Perennials in your garden Agriculture Canada Publication 1754/E 630.4 C212 P 1754 1983 OOAg Canada ©Minister of Supply and Services Canada 1983 Available in Canada through Authorized Bookstore Agents and other bookstores or by mail from Canadian Government Publishing Centre Supply and Services Canada Ottawa, Canada, K1A 0S9 Catalogue No. A53 1754/1983E Canada: $2.95 ISBN 0-660-1 1334-1 Other countries: $3.55 Price subject to change without notice Canadian Cataloguing in Publication Data Cole, Trevor J. Perennials in your garden Issued also in French under title: Les fleurs vi- vaces de votre jardin. "This publication replaces publications 968, Des- criptive notes on herbaceous perennials for Cana- dian gardens, and 970, Growing herbaceous perenni- als, by R.W. Oliver." 1. Perennials. 2. Gardening. I. Canada. Agricul- ture Canada. II. Titfe. SB434.C6 i635.9'32 C83-097208-0 * ■ '■ " -- .- I Perennials in your garden Trevor J. Cole Research Station, Ottawa, Ontario This publication replaces publications 968, Descriptive notes on herbaceous perennials for Canadian gardens, and 970, Growing herbaceous perennials, by R.W. Oliver. § Canada § Egalement disponible en francais. CONTENTS Introduction/5 Planning/8 Location/ 8 Site preparation/ 8 Design/ 9 Hardiness/9 Culture/9 Planting/9 Care/ 12 Fertilizing/12 Watering/12 Staking/12 Transplanting/14 Propagation/ 15 Fall maintenance/ 17 Winter protection/17 Spring renovation/17 Pests and diseases/ 17 Recommended plants/19 Using plants/60 Plant societies/67 Key to scientific names/69 INTRODUCTION All plants that live for more than 2 years are perennials. A herbaceous perennial is technically a perennial that does not produce woody stems and that dies down to the ground each fall and overwinters in some form of resting crown. The botanist restricts his discussion of herbaceous perennials to plants that fit this definition. In the garden, however, the term has a much looser meaning and is used for any of the hundreds of overwintering plants suitable for growing in a perennial border. It includes bulbs, tubers, and rhizomes, as well as plants that do not die down to the ground each year. For the sake of simplicity, then, the term perennial is used in this publication, without the modifier herbaceous, to include all the kinds of perennials described above. Although certain perennials, particularly irises and peonies, have been culti- vated in the East for hundreds of years, perennial borders as we know them have their origins in the monasteries of medieval Europe. One of the functions of these monasteries was to heal the sick. To this end, they planted borders of plants known for their medicinal properties. Over the course of time, other plants came to be included for their decorative rather than their utilitarian value. From these early collections evolved the perennial borders that reached their peak of popularity around the turn of the last century. This formal perennial border was generally planted in front of a wall, fence, or hedge, which provided a backdrop. Scaled-down versions of this style still have a role in modern gardens. Following the Second World War, houses and lots became smaller. Formal perennial borders then fell from fashion and the concept of island beds began to gain popularity. Island beds are free-form plantings of perennials, situated in the lawn area without any backdrop. Any shape that complements the garden design can be used. Because they are viewed from all sides, plant supports are difficult to hide. Dwarf varieties and self-supporting plants suitable for island beds have therefore become popular. Present trends favor using perennials in mixed borders. Few people have room for a flower bed consisting solely of perennials. Now, clumps of perennials or individual perennial plants are being included in borders with shrubs, bulbs, and annual plantings. Figures 1 and 2 show plans for both a conventional border and an island bed suitable for a small garden. Because the availability of varieties is so variable, species are listed only by color and height. Any varieties available locally and fitting these descriptions can be used. • 2 -5 3 • .tov £ \ ti \ •a ^2 > ■c-1 *•"- \ CJ.O cj \ om • \ Q.O \ &-£ • 0 O- X°° \ — s\ O -* \ . > •5 E \ o o 42 N \ 1< • c • — ) o \ • > • CD -J o • \ ■a c / ~° s <° ■ — D. / -Q 8 « / > f£ > 1 X C/3 \ r- to • j to • O \ CM l uQ E_ 1 5i 1 -Si « >^ a Cb .^ T3 Cr S <= 'C "* ^ a • 3 XI > ■2 o to C ~ ) -*: C Q < _o • oo • ■6 • o3 to • is Oi< §i? 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Avoid low areas that collect cold air, because young shoots growing there are more likely to be injured by late spring frosts and the fall flowering period is curtailed in these areas. Also avoid planting close to trees, which compete for the available moisture and fertilizer. Site preparation Because perennials normally occupy the same site for several years, good preparation of the soil is essential before planting. When you are making a new bed in an area that was previously lawn, lift the sod before digging. Stack sod with the grass turned down for a year if you wish it to decompose quickly into good topsoil for topdressing the garden. Dig the area and carefully remove all perennial weeds. Quack grass (also known as couch, twitch, quitch, quick, and witch grass) and thistle are both so invasive that even a small piece of root left in the garden can give rise to a new colony. Once established in a clump of growing perennials, these weeds are almost impossible to remove. Therefore unless you know the area is free from these weeds, hand digging is preferable to mechanical cultivation. A rotary tiller merely chops these weeds into small pieces that propagate prolifically. On light soils work in as much humus as possible. Use compost, peatmoss, well-rotted manure, or leaf mold. On very sandy soils a topdressing of 10 cm deep is not excessive. By planning ahead, you can prepare the bed in the spring, green-manure during the summer, and plant in the fall or the following spring. Green-manuring is an inexpensive way to enrich the soil with humus. To green-manure, seed the bed in the spring with a quick-growing cover crop such as buckwheat, winter rye, mustard, or rape. Then dig the crop into the soil just as it flowers. Replace the nitrogen that is depleted from the soil during decomposition of the cover crop by adding 25 g of ammonium sulfate per square metre. When cowpeas, vetches, or clover is used as a cover crop, fertilizer is not needed because these plants have an association with bacteria that change nitrogen into a form that can be utilized by plants in nodules on their roots. In areas with a long growing season, three cover crops can be grown in 1 year. Improve clay soils by adding sand as well as humus. The problem with clay soils is poor drainage. Any material that opens the soil is beneficial. Use peatmoss only when no other form of humus is available, because it retains a lot of water. Design Whether you are making a large perennial border or simply using a few clumps of perennials in a mixed planting, planning is most important. Start your plans in the winter while other gardening chores are minimal. Consider first the availability of plants. Get a list of plants that will be available from your local nurseries in the spring. Unfortunately the choice is often limited and there are few nurseries in Canada specializing in perennials that are willing to ship plants. A list of societies that can advise you on where to order perennials is provided at the end of this publication. When planning your garden, keep in mind season of bloom, color, and height. Scatter plants flowering in the same season throughout the border. Separate flowers with similar or clashing colors, unless they bloom at different times. Do not hide small plants behind tall ones. Use tall plants to hide the bare spaces left when early-flowering plants, such as tulips, die down. Sketch your plan to scale onto squared paper. Use colored pencils to illustrate color balance, numbers to represent heights, and letters to indicate flowering times. Finally, decide how many plants are needed for each block. The distance left between upright-growing plants should be roughly half their eventual height. Leave even more room than this between the dwarf, spreading forms used at the front of the border. Large groups of a few perennials is more effective than smaller groupings of many perennials. A grouping of five or six plants is usually considered adequate. With the possible exception of peonies, avoid groupings of less than three. Hardiness The hardiness ratings assigned to trees and shrubs cannot be given to pe- rennials because they die down to soil level each winter. Hardiness of perennials therefore depends more on soil temperature, which is affected by snow cover, than on air temperature. An area that sustains a heavy snowfall can grow a much wider range of plants than one with similar minimum temperatures but lighter snowfall. Consult your local nurserymen and members of your nearest horticultural society for information on what perennials do well in your area. In areas that usually receive a good snow cover, a freak winter with little snow, or an unusual midwinter thaw, can lead to the loss of plants that are normally considered hardy. CULTURE Planting In regions of the country with mild winters, tall is the best time to plant. Soil is easier to work and fewer other gardening jobs need to be done in fall than during the growing season. In areas with harsh winters and little snow cover, however, fall planting is not advisable. In these areas new plants do not have time in fall to form a root system strong enough to withstand the severe frost heaving that commonly occurs in winter, and the young plants are thus subject to severe dessication in early spring. Where reliable snow cover is expected, planting can take place in early fall or in spring. Irises and peonies, however, need more time than most plants to anchor themselves in the soil before freeze-up. Plant irises as early in August as possible, and peonies in late August or about 8 weeks before hard frosts are expected. Many perennials are now sold in pots. To plant potted perennials, remove the pot and place the soil ball in the ground at the same level as it was in the pot (Fig. 3). When you are dividing your own plants or using divisions from friends, plant them with the dormant buds just below soil level. Plant peonies with the buds between 3 and 8 cm below ground level. Outside these limits, the plants grow but do not flower. The old tale about peonies taking 7 years to flower after being moved probably derived from planting them too deeply (Fig. 4). Irises should be planted with the thick rhizome, from which the roots grow, at soil level. The rhizome must be exposed to the sun to avoid rot. Plant it on a saddle of earth with the roots down either side (Fig. 5). Pack the soil firmly around the roots, leaving the rhizome exposed. _ ■■»■.. i - \Wi i * i^*- Wr Fig. 3. Plant pot-grown plants at soil level. 10 jiUzh^Cl1 Fig. 4. Peonies (Paeonia) must be planted at the correct depth to flower properly. \ o o o v o ra J * O J/o o O -° ^ •o • 0 O «^> /~\ Fig. 5. Plant irises on a ridge and at the correct depth. 11 Care During the growing season the chief battle is against weeds. When allowed to gain control, weeds reduce the growth of desirable plants or choke them out completely by competing for available water and nutrients. Hoeing is the best way to combat weeds. Use a Dutch or push hoe as soon as the weeds are a couple of centimetres tall and cut them off just below the ground. Be careful not to disturb the roots of the perennial plants, especially in areas where no perennials are visible. Some plants are late to appear and their shoots are just below the soil surface. Unless they are needed for drying, flower heads should be cut off as soon as the flowers fade. Removal of flowers prevents seed production, which generally improves flowering the next year. In some plants, especially delphiniums, remov- ing old flower heads may promote the formation of a second crop of flower spikes, which extends their season of value. Fertilizing Unless you have green-manured, new beds should be fertilized during con- struction using a general fertilizer such as 7-7-7 at 100 g/m2. Scatter the fertilizer over the surface and work it in during digging. Fertilize again in mid-June at half the above rate. Established borders need fertilizing in the early spring to boost the early growth of the plants. Sprinkle 7-7-7 or 6-9-6 round the plants at about 75 g/m2, taking care not to leave fertilizer granules on the young shoots. Alternatively, you can topdress the bed carefully with well-rotted manure. Fork the bed over lightly, to about half the depth of the tines, to work in the chemical fertilizer or the manure and to break up the winter crust on the soil surface. Watering In general, perennials are fairly drought resistant. However, in prolonged dry periods it is necessary to water. When irrigation is needed apply enough water each time to soak the soil deeply. You should aim at giving 3-5 cm of water. A few straight-sided containers can be scattered over the area to measure the amount of water applied. Sandy soils need watering more frequently than loams or clay soils. They also leach out the fertilizer more readily. Supplementary feeds can be applied during watering by using a soluble fertilizer concentrate and a diluter. When water for irrigation is not readily available in areas of low rainfall, grow plants adapted to dry conditions. Consult the list of plants suitable for growing under special conditions, given in the section "Using Plants". Staking Many modern varieties do not need staking under normal conditions, but the older, taller forms do require some form of support. 12 Fig. 6. Several stakes and criss-cross twine support plants well. w ^ v^ Fig. 7. Plants that have been allowed to flop over are difficult to tie up. Stake plants requiring support early in the season. The best supports are twiggy branches pushed into the ground around the perennial so that the plant can grow up through them. More commonly used are wooden stakes or bamboo canes and string. 13 In one-sided borders when only one stake is used, it should be placed behind the plant. However, better support is achieved when several stakes are used (Fig. 6). Always tie the plants early in the season. When plants are not tied up until after they have fallen over, they present a bunched appearance (Fig. 7) that is unnatural and unattractive. Transplanting Once the border is finally planted, some maintenance is still usually required every few seasons to keep the plants within bounds. Plants grow at different rates. Many clumps can be left 6 or 7 years without tending but others must be dug up and divided every 2 or 3 years to keep them from becoming too crowded. Occasionally you also need to divide a plant to replace another that has died. Lift plants in spring as soon as new growth can be seen, or transplant in early fall. When the clumps are not too large, you can break them apart by hand, but generally you need the help of a couple of garden forks. Place the forks back to back in the center of the clump. Then push the prongs down into the crown of the plant and pull on the handles to split the clump in half. Repeat as often as necessary to obtain pieces small enough to break apart by hand (Fig. 8). Replant small pieces with three or four old shoots taken from the outside of the plant. The center of the clump should be thrown out. One clump can yield 20 or more pieces suitable for replanting. : V *>f Iw^fe* * Fig. 8. The final stage of dividing a perennial. 14 Propagation The home gardener can propagate perennials by seed, from cuttings, or by division. In the section "Recommended plants" the best method for propagating each species is indicated by the letters s, c, or d. Seed Many gardening books tell you to sow perennial seed in August. This method was originally developed to suit the British climate, where winters are both mild and short. Although this advice may be suitable for some parts of British Colum- bia, in most of the rest of Canada it is not appropriate. Our growing season is too short and our winters too hard for small seedlings to survive. In Canada sow perennial seeds indoors in April, if you have sufficient room, or outdoors as soon as the soil is dry enough to work. The new plants then have the full season to grow to a reasonable size before winter comes. Most of the large seed firms offer many perennials that can be grown from seed, and although your choice of cultivated varieties is limited, you can still obtain a good display from seed alone. Cuttings Soft cuttings of many species of perennials root easily. Soft cuttings are obtained in the spring when the new growth is about 15-20 cm tall. Trim off the lower leaves and, with a sharp knife, cut the stem just below the point from which the leaves are removed (Fig. 9). Fig. 9. A softwood perennial cutting ready to root. 15 Dip the base of the cutting in one of the hormone rooting powders (softwood grade) and tap off any excess. In a shady part of the garden insert the cutting to the base of the remaining leaves in soil that has had some sand worked into it for good drainage. Until rooting takes place cover the cutting with a large glass jar, or provide a tunnel for several cuttings by hanging polyethylene sheeting over wire hoops (Fig. 10). H*** Fig. 10. Rooting tunnels can be easily made at home. Space the cuttings about 15 cm apart, and leave them undisturbed until fall when they should be moved to their final locations. When cuttings must be rooted close together because of space shortage, lift them as soon as they have rooted and replant them in rows about 15-20 cm apart. Bigger plants result from following this procedure but some do not survive transplanting. Division Most perennials can be propagated by division, as outlined in the section "Transplanting". This method works well with plants that have fibrous roots growing from a central crown, such as day-lilies, sneezeweed, asters, and ber- gamot. Some of these have woody connecting roots, which may have to be cut with a knife or pruning shears. Plants that bloom early in the year are best divided in the fall, whereas those that are late to flower are left until spring. However, a border can be renovated with success at either season. 16 The exception to these guidelines are irises, which should be divided in July or early August; Oriental poppies, which should be divided in August; and peonies, which should be moved or divided only in late August or September, depending on the length of the growing season. Fall maintenance Once a sharp frost has killed the last of the flowers, cut down the year's growth. In regions with good snowfall cut the stems at ground level. Where a good snow cover is uncertain, leave the stems 20-25 cm high to help trap any snow that does fall. The following spring cut the stems back to ground level. Some books advocate using the cut-off stems as a mulch. However, when cut stems are left, mice come to eat the seeds and stay to eat bulbs and buds, causing severe plant damage. Also, many fungus diseases overwinter on old foliage, so its removal is a good sanitary measure. Winter protection In areas where a blanket of snow is uncertain, provide some other form of insulation. After the ground has frozen, cover the bed with a mulch of straw or dry leaves. Leaves are not as good as straw because they tend to pack down during the winter. Lay branches or evergreen boughs on top of the mulch to stop it from blowing away. When the covering is applied before the ground is frozen, dormant buds may be dug up and eaten by rodents sheltering in the mulch. Spring renovation Once severe frosts are finished in the spring, remove the mulch. As soon as the soil dries out enough to walk on it, sprinkle a light dressing of a complete fertilizer such as 7-7-7 (50-75 g/m2) and carefully fork it into the top 10-15 cm of the soil. Take care near the crowns of the plants that you do not damage the developing buds. Pests and diseases Although most perennials are tough, their health and beauty may still be adversely affected by attacks from pests and diseases. Aphids, leafhoppers, slugs, snails, and mites attack nearly all plants, including perennials. Most people are probably aware of the symptoms of such general pest infestations. A few pests, however, are peculiar to certain perennials. Some of these for which the gardener should be on the lookout are described here. Leaf miners The adult is a small fly that lays its eggs on the undersides of leaves. The larvae tunnel inside the leaves, marking them with near-transparent trails or large. 17 pale blotches. Various species of fly attack particular perennials. Columbines and chrysanthemums are especially prone. Control this pest by pinching the ends of the tunnels to squash the larvae or by spraying with an approved systemic insecticide. Ants Although ants do not actually feed on plants, they do spread plant lice from infected to healthy plants. Their underground nests can weaken a plant by remov- ing soil from round the roots. Ants are often attracted to the buds of peonies. They seem to be feeding on the nectar excreted from the buds and are not directly harmful. Any of the commercial ant powders or baits are effective for their control. Borers Most stem borers are kept under control by good sanitation. Removing old stems from the border each fall eliminates most of the borers. The one borer that may give trouble is the iris borer. These pests tunnel into the rhizomes (Fig. 1 1 ) and cause wilting and yellowing of the foliage. They also leave the rhizome subject to attack by the foul-smelling soft rot disease. Control of the iris borer can usually be achieved by drenching the plant and the surrounding soil with an approved systemic insecticide. Thrips Thrips are usually first detected by the damage they cause. These small, dark-colored insects scrape the surface off plants and suck the sap. They are particularly fond of developing buds, and their activity here is signaled by pale streaks on the flowers when they open (Fig. 12). Thrips are often a severe pest on day-lilies, but they also attack irises and lilies. Any spray recommended for aphids should control them. Leaf spots Few of the various leaf spot diseases that attack perennials are serious. Sanitary measures such as removing infected leaves as soon as they are seen and cleaning up the plants in the fall generally keep the disease under control. Rots The most serious rot to guard against is soft rot of iris (Fig. 13). This bacterial disease is easily recognized by soft, watery tissue in the rhizomes and by the repulsive odor. Soft rot is encouraged by the presence of iris borers and by planting the rhizomes so deeply that they cannot ripen in the sun. Cut infected parts out with a sharp knife. Sterilize the knife between each cut by dipping it in rubbing alcohol. Mildew The commonest and most visible of the diseases that attack perennials is mildew. This disease occurs in late summer and its spread is encouraged by hot. humid weather. In arid regions mildew is not as serious a problem. Mildew attacks many plants, but it is particularly bad on phlox, asters, bergamot, and delphiniums 18 (Fig. 14). A gray felty-looking deposit covers the leaves. It causes premature leaf-drop and weakens the plant. Mildew is difficult to control chemically. However, attacks can usually be minimized by regular division. Small clumps containing only a few stems allow good air circulation, which helps prevent a rapid spread of this disease. RECOMMENDED PLANTS In the descriptions that follow, only the more common and fairly available plants are listed. The letters c (cutting), d (division), and s (seed) indicate the best method for propagating the various species listed. For more details and a larger list of the cultivated plants available, termed cultivars, consult Canadian Garden Perennials by A. R. Buckley. This book, which details 35 years of perennial plant evaluation at the Central Experimental Farm in Ottawa, is available through your local library. ACHILLEA yarrow This fairly large group of plants includes three forms that are commonly used in the perennial border (Fig. 15). A, filipendulina fernleaf yarrow July-Sept, d 100-150 cm This species is characterized by flat, plate-like heads of yellow flowers. It grows well in dry, sandy soils and has a stiff, upright habit, seldom needing support. Gold Plate and Coronation Gold are the two cultivars most commonly grown. Coronation Gold is the smaller of the two, with slightly smaller heads of flower about 8 cm across. The flower heads are good for drying. A. millefolium common yarrow June-Sept. c,d 50 cm The common yarrow is a white-flowered, invasive weed. When it seeds itself into a lawn it is almost impossible to eradicate. Luckily the forms with colored flowers are not as invasive. Cerise Queen, Fire King, and Red Beauty are sometimes available. They are all shades of red, fading to pink with age. 19 Fig Iris borers cause discolored Fig. 12. The effect of thrips feeding on foliage. day-lily flower buds (Hemerocallis). :*'*■ Fig. 13. Soft rot is difficult to control Fig. 14. Mildew can defoliate phlox some in iris. years. 20 Fig. 15. The three forms of Achillea (from left to right): fernleaf yarrow, sneezewort, and common yarrow. Fig. 16. Sea-hollys (Eryngium) are both smaller and bluer than globe thistles (Echinops). 21 Fig. 17. Modern day-lily cultivars (Hemerocallis) come in a wide range of forms and colors. Fig. 18. The leaves of plantain-lilies (Hosta) brighten shaded areas. 22 Fig. 19. These irises bloom again in the fall. 23 Fig. 20. Spike gay feather (Liatris spicata) can grow in most types of soil. Fig. 21. A selection of the colors available in summer phlox (Phlox paniculata). 24 A. ptarmica sneeze wort June-Aug. d 80 cm Unlike the other two species, the flowers of sneezewort are in small, globe- like heads. The cultivar The Pearl, with white flowers, is the form most usually available. ACONITUM monk's-hood A. napellus helmetflower July-Aug. dys 100-150 cm These upright plants, sometimes known as the common monk's-hood, have soft growth that generally needs staking. This species is good for shaded areas with moist soil, but it can take a fair amount of sun without burning. Like all monk's- hoods, the roots and foliage are poisonous, so be sure to wash thoroughly after dividing these plants. The flowers are blue, occur in spikes, and resemble an upturned cowl. There are several named forms. AJUGA bugleweed These low plants are useful for edging and for placing at the front of a perennial border. They are apt to spread into the lawn but are easy to control with weed killers. They make good groundcovers in sun or shade. A. pyramidalis pyramid bugleweed June d 15-25 cm This form is the slowest growing species of Ajuga, producing mounds rather than mats of foliage. The flowers are a deep blue. A. reptans carpet bugleweed May- June d,s 10-20 cm The regular green form is best for shady spots. In the sun one of the cultivars with variegated foliage, such as Gaiety, is preferable. Both spread by runners and have blue flowers. 25 ALCEA hollyhock A. rosea hollyhock July-Aug. s 100-250 cm Although strictly a biennial (flowering the second year from seed), hollyhock is most often planted in a mixed border. It often lives for several years. Easy to raise from seed (which is often listed under the old name Althaea), hollyhocks are available with single or double flowers. In some parts of the country, hollyhock rust disease can almost defoliate the plants by flowering time. Observing strict sanitation in the fall and changing the location of the plants in the garden help to control this disease. ANCHUSA bugloss These border plants are valuable because of their uncommonly bright blue flowers. Because they are relatively short lived, they should be propagated frequently. A. azurea Italian bugloss June c 100-150 cm This species is the only one usually offered for sale, generally as one of the named forms such as Dropmore or Loddon Royalist. When the heads are removed after flowering, the plant may bloom again in August. ANEMONE windflower These plants range from a few centimetres to 1 m tall. Many are best suited in the rock garden but the following species are good border plants. A. hupehensis Chinese anemone Aug.-Sept. d 50 cm This pink-flowered species is rarely seen, but the white-flowered cultivar Honorine Joubert is quite common. 26 A. xhybrida Japanese anemone Sept.-Oct. d 50-100 cm This name covers a group of hybrids with somewhat mixed parentage. Flowers may be single or semidouble and vary in color from white to deep pink. There are many named forms. They grow well in shade and thus can be used among shrubs. In areas with short growing seasons, flowers may be frozen by an early frost unless protected. A. sylvestris snowdrop anemone June s,d 20 cm Although the plant can grow in full sun, the flowers last longer when grown in shade. The silky seed heads are attractive when the flowers are done. A. vitifolia grape-leaved anemone Aug. d 60 cm As its common name suggests this species, and its cultivar Robustissima, have leaves somewhat like those of the grape. Flowers are pink. ANTHEMIS dog-fennel A. tinctoria golden Marguerite July-Aug. d 60 cm There are many named forms of this species, but Kelwayi is the most common. They differ slightly in height and shade of yellow. The seed is both fertile and freely produced. In some areas of the country this plant is becoming a weed. AQUILEGIA hybrids columbine Although there are many species of columbine, the plants generally grown in borders are the long-spurred hybrids. Columbines have no morals and most of the species cross-pollinate with reckless abandon. They are easy to grow from seeds if the seed is chilled for 30 days before sowing. Unless only one form is grown, all seedlings should be treated with suspicion. The commonest hybrids are Crimson Star (May-June s 60 cm), with large crimson and white flowers with long spurs; McKana's Giants (June-Aug. s 80 cm), with very long-spurred flowers in a variety of colors; and Mrs. Scott-Elliot (June-Aug. s 70 cm), available in a ^ood color range but with shorter spurs. 27 ARABIS rock cress Although this genus is much used in the rock garden, rock cress is also an excellent plant for the front of a border. A. caucasica wall rock cress early spring c, d 20 cm The species is white-flowered, but cultivars of this or the closely related A. xarendsii may have pink flowers. A double-flowered cultivar grows about 10 cm taller. The variegated form is attractive even when not in flower but grows more slowly. ARTEMISIA wormwood This genus is grown mainly for its silver foliage, which makes an excellent filler in flower arrangements. A. ludoviciana var. albula ghostplant d 90 cm The foliage of the cultivar Silver-king is a useful foil to flowers in arrange- ments. The flowers are inconspicuous. A. schmidtiana d 30 cm The cultivar Silver Mound produces distinctive, silvery hummocks useful for edging. ARUNCUS goatVbeard A. dioicus goatVbeard June-July d,s 90-120 cm Best suited to the larger border, goafs-beard can reach shrub-like pro- portions. The large, divided leaves are attractive all summer long. The plumes of creamy flowers are very distinctive. It is good for part shade and for wet locations. It is usually listed as A. Sylvester. 28 ASTER aster As the aster is such a common wildflower throughout Canada, gardeners tend to belittle this most useful addition to the flower bed. Plant hybridizers have combined many of our native species to produce plants that range from a few centimetres to 2 m tall and come in all shades of mauves, blues, pinks, and reds. The addition of some of the European species has given rise to early-flowering cultivars that extend the season. A. alpinus alpine aster June dys 25 cm This dwarf, summer-flowering species is useful for small gardens. A. amellus Italian aster Aug. d 60 cm This species comes in a range of early-flowering hybrids with grayish foliage. A. novae -angliae New England aster Sept.-Oct. d 90-150 cm These comprise the taller of the groups of fall-flowering asters. A. novi-belgii New York aster Sept.-Oct. d 15-150 cm Together, the New England and New York asters make the group of plants known as Michaelmas daisies, named after their season of flowering. The New York asters are the largest group, with the greatest range in height. This section includes the many cushion and mound-shaped plants used as edging. See also the Agriculture Canada publication 1271, Hardy asters for the autumn garden. ASTILBE hybrids astilbe June-July d 60-90 cm Few plants can equal the soft feathery elegance of astilbes growing in a suitable location. Given a moist, lightly shaded site, they bloom freely for a considerable period. Even in full sun they grow well, provided they do not suffer drought. There are many cultivars in shades of white, pink, rose, and red. 29 AVRINIA A. saxatilis mad wort May c,s 25-30 cm This species forms a sheet of yellow in the spring. It is slightly invasive. The named forms, such as Dudley Neville with biscuit-colored flowers, are preferable. It is generally listed as Alyssum saxatile and also has gold-dust or goldentuft madwort as common names. BERGENIA B. cordifolia giant rockfoil spring d 30 cm Only this species is generally available, although others are equally worth growing. The large, leathery leaves persist all winter (so this plant is not a true herbaceous perennial). Sprays of pink flowers appear in early spring. This species thrives best in moist places, although it can tolerate drier conditions. BOLTONIA B. asteroides false starvvort Aug.-Sept. d,s 150-200 cm Looking like small-flowered asters, these plants are best at the back of the border. This species is the commonest. The flowers are white to pink. BRUNNERA B. macrophylla Siberian bugloss spring d 30 cm Closely related to Anchusa. this species has paler blue flowers in clusters resembling forget-me-nots (Myosotis). They grow well in part shade and often flower with earlv shrubs and daffodils. 30 CAMPANULA bellflower Bellflowers are one of the larger groups of perennial plants. Many are low or trailing, suitable for the rock garden. Others are excellent border subjects. A few are invasive weeds. Most have cultivars that expand the range of colors. C. glomerata clustered bellflower June-July d 60 cm This plant has blue to purple flowers clustered at the top of the stems. C. lactiflora milky bellflower June-Aug. c,d 90-120 cm The flowers are white or light blue. Some cultivars are darker. This species flowers well in part shade. C. latifolia broad-leaved bellflower June-July s,d 90 cm This species grows even in poor soils but is apt to seed itself freely. C. medium Canterbury-bells June-July s 30-45 cm Sow this biennial in a shady spot or indoors in spring to give flowers the following summer. Transplant the seedlings 15 cm apart when they are large enough to handle (about two pairs of true leaves), then move to the flowering site in early fall or very early spring. Most seed catalogs list at least one strain of Canterbury-bells. C. persicifolia peach-leaved bellflower July-Aug. cyd,s 30-90 cm One of the best of the bellflowers, this species can be grown from seed. The named forms, however, must be propagated by cuttings or division. C. rapunculoides creeping bellflower July 50-150 cm This plant has tall, slender spikes of mauvish flowers rising from a crown of basal leaves that are wedge-shaped with toothed margins. Leaves on the flower 31 stems are long, without stalks. A good description is given here so that you can avoid this plant. It is one of the most invasive of garden flowers. C. rotundifolia harebell July-Sept. s, d 30-40 cm Although it is slightly invasive in that it seeds freely, this plant is worthwhile. The species is blue, but white and purple forms also exist. CENT AV RE A knapweed This tough, generally hardy genus grows best in poor, dry soils. The flowers resemble the annual cornflower and are freely produced when faded blooms are removed. C. dealbata Persian centaurea June-Sept, d 60 cm Attractive even when not in flower, this plant has leaves that are silvery on the underside. Flowers are pink. rose, or red. depending on the cultivar grown. C. macrocephala globe knapweed June-July s 120 cm This species is the giant of the family with bright yellow, thistle-like flowers. Flower heads dry well for winter decoration once the seed is shed. C. montana mountain bluet May-Aug. d 60 cm This species is the most widely grown of the knapweeds. It most closely resembles the annual cornflower. CHRYSANTHEMUM chrysanthemum Although there are many species of chrysanthemum that can be grown in the perennial garden, the following three, with their myriad of cultivars. are indispens- able. 32 C. coccineum pyrethrum June-July d 60-90 cm Dark green, lacy foliage acts as a foil for single, anemone, or double flowers in a wide range of colors. Excellent as cut flowers, the plants should be cut almost to ground level after flowering to encourage blooming again. C. x morifolium mum Aug.-Oct. c,d 20-40 cm This species includes all the mums grown as pot plants and greenhouse crops, as well as the fall-blooming cushion mums grown in the garden. Flower types, colors, and blooming dates vary widely. The milder the winter, the more varieties are available, but even on the prairies, fine cultivars that originated at the local research stations can be grown. C. xsuperbum Shasta daisy June-Aug. d 80-90 cm This is the correct name for the plant generally listed in catalogs as C. maximum, which is just one of several species used to produce this group of hybrids. Foliage is lighter and coarser than in the pyrethrum. Flowers are white, or occasionally cream, and up to 15 cm across. They may be single or double and are good for cutting. CIMICIFUGA bugbane These striking plants have tall, slender spires of white flowers. The common name is a translation of its latin name. It is given because of the odor of the flowers, which is said to banish bugs. C. racemosa black snakeroot Aug.-Sept. d,s 200 cm This common species of bugbane is well worth a place in any garden. C. simplex Kamchatka bugbane Sept. -Oct. d,s 100 cm This dwarf species flowers too late in the season for many parts of Canada. Where it is able to bloom before frost, it is a very desirable plant. 33 CONVALLARIA lily-of-the-valley C. majalis lily-of-the-valley May-June d 15 cm Because its spreading roots soon start to crowd other plants, this well-known plant is not really suited to the perennial border. It is, however, very useful as a groundcover, particularly in shade. Only this one species is grown, and although there are pink and double- flowered forms, the common white form is the only one available. When the flowers become smaller and less freely produced, lift the plants and divide the clump. Replant in soil enriched with humus and fertilizer. COREOPSIS tickseed These mostly short-lived perennials have bright yellow, daisy-like flowers. Division every 2 years is needed to keep the plants young and to make them last much longer. C. grandiflora large-flowered tickseed June-Sept, d 25-90 cm Although this species is rarely grown, it is the parent of several worthwhile cultivars. These cultivars vary greatly in height, but, provided the old flowers are removed, all bloom over a long season. C. verticillata thread-leaved tickseed July-Sept, d 45-60 cm This species looks quite unlike all the other tickseeds. having very thin, narrow, divided leaves. As in all tickseed, the flowers are bright yellow. DELPHINIUM perennial larkspur Almost every garden should find space for these well-known, stately, dis- tinctive plants. After flowering, cut off the flower stems at the next leaf down to promote a second crop of smaller blooms late in the season. There are three main groups that the amateur gardener can readily obtain. 34 D. x belladonna belladonna delphinium June c,s 90-120 cm This group of plants has flower trusses that are fairly open rather than tightly packed. The trusses make a good cut flower because the spikes are smaller and lighter than those of other species. The cultivar Blue Bees, often found in seed catalogs, belongs to this group. D. elatum common delphinium June-July c,s 90-200 cm Under this general heading are placed all the many large-flowered hybrids that typify this genus. Most of these can only be reproduced from cuttings, but the Pacific Giant hybrids come true from seed and are available in most seed catalogs and large garden centers. Seeds should be frozen, not just chilled, for 24 h before sowing and germinate best at cool temperatures (7-10°C). D. grandiflorum butterfly delphinium June-July s 40 cm This race of dwarf, short-lived delphiniums, which often blooms the first year from seed, seems to be less hardy than the other forms and should perhaps be restricted to the milder parts of the country. Connecticut Yankees is the most readily available form. DIANTHVS pink Although pinks are predominantly rock garden plants, a few species are useful at the front of the perennial border. Their mat-forming habit, which smothers weeds, freedom of flowering, and delightful perfume make them a most useful addition to the garden. D. barbatus sweet-William May-June s 15-45 cm This biennial flowers the second year from seed. Sow in late spring, trans- plant the seedlings into garden rows, and move to their final location in the fall. There are several named forms, of which the dwarf Indian Carpet lives for several years. They do not usually come true from self-collected seed. 35 D. deltoides maiden pink June c,s 15-30 cm Some of the best cultivars of this widespreading plant with dark green foliage have red or carmine flowers. D. plumarius cottage pink June-July c 20-30 cm Included under this name are the many forms of border pinks and carnations that are hardy only in coastal British Columbia, as well as some of the mound pinks that are hardy on the prairies with protection. All have pale green, grassy foliage. The flowers vary from white to dark red. DICENTRA bleedingheart The common bleedingheart is a long-time garden favorite, but others deserve to be better known. D. eximia plume bleedingheart May-Aug. dys 45 cm This species is unfortunately seldom offered in catalogs. The flowers are red, on arching stems. This plant grows in part shade. D. formosa western bleedingheart May-Sept, d 30-45 cm This species is similar to the last species but spreads by underground runners. It is a shade-loving plant, with several forms ranging from white to pink to crimson. D. spectabilis bleedingheart May d 90 cm Despite its showy nature, this plant needs care in its placement. The foliage starts to die down early in the season and needs screening from view by other plants by midsummer. 36 DICTAMNUS D. albus gasplant June-July d,s 60-90 cm This plant is known as the gasplant because of an ignitable gas given off by the flower stalks. It is a dependable, hardy plant, which has dark, glossy leaves. Flowers are white, tinged with pink, in tall spikes. There is also a purple form. The seed pods are good for dried-flower arrangements. DIGITALIS foxglove Another biennial, this plant should be grown in the same way as sweet- William (Dianthus barbatus). They grow best in full sun or part shade. D. purpurea common foxglove June-July s 90-150 cm Although the species is seldom grown, two hybrid strains. Giant Shirley and Excelsior, are available in many seed catalogs. Both give imposing spires of bell-like flowers in a wide range of colors. DORONICUM leopard's-bane Although the need to banish leopards is small in most Canadian gardens, this plant is still worth growing for its early-flowering habit. D. cordatum May d 45-60 cm This species is the one most generally offered for sale. Flowers are bright yellow, daisy-like, and up to 5 cm across. The plants wilt badly during hot weather but recover at night. It is often listed as D. caucasicum. ECHINACEA purple coneflower A close relative of the black-eyed-Susan (Rudbeckia hirta), purple coneflow- ers are good as cut flowers when fresh, or the cones can be dried for winter arrangements. 37 E. purpurea Aug. -Oct. d 80-120 cm This species is the best for garden use. Cultivars are available with white or red petals. ECHINOPS globe thistle Very hardy plants, these species have grayish leaves and globular thistle-like flower heads that dry well. E. ritro small globe thistle July-Sept, d 90-120 cm There is considerable confusion surrounding the correct botanical name of this species, but the gardener need only know the cultivar names. Taplow Blue is probably the best, with Blue Globe a close second, regardless of the species with which they are associated. EPIMEDIUM barrenvvort These spring-flowering plants are best in shade. They are distinctive and easy to identify by their leaves. One side o\ each leaf is larger than the other. E. grandiflorum large-flowered barrenvvort May d 30 cm The flowers are up to 5 cm across and are red with violet inside. There is also a form with lilac flowers. E. xrubrum red barrenvvort May d 30 cm The red flowers are carried in clusters o( 20 or more. The young foliage is also flushed a copper color. This species is often listed as E. coccineum in catalogs. EREMURUS foxtail-lilv These plants are most distinctive in the border. They are grown from a crown of very fleshy roots, which need winter protection in most of Canada. The newly 38 emerged flower buds may also need protection against cold winds in early spring. In spite of all this extra work, they are still worth growing. They are usually sold by bulb merchants, rather than by perennial nurseries. E. elwesii May-June d,s 200 cm The flowers are pale pink and slightly fragrant. E. robustus May-June d,s 120 cm The color is similar to the last species but the plant does not grow as tall. E. stenophyllus July d,s 90-150 cm This striking plant has great spikes of yellow flowers. There are also several hybrids between this and other species, offering a wide range of colors, but unfortunately they are seldom available. ERIGERON fleabane This genus includes many native species with small daisy-like flowers. Cultivated forms have flowers up to 5 cm across. E. speciosus June-Aug. d 45-80 cm The species itself has violet flowers but is seldom grown because the cultivars are much superior. They come in a range of colors from white through pink and violet to blue. The flowers may be single or double. They need a snow cover to survive temperatures below about -30°C. ERYNGIUM sea-holly Somewhat like a small globe thistle (Echinops), these plants have more prickly leaves, often with a distinct blue sheen (Fig. 16). E. amethystinum amethyst sea-holly June-Sept, d 40 cm All parts of the young growth have a steel-blue color. This species makes a striking addition to the front oi a bed. 39 E. planum July-Aug. d 90 cm Although this species is the one most often offered for sale, it is not as good a plant as E. amethystinum. Only the flowers and the leaves just below them have the blue color. EUPHORBIA spurge This genus includes the Christmas poinsettia, one very popular border plant, and others that deserve to be better known. E. epithymoides cushion spurge spring d 45 cm Also listed as E. polychroma in some catalogs, cushion spurge forms neat mounds of bright yellow in early spring. As in the poinsettia. the flowers are inconspicuous; it is the colored leaves, the bracts, immediately below them that make the display. In the fall, foliage turns bright red. E. griff ithi Griffith's spurge June-July d 60 cm A taller, more slender species than the last, this fairly recent introduction, with its brilliant orange bracts, is becoming better known. E. myrsinites myrtle euphorbia June d,s 10 cm This creeping plant is grown more for its gray spiky foliage than for its yellow bracts. FILIPENDVLA meadowsweet This genus is closely related to Spirea. The plants grow best in a moist, shady location. F. rubra queen-of-the-prairie June d,s 120-250 cm As its common name suggests, this plant is very hardy. Its peach-colored flowers are in feathery spikes. 40 F. ulmaria queen-of-the-meadow June d,s 60-120 cm This species is the European counterpart of/7, rubra and is almost as hardy. The flowers are white. F. vulgaris dropwort July-Aug. d,s 60-180 cm Despite several changes in name, this very good plant can stand quite dry conditions. The foliage is ferny and the cream flowers are in upright spikes. It is probably listed as F . hexapetala in most catalogs. GAILLARDIA blanketflower G. x grandiflora June-Aug. c,d 15-90 cm This group of yellow to red daisy-flowered perennials includes many culti- vars that are short lived unless propagated frequently. They are good as cut flowers but the plants tend to be weak and need support. Most of the named forms grow 80-90 cm tall, but Baby Cole is a dwarf at 15 cm. GEUM avens The brilliant colors of avens make them difficult to place in the border, but their long flowering season makes them a valuable addition. G. xborisii June-Aug. d,s 30 cm These brilliant orange flowers are borne over a mounded plant. G. 'Lady Stratheden' and G. 'Mrs. Bradshaw' May-Sept, s 60 cm These two cultivars are available in many seed catalogs. They have double flowers of yellow and red, respectively. 41 GYPSOPH1LA G. paniculata baby's-breath June-Aug. c 25-90 cm Indispensible to flower arrangers, baby's-breath resents being disturbed. The species is white with single flowers. More generally grown are Bristol Fairy and Perfecta, with double flowers. There are also dwarf and pink-flowered forms. HELENIUM sneezeweed H. autumnale July-Sept, d 60-120 cm The species itself is native in eastern North America and has a straggly growth habit. It has given rise to many fine cultivars, in shades from mahogany to butter yellow. HELIANTHUS hybrids sunflower This genus has daisy-like flowers. The plants are fall flowering, in shades of yellow, and are best suited to the back o\ the border. Propagate by division. HELIOPSIS hybrids orange sunflower This genus is very similar to Helianthus, but generally smaller. HEMEROCALLIS hybrids day-lily June-Sept, d 45-120 cm The familiar orange day-lily that has naturalized itself in many areas is quite unlike the modern hybrids. These hybrids now come in a wide range of shades, from a near-white to bright red. Bicolored flowers may have a contrasting stripe on each petal or alternate petals in different colors. Petals may be strap-like or broad and overlapping. Cultivars with double flowers are also now becoming available (Fig. 17). Day-lilies are tough, hardy, and reliable. They grow in almost any soil and in wet or dry locations. They make a good groundcover as long as perennial weeds, especially quack grass, are not present. Their spreading roots are particularly useful for preventing erosion on slopes and banks. 42 HEVCHERA alumroot H. sanguined coralbells May-June d 45-60 cm Not as well known as perhaps it deserves to be, this species is one parent of a group of named hybrids. They are shade and moisture lovers but can grow in dryer sunny soils. The delicate flower spikes are particularly useful in small flower arrangements and are available in many tones of pinks and reds. HIBISCUS mallow H. moscheutos common rose mallow Aug.-frost dys 90-150 cm This species, with its hugh, showy flowers, should not be tried in cold parts of the country. In Ottawa, even with winter protection, it is slow in coming to life in the spring. Grow in full sun, in a moist soil. There are several named varieties in various colors. Do not confuse this species with the shrubby rose-of-China (Hibiscus syriacus), which is hardy only in the mildest parts of Canada. HOSTA species and hybrids plantain-lily May-Aug. d 30-100 cm This is one of the most useful plants for shady areas. The foliage comes in a wide range of colors, from yellow to near-blue with central and marginal variega- tion (Fig. 18). The leaves may be smooth, wavy, or crinkled and are strap-like or almost circular. Flower spikes are often sweetly scented and the pendulous bell-shaped flowers may be white, mauve, or lilac. There is much confusion in the nursery industry over naming the more than 500 species and cultivars that are known. Many nurseries offer a selection of forms, although there is no Canadian nursery that specializes in these plants. IBERIS candytuft /. sempervirens perennial candytuft May-June c,s 20-30 cm This species is a rock garden plant that is sometimes used as edging in borders. It is a small shrub with woody stems and evergreen leaves. The flowers are white and delicately scented. 43 INCARVILLEA trumpetflower /. delavayi Chinese trumpetflower May-June d,s 40 cm This plant is slow to emerge in the spring and care must be taken to avoid damaging the shoots below ground during early cleanups. The rose pink flowers are carried in spikes above the glossy, green foliage. This species should not be tried on the prairies; even in Ottawa it needs winter protection. It is sometimes listed in catalogs as garden, or hardy, gloxinia. IRIS iris These well-known plants are one o\~ the mainstays of the perennial border. There are several hundred cultivars, and a Canadian society devoted to their culture has been formed. Tali bearded iris June and Sept. d 60-100 cm Possibly the most widely grown of any group of perennials, the tall bearded iris needs full sun and good drainage. It is subject to the borer, which is a serious pest, as well as to a bacterial rot. but when planted with the top of the rhizome above the soil, these pests can generally be detected before they do much damage. Although most forms o\~ the tall bearded iris bloom in June, a new race that blooms again in September is gradually coming on the market. When they come back into bloom they flower until hard frost kills the buds. Although they do not yet have the range of colors available in the spring-flowering forms, they are improv- ing each year and are well worth looking for (Fig. 19). Dwarf bearded iris Apr.-May d 10-30 cm Not as well known as the tall bearded iris, the dwarfs are much earlier flowering and play an important role in giving color early in the season. They have almost as wide a color range as their tall relatives, but because they do not have the long, many-flowered spikes, their effect is more fleeting. Siberian iris May-June d 60-120 cm Siberian iris do not have the large showy flowers of the tall bearded group, but their rugged flowers last better and withstand wind and rain without bruising. Grow them in sun or part shade and in dry. moist, or even wet locations. 44 KN1PH0FIA torch-lily K. uvaria red-hot-poker July-Aug. d 80-150 cm In the milder parts of the country, the striking spikes of red-hot-poker, also known as the poker plant, provide a focus in the summer border. Named forms are no longer red; they range from cream, through pink, to orange and yellow. LAMIASTRUM L. galeobdolon yellow archangel July dys 45 cm The cultivar Florentinum is a useful groundcover that can be grown at the front of a border. The yellow flowers are in dense clusters and the foliage is mottled silver and green. It is generally listed in catalogs under its old name Lamium. LATHY RUS vetchling L. latifolius perennial pea July-Sept. dys 60-250 cm This perennial form of the sweet pea is a climber that needs some form of support early in the season. Although the flowers are not as large as those of the annual, they are freely produced and sweetly scented. Named forms with white or deep pink flowers are occasionally available. The species has blooms of rose pink. LI A TRIS blazingstar Blazingstars are unusual in that, unlike most plants, their flower spikes open from the top downwards. They grow best in sandy soils. L. pycnostachya Kansas gay feather Aug.-Oct. s 90-150 cm The dense spikes of purple flowers can be used for fresh or dried arrange- ments. 45 L. scariosa blazingstar Aug.-Oct. d,s 60-90 cm Similar to the last species, but shorter, there are several named cultivars of this species in shades of white and purple. L. spicata spike gay feather Sept. s 90 cm Because this species does not need such arid conditions as the previous species, it is the most commonly grown. Flowers are usually reddish purple, but there is also a white form (Fig. 20). LILIUM hybrids lily June-Aug. d,s 50-150 cm The lilies are a complex group of bulbs, divided into several different groups depending on their parentage and flower type. For the average home gardener they are colorful, dependable, and often scented. They prefer a soil rich in humus and grow well in association with shrubs. There are lily societies in Ontario and on the prairies who can supply information on types suitable for these regions. Consult "Plant Societies" in this publication for your nearest society. LIMONIUM sea-lavender L. latifolium common sea-lavender Aug. -Sept. s 60-90 cm Often known as Statice, this sea-lavender is prized for its bluish, papery flowers that dry well and are useful in winter arrangements. As its native habitat is the seashore, it may prove useful where winter road salt may cause problems for other species. LINVM flax One member of this family provides the flax used in weaving. All species need full sun because their flowers remain closed in the shade. 46 L. flavum yellow flax June-July cyd,s 40 cm This species is not hardy enough for all regions but worth trying in milder areas for its masses of bright yellow flowers. L. perenne perennial flax June-July dys 60 cm This short-lived species is easy to raise from seed. The flowers are light blue. A related species, L. narbonense, is even more striking but seldom offered for sale. LUNARIA honesty L. annua honesty July-Aug. s 90-120 cm Also known as the silver-dollar-plant, this biennial is easily raised from seed. The flowers are not showy, but the flat, papery seed pods are much prized for winter decoration. LUPINUS hybrids lupin June-July c,s 80-90 cm One of the most vivid and variable of all perennials, it is one of the few genera that has all three primary colors, red, yellow, and blue, in its flowers. The Russel hybrid strain is so superior that it has eclipsed all others. Lupins need an acid soil and a shaded root. When conditions are favorable they flourish, but without the proper environment they can be among the most frustrating of plants to grow. They are fairly short-lived anyway, but strict attention to removing old flower spikes before they set seed can prolong life. LYCHNIS campion Lychnis and the closely related Silene contain many weedy species. There are, however, a few of horticultural merit. 47 L. chalcedonica Maltese-cross July d,s 60-90 cm Because of the intense red of the blossoms, care must be taken in choosing companion plants for this species. L. coronaria rose campion July-Aug. s 40-60 cm This pretty little plant is short-lived but propagates itself easily from seed. The foliage is felty with long silvery hairs. LYSIMACHIA loosestrife L. punctata dotted-leaved loosestrife June-July d,s 80 cm Also called garden or yellow loosestrife, this plant spreads by underground runners and can become invasive in rich soils. The yellow flowers occur in whorls between the leaves. LYTHRUM hybrids purple loosestrife July-Sept, c 60-120 cm Selections are available from two species of Lythrum, the european L. salicaria and the North American L. virgatum. Both have given rise to a range of cultivars in various shades of purple and of varying heights. They grow well in both shady and damp locations and in poor or rich soils. See also the Agriculture Canada publication 1285. Lythrums for home gardens. MACLEAYA M. cordata plume poppy July-Aug. d 180-240 cm This plant is probably too large for most gardens, and it increases so rapidly that once introduced it is hard to eliminate. The foliage is fawn green above and silver below, and the pale yellow flowers are minute but born in profusion. It is easily identified by the orange sap which is exuded by the cut roots. It should be avoided. 48 MERTENSIA bluebells M. virginica Virginia bluebells May d 60 cm Best grown in shade, Virginia bluebells dies down soon after flowering. It should be interplanted with later-maturing plants such as plantain-lily (Hosta) or Astilbe to avoid having a bare spot in the border. MONARDA hybrids bergamot June-Sept, d 80-100 cm Monarda hybrids are the result of crosses between various North American species, particularly M. didyma, the bee-balm or Oswego-tea, and M. fistulosa. All have aromatic foliage that can be used in pot-pouris or drinks. Flowers are in shades of pink, red, and purple. Their one fault is a tendency to become covered with mildew, which causes the loss of the lower leaves. NEPETA catmint Although cat lovers may want to grow catnip (N. cataria) in a perennial border, it is not nearly as good a plant as N. xfaassenii. N. xfaassenii catmint July d 30 cm This plant has silvery leaves and spikes of lavender flowers. Its foliage has a scent when crushed that attracts some people. Cats, however, are indifferent. It is often sold as/V. mussinii, which is one of the parents of this plant but which is not as attractive as its offspring. N. grandiflora large-flowered catmint June-Aug. d 60-120 cm The foliage is both less silvered and scented than the last species, but the blue flowers are more showy. There are a couple of named forms, of which Blue Beauty is often available. 49 OENOTHERA evening-primrose Although many evening-primrose live up to their name by flowering at night, the best perennial forms are open by day as well. O. missouriensis Ozark sundrops June-Sept. d,s 25 cm This plant likes full sun, where the red buds open into bright yellow, cup-shaped flowers. O. tetragona evening-primrose June-Sept, d 30-60 cm This plant is still listed in some catalogs as O. fruticosa var. youngii. Whatever its name, it is one of the more brilliant yellow plants for the front of the sunny border. There are several named clones such as Illumination and Yellow River. PAEONIA hybrids peony June d 80-100 cm Many people grow peonies even when they have few other perennials. They are dependable and subject to few diseases, and they can be grown successfully for many years without needing to be moved. There are several types of flowers including single, double. Japanese, and bomb, and some catalogs list their plants according to flower type. Peonies are one flower where the newer forms are not necessarily better than the traditional ones. Many of the best forms have been around for more than 70 years. Tree peonies, which die back to a woody stem rather than to the ground, arc somewhat tender and should only be grown in the milder areas of Canada. PAP AVER P. orientale Oriental poppy May-June c (root) 60-80 cm Although the brilliance of this flower ensures its place in the garden, its foliage is untidy as it dies down in late summer, and care should be taken in selecting a location. 50 Flowers come in a wide range of colors from white through pinks and reds to a dark mahogany. Because the plants die down early, be careful during fall cleanup not to dig up the plants by mistake. Unless pot-grown plants can be obtained, plant poppies only in late Septem- ber and mulch them the first winter. PENSTEMON hybrids beardtongue June-Aug. c 60-120 cm The beardtongues are a North American plant that do not get the attention they deserve. Many of the species make excellent garden plants, particularly in the dryer parts of the country, but unless you join the American Penstemon Society, they are almost impossible to obtain. Several plant breeders have developed a range of hybrids. The colors are mostly shades of blue, mauve, pink, and red, and several are available either as named forms, such as Prairie Fire, or as a mix, like Seeba hybrids. PHLOX phlox Two species of phlox are widely used in the perennial border: one for edging, the other in the main display. P. paniculata summer phlox July-Aug. c,d 45-150 cm One of the most dependable of perennials, summer phlox deserves a place in every garden, whether or not other perennials are grown. The wide range of colors makes them easy to blend into any setting and the beautiful perfume gives a welcome fragrance (Fig. 21). There are several dwarf varieties about 50 cm tall that are useful toward the front; a few varieties reach three times this height. Most phlox cultivars range from 70 to 100 cm. Phlox grow best in full sun and rich, moist soil. However, they are very adaptable and can grow and flower in a shady soil in shade. Their one drawback is a susceptibility to mildew, which coats the leaves and causes defoliation. Combat this disease by dividing regularly to keep the clumps small and by planting only in areas with good air circulation. P. subulata moss pink May c 10-15 cm Although the moss pink is a rock garden plant, it has found great favor as an edging plant for the front of a border. It quickly forms a mat that suppresses most weeds. 51 PHYSAUS Chinese-lantern P. alkekengi bladdercherry July d,s 30 cm Although this plant flowers in July, its period of display is during the winter. The bright orange lanterns enclosing a single red fruit are attractive in dried-flower arrangements. It is also commonly called the Chinese- or Japanese-lantern. The plant can become a weed because it spreads by underground runners. PHYSOSTEGIA false dragonhead P. virginiana obedientplant Sept. d 80-150 cm This plant is useful for flower arrangements because the individual flowers can be rearranged to face any direction on the stalk. It is a stiff, upright plant with flowers of white or shades of pink. PLA TYCODON balloonflo wer P. grandiflorus July-Aug. d> s 30-60 cm The flowers of this plant are upturned bells. It derives its common name from the inflated buds. Flowers may be blue or white. Dwarf forms such as Apoyama are suitable for the front of a border. POLEMONIUM JacobVladder P. caeruleum JacobVladder June-Sept. d,s 45-60 cm The leaflets are alternately placed on the mid-rib and represent a form of ladder. The flowers are blue, occurring in clusters above the foliage. This plant is useful because of its long season of flower. 52 POLYGONUM knotweed P. cuspidatum Japanese knotweed Aug.-Sept. d 180-240 cm Avoid this plant, also known as Japanese or Chinese bamboo, because it is most invasive and persistent. There are dwarf forms that are said to be less invasive, but caution is indicated. POTENTILLA hybrids cinquefoil June-Aug. d 40-60 cm Hybrids have been bred from many different herbaceous cinquefoils (not to be confused with the shrubby kinds). They are valuable for edging and come in shades of yellow, orange, and red. The flowers are often double and resemble portulaca. PRIMULA primrose Primroses, in general, need a soil rich in humus, freedom from drought, and a shady site. Most species are hardy only in mild parts of the country, but a few can survive, and thrive, in cold climates. P. denticulata drumstick primrose spring dys 30 cm One of the most tolerant of primroses, it has almost globe-shaped heads of flower. The flower heads start to open down among the leaves, and, as the stems elongate, rise above them. The flowers are lilac mauve or occasionally white. P. japonica Japanese primrose June s 60-90 cm This plant likes shady, moist areas. When conditions are right, it seeds itself and forms large colonies. The flowers are in many shades of pink and red and occur in whorls on the stem. 53 P. xpolyantha polyanthus spring d,s 15-25 cm This complex group offers one of the widest ranges of colors of any plant. Often sold as spring pot-plants, they are good garden plants in areas where winters do not go below about — 35°C. P. sieboldii Siebold's primrose May-June d,s 25 cm This species can stand more sun and drier conditions than most. The pink flowers may be splashed with white in varying amounts. It is one of the best of the garden primroses. PVLMONARIA lungwort An easy, shade-loving, spring-flowering plant, lungwort is unusual in that its flowers open pink and then turn blue as they age. P. angustifolia lungwort Apr. -May d 30 cm The foliage is very rough, plain green, and narrow. Some cultivars have bright blue flowers. P. saccharata Bethlehem-sage Apr .-May d 30-40 cm The foliage is wider than that in the preceding species and has spots and speckles of white. Cultivars are red flowered. RUDBECKIA coneflower This genus o( chiefly North American origin includes the familiar black- eyed-Susan. R. fulgida var. speciosa July-Sept, d 80 cm Because o\ its long flowering period this plant is very useful. Cultivars such as Goldquelle with double flowers are an improvement on the species. 54 R. laciniata July-Sept, d 200-350 cm The cultivar Golden Glow is familiar to many gardeners. It spreads rapidly and survives well in neglected gardens. The flowers are bright yellow and almost globe-shaped. SALVIA sage In addition to the well-known, tender scarlet sage (S. splendens) and the sage used as a culinary herb (S. officinalis), there are several species that can be grown in the border, particularly in milder parts of the country. S. azurea azure sage Sept.-Oct. s 150 cm This fairly short-lived plant is easy to raise from seed. Its blue flowers are rare this late in the season and make this plant especially useful. The cultivar Grandi- flora is also known (and sometimes sold) as Pitchers sage (S. pitcheri). S. sclarea clary Aug.-Oct. s 100 cm This biennial or short-lived species is sometimes available from the larger seed houses. It is of particular use to flower arrangers because the colored bracts can be dried for winter use. S. xsuperba superb sage June-Aug. dys 40-80 cm One of the most showy of all sages, this species forms stiff, well-balanced plants with spikes of purple flowers. The cultivar East Friesland is smaller but just as free flowering. SANGVINARIA bloodroot S. canadensis bloodroot Apr. d,s 25 cm A plant native to eastern woodlands, this species takes almost full sun. Flowers appear before the bluish green leaves. The double form. Multiplex, is worth searching catalogs for. SS SAPONARIA soapwort S. officinalis bouncing-Bet July-Oct. s 100 cm Although this plant is attractive when in flower, its rampant nature and abundant seed make it invasive. The species has pale pink to mauve flowers. Double-flowered cultivars with white, rose, or red flowers are much superior. SCABIOSA scabious S. caucasica bluebonnets July-Sept. dys 100 cm A plant that likes an alkaline soil and cool summers, bluebonnets are difficult to establish, but given the right conditions they are quite showy. One of the common names, pincushionflower, best describes the blooms. Named forms in a range of colors are occasionally available. SEDUM stonecrop S. spectabile showy stonecrop Sept.-Oct. d 40-60 cm This species is the only one of a large genus that is commonly grown in perennial borders. Most of the species in this genus are dwarf forms more suitable for the rock garden, although they can also be used for edging. The showy stonecrop is an erect plant with fleshy leaves. The species is pink-flowered but cultivars such as Autumn Joy, Carmen, and Meteor have more brilliant blooms. There is also a form with variegated foliage. SIDALCEA hybrids prairie mallow June-Sept, d 80-120 cm Although not well known, prairie mallows are impressive perennials with flowers like hollyhocks. They need a moist soil and should be cut back after flowering and not be allowed to go to seed. There are over 20 named hybrids in colors from pale pink to deep red. 56 SOLIDAGO hybrids goldenrod As goldenrod is native to much of Canada, gardeners tend to despise this plant. Breeding work in Europe, crossing the North American and European species, has given rise to cultivars that flower from June to October, at heights from 30 to 180 cm and in a range of yellow shades. Few ever appear in nursery catalogs. xSOLIDASTER xS. luteus Aug.-Sept. d 80 cm This plant is a result of crossing goldenrod with aster. It has small, yellow, aster-like flowers in arching sprays. STOKESIA Stokes' aster S. laevis cornflower aster July-Sept, d 40 cm Best in milder areas, cornflower asters produce blue flowers similar to the annual China aster (Callistephus). It requires full sun and well-drained soil. THALICTRUM meadow-rue These attractive perennials have fine, often blue green leaves. The flowers have no true petals but give a mist-like appearance. Meadow-rue likes part shade or a moist soil in full sun. T. aquilegifolium columbine meadow-rue May-June d 60-90 cm This early-summer- flowering species has fluffy mauve or white flowers. Of the several named forms Thundercloud is one of the best. T. flavum yellow meadow-rue July-Aug. d 60-90 cm Flowering later than the preceding species, this plant has pale yellow flowers. Illuminator is a brighter shade. 57 T. rochebrunianum lavender-mist July-Sept, d 120-180 cm The last species to flower in this genus, this is one of the best of the meadow-rues. Its common name is an apt description. TRADESCANTIA hybrids spiderwort June-Sept, d 60 cm A group of showy, upright plants, the hybrids display flowers in shades of white, blue, mauve, and carmine red. Their one fault is a tendency to self-sow. Generations of seedlings gradually revert to blue. TRILLIUM species wake-robin May s 30-40 cm Although they are best suited to shaded areas, wake-robins can also grow in the sun in damp soils. Several species are sometimes offered for sale. T. grandi- florum is the easiest to cultivate and the most commonly available of these species. TROLLIUS globeflower These useful, early-flowering plants often bloom again in the fall. They grow best in slightly wet locations but can flower well in dryer light soils. T. asiaticus Asiatic globeflower May- June d, s 40 cm The flowers of this species are cupped rather than globular. This plant is worth growing for its unusual orange flowers, which differ from the more usual yellow forms. T. europaeus European globeflower May-June d 60-90 cm This species is one parent of a range of hybrids with flowers that shade from pale yellow to vivid orange. First Lancers, Goldquelle, and Orange Princess are probably the best known of the cultivars. 58 VERONICA speedwell Blue flowers in midsummer make speedwell almost indispensible. Many species are dwarf, trailing plants suitable for the rock garden but the following are good border specimens. V. incana wooly speedwell June-July c,d>s 40 cm Spikes of pale blue or pink flowers above silver gray foliage make this species a most attractive plant for the front of the border. V. latifolia Hungarian speedwell June-July d 30-40 cm The cultivar Crater Lake Blue belongs in this species and is probably the best known of all the speedwells. The flowers are bright blue in spikes over dark green leaves. V. spicata spiked speedwell July-Aug. d 30-40 cm A plant of stiff, upright habit, this species is a parent of several cultivars such as Barcarolle, Minuet, and Wendy, with flowers of blue, pink, or white. VIOLA hybrids violet, pansy Apr.-Oct. c,s 10-30 cm In most of Canada both violets and pansies are best treated as biennials and should be overwintered under a deep mulch. Occasionally the odd plant is able to survive very low temperatures, living to flower a third year. These low plants flower best in light shade and moist soils. Most seed catalogs list several named forms. Chill the seed for at least 24 h below 4°C for best germination. 59 USING PLANTS Consult the following list to determine which species are suitable for special purposes or for growing under unusual conditions. Uses oo Ot LU oo LU a oo oc OC LU 00 £ < lu o E/3 oc O Zj 00 £ a: LU 00 LJU o -J Li. o -J o 00 < LU OO -J o LL. -J Li. OC LU o LU H Z H Z LU Q 00 oo a* < o oo O z Li. O -J a. LJL Q < as a < aS G < O H >- OC s _J H — < < X LU OC Cl. D < 3 E2 as ai Species and hybrids 00 S £ Q OO oo U. U Q u. Li. Achillea A . filipendulina X X X X A. millefolium X X X X A. p tar mica X X X X Aconitum napellus X X X X X Ajuga A. pyramidalis X X X A. reptans X X X X Alee a rosea X Anchusa azurea X Anemone A. hupehensis X X A . x hybrida X A. sylvestris X X A. vitifolia X Anthemis tinctoria X X Aquilegia hybrids X X X X Arabis A . x arendsii X X A. caucasica X X X Artemisia A. ludoviciana var. albula X X X A . schmidtiana X Ar uncus dioicus ( — A . Sylvester) X X X 60 Uses oo UJ oo LU a oo UJ oo £ < uj O 00 ac o Lj 00 £ uj oo UJ o -J -J LU o Uh -J 5 00 < UJ 00 -J O -J Uu -J uu O UJ H Z Z LJ Q OO H oo < O 00 -J o -J uu UU Q < O < a < 5 H > 2 2 _j H UJ-J < < X -J & o- D < D 2 C£ Qi Species and hybrids OO 2 £ Q oo oo UU U Q LL uu Aster A. alpinus X X A. amellus X X A. novae-angliae X X A. novi-belgii X X Astilbe hybrids X X X X X X* Aurinia saxatilis ( = Alyssum saxatile) X X Bergenia cordi folia X X Boltonia aster oides X X Brunnera macrophylla X Campanula C. glomerata X X C. lactiflora X X X X C. latifolia X X X X C. medium X X C. persicifolia X X X C. rapunculoides X X X C. rotundifolia X X X X Centaurea C. dealbata X X C. macrocephala X X X* C. montana X X X Chrysanthemum C. coccineum X C. Xmorifolium X X C. x super bum X X ( = C. maximum) Cimicifuga C. racemosa X X X X C. simplex X X X X * Seed heads. Uses oo QC UJ oo LU a oo QC oo £ < Li] o oo QC o 23 C/5 £ QC LU OO QC LU o -J -J — o Li. 5 OO < oo -J o Li, -J Li. OC o LU Z H Z Q oo H 00 DC < O 00 a z -J Li. o -J Li. Q r t i < Eg a < a < o H >- G£ s -J H — < < X, UJ a; Q- 3 < ID 5 a: 0£ Species and hybrids IT) s £ a oo oo u_ U Q Li. Li. Convallaria majalis X X X X Coreopsis C. grandiflora X X X X C. verticil lata X X Delphinium D . x belladonna X X X D. elatum X X X D. grandiflorum X X X Di an thus D. barbatus X X D. deltoides X X X D. plumarius X X X X Di centra D. e.ximia X X X D . formosa X X X X D. spectabilis X X X Dictamnus albus X X X* X X Digitalis purpurea X X Doronicum cordatum ( = D. caucasicum) X X X Echinacea purpurea X X X X* Echinops ritro X X X X Epimedium E. grandiflorum X X E. Xrubrum ( = E. coccineum) X X Eremurus E. elwesii X E. robustus X E. stenophyllus X * Seed heads. 62 Uses Species and hybrids oo QC LU 00 LU o oo 0£ LU 00 £ < uu o oo at o Lj co £ LU 00 LU o -J -J o -J o 00 < LU 00 -J O -J -J Li- as LU 2 o LU H Z Z Q oo 00 < o 00 o z -J -J o -J Q LU < DC o < a < 5 h- > 2 2 J H < < X OC CL D < D 2 Oi ft! 00 S £ Q 00 00 U- U Q Li. PL, X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X* X X X X X X X X X X X X X X X X X X X X X X X X* X X Erigeron speciosus Eryngium E. amethystinum E. planum Euphorbia E. epithymoides E. griffithi E. myrsinites Eilipendula F . rubra F. ulmaria F . vulgaris Gaillardia x grandiflora Geum G. xborisii G. hybrids Gyp sop hi I a panic id at a Helenium autumnale Helianthus hybrids Heliopsis hybrids Hemerocallis hybrids Heuchera sanguinea Hibiscus moscheutos Hosta species and hybrids Iberis sempervirens Incarvillea delavayi Iris tall bearded dwarf bearded Siberian 63 Uses Species and hybrids Q < X oo 00 5 oo H O oo < LiJ as < oo 5 GO >- OS Q oo as o -J O z as 0- 00 oo as O -J Li- as LJU 00 oo as o u. -j < Li. 00 OS o -J Li. f- U oo as o Li. Q as Q oo as LJU O -J u. H Z < as a < as Li, LJU a < o Li. H Z < as O < as Li. Kniphofia uvaria X X Lamiastrum galeobdolon (= Lamium galeobdolon) X Lathyrus latifolius X X X Liatris L. pycnostachya X X X L. scariosa X X X L. spicata X X Lilium hybrids X X X Limonium latifolium X X Linum L. flav urn X X L. perenne X X Lunaria annua X X Lupinus hybrids X X Lychnis L. chalcedonica X X X L. coronaria X X Lysimachia punctata X X X X Lythrum hybrids X X X X X Macleaya cordata X X Mertensia virginica X X Monarda hybrids X X X X X X X Nepeta N. xfaassenii X X N . grandiflora X X Oenothera O. missouriensis X X X O. tetragona X X x 64 Species and hybrids UJ Q < X CO GO -J 5 GO H GO 00 < UJ OS < H UJ CO OS UJ £ O CO . J -J UU O a CO z >- o< OS CL Q CO Uses co OS UJ O -J uu OS UJ CO CO OS UJ o -J uu -J -J < Uu co as UJ o _J uu H U co aS UJ O _J tu Q 5 Q co as UJ O -J uu H Z < as a < as uu UJ a < Lj o H Z < as a < as UU Paeonia hybrids Papaver orientale Penstemon hybrids Phlox P. paniculata P. subulata Physalis alkekengi Physostegia virginiana Platycodon grandiflorus Polemonium caeruleum Polygonum cuspidatum Potentilla hybrids Primula P. denticulata P. japonic a P. Xpolyantha P. sieboldii Pulmonaria P. angustifolia P. saccharata Rudbeckia R. fulgida var. speciosa R. laciniata Salvia S. azurea S. sclarea S. Xsuperba Sanguinaha canadensis Saponaria officinalis * Seed heads. X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X 65 Uses Species and hybrids LU Q < 00 oo -J o oo 00 o 00 < LU aS < LU 00 -J o 00 >- as Q 00 O -j u. O z as a. oo aS LU O Li. as LU S oo oo as LU o -J _j < Li. oo 06 LU o UL U oo C6 LU o -J Li. Q LU a oo as LU Li. H Z < a: a < as Li. LU a < 23 o Li. H Z < aS a < as Li. Scabiosa caucasica X X X Sedum spectabile X X X X Sidalcea hybrids X X X X Solidago hybrids X X X X x Solidaster luteus X Stokesia laevis X Thalictrum T. aquilegifolium X X X X T. flavum X X X X X T. rochebrunianum X X X X Trade scantia hybrids X X Trillium species X X X Trollius T. asiaticus X X X X X T. europaeus X X X X X Veronica V. incana X X V . latifolia X X V. spicata X X X Viola hybrids X X X X X X 66 PLANT SOCIETIES The following societies specialize in the culture of perennials. Consult them for information on the best types for growing in your area and advice on where to obtain the species and hybrids in which you are interested. Alpine and rock garden Alpine Garden Club of British Columbia Josephine Bridge 1310 W King Edward Avenue Vancouver, B.C. V6H 1Z9 American Rock Garden Society Mr. Norman Singer Norfolk Road South Sandisfield, MA 01255, USA Vancouver Island Rock and Alpine Garden Society Mrs. E. Harkness 575 Towner Rd. R.R. 1, Sidney, B.C. V8L 3R9 Beardtongue American Penstemon Society Mr. O. M. Steward P.O. Box 33 Plymouth, VT 05056, USA Chrysanthemum Canadian Chrysanthemum and Dahlia Society Mr. L. Dickson 24 Eden Mills Dr. West Hill, Ont. M1E 4L2 Day-lilies American Hemerocallis Society Mrs. A. W. Parry Signal Mountain, TN 37377, USA 67 Iris American Iris Society Mr. R. Mullin ' Route 3 Pawnee, OK 74058, USA Canadian Iris Society Miss J. Laurin 199 Florence Avenue Willowdale, Ont. M2N 1G5 Lily Canadian Prairie Lily Society Dr. E. A. Maginnes 614 Acadia Drive Saskatoon, Sask. S7H 3V9 North American Lily Society Mrs. D. B. Schaefer R.R. 2, Box 33 Waukee, IO 50263, USA Ontario Regional Lily Society Mrs. G. Brown R.R. 1 Harley, Ont. NOE 1E0 Peony American Peony Society Mrs. G. Kessenich 250 Interlachen Rd. Hopkins, MN 55433, USA Plantain-lily American Hosta Society Mrs. O. Langdon 5605 1 1 Avenue South Birmingham, AL 35222, USA Primrose American Primrose Society Mr. G. K. Fenderson Grout Hill South Acworth, NH 03607, USA 68 KEY TO SCIENTIFIC NAMES Preferred common names are listed alphabetically in roman type in the left column, with the scientific names under which they appear in this publication in the right column. Synonyms for scientific names and alternate common names mentioned in the publication also appear in the left column, in italics. alpine aster Althaea alumroot Alyssum saxatile amethyst sea-holly anemone, Chinese anemone, grape-leaved anemone, Japanese anemone, snowdrop archangel, yellow Ar uncus Sylvester Asiatic globeflower aster, alpine aster, cornflower aster, Italian aster, New England aster, New York aster, Stokes' astilbe avens azure sage baby's-breath balloonflower bamboo, Chinese bamboo, Japanese barrenwort, large-flowered barrenwort, red bea-balm bearded iris, tall bearded iris, dwarf beardtongue belladonna delphinium bellflower, broad-leaved bellflower, clustered bellflower, creeping bellflower, milky bellflower, peach-leaved bergamot Bet, bouncing- Bethlehem-sage Aster alpinus see Alee a Heuchera see Aurinia saxatilis Eryngium amethystinum Anemone hupehensis Anemone vitifolia Anemone xhybrida Anemone sylvestris Lamiastrum galeobdolon see Aruncus dioicus Trollius asiaticus Aster alpinus Stokesia laevis Aster amellus Aster novae-angliae Aster novi-belgii Stokesia Astilbe Geum Salvia azure a Gypsophila paniculata Platycodon grandiflorus Polygonum cuspidatum Polygon um cuspidatum Epimedium grandiflorum Epimedium X rubrum Monarda hybrids Iris Iris Penstemon Delphinium x belladonna Campanula latifolia Campanula glomerata Campanula rapunculoides Campanula lactiflora Campanula persicifolia Monarda hybrids Saponaria officinalis Pulmonaria saccharata 69 black snakeroot bladdercherry blanketflower blazingstar bleedingheart bleedingheart, plume bleedingheart, western bloodroot bluebells, Virginia bluebonnets bluet, mountain bouncing-Bet broad-leaved bellflower bugbane, Kamchatka bulgeweed, carpet bugleweed, pyramid bugloss, Italian bugloss, Siberian butterfly delphinium campion, rose candytuft, perennial Canterbury-bells carpet bugleweed catmint catmint, large-flowered catnip centaurea, Persian Chinese anemone Chinese bamboo Chinese-lantern Chinese-lantern Chinese trumpettlower chrysanthemum Chrysanthem maximum cinquefoil clary clustered bellflower columbine columbine meadow-rue common delphinium common foxglove common monk's-hood common rose mallow common sea-lavender common yarrow coneflower coneflower, purple coralbells Cimicifuga racemosa Physalis alkekengi Gaillardia x grandiflora Liatris scariosa Dicentra spectabilis Di centra eximia Dicentra formosa Sanguinaria canadensis Mertensia virginica Scabiosa caucasica Centaurea montana Saponaria officinalis Campanula latifolia Cimicifuga simplex Ajuga reptans Ajuga pyramidal is Anchusa azurea Brunnera macrophylla Delphinium grandiflorum Lychnis coronaria Iberis sempervirens Campanula medium Ajuga reptans Nepeta xfaassenii Nepeta grandiflora Nepeta cataria Centaurea dealbata Anemone hupehensis Polygonum cuspidatum Physalis Physalis alkekengi Incarvillea delay ay i Chrysanthemum see Chrysanthemum x superbum Potentilla hybrids Salvia sclarea Campanula glomerata Aquilegia hybrids Thalictrum aquilegifolium Delphinium elatum Digitalis purpurea Aconitum napellus Hibiscus moscheutos Limonium latifolium Achillea millefolium Rudbeckia Echinacea Heuchera sanguine a 70 cornflower aster cottage pink creeping bellflower cushion mum cushion spurge daisy, Michaelmas daisy, Shasta day-lily delphinium, belladonna delphinium, butterfly delphinium, common dog-fennel dotted-leaved loosestrife dragonhead, false dropwort drumstick primrose dwarf bearded iris Epimedium coccineum euphorbia, myrtle Euphorbia polychroma European globeflower evening-primrose false dragonhead false starwort feather, Kansas fennel, dog- fernleaf yarrow Filipendula hexapetala flax, perennial flax, yellow fleabane foxglove, common foxtail-lily garden gloxinea garden loosestrife gasplant gayfeather, Kansas gayfeather, spike ghostplant giant rockfoil globeflower, Asiatic globeflower, European globe knapweed globe thistle, small gloxinia, garden gloxinia, hardy goafs-beard gold-dust Stokesia laevis Dianthus plumarius Campanula rapunculoides Chrysanthemum X morifolium Euphorbia epithymoides Aster Chrysanthemum X superbum Hemerocallis hybrids Delphinium X belladonna Delphinium grandiflorum Delphinium elatum Anthemis Ly si mac hi a punctata Physostegia Filipendula vulgaris Primula denticulata Iris see Epimedium Xrubrum Euphorbia myrsinites see Euphorbia epithymoides Trollius europaeus Oenothera tetragona Physostegia spp. Boltonia aster oides Liatris pycnostachya Anthemis spp. Achillea filipendulina see Filipendula vulgaris Linum perenne Linum flavum Erigeron Digitalis purpurea Eremurus Incarvillea delavayi Lysimachia punctata Dictamnus albus Liatris pycnostachya Liatris spicata Artemesia ludoviciana var. albula Bergenia cordifolia Trollius asiaticus Trollius europaeus Centaurea macrocephala Echi nops vitro Incarvillea delavayi Incarvillea delavayi Ar uncus dioicus Aurinia saxatilis 71 golden Marguerite goldenrod goldentuft madwort grape-leaved anemone Griffith's spurge hardy gloxinia harebell helmetflower hollyhock honesty Hungarian speedwell iris, tall bearded iris, dwarf bearded iris, Siberian Italian aster Italian bugloss Jacob's-ladder Japanese anemone Japanese bamboo Japanese knotweed Japanese-lantern Japanese primrose Kamchatka bugbane Kansas gayfeather knapweed, globe knotweed, Japanese La mi urn arge-flowered barrenwort arge-flowered catmint arge-flowered tickseed arkspur, perennial avender-mist eopard's-bane ily ily, day- ily, foxtail- ily-of-the-valley ily, plantain- ily, torch- oosestrife, dotted-leaved oosestrife, purple oose strife, garden oosestrife, yellow ungwort upin madwort nadwort, goldentuft naiden pink Anthemis tinctoria Solidago hybrids Aurinia saxatilis Anemone vitifolia Euphorbia griffithi Incarvillea delayvayi Campanula rotundifolia Aconitum napellus Alee a rosea Lunaria annua Veronica latifolia Iris Iris Iris Aster amellus Anchusa azure a Polemonium caeruleum Anemone x hybrida Polygonum cuspidatum Polygonum cuspidatum Physalis alkekengi Primula japonica Cimicifuga simplex Liatris pyenostachya Centaurea macrocephala Polygonum cuspidatum see Lamiastrum Epimedium grandiflorum Nepeta grandiflora Coreopsis grandiflora Delphinium Thalictrum rochebrunianum Doronicum Lilium hybrids Hemerocallis hybrids Eremurus Convallaria majalis Hosta species and hybrids Kniphofia Lysimachia punctata Lythrum hybrids Lysimachia punctata Lysimachia punctata Pulmonaria angustifolia Lupinus hybrids Aurinia saxatilis Aurinia saxatilis Dianthus deltoides 72 mallow, common rose mallow, prairie Maltese-cross Marguerite, golden meadow-rue, columbine meadow-rue, yellow meadowsweet Michaelmas daisy milky bellflower monk' s -hood, common moss pink mountain bluet mum mum, cushion myrtle euphorbia Nepeta mussinii New England aster New York aster Oenothera fruticosa var. youngii obedientplant orange sunflower Oriental poppy Oswego-tea Ozark sundrops pansy peach-leaved bellflower pea, perennial peony perennial candytuft perennial flax perennial larkspur perennial pea Persian centaurea phlox, summer pincushion flower pink, cottage pink, maiden pink, moss Pitchers sage plantain-lily plume bleedingheart plume poppy poker plant poinsettia polyanthus poppy, Oriental poppy, plume prairie mallow Hibiscus moscheutos Sidalcea hybrids Lychnis chalcedonica An the mis tine tor ia Thalictrum aquilegifolium Thai ictr um flavum Filipendula Aster Campanula lactiflora Aconitum nape 1 1 us Phlox subulata Centaurea montana Chrysanthemum X morifolium Chrysanthemum X morifolium Euphorbia myrsinites see Nepeta xfaassenii Aster novae-angliae Aster novi-belgii see Oenothera tetragona Physostegia virginiana Heliopsis hybrids Papaver orient ale Monarda hybrids Oenothera missouriensis Viola hybrids Campanula persicifolia Lathyrus latifolius Paeonia hybrids Iberis sempervirens Linum perenne Delphinium Lathyrus latifolius Centaurea dealbata Phlox paniculata Scabiosa caucasica Dianthus plumarius Dianthus deltoides Phlox subulata Salvia azurea Hosta species and hybrids Dicentra eximia Macleaya cordata Kniphofia uvaria see Euphorbia Primula x polyantha Papaver orient ale Macleaya cordata Sidalcea hybrids 73 primrose, drumstick primrose, evening- primrose, Japanese primrose, Siebold's purple coneflower purple loosestrife pyramid bugleweed pyrethrum queen-of-the-meadow queen-of-the-prairie red barrenwort red-hot-poker rock cress, wall rockfoil, giant rose campion sage, azure sage, Bethlehem- sage, Pitchers sage, superb Salvia pitcheri scabious sea-holly, amethyst sea-lavender, common Shasta daisy showy stonecrop Siberian bugloss Siberian iris Siebold's primrose silver-dollar-plant small globe thistle snakeroot, black sneezeweed sneezewort snowdrop anemone soapwort speedwell, Hungarian speedwell, spiked speedwell, wooly spiderwort spiked speedwell spike gayfeather spurge, cushion spurge, Griffith's starwort, false Statice Stokes' aster stonecrop, showy summer phlox Primula denticulata Oenothera tetragona Primula japonic a Primula sieboldii Echinacea Lythrum hybrids Ajuga pyramidalis Chrysanthemum coccineum Filipendula ulmaria Filipendula rubra Epimedium x rubrum Kniphofia uvaria Arabis caucasica Bergenia cor di folia Lychnis coronaria Salvia azure a Pulmonaria saccharata Salvia azurea Salvia Xsuperba see Salvia azurea Scabiosa Eryngium amethystinum Limonium latifolium Chrysanthemum x superbum Sedum spectabile Brunnera macrophxlla Iris Primula sieboldii Lunaria annua Echinops ritro Cimicifuga racemosa Helenium Achillea ptarmica Anemone sylvcstris Saponaria Veronica latifolia Veronica spicata Veronica incana Tradescantia hybrids Veronica spicata Liatris spicata Euphorbia epithymoides Euphorbia grijfithi Boltonia asteroides see Limonium latifolium Stokesia Sedum spectabile Phlox paniculata 74 sundrops, Ozark sunflower sunflower, orange superb sage sweet-William tall bearded iris thistle, small globe thread-leaved tickseed tickseed, large-flowered tickseed, thread-leaved torch-lily trumpetflower, Chinese vetchling violet Virginia bluebells wake-robin wall rock cress western bleedingheart windflower wooly speedwell wormwood yarrow, common yarrow, fernleaf yellow archangel yellow flax yellow loosestrife yellow meadow-rue Oenothera missouriensis Helianthus hybrids Heliopsis hybrids Salvia X superba Dianthus barbatus Iris Echi nops ritro Coreopsis verticillata Coreopsis grandiflora Coreopsis verticillata Kniphofia Incarvillea delavayi Lathyrus Viola hybrids Mertensia virginica Trillium species Arabis caucasica Dicentra formosa Anemone Veronica incana Art erne sia Achillea millefolium Achillea filipendulina Lamiastrum galeobdolon Linum flavum Lysimachia punctata Thalictrum flavum 75 CONVERSION FACTORS Metric units LINEAR millimetre (mm) centimetre (cm) metre (m) kilometre (km) Approximate conversion factors Results in x 0.04 inch x0.39 inch x 3.28 feet x 0.62 mile AREA square centimetre (cm2) square metre (m2) square kilometre (km2) hectare (ha) x 0.15 square inch x 1.2 square yard x 0.39 square mile x 2.5 acres VOLUME cubic centimetre (cm3] cubic metre (m3) CAPACITY litre (L) hectolitre (hL) WEIGHT gram (g) kilogram (kg) tonne (t) x 0.06 cubic inch x 35.31 cubic feet x 1.31 cubic yard x0.035 cubic feet x 22 gallons x 2,5 bushels x 0.04 oz avdp x 2.2 lb avdp x 1.1 short ton AGRICULTURAL litres per hectare (L/ha) x 0.089 x 0.357 x 0.71 millil itres per hectare (mL/ha) x 0.014 tonnes per hectare (t/ha) x 0.45 kilograms per hectare (kg/ha) x 0.89 grams per hectare (g/ha) x 0.014 plants per hectare (plants/ha) x 0.405 gallons per acre quarts per acre pints per acre fl. oz per acre tons per acre lb per acre oz avdp per acre plants per acre DATE DUE DATE DE RETOUR FEB 7 £ FEV L J 1986 ,1988 M ^iR - 3 1995 rrnn v* ■ AOUT L L 1990 LOWE-MARTIN No. 1137 630.4 C212 P 1754 1983 OOAg Cole, Trevor J. Perennials in your garden im^nARLi BI8LIOTHEQUE AGRICULTURE CANADA OTTAWA " A OC5 3 ^073 0002330b b