sizes, shapes and
appropriate grasses.
3. Use appropriate plants and zone
the landscape according to the water
needs of the plants.
4. Consider improving the soil with
organic matter like compost or manure.
5. Consider mulches like wood chips.
6. Irrigate efficiently with properly
designed systems (including hose-end
equipment) and by applying the right
amount of water at the right time.
7. Maintain the landscape
appropriately by mowing, pruning and
fertilizing properly. ^ ^
The Four Wildlife Gardening Principles
Illustrated at the Chatfield Arboretum
Nature Center Garden
1. Think locally when planning and
designing your yard:
A. Note the assets and limitations of
your yard.
B. List species you want to attract.
C. List species you do not want to
attract.
D. Note associations you want
(predator/prey, pollination, etc.).
2. Provide basic wildlife habitat
needs consistently:
A. Food.
B. Water.
C. Shelter.
D. Protection from environmental
dangers.
E. Habitat diversity.
F. Effective habitat arrangement.
G. Consistent, year-round
provisions.
3. Be Prepared for wildlife mischief
management:
A. Be creative - Problems often
become opportunities.
B. Be persistent - It never ends, you’ll
win for awhile, but never forever.
4. Encourage curiosity and respect:
A. Explore wildlife photography.
B. Explore wildlife drawing.
C. Develop and compare wildlife lists.
D. Try to visualize the garden as the
critters see it.
27
Water-Smart Gardening™ at Denver Botanic Gardens:
The Visitor Center Garden
A Colorado Native Plant Garden
Marcia Tatroe
Chris Hartung, horticulturist at Chatfield
Arboretum, called early in the summer of 1992
to ask if I might be interested in helping develop
a Colorado native plant garden for the front of
Chatfield’s historic school house. I thought it
sounded like a great idea — that is, until he casu¬
ally added that the garden needed to be finished
and flourishing in only six weeks, to be featured
at an upcoming arboretum function. Given so
little time, this didn’t seem to me to be even
remotely feasible. Still, he wanted to try. So, we
scheduled a plant buying trip for the following
week, and Chris started to prepare the site.
Surrounded by concrete on all sides, the
garden is 12 feet by 120 feet, and slopes gently
away from the schoolhouse towards the south¬
west. No trees or buildings shade this location
at any time of day and so the soil here really
bakes. The existing soil was the typical clay and
gravel subsoil fill that most homeowners
encounter when they start a new garden. How¬
ever, Chris has a piece of equipment that the
average homeowner does not. Since Chatfield is
an operating farm, he has a tractor which he
used to make light work of the drudgery usually
associated with soil amending. He removed
approximately half of the soil and replaced it
with an equal amount of compost. Then, by
hand and machine, he thoroughly dug the com-
Marcia Tatroe is a globetrotting gardener who
has said that gardening in Colorado is much
better than in England! She's also said, "If there
is a plant on the moon. I'll want it." Her garden
filis the entire front yard and most of her back-
28 yard, much to the amazement of her neighbors.
post in to a depth of one to three feet. We were a
little concerned that this mixture might be too
rich for xeric plants, but on the other hand,
drainage was now excellent.
Joined by a couple of intrepid volunteers,
we met on a hot Saturday in July to assemble
the garden. First, we positioned a dozen or so
boulders somewhat randomly throughout the
area to give the garden “bones.” Then we placed
the shrubs in groups along the spine of the hill¬
side as well as tucking a few here and there
among the rocks. Finally, we planted the flowers
and grasses densely in drifts to fill in all of the
remaining spaces. We gave some thought to tex¬
ture, bloom color and bloom season when
arranging the plants, but there was more plant
tossing than careful placement.
Thankfully, my original fears turned out
to be completely unfounded — the garden was in
full bloom in a month’s time. Natives of really
extreme climates will often rush into growth in
this way to take advantage of what might be
only temporarily suitable conditions.
Most of these plants were initially very
small, so for the first few weeks Chris watered
often and heavily. Since then, he has watered
only when he can find the time, more frequently
in the spring, after adding new transplants to
the garden, but generally no more than once a
month in summer. Weeds and gophers continue
to be his most persistent challenges. Weeds are
hand-pulled but gophers aren’t so easily dis¬
patched. Chris says he often feels like the char¬
acter in the movie “Caddyshack,” who like him¬
self, declares war on a gopher and loses —
soundly!
Plants in the Xeriscape Demonstration Garden at DBG can create attractive natural landscapes like this.
While some of the plants did not survive
that first winter, the resulting gaps allowed
Chris the opportunity to try some new things
the following season.
Meanwhile, the shrubs have matured and
became a more dominant feature in the planti¬
ng. Fembush ( Chamaebatiaria millefolium),
leadplant ( Amorpha canescens), snakeweed
(' Gutierrezia sarothrae), rock spirea ( Holodiscus
dumosus ), winterfat ( Ceratoides lanata), and big
western sage ( Artemisia tridentata ) all provide
structure and year-round interest. Many of the
penstemons, while performing very well for one
or two seasons, were not long-lived. Perhaps the
soil mix was too fertile for some of these after
all. But, large clumps of stately red Penstemon
rostriflorus (now P. bridgesii ) are still thriving,
and fiery-orange P pinifolius set the bed ablaze
in mid-summer. Tough, blue P strictus and mat¬
forming P fruticosus have persisted as well. The
groundcover pussytoes ( Antennarea parvifolia)
has spread enthusiastically, as has the short¬
lived but freely self-sowing yellow daisy, Theles-
perma ambiguum. Purple coneflower (Echi¬
nacea purpuera ), Missouri evening primrose
(i Oenothera missouriensis), Zinnia grandiflora,
goldenrod ( Solidago sparsiflora ) and chocolate
flower ( Berlandiera lyrata ) all survive and pros¬
per from the original planting. Grasses — big
and little bluestem (Andropogon gerardii and A.
scoparius, syn. Schizachyrium scoparium), Indi¬
an rice grass ( Oryzopsis hymenoides ) and blue
grama ( Bouteloua gracilis) — soften the brash¬
ness of the mostly red and yellow color palette
and also lend an aspect of authenticity to the
garden’s overall prairie style.
This garden demonstrates just a hint of
the potential that native shrubs and flower offer
the Colorado gardener. It is as full, lush and sat¬
isfying as any pampered English border. But,
more importantly, it better captures and reflects
our own regional character and charm. Further,
it does so with less work and water than would
a similar garden composed of more traditional
border flowers. For every maladapted import,
there is a native alternative better suited to our
unique climate and conditions. We simply need
to get into the habit of making more rational
plant choices. Like all successful gardens, the
Chatfield Visitor Center Garden is continually
changing and evolving — to really appreciate its
beauty, you’ll want to visit often. 29
Water-Smart Gardening™ at Denver Botanic Gardens:
Sample Plants Rated by Water Needs
Key to Water Requirements
High Watering Zones (H):
18 - 20 gals, added / sq. ft. / irrigation season
.5” added 3 times / week (when there is no rain)
30” +/- added / irrigation season
Typical turf: Kentucky bluegrass
Moderate Watering Zones (M):
10 +/- gals, added / sq. ft. / irrigation season
.75” added once / week (when there is no rain)
15” +/- added / irrigation season
Typical turf: Turf-type tall fescue
Low Watering Zones (L):
0-3 gals, added / sq. ft. / irrigation season
.5” added every other week
(only when very hot & dry)
4.5” +/- added / irrigation season
Typical turf: Buffalograss (as a lawn)
Notes:
Watering zone indications for plants in
these lists are intended to show preferred condi¬
tions. Many of the plants will grow with either
more or less water, under some circumstances.
The amounts of irrigation indicated for
each watering zone are based on Denver Metro
area average conditions (full sun, level ground,
and soil with moderate clay content).
When (+/-) is shown with H, M, or L, it
indicates that the plant is adapted both to some¬
what more and less water. (?) indicates a best
guess, but more observation in landscape culti¬
vation is needed.
The Water-Smart Flower Garden
Ballota pseudodictamnus L
Callirhoe involucrata, Poppy mallow L
Digitalis lanata, Grecian foxglove L M
Marrubium rotundifolium L
Mirabilis multiflora, Wild four o’clock L
30 Senecio longilobus, Threadleaf groundsel L
The Rock Alpine Garden
Agastache rupestris L M
Anacyclus pyrethrum var. depressus
Atlas daisy M +/-
Bolax glebaria L M ?
Cotula potentillina,
syn. Leptinella potentillina L M ?
Gazania krebsiana L M ?
Osteospermum jucundum L M ?
Penstemon digitalis TTusker Red’ M
Phlomis russeliana, Jerusalem sage M +
Tulipa fosteriana L M
Veronica liwanensis L M
The Xeriscape Native Plant Garden
Mahonia fremontii, Fremont’s mahonia L
Peraphyllum ramosissimum, Squaw apple M +/-
Prunus andersonii, Desert peach L
Psilostrophe bakeri, Baker’s paperflower L
Rhus microphylla, Littleleaf sumac L
Shepherdia rotundifolia,
Roundleafbuffaloberry L
The Chatfield Arboretum
Nature Center Garden
Caryopteris x clandonensis, Bluemist spirea L
Chamaebatiaria millefolium, Fembush L
Chrysothamnus spp., Rabbitbrush L
Echinacea purpurea, Purple coneflower M
Helianthus maximilianii
Maximilian’s sunflower M
Salvia azurea, Blue, or pitcher sage L M
The Chatfield Arboretum
Visitor Center Garden
Andropogon gerardii, Big bluestem M +/-
Schzachyrium scoparium, syn.
Andropogon scoparius, Little bluestem L
Berlandiera lyrata, Chocolate flower L
Penstemon pinifolius, Pineleaf penstemon L M
P strictus, Rocky Mountain penstemon M
Zinnia grandiflora, Prairie zinnia L
Nifty Flowers for Nifty Rocky Mountain Landscapes:
The Perfect Perennial
for the American West
Bob Pennington
Imagine, if you will, the “perfect perenni¬
al.” More specifically, imagine the perfect peren¬
nial for the American West. Such a plant would
have to meet quite an array of criteria — to be
considered as a perfect plant such a perennial
must be able to withstand not only searing sum¬
mer heat and bitter winter cold, but also sum¬
mer nights that might be near freezing as well.
Such a plant ought to thrive at a wide range of
elevations and be able to cope with both intense
sunlight and more shaded areas. The perfect
plant would not be particular as to its soil
requirements and would be pest and disease-
free. The perfect plant would also have a long
blooming season, be easily propagated, and pos¬
sess an attractive and unique flower. No, this is
not “The Twilight Zone” — such plants do exist.
My nomination for the perfect perennial is
a curiosity in many ways. Although it is the
namesake genus of a family including many
well-known genera, it is itself little known or
grown. The Scrophulariaceae include such well-
known horticultural standards as snapdragons,
foxgloves, and of course, penstemons. But the
Scrophularia or “figwort” is rarely seen in gar¬
dens, and certainly not appreciated.
Several different members of the genus
Scrophularia have been suggested as the perfect
perennial. My submission is for Scrophularia
desertorum. S. desertorum naturally occurs
along the east slopes of the Sierra Nevadas, in
Bob Pennington, along with three generations of
his family, runs Agua Frio Nursery in Santa Fe,
New Mexico. This nursery is one of the mightiest
of the many marvelous "micro-nurseries" and
native plant centers of the great Southwest.
the Panamints and White Mountains of Califor¬
nia, and in several mountain ranges in Nevada.
Its altitude range is from 1,200 meters to 3,000
meters (4,000 feet to 9,800 feet), and it grows in
dry sagebrush and pinon-juniper communities,
often in crevices and among boulders.
The seed I collected was from plants grow¬
ing at the east foot of Sonora Pass in California.
Seedlings from this collection have been grown
in Santa Fe for three or four years, and we have
experienced no difficulty either in propagation
or in cultivation. At Agua Fria Nursery, the
plants are watered heavily every night, while in
my trial garden they survived one of the hottest
and driest summers in our history, 1994, with
no supplemental watering in July and August.
The source plants of my seed were growing
under the shade of ponderosas, while those in
my graden are subjected to the unrelenting sun
of our 7,000 foot elevation. I have yet to see
either insect or disease pests affect my plants.
S. desertorum attains an average height of
3 feet, blooms from early July until killing frost,
and has a unique flower both in form and color.
The shape of the corolla is described as “globu¬
lar, the throat not or only slightly constricted.”
To those familiar with the Saturday morning
cartoon, “Ghost Busters,” the flower bears a
haunting resemblance to the ghost “Slimer.” The
color is wrong, as the ghost is lime green and S.
desertorum is a velvety, dark cherry red. A few
white forms were also grown this season so pos¬
sibly other variations may exist as well.
Although to be scrofulous is to be morally
bankrupt, growing Scrophularia will materially
enrich the garden. 3 1
Nifty Flowers for Nifty Rocky Mountain Landscapes:
..-s'
. . •>»*///*»»♦
:iV- , "''/«.«••
..
•v. V*"-’
X %,.?
Floral Fantasies Fulfilled
Jim Knopf
It appears that the
, , “Holy Grail”
of native,
water-
wise, wildlife
plants has been
found. Growing at
7,000 to 8,000 feet,
in two remote
i . ,1:v-T. >v u, y ■ [s:jg southwestern
tjr- New Mexico
counties,
{''.(frill 'fw Mimbres
figwort
( Scrophularia
' Macrantha ) appears to ful¬
fill the long-standing floral fan¬
tasies of botanical “Holy Grail” hunters. Though
extremely limited in nature, in gardens it
thrives in sun, shade or in between. It also
thrives in wet, dry or intermediate conditions.
It does not appear to be finicky about soil type.
32 Deer don’t show any interest in munching it —
even in neighborhoods where deer outnumber
humans. Hawkmoth enthusiasts are almost cer¬
tain to be rewarded by sights of scroph-seeking
sphinx moths during the crepuscular hours.
Perhaps best of all, hummingbirds are highly
attracted by “ambrosia of scrophularia.” Mim¬
bres figwort is pretty and it is easy to propagate
from cuttings or from seed. It appears to be
totally hardy in the coldest Denver winters, and
would you believe ? ... it blooms from late
spring well into late fall. What more could be
asked? Alas, it has no fragrance.
Scrophularia desertorum and Scrophular¬
ia macrantha are nearly identical in appear¬
ance, except that S. macrantha has lovely pink¬
ish-red flowers while S. desertorum has flowers
ranging from all white to all red, but most being
two-tone (the upper part being reddish and the
lower part being whitish).
Drawing: Scrophularia desertorum is nearly
identical to Mimbres figwort except for the color
of the flowers.
Top & bottom left:
Mimbres figwort
( Scrophularia macranthd).
Hummingbirds love it,
deer don’t.
Bottom: Purple banner variety
of sawsepal penstemon
( Penstemon glaber
‘Purple banner ’).
Nifty Flowers for Nifty Rocky Mountain Landscapes:
Sawsepal Penstemon (Penstemon glaber)
Kelly D. Grummons
Intense blue flowers are such a treasure to
most gardeners. In our brilliant Rocky Moun¬
tain sunlight, pale blues can’t rival the tones
brought out in our yellow, orange and red flow¬
ers. But if the blue is bright enough, the flower
is considered a real gem.
Two years ago, while plant hunting in the
Bighorn Mountains of north-central Wyoming, I
was stunned with the vibrant beauty of
sawsepal penstemon ( Penstemon glaber ) on
roadsides. I recalled having seen the one-sided,
large- flowered, royal blue beardtongue as a
child on my grandmother’s ranch between the
towns of Dewey and Custer, South Dakota. With
further investigation, I did find it growing
sparsely at the ranch in the clay “redbeds.” On a
hunch, I followed the red clay vein about 15
miles northeast into Wyoming, a few miles east
of Newcastle, into an area local ranchers call
“the limestone.” Here the populations oi Penste¬
mon glaber were more abundant, dominating
steep roadcuts where very few other plant
species grew. They seemed to be a favorite of
summer-pasturing cattle. Fortunately for me,
they were most often out of reach of my bovine
competition.
P. glaber can be found in Montana,
North Dakota, Wyoming, South Dakota and
Nebraska. Claude Barr mentions it growing
Kelly D. Grummons is head grower at Paulino
Gardens in Denver. He received a B.S. in horti¬
culture at Colorado State University, and was
an intern at the Brooklyn Botanic Garden. He
grew up in the Black Hills of Wyoming, and has
34 a special passion for native prairie plants.
near Pueblo (Colorado?). The species is char¬
acterized by relatively large, glabrous (shiny),
deep-green leaves, 2 to 4 inches long and .75
to 1.5 inches wide. The leaves are usually
without a distinct petiole, simply wrapping
around the flower stem. The flowers range
from deep blue to purple blue with a lighter
throat and are usually about one inch long.
P glaber is often confused with the shorter-
lived but similar P alpinus which rarely
approaches P glaber in color intensity.
Hortculturally, P. glaber has many desir¬
able characteristics, primarily that it is blue and
secondarily that it is long-lived, for a penste¬
mon. Plants often form clumps up to one foot
across in the garden. Bloom time and duration
of bloom are valuable factors also — flowering
generally occurs throughout June and July. Sev¬
eral flowers occur from each point along the
flowering stem, one after the other, so that even
later, as the upper flowers are opening, lower
flowers are still emerging.
In Jewels of the Plains, author Claude
Barr mentions the longevity ofP glaber and
also that the flower color may be quite pale in
years of more rain. I find that in the garden it
should be grown with little or no water once
flower spikes begin their ascent, otherwise the
color is greatly washed out. Undoubtedly, this
species’ longevity, flowers, and great foliage will
make it valuable to the penstemon breeder.
The ultimate blue form ofP glaber — pend¬
ing further garden evaluation — may be ‘Dayton
blue’, found near Dayton, Wyoming. An incredi¬
bly robust, “grape juice purple” flowered plant
was found on the western side of the Big Homs
and is named ‘Purple Banner.” This plant
appears to be an interspecific hybrid. Whoever
said, “We don’t have enough color in the low-
water garden!”? Imagine these sapphires and
garnets among mounded pink marshmallowy
drifts of Oenothera speciosa or the white and
pink clouds of Penstemon ambiguusl
P glaber is easily propagated at home by
gently pulling offsets away from the mother
plant in fall or early spring. These offsets will
usually have a few roots and can be placed
directly in the garden — give them a little extra
water for a couple of weeks. Seed planted one-
quarter inch deep in a bed prepared with a
small amount of compost in October will germi¬
nate readily in April and May. They can then be
transplanted in fall for a dazzling summer show.
In the greenhouse, medium to soft cuttings root
easily in peat and perlite with gentle bottom
heat. Shade the cuttings lightly with cloth for a
week or two until the leaves remain turgid.
Avoid using a mist system and control fungus
gnats because their feeding larvae are lethal to
the callus tissue.
P glaber is not readily available at local
nurseries at this time but should be in a year or
two. Seed may be available through the Ameri¬
can Penstemon Society in their seed exchange
(to members only).
35
Nifty Flowers for Nifty Rocky Mountain Landscapes:
Weeds We Like
Mikl Browner
When my wife and I moved out of Boulder
a couple miles into the open prairie with no
trees to break the wind or for shade, we were
shocked at how many plants died. In the mid¬
west where we had grown up, plants, given rea¬
sonable care, lived. However, here my beloved
trilliums turned to dust before my eyes and Lin¬
da’s foxgloves never bloomed. Certainly we had
lessons to learn about watering, soil-building
and micro-climates, but it was obvious that one
of our biggest problems was our choice of plants.
When I was in the Peace Corps in India,
I often ran into predicaments with no apparent
solutions; and I learned to follow the natives
and imitate them even if it seemed foolish. In
our new frontier world, Linda and I learned to
imitate not only the successes of Panayoti
Kelaidis, Jim Knopf and others, but also the
successes of plants in the vacant ten-acre lot
adjacent to us. What appeared at first to be a
barren lot with short grass and some weeds
turned out to be quite a resource. Now, ten years
later, many of those “weeds” are hosted and
admired in our xeric garden.
One of my favorites is Tradescantia occi-
dentalis, the western spiderwort. I admit that
part of my love for it probably comes from the
resemblance of its bloom to the trillium’s, but
unlike the woodland trillium, whose three-
petaled blooms are nestled low against low
foliage, western spiderwort’s unusual purple-
blue three petals perch in clusters at ends of 16-
to 24-inch stems. The narrow blue-green grass¬
like leaves arch obliquely from the stem, con-
Mikl Browner, when not up a tree doing "horti-
culturally correct" professional pruning, runs
Harlequin's Market, an up-and-coming Boulder
36 nursery specializing in xeric and native plants.
trasting nicely in groups of shorter grasses like
blue avena, or stand out as a poised warrior
(spider) over a low ground cover. The May-June
flowers only last a day but are produced prolifi-
cally for two to three months, or until the
ground dries up. In the wild, it survives well in
full sun, but its appearance may be improved in
part shade. Unlike the more commonly avail¬
able Tradescantia X andersoniana and T. vir-
giniana, T. occidentalis is truly xeric, and
although it reseeds, it does not spread aggres¬
sively by rhizomes in a xeric garden. It’s true,
the flowers do fold up in the noon-day sun, and
after blooming, the plant may shrivel up or look
coarse; but I can shear it, or I can overlook these
undesirable traits as a true champion’s noble
defenses and can wait for its gold stamens
against purple petals in the next season.
Another great favorite of the neighborhood
(that is, the shortgrass prairie) is Penstemon
secundiflorus. The long, spoon-shaped blue-gray
leaves put up 10 to 16 inch leafed flower spikes
of lavender- violet beardtongues blooming in
May-June. This is a tough xerophytic plant,
needing no watering once established. Single
specimens are charming, but a spectacular mass
can be achieved by crushing the dried seed pods
over sandy ground. Don’t expect the flowers to
last all summer, but if you deadhead some of the
seed pods, the foliage looks cleaner and the
bluish color makes a great foil for lower flowers
like Phlox nana (Santa Fe phlox) or Callirhoe
involucrata (poppy mallow).
By the end of August when so many
plants have finished their blooming and many
other natives are dry and shriveled, Liatris
punctata (dotted gayfeather) is just coming
strong. By then its tufts of rough, very narrow
leaves have sent up thin, stiff-leafed flower
spikes 10 to 16 inches tall. These “feathers” of
lovely lavender-purple flowers continue bloom¬
ing for more than a month, sometimes till frost.
They are stunning, especially in large clumps.
Even in a dry year the energy stored up in its
long, thick taproot gives a good fall display. Full
sun and sandy-gravelly soil is its home, and no
additional watering is required once established.
These are just some of the beautiful
“weeds” that can be welcomed into a western
garden. A few more of my favorites are:
Oenothera hrachycarpa, the evening primrose
whose large yellow cups fade to burnt orange;
Verhascum hlattaria, the moth mullein having
yellow flowers with violet centers fluttering up
tall, thin spikes; the sand lily, (Leucocrinum
montanum ) whose six-petaled pure white flow¬
ers nestle against grassy foliage, and Gaillardia
aristata whose bold Indian blanket red and yel¬
low flowers enliven the dry summer.
In terms of a western garden aesthetic,
there are many fine foreigners that fit in well
here; but let’s not overlook the wealth of natives
which are both beautiful and (in the right spot)
sustainable. They are becoming more available
in nurseries, and if they are growing wild in
your neighborhood, don’t be too quick to pull an
unidentified “weed.”
Top left: Sidebells penstemon
( Penstemon secundiflorus ).
Bottom left: Pineleaf penstemon
( Penstemon pinifolius).
Above: A collection of penstemons
attractively used as a mass planting.
Nifty Flowers for Nifty Rocky Mountain Landscapes:
Penstemons to Star in
Your Waterwise Garden
Ellen Wilde
I first became aware of penstemons when
I moved to northern New Mexico almost twenty
years ago and saw these lovely scarlet tubes,
pendent from tall stems, everywhere, as I hiked
the mesas and ponderosa pine woodlands in the
summer and fall. I could not rest until I had
identified them as Penstemon barbatus. As a
gardener, I had to collect seed and try them;
they grew easily in my garden. I learned about
other penstemon species that grow in New Mex¬
ico, found them and also had success growing
them from seed. A friend, to whom I raved about
them, had heard of the American Penstemon
Society and sent me a membership; Penstema-
nia took hold! I learned from the Society that
there are over 250 species in all colors and sizes
and I have experimented with growing about
100 of them. Three-quarters of those have per¬
formed well in my unimproved clay-loam soil
with light mulch and very little supplementary
water. They endure temperatures as high as
100° F and as low as minus 40° F without snow
cover. Strong winds, hail, and extended periods
of drought don’t faze them. Species native to my
region even volunteer among the native grasses,
in the gravel paths, and where sand accumu¬
lates in the little swales and checkdams that I
build to stop runoff. What plant could be more
desirable for waterwise gardening? They are
beautiful in flower and also when not bloom-
Ellen Wilde ran the American Penstemon Soci¬
ety seed exchange for five years. She is active
in the New Mexico Native Plant Society, and is
on the board of the new Santa Fe Botanical
Garden. She loves learning about western
native plants, and her long-standing passion
38 for penstemons shows in her lovely garden.
ing — easy, never become a pest, and many
attract butterflies and hummingbirds.
I hope you will use them in your garden
and get started just as I did, by collecting seed
from those that grow in your area. Loosen a
patch of soil, top it with some coarse sand, sprin¬
kle on some gravel to keep birds from stealing
the seed and watch for the little seedlings to
appear in April. Transplant if you get too many;
they should not be crowed. A few species will
bloom in their first year, but most will bloom the
second year and for many years thereafter.
Most penstemon species of the Rocky
Mountain region do not do well in the typical
perennial border. Crowding, too rich soil and too
much water are fatal. Instead, use them in dif¬
ferent ways all around your property. Many
such as PP. palmeri, cardinalis, ambiguus,
clutei, and barbatus will make outstanding spec¬
imen plants beside a mailbox or at a comer of
the house. A rock garden will make a perfect
home for PR pinifolius, (scarlet and yellow),
virens, teucrioides, laricifolius, crandalii, alberti-
nus and linarioides. In a grassy meadow, the
tall erect spikes of PP virgatus and virgatus ssp.
asa-grayi look beautiful and don’t make basal
mats of leaves to crowd out the grass. P virens is
a small plant with wonderful short blue spikes
that is at its best under pines where it gets sun
only part of the day. P strictus, called Rocky
Mountain penstemon, has a basal mat of rich
green foliage which looks good all year. The roy¬
al purple flower spikes rise from it in May and
occasional ones appear through the summer.
The mat enlarges rapidly; this one could be
called a pest in some situations where increase
is undesirable. But how can anything so beauti
fill be called a pest? It will take some shade and
more water than most, if it has good drainage.
The majority of penstemons bloom in May and
June, but some such as P nitidus, bloom earlier
and some, such as PP. barbatus and rostriflorus
(formerly bridgesii), bloom later, extending the
season well into the fall. Penstemons and pen-
stemon seeds are available from many sources.
Seeds ripen about six to seven weeks after the
flowers are gone. They are in hard little tan
capsules that often need to be broken to release
the seeds. Sometimes the capsules release the
seed easily and these need to be collected before
they drop. The seed should be kept dry until
planted.
The American Penstemon Society (c/o Ann
Bartlett, 1569 South Holland Court, Lakewood,
Co. 80232) has a seed exchange with penstemon
seed from all over North America, in addition to
being the best source of information on penste¬
mons. The dues are only $10.00 per year. Com¬
mercial sources of seed are: Rocky Mountain
Rare Plants (P.O. Box 200483, Denver, Co.
80220-0483, catalog $1.00); Plants of the South¬
west (Rt. 6, Box 11A, Santa Fe, New Mexico
87501, catalog $3.50, price list free), North-
plan/Mountain Seed (P.O. Box 910, Moscow, Id.
83843, catalog $1.00); Alplains (32315 Pinecrest
Court, Kiowa Co. 80117, Catalog $1.00); North¬
west Native Seed (915 Davis PI S, Seattle. Wa.
98144, catalog $1.00). Catalogs contain much
useful information also, so send for several.
Many nurseries offer penstemon plants;
these should be considered if you can’t wait to
have some penstemons. Small plants in two-to-
four inch pots generally will need quite a bit of
coddling to be weaned from the potting mix in
which they are grown, and the frequent water¬
ing they receive in the nursery; they cannot be
considered drought tolerant their first year.
Plants in gallon containers have been weaned
and should establish well if the soil in the con¬
tainer is fairly similar to that in which you are
planting them.
Be waterwise and enjoy these colorful
western beauties! Before you know it, you too
will become a “penstemaniac”!
Authentic Aesthetics— Landscaping with Rocky Mountain Natives:
Native Landscaping for Many Reasons
Alison Peck
People have many reasons for their inter¬
est in native-plant landscaping. Some of us are
fascinated by native plants and want to sur¬
round our homes with them. We enjoy working
with native plants, discussing them — their
availability, how to propagate them, what is
“native”?, and how to create an environment
they will thrive in . . . all issues relating to the
plants themselves. Many of us who are interest¬
ed in native-plant landscaping are primarily
plant people. We may even consider native
plants with more interest and concern than we
give our human neighbors. The continued exis¬
tence of a healthy community of native plants is
important for a wide variety of reasons.
Some of us pursue native-plant landscap¬
ing because we love the beauty of this place and
wish to re-create some of that beauty in the
landscapes we live in. There is also resource
conservation: well-designed and well-created
native plant landscapes consume little or no
water, fertilizer or pesticides. And some of us
wish to provide homes for birds and insects that
we enjoy. While these are all goals often associ¬
ated with the use of native plants in landscap¬
ing, only the first goal requires the use of native
plants. As an experienced landscape designer, I
am confident that I could design and install a
landscape that looked “native” to many Front
Range citizens, which conserved resources and
Alison Peck, when not running Matrix Gardens
(a Boulder, Colorado landscape design and
construction business specializing in edible land¬
scapes, water and energy-efficient designs and
permaculture) spends time ruminating about
who gets the best of her edible landscapes . . .
40 aphids, deer, raccoons or maybe humans,
which provided wildlife habitat, without using
any native plants. But simply assembling a
landscape of native plants does not yield a
native landscape. By a native landscape, I mean
a landscape that appears , functions and evolves
as does a natural, indigenous landscape. I would
even venture to say that all of the plants and
animals inhabiting what is left of our native
wildlands benefit much more from the creation
of landscapes which function as native land¬
scapes, and which minimize disturbance and
destruction of natural areas, than from the pic¬
ture-perfect assemblies of native plants which
require artificial life support.
It is easy to overlook that a native land¬
scape, a landscape native to this place, is more
than an assembly of native plants. Those of us
interested in native-plant landscaping share
many questions and concerns with those people
working in the new field of ecological restora¬
tion. Ecological restoration has as its goal the
restoration of landscapes which have been dam¬
aged by human activity. There are many ques¬
tions that arise: how do we know what to
restore, and what is our measure of success?
What point in the history of the landscape do we
take as our goal? Are we striving to re-create a
landscape which is pre-human? How did the
indigenous people interact with and manage the
landscape? If we decide on our goal, how do we
re-create this particular landscape? Once the
landscape is re-created, do we want it to always
stay this way, or is it going to evolve into some¬
thing different? These questions may be more
far reaching, and have a wider scope, than the
questions most of us consider when we wish to
do native-plant landscaping, but I believe that
any of us who are interested in creating healthy,
self-sustaining native plant landscapes will
eventually approach these questions.
The inevitable conclusion that ecological
restorers have come to is that ecological restora¬
tion requires the re-establishment of native
plant and animal communities within the same
context which shaped the original landscape.
This context includes the soils, the hydrological
cycles, the energy and nutrient cycles; all of the
conditions and forces which contained the pre¬
disturbance landscape. Without this, what is
created will not function and evolve as the origi¬
nal landscape did. Clearly, a complete restora¬
tion is not possible in most situations because
we have lost too many of the pieces. A restored
riparian ecosystem must experience the periodic
flooding and hydrological cycles which created
it, or it will evolve into something else which
may no longer provide habitat to native plants
and animals. A prairie must be subject to graz¬
ing and fires. The more pieces which can be
included, the closer the restoration will be to the
original. These same questions and understand¬
ings can be applied to our discussion of native
plant landscaping. We can look beyond appear¬
ance to consider the conditions within which we
create a native landscape and how the land¬
scape functions.
How can we create landscapes which
resemble and function as native landscape? The
few simple ideas I have come across fall into two
general areas: looking at the conditions within
which the new landscape will be created, and
studying the existing and possible functions of
the landscape. These can be done by studying
the site within which you wish to help create a
new landscape; learning as much as possible
about the plants, animals, soils, climate and
people involved in the landscape and asking
what effect this new landscape will have on the
world. In studying the site, one can look at the
climate, water, energy and nutrient cycles, exist¬
ing plants and animals and anything else which
will effect how the new landscape is created,
how it is established and how it evolves. Some of
the questions to ask might be:
How does water circulate? Where does it
come into the landscape? Is it clean? What
are the pollutants? How will the landscape
Sand lily ( Leucocrinum montanum). An easily-grown
native unfortunately little known in the nursery trade.
get the water it needs? Will water need to be
imported? Where will it come from and how
will using it affect surrounding areas?
How does air move across the land? What
does it bring with it (weed seeds, sand, trash)?
Is it a drying wind? A cold or warm wind?
What is the existing soil? How is it differ¬
ent from the native undisturbed soil in which
the original native landscape grew? What
can be done to help re-create the soil in which
native plants thrive?
What plants are already growing on the
land? Will they be compatible with the plants
I wish to introduce: If not, how do I get rid of
them? How will my method of weed control
affect what grows in the future? How will it
affect surrounding life?
As we learn about the site and get a sense
of its cycles and patterns, we can begin to see
where particular plants and plant communities
may find a home. As we learn about where the
materials we use in landscaping come from, and
what the products of the landscape are, we can
find ways of landscaping that are minimally
destructive to the natural areas that do remain.
And perhaps we can help create landscapes
which enhance the beauty and vitality of the
natural world; landscapes which are native in
the sense that they inhabit and participate in
the local web of life. The fragmented patches of
native plant landscapes which we re-create in
our backyards will never provide habitat for
large native mammals, but perhaps they can
still be important in preserving the life which
supports us all. 41
Authentic Aesthetics— Landscaping with Rocky Mountain Natives:
Going “All the Way 99
Nancy Daniel
When going “all they way,” a landscape
that features native plants has one simple prin¬
ciple — your home should look and feel as if it
grew out of its natural environment. From the
outside it would seem as if no single element of
the original landscape had been destroyed.
Looking out the windows one would feel as if the
house had been there forever — at home in its
native surroundings.
Nature may appear to be random and
chaotic to some, but this should never discour¬
age you from accommodating her freewheeling
adventures in your yard. A native landscape
will inevitably change with time. Plan ahead
so these changes work to your advantage.
Plant seeds of flowers and grasses in colonies,
rather than prepackaged mixes everywhere.
Plant, too, for the optimal size and
growing habits of your plants, so that even
when the plants grow together, they won’t
impair your home’s walls, foundations or
plumbing. Then allow nature to take
over. The natural materials and plants of the
Rocky Mountain region offer a rich palette of
colors, shapes, forms and textures. When
used to design your environment and
answer your needs for open and closed
spaces, a native landscape will be an ever-
changing yet everlasting source of pleasure.
*
42
Nancy Daniel, landscape architect,
runs Native Landscapes, a landscape
design and construction business,
from a wonderful natural setting in
the pinon-juniper landscape of
Santa Fe, New Mexico,
Authentic Aesthetics — Landscaping with Rocky Mountain Natives:
For More Livable
Urban Surroundings
Susan Eubank
If we planted blue grama and buffalograss
in some urban areas and let the natural rainfall
determine their greenness, perhaps some of the
artificiality of the urban environment would
also disappear.
My personal choice for natives is based
primarily on aesthetics. As a country girl, forced
to live in a city, the natives in my garden bring
me closer to that rural environment I miss. I do
have non-natives in my garden — that too is
based primarily on aesthetics.
There has been a recent flurry of discus¬
sion in the popular horticulture press about the
use of natives as garden plants. It is heartening
to see recommendations for plants other than
the traditional English perennial border plants,
but the controversy surrounding the subject is
distressing to this particular plant lover. I quick¬
ly made my own comparison to xenophobia
when I read about how adamantly some people
advocated using only natives in home landscap¬
ing — Let’s not bring that fear into the current
debate about garden plants.
Some introduced plants are a problem for
the stability (purity) of the plant ecosystems
which they have invaded, but aliens like
tamarisk, Russian olive, and purple loosestrife
threaten whole habitats including the animal
populations which depend on the natives for
Susan Eubank, former associate librarian at
Denver Botanic Gardens, is now the librarian at
the American Alpine Club in Golden, Colorado.
Susan is also editor of Soximoniano, the
newsletter of the Rocky Mountain Chapter of
the North American Rock Garden Society.
food. Another reason to plant natives in our
yards is so the local animal populations (includ¬
ing bears and cougars?) will continue to have
some semblance of the habitat that existed prior
to contact with Europeans.
43
Below: An attractive water-conserving
mixture of native and introduced plants.
Right: Native, low-maintenance tallgrass meadow
at Denver Botanic Gardens.
Bottom: A reconstructed Pinon-Jumper landscape
creating an attractive, low-maintenance setting
for these adobe buildings in Santa Fe.
Opposite page: Purple coneflower < Echinacea
purpured). Native of tallgrass meadows.
Authentic Aesthetics— Landscaping with Rocky Mountain Natives:
When Is a Native “Native?”
John Lawyer
When considering the use of introduced
plants, consider the following questions:
1. Is the species potentially invasive,
whereby it becomes a weed?
2. Will the species disrupt, or will it main¬
tain the desired natural look?
3. Will the species be a host or carrier of
pests and diseases, and will it be resistant
to those which occur naturally?
4. Will it survive and serve the intended
purpose?
In response to the perennial question,
“What is a native plant?,” a better question
might be, “WHEN is a native native?” To illus¬
trate the problem, consider the case of dawn
redwood ( Metasequoia glyptostroboides), which
fossil records indicate was widespread in North
America and Asia from 23.7 to 1.6 million years
ago. Before the 1940’s it was thought to be
extinct. However, when a small grove was dis¬
covered alive and well in China the question
became . . .“should dawn redwood again be con¬
sidered a Rocky Mountain native plant?”
The ginkgo tree ( Ginkgo biloba) is another
example. Fossil records indicate that this tree
grew in western North America, Asia and
Europe from 208 to 144 million years ago. Gink¬
go State Park in eastern Washington was estab-
John Lawyer is president of Lawyer Nursery
(Plains, Montana, and Olympia, Washington) a
wholesale company providing a large selec¬
tion of seedlings, transplants and cutting-grown
nursery liners of native and naturalized trees
and shrubs to the wholesale nursery trade.
lished to protect fossils of ginkgo trees. Long
considered extinct, it is now considered to have
survived under natural conditions in Chekiang
province in China. It was returned to the United
States in 1784, and could again be considered a
Rocky Mountain native species.
“What is a native plant?” “How native is
native enough?” “When is a native plant really a
native plant?” Inevitably these questions will be
answered differently by different people, at dif¬
ferent times. Fortunately, there is room for a
variety of answers, and lively but tolerant dis¬
cussion is to be encouraged, keeping in mind
that, “always” and “never” should “seldom” be
taken too seriously, and all rules “probably”
have exceptions.
45
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A comprehensive dictionary of plants cultivated
in the United States and Canada.
Bowers, Janice Emily. 100 Roadside Wildflowers
of Southwest Woodlands. Tucson: Southwest
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Good color photos, very good selection of wild¬
flowers, and very interesting text.
Brockner, Sylvia B., Jeanne R. Janish, James N.
Borland. Native Plants of Genesee and How to
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Good color photos, helpful drawings, and infor¬
mative text.
Griffiths, Mark. The Royal Horticultural Society
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Timber Press, 1994.
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the latest system of nomenclature. More than
60,000 plants and more than 30,000 cultivars.
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Region. Boulder, Colorado: Johnson Books, 1991 .
A well-illustrated, comprehensive guide to water-
wise gardening, including detailed information
about the water needs of many garden plants.
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A complete and unusually helpful, thoroughly
illustrated book about realistic, showy flower
46 gardening in the “Cottage Garden” tradition.
Natural History
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of the Great Plains Grasslands & Hills. Minnea¬
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Benyus, Janine M. The Field Guide To Wildlife
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Farrar, Jon. Wildflowers of Nebraska & the Great
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Freeman, Craig C. and Eilleen K. Roadside
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Kindscher, Kelly. Edible Wildplants of the Prairie:
An Ethnobotanical Guide. Lawrence, Kansas:
University of Kansas, 1987,
A helpful guide to ethnobotanical information
about Great Plains plants.
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related human cultural history.
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Garden Philosophy & Environmental Issues
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range of horticulture topics.
Water-Smart Gardening™ is a trademark of Denver Botanic Gardens.
Front cover photo: The Water-Smart Garden at Denver Botanic Gardens designed by Lauren Springer.
Back cover photo: The Colorado Springs Xeriscape Demonstration Garden has rock walls and paving
that reflect the nearby redrock formations, and many hardy, attractive flowers.
Photo credits: All photos by Jim Knopf (except: Calceolaria biflora by Panayoti Kelaidis,
Penstemon pinifolius and penstemon collection by Ellen Wilde).
Illustrations throughout courtesy of the Water Resources Department of Colorado Springs, Colorado,
Shcreck Designs (except: Mimbres figwort and Tulip gentian by Jim Knopf).
Denver Botanic Gardens
909 York Street
Denver, CO 80206-3799
Non Profit Org.
U.S. Postage
PAID '
Permit No. 205
Denver, Colorado
Mountain, Plain and Garden Printed on recycled paper using soy-based inks
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