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INCLUDE THE ARBORETUM FOUNDATION IN YOUR ESTATE PLANS~ The best in perennials and flowering shrubs Bare-root & potted David Austin & Old Roses Herbaceous & Tree Peonies 16215 140th PL NE • Woodinville, WA 98072 483-9382 V J Arrays nuRHRitt Over 50 pears of quality plants and service Since 1940 Growers and Propagators of Choice Nursery Stock Seattle ^ Bellevue ❖ Bremerton A personal approach to professional asset management and trust administration Niki Hermanson 206*464*5209 Barbara Potter 206*464*5292 Norton Building 801 Second Avenue, 16th Floor Seattle, WA 98104 Washington Park Arboretum Bulletin VOLUME 59, NUMBER 1 Published by The Arboretum Foundation for the University of Washington The Arboretum Foundation (206) 325-4510 FAX: 325-8893 Gift Shop: 543-8800 UW Programs: 543-8800 THE ARBORETUM FOUNDATION OFFICERS John Behnke, President Vice Presidents: Deborah Andrews Duane Kelly STAFF Susan Hebert, Executive Director Cindy Jackson, Adminis- trative Assistant Pam Tharl, Bookkeeper Carol Niccolls, Secretary Jane Searing, Treasurer Steve Garber, Immediate Past President CONTRACTORS Elliott Bronstein, Editor, Ground Work Regen Dennis, Public Relations Jan Silver, Editor/Designer, Arboretum Bulletin EDITORIAL BOARD WASHINGTON PARK ARBORETUM BULLETIN Jan M. Silver, Editor/ Designer Tom Berger, The Berger Partnership, Landscape Architects Richard Contreras, Arboretum Foundation liaison; VP Corporate Communications, Northern Life Jeannine Curry, Secretary Valerie Easton, Book Review Editor; librarian, Center for Urban Horticulture Stephanie Feeney, author Daniel J. Hinkley, Heronswood Nursery, Ltd. Arthur R. Kruckeberg, Ph.D., UW Department of Botany Steven R. Lorton, Northwest Bureau Chief, Sunset Magazine Ciscoe Morris, Horticul- turist, Seattle University Sue M. Nicol, Horticultur- ist, Woodland Park Zoo Jan Pirzio-Biroli, The Arboretum Foundation Mary Robson, Extension Agent, King County Richard Walker, Ph.D., Professor Emeritus, UW Department of Botany Jan Kowalczewski Whitner, author John A. Wott, Ph.D., Director, Arboretum Martha Wingate, Student, Center for Urban Horticulture UNIVERSITY OF WASHINGTON John A. Wott, Ph.D., Director, Arboretum Tracy Omar, Assistant Curator and Recorder Christina Pfeiffer, Horticulturist Dana Kirley, Education Coordinator Barbara Selemon, Propagator Dave Stockdale, Education Coordinator UNIVERSITY OF WASHINGTON CENTER FOR URBAN HORTICULTURE Clement W. Hamilton, Ph.D., Director CITY OF SEATTLE DEPARTMENT OF PARKS & RECREATION Ken Bounds, Acting Superintendent Where in the Arboretum? The cover Find Ilex aquifolium ‘Rubicaulis Aurea’ near WPA’s Holly section, one of the finest such collec- tions in the United States. Ask the reception- ist at GVC to mark 6-3E and 7-3E on your map of the Arboretum. Concerning This Issue... The change in the air goes beyond fall turn- ing to winter and the twentieth century rapidly moving into the twenty-first. From now on, in addition to bringing you gardening ideas and information, the Bulletin will explain how WPA’s growth and change is shaping up to meet your needs. WPA is putting together a master plan — guidelines to help make the collections, grounds, and services of WPA more useful to the public. If you would like to be part of this change, please call us to volunteer. We can use advice, as well as support, in the Washington Park Arbo- retum.— Jan Silver, Editor The Washington Park Arboretum Bulletin is published quarterly as a bonus of membership in The Arboretum Foun- dation, Seattle, Washington. Volume 59:1 © 1996 The Ar- boretum Foundation. ISSN 1046-8749. The Arboretum Foundation is a non-profit organiza- tion that was chartered to further Washington Park Arbo- retum development, projects, and programs through volunteer service and Find raising. Its mission is to ensure stewardship for the Washington Park Arboretum, a Pacific Northwest treasure, and to provide horticultural leadership for the region. This stewardship requires effective leader- ship, stable funding, and broad public support. WPA is administered cooperatively between the Uni- versity of Washington, its Center for Urban Horticulture (CUH), and the City of Seattle Department of Parks and Recreation. The programs and plant collections are a re- sponsibility of CUH. WPA is a living plant museum emphasizing trees and shrubs hardy in the maritime Pacific Northwest. Plant col- lections are selected and arranged to display their beauty and function in urban landscapes, to demonstrate their natu- ral ecology and diversity, and to conserve important species and cultivated varieties for the future. The Arboretum serves the public, students at all levels, naturalists, gardeners, and nursery and landscape professionals with its collections, edu- cational programs, interpretation, and recreational oppor- PHOTO BY JOY SPURR tumties. Contents 22 Where in the Arboretum P Finding woody plants in this issue Inside cover: Holly (on cover) 5 Pernettya & Gaultheria 10 Madrone 21 Container trees & shrubs 22 Conservation trees in WPA Departments 14 New on the Shelves: Creating Fine Gardens by Valerie Easton Book Reviews 15 Rock Garden Plants of North America reviewed by Alice Lauber 16 North American Landscape Trees reviewed by Jim Clark 22 In the Washington Park Arboretum by John A. Wott Peatures 4 Next for the Genus Pernettya by Brian O. Mulligan 5 Pernettya and Gaultheria in WPA by Christina Pfeiffer 6 Garden with a Mission — Washington Park Arboretum by Clement W. Hamilton & John A. Wott 8 Managing Pacific Madrones in the City by Dana Kelley Bressette 10 Finding Madrones at WPA by Christina Pfeiffer 12 Winter Shrub from Down Under — Grevillea victoriae by Michael Lee 17 Using Woody Plants in Containers by Richard W. Hartlage 26 Torch Lilies for All Seasons by Roger Pierce 26 Wintergreen (Gaultheria procumbens ) Next for the Genus Pernettya PHOTO e^TEXT BY BRIAN O. MULLIGAN Pernettya is increasingly popular for its richly colored fall berries. In his final article, Director Emeritus Mulligan explains why Pernettya merged into the genus Gaultheria , familiar for wintergreen and salal. The genus Pernettya was designated by a French botanist, Charles Gaudichaud- Beaupre in 1825, to honor Antoine J. Pernetty, author of the history of Bougainville’s voyage to South America. He then transferred Linnaeus’ Arbutus mucronata of 1781 to his new genus, eventually followed by other authors who added other newly discovered species. The principal characters of plants in Pernettya were their evergreen shrubby habit, the flower anthers with two short, upright spurs instead of being long and reflexed as in Arbutus and Arctostaphylos , and primarily the fruits, which were a five-celled berry instead of a capsule as in Gaultheria. Gaultheria had been created earlier by Carolus Linnaeus in his famous Genera & Spe- cies Plantarum of 1753, to commemorate Doc- tor Gaultier, a physician of Quebec city. Gaultheria procumbens (wintergreen), a North American native, was the intial species named then. Gaultheria hispida from Tasmania (1810) and G. shallon (salal) from the Pacific west coast (1814) came next. Many more succeeded these species from eastern Asia, New Zealand, and cen- tral and south America, as plant explorers found and introduced them. About 200 Gaultheria species are now known. In their 1935 discussion of these two gen- era in New Zealand, Tasmania, and Australia, B. L. Burtt and Sir Arthur Hill of The Royal Botanic Gardens, Kew, London, described eight species of Gaultheria and four of Pernettya. They also noted six different hybrids among the gaultherias from New Zealand, the majority from the North Island, and five between Gaultheria and Pernettya species on both islands wherever the parent species occurred. Although recogniz- ing so many hybrids between the two genera, Burtt and Hill did not at this time suggest unit- ing them, believing that more field study was needed. Dr. Hermann Sleumer of Leiden, the Netherlands, who revised the genus Pernettya twice, in 1935 and again in 1985, continued its separation from Gaultheria in his work. In a doc- toral thesis in 1969, however, P. F. Stevens at Edinburgh University concluded that Pernettya was not maintainable as a genus. Then in 1990, a thorough and very de- tailed account was published by D. J. Middleton and C. C. Wilcock of the University of Aber- deen. They studied all the different facets of the species of Pernettya and Gaultheria , both in liv- ing and dried material. There was overlap. In the characters of the fruits, which have been principally used to sepa- rate the two genera in the past, they found some pernettyas with fleshy calyces (e.g., P. laneeolata ), some gaultherias with dry ones (e.g., G. wardii ), and some in which they are fleshy in varying degrees (e.g., P. pumila , P. tasmanica). In such features as leaf shape and size, indumentum, se- pals, and ovary, the two genera also overlap. The basic chromosome number for all species is 1 1, although some are tetraploid with 44, and one species, G. insana (from Chile), even has some hexaploid plants. The original article concludes, “Thus Pernettya should not be maintained as a sepa- rate genus from Gaultheria , the only character which separates them being the fruit which even then is not completely discontinuous.” The au- thors also list Gaultheria species with their syn- onyms; some of these we grow in the Northwest from time to time when available. They include: G. laneeolata ; G. macrostigma ; G. mucronata with varieties angustifolia and mierophylla\ G. myrsinoides (P. prostrata ); G. parvula (P. nana)\ G. poeppigii var. linifolia ( R linifolia ); G. pumila var. leucoearpa ( P leucocarpap and G. tasmanica. Although not mentioned in this article, all other hybrids previously named as X Gaulnettya are now to be included in Gaultheria under this decision: e.g, G. x w isleyensis and G. x oaxacana (from Mexico). In a letter to The Plantsman (1991), D. J. Middleton provides the history of the former hybrid and adds a Latin descrip- tion to validate the name. 4 Washington Park Arboretum Bulletin Where in the Arboretum? Pemettya & Gaultheria ,f>*y » — if/ & In a visit to the Joseph Witt Winter Garden, you can see Pemettya littomlis , Gaulth- eria procumbens (wintergreen), and Gaultheria shallon (salal). The labels have not yet been changed to reflect the umbrella genus, Gaultheria. Observe the taxonomic relationships discussed, as well as the function of these plants in a garden setting. Pemettya littoralis is planted near the Stewartia monodelpha at the north entrance (35- 1E on WPA map). Native to Chile, these plants were grown from wild- collected seed. This species has not been widely grown in the region, but looks to be a good addition. It is nearly a foot tall, and spreads by underground stems into a nice mass planting. P. littoralis was added to the garden as a ground cover, and for its glossy evergreen foliage and winter berry display. Gaultheria procumbens is growing beneath the variegated holly at the southeast side of the garden (34- IE). This very low-growing ground cover has leathery, oval leaves and bright red edible berries in winter. It is delicate to get established but well worth the effort for a woodland or naturalized garden setting. Northwest native Gaultheria shallon can be seen along the naturalized east edge of the garden. Another interesting plant related to this group is the garden hybrid Arbutus 'Marina' (35-1E). A medium-sized tree, it carries the characteristic dramatic bark of the Pacific mad- rone parent with the prolific fall flower display of the other parent, Arbutus unedo (the straw- berry tree). Ground-cover Aretostaphylos uva-ursi (kinnikinnick) is growing nearby. Travel south to the Rhododendron Glen parking lot to see a fine mature specimen of Gaultheria x wisleyensis 'Wisley Pearl' ( 12-8E). It is growing on sexes. Several cultivars featuring single berry colors are available at nurseries. Gaultheria and Pemettya can take some effort to get established in the garden, but once they get a foothold are fairly trouble free. They prefer slightly acidic organic soils, as do other ericaceous plants. Extra attention to watering during the first few years of establishment is vital. WPA lost several Pemettya plants, but those that established are vigorously spreading into the remaining space. Gaultheria can be slow to establish, and plants with some shelter at the edge of other shrubs seem to survive best, later spreading out into the more open areas. Most can be propagated by layers or by cuttings. The many species and selections of Pemettya and Gaultheria are very worthy additions for Northwest gardens. — Christina Pfeiffer, hor- ticulturist, WPA Drawings: Plant Kingdom Compendium References Burtt, B. L., and Sir A. W. Hill. 1935. “The Genera Gaidtheria and Pemettya in New Zealand, Tasmania, and Australia.” Jour. Linnean Soc. Botany 49 ( 332 ) :6 1 1-645. Middleton, D. J. December 1991. “ Gaultheria x wisleyensis , a Not So New Hybrid.” The Plantsman 13 (3):1883-1890. Middleton, D. J., and C. C. Wilcock. 1990. “A Critical Examination of the Status of Pemettya as a Genus Distinct from Gaultheria .” Edinburgh Journal oj' Botany 47(3) :29 1- -301. Vol. 59:1 5 Photo: (formerly) Gaulnettya wisleyensis ‘Wisley Pearl) line drawing: formerly ) Pemettya mucronata Garden with a r^ission Washington Park Arboretum BY CLEMENT W. HAMILTON AND JOHN A. WOTT a All of us have found ourselves explaining to friends and acquain- tances the purpose and signifi- cance of the Washington Park Arboretum. Our need to do so is especially important as we plan the Arboretum’s renewal for the next century. People who use WPA and plan for it want to know: What is an arboretum? What makes the Washington Park Arboretum special? Whom does the Arboretum serve, and how? Answering just those questions in a concise and complete manner is the purpose of an or- ganizational mission statement. All three partners in the Arbore- tum— the University of Washington Center for Urban Horticulture, the City of Seattle Depart- ment of Parks and Recreation, and the Ar- boretum Foundation — have their own mission statements, which work well. So it was decided in late 1995 that a good mission statement is nec- essary for the Arbore- tum itself. The task of creat- ing a mission statement was assigned to The Arboretum and Botanic Garden Com- mittee (ABGC). The committee is com- posed of representa- A mission statement should be ajjood script to explain an institution V purpose duinpf a one-minute elevator ride. Becca Hanson ■, The Portico Group V he Washington Park Ar- boretum is a living plant mu- seum emphasizing trees and shrubs hardy in the maritime Pacific Northwest. Plant collections are selected and arranged to display their beauty and function in urban landscapes, to demonstrate their natural ecol- ogy and diversity, and to conserve important species and cultivated varieties for the future. The Arbore- tum serves the public, students at all levels, naturalists, gardeners, and nursery and landscape profes- sionals with its collections, educa- tional programs, interpretation, and recreational opportunities. dves from all three of WPA’s part- ner organizations, a neighbor- hood representative, and a Governor’s appointee. First, the University of Wash- ington generated ideas and a draft statement. Many staff, students, and constituents contributed to this first phase, bringing forth enough good concepts to fill a book. ABGC then sought to combine the most essential ideas into draft mission statements. Along the way, the committee also surveyed mission statements of other public gardens and found several re- curring forms. Some were extremely com- pact and memorable but too generic, such as this one: “To dis- cover and share knowledge about plants and their envi- ronment in order to preserve and enrich life.” That’s fine, but where is the unique- ness? Other gardens took a more expan- sive approach, with statements consisting of many paragraphs that were admirably complete but lacked a concise, easily re- membered central message The Arboretum’s master plan for the 6 Washington Park Arboretum Bulletin coming century is being led by The Portico Group, Seattle planners. As Becca Hanson of that firm noted, “A mission statement should be a good script to ex- plain an institution’s purpose during a one-minute elevator ride.” The most effective mission statements begin with a memorable core sentence that differentiates the garden in question from all other gardens, museums, and institutions by emphasizing its unique aspects. In summer 1995, we submitted two draft statements to the ABGC, which over the next several months, along with its other business during these exciting times, were discussed, edited, discussed, and edited again. Finally, on January 4, 1996, the Committee voted to adopt the mis- sion statement boxed on the opposite page. Note that the first sentence, printed in boldface, is the core state- ment that can stand alone where a short statement is required, say for that one- minute elevator ride. The second sentence elaborates on the purposes of the plant collections, and the third sentence explains who the Arboretum audiences are and how they are served. A good mission statement can be adapted and amended as an in- stitution evolves. Accordingly, the Arboretum looks forward to the evolution of this statement even as the Arboretum evolves. We are pleased to offer this mission statement to all of the Arboretum’s constituents and hope you find it useful when you ex- plain to people why the Arboretum deserves their support and inter- est, and how it benefits all the people of the Pacific Northwest. These are heady times, when the Arboretum’s message must reach as many persons as possible. We believe that ours is the right message for the times. cc We are pleased to offer this mission statement to all the Arboretum’s constituents..^^ Clement Hamilton is director, University of Washington Center for Urban Horticulture. John Wott is director, Washington Park Arboretum. Vol. 59:1 7 Pacific Madrones in the City PHOTOS & TEXT BY DANA KELLEY BRESSETTE One of the most interesting and pic- turesque trees in the Pacific Northwest is the Pacific madrone, Arbutus menziesii. Its reddish, peeling bark and often leaning trunks make it an especially attractive feature of many landscapes. This ericaceous cousin to huckleberry, heather, salal, and rhodo- dendron is the only large broadleaved evergreen tree native to the Puget Sound region. It is com- monly found clinging to rocky south- or west- facing bluffs above Puget Sound. Caring for Madrones Pacific madrones in a landscape require minimal care. They do best with little or no com- petition. Native shrubs such as salal ( Guultheria shallon) are the preferred companions, although madrones may do well in grassy areas as long as the area is well drained. Keep in mind, however, that madrones are messy trees: They shed leaves and bark throughout the summer. Allowing fallen leaves to remain on the ground or mulch- ing with fine bark or other materials may pro- vide many benefits including suppression of competitors. Fertilization and irrigation are not required. Avoid severe pruning, especially limbing that ex- poses bark, although removal of dead branches may be necessary. Moderate trimming or pinch- ing to encourage bushiness may increase vigor. Tall, spindly madrones in new housing develop- ments are perhaps best cut down and allowed to stump sprout, thus creating a bushy tree that better adapts to the new environment. Although madrones may not acclimatize well after development, they appear to be very successful at colonizing after a disturbance. Healthy madrones can often be seen along road- sides and logged areas. When Canker is a Culprit Unfortunately, many established trees can have dead or dying twigs and branches. Large, old madrones in parks and landscapes, highly valued for their aesthetic appeal, are in decline. Concerned citizens such as the neighborhood group “Save Magnolia’s Madrones” want to know if it is possible to slow or halt their de- mise. This group funded my research at the Cen- ter for Urban Horticulture and several other projects being conducted at the University of Washington. On the bright side, although many diseases may infect the Pacific madrone, healthy young trees can be found bearing fruit quite abundandy. Although many individual trees are dying, there is no evidence that the entire species is at risk. Canker diseases are having the greatest im- pact on madrones. Most simply put, a canker is a dead spot on the trunk or branch. As time passes, a sunken area is created by growth of healthy tissue around the dead tissue. Cankers are often caused by fungal infection and may grow larger as the disease advances. 8 Washington Park Arboretum Bulletin opposite page: Spindly madrones in new developments are best cut down and allowed to regenerate through stump sprouting. left: The progression of disease can easily be seen on this severely cankered old madrone at Richmond Beach Recreational Park , north of Seattle. below: Carved graffiti is a common sight on the smooth bark of Pacific madrone. Look for the following characteristics of four types of cankers observed on Pacific mad- rone: 1 . a smooth and apparently healthy margin; 2. a necrotic or dead region at the margin of the canker, suggesting advancing disease; 3. a necrotic region accompanied by cal- lusing (extra cell growth); this matches the de- scription for hendersonula dieback caused by the fungus Nattrassia mangiferae (formerly Hendersonula toruloidea). 4. blackened bark indicating rapid death of stem tissue. Damage to bark can predispose trees to in- fection. Infection may also occur in unwounded trees under specific conditions, i.e., 25°C or 72°F for hendersonula dieback. Damage may result from natural events: wind may cause broken limbs or rubbing branches; freezing may cause sunscald or frost cracking; rodents or insects may chew or bore holes in the bark. People cause damage in many ways: Lawn mowers and line trimmers often are brought too close to the base of trees; pruning can create open wounds; people climbing on leaning trunks cause abrasion; nails are used to post signs, and Vol. 59:1 9 Where in the Arboretum? Finding Madrones at WPA A backdrop of large native trees provides Northwest character to the Washington Park Arboretum. Pacific madrones are well distributed throughout this matrix of native vegetation. The striking colors and form of the madrone are vital to WPA’s natural landscape. These beautiful trees add a grace and presence not matched by any other native species. The various maladies noted in Dana Bressette’s article are, unfortunately, also well represented at the Arboretum. We estimate that at least half of the existing trees are in some stage of decline, and we probably lose close to ten percent of the population annually. Over the last three years, eleven trees have been removed. While dead trees appear each year, so do healthy young seedlings. We are encouraged by the appearance of these new trees, which are retained when they sprout in locations that will allow them to develop to maturity. Some come up in inappropriate locations, however, and must be weeded out. Pacific madrone appears mostly in areas of higher elevations with pre- dominantly glacial till soils. These locations include: the higher elevations on Foster Island, the Pinetum, the tops of Yew and Honeysuckle hills, and the larger area encompassing the Hamamelis (witch hazel) collection, Holly col- lection, and the south woods above the rockery. In our efforts to retain a good madrone population at the Arboretum, we have been a test site for some of the ongoing research being conducted at the University of Washington. Some new trees planted here are part of those studies, such as Tony Shoffner's work. — Christina Pfeiffer ; horticulturist , WPA make treehouses or benches; and graffiti is of- ten found carved into the smooth bark of mad- rones. Another factor that increases the suscepti- bility of madrones to canker diseases is exposure of the trunk and branches to the sun. The re- sulting geometry of an individual madrone is highly influenced by light availability during its lifetime. Trees that have been growing in full sun tend to have a bushy growth habit so that a thick canopy of leaves protects the bark. Mad- rones growing under other trees or at a forest’s edge often lean as they continuously seek light. Madrones in a forest grow tall to reach the top of the canopy as they compete with other trees. Building development severely impacts mad- rones when previously shaded trunks and branches become exposed. Thick bark that de- velops on older branches and trunks (larger than four inches in diameter) in the shade sloughs off when exposed to the sun’s heat. You can readily observe this phenomenon on many trees where thick bark has been retained on the north side of the stem but has peeled off of the south side. The thin, reddish bark is more susceptible to damage and infection than thick bark. Poor drainage may also increase suscepti- bility to canker diseases. You often will find can- kers near the base of trees in soils with low permeability. The density of madrones and the number of diseased trees in an area also influ- ence susceptibilty of individual trees. Genetic variability of disease resistance or susceptibility may play a signficant role. Replanting is likely to be successful where the number of diseased trees in an area is not too high. Tony Shoffner, a graduate student at the Center for Urban Horticulture, is studying 10 Washington Park Arboretum Bulletin A CALLUSED CANKER, TYPICAL OF HENDERSONULA DIEBACK. the effects of light intensity, irrigation, and soil inoculation on newly planted madrones. Another graduate student in the UW Col- lege of Forest Resources is working on identi- fying the pathogens that infect madrones. The ultimate research goal will be to de- velop disease-resistant varieties and ways to propagate them. Even though many individual madrones are doomed, with knowledge of how to better care for them in the urban environment and with re- planting efforts, the Pacific madrone should con- tinue to be a valuable ornamental tree. More Reading Adams, A.B., and Clement Hamilton. 1997. Decline of the Pacific Madrone (proceedings of the Madrone Symposium, April 28, 1995, Seattle). Center for Urban Horticulture. Bressette, Dana K. 1995. “Determining Causes of Decline of Pacific Madrone in Urban Landscapes of the Pacific Northwest.” Master’s thesis, available at the Elisabeth C. Miller Library, Center for Urban Horticulture, Seattle. Davison, A. D. 1972. “Factors Affecting Develop- ment of Madrone Canker.” Plant Disease Reporter 56:50-52. Hunt, R. S., B. Callan, and A. Funk. 1992. “Common Pests of Arbutus in British Columbia. Pacific Forest Research Centre, Canadian Forest Service, pest leaflet FPL 63. MacDonald, P. M., and J. C. Tappeiner. 1990. “Arbutus menziesiiP In: Silvics of North America. Burns, R. M., and B. H. Honkala, technical coordinators. 2: 124-132. Dana Kelley Bressette has a master’s degree from the University of Washington Center for Urban Hor- ticulture. Vol. 59:1 11 A new introduction for the hummingbird in winter. Winter Shrub from Down Under — Grevillea victoriae PHOTO C^TEXT BY MlCHAEL LEE Australia is one of those warm and sunny places that beckon when the wet gloom of winter approaches. Alas, few of us can escape to such balmy climates regularly, and few plants from those climates are hardy in Northwest gardens. One Australian shrub that shows remarkable promise here, however, is Grevillea victoriae. The grevilleas in all their diversity are staples in California, from the towering, feathery silk-oak, G. robusta , to a range of sprawling shrubs with small leaves and flowers in orange and scarlet. A few 12 Washington Park Arboretum Bulletin of the hardiest have grown for years in warmer Northwest gardens, among them G. juniperinu f. sulphured and G. rosmarinifolia. Other members of the protea family seen in Northwest gardens include the Chilean fire tree, Embothrium coccineum , exploding with flaming orange flowers in May, and an occasional Lomdtid grown for its handsome divided foliage. Last winter, the hybrid Grevilleu Torrinda Constance’ in my garden carried its tubular scarlet flowers right through the 20°F January freeze. What ten de- grees more would have done to it may be another matter, but the genus clearly warrants further experimentation. I was introduced to Grevilleu victoriae by the late, great California plantsman, Marshall Olbrich. At his Western Hills Nursery, a horticultural mecca west of Santa Rosa, California, he showed me a gorgeous eight-foot specimen in full bloom in November and insisted I take a starter home to try. I expected it would collapse at the first serious frost, but Marshall felt I would be pleasantly surprised. How right he was! Like most plants from the Southern Hemisphere, G. victoriae (which lacks a common name) is almost explosively fast growing. One-gallon plants reach four to six feet in a few years. Largest Seattle-area plants are nearly eight feet tall. The growth is strongly but gracefully erect, with luxuriant evergreen foliage on slen- der, silvery beige twigs. The narrowly ovate, two- to four- inch leaves are green above, silver and hairy below, giving much the same color impression as Seneeio ‘Sunshine’. In late summer, the long flower show begins. Clustered buds in metallic orange gradually expand to nearly an inch long, each bloom decorated with a long, curling stigma. By November, twenty or more luminous red-orange flow- ers crowd each pendant cluster. The exotic display continues through almost any weather, well into spring. Our growing winter population of Anna’s humming- birds should be thrilled with these blooms. Grevilleu needs whatever Australian -like conditions we can provide. Adequate drainage and full sun will do in warmest zones; add a sheltering wall and perhaps overhead eaves in colder areas. We have no data yet, but its outstanding perfor- mance elsewhere suggests this beautiful shrub is well worth a try west of the Cascade range. Few shrubs are easier to grow. Grevilleu species are very drought-hardy and should not be watered once established. They and the other pro teas dislike phosphorus and neither need nor want fertilizer. Even in poor soil, they grow fast and lush. Once settled in, G. victoriae quickly makes a handsome and healthy shrub at least as tall as the gardener and four to six feet wide. This distinctive plant is also easy to propagate. I take three- to four- inch cuttings in July or August, wound them, dip in liquid rooting solution, and stick into perlite under mist. They should also root well in sand with a plastic bag over the pot. Even without bottom heat, the cuttings root by fall. With silvered foliage, exotic Vermillion flowers from fall through spring, and exuberant, pest-free growth in any sunny, well-drained spot, Grevilleu victoriae is an exciting prospect for Northwest gardens. Michael Lee has been in private practice as a landscape architect since 1979. He specializes in wildlife and vegetation studies. Vol. 59: 1 13 New on the Shelves Creating Fine Gardens BY VALERIE EASTON There are a great many beautiful and glossy gardening books, new and old. Although these books are much re- viewed and admired, usually only the captions are read. We sigh with envy but learn little about the gardeners themselves and their ideas and mo- tivations, let alone how such horticultural mar- vels were actually created. Where were the plants found, were the gardens double-dug, and was a professional garden designer consulted? A new crop of garden books will impress with fine photographs, yet they actually deserve to be read cover to cover for the fascinating and practical information they give about gardens and their makers. Druse, Ken. The Collector’s Garden: Design- ing with Extraordinary Plants. New York: Clarkson Potter, 1996. Druse not only shows us some of the most gorgeous private gardens all over the country, but he answers the ques- tions that always come to mind when you see such photos. An example is the garden of Lauren Springer (author of The Undaunted Garden). Springer reports that she “killed a ton of plants” while learning about the Denver climate and says, “I love plants that are busy — always visited by in- sects, hummingbirds, and bees. I like a lot of bugs.” This is the land of consideration we less famous gardeners keep in mind when choosing plants, and it is reassuring to think that some- one who creates such amazing color harmonies considers bugs, too. In these pages, you learn that many of the best-known gardeners share plants and informa- tion; that five years ago Dan Hinkley, co-owner of the successful Heronswood Nursery, Kingston, Washington, could not find a local re- tail nursery that would stock his unusual speci- mens; and that even the tiniest of gardens can artistically house a vast array of plants. Jerry Flintoff’s one-fifth acre in suburban Seattle is described by Druse as “nearly beyond description... a garden which might have the most concentrated collection of botanicals anywhere. Of Flintoff himself, Druse says, “He inspires some of the most influential dissemina- tors of information, taste, style, design and plants in the country.” Flintoff, Hinkley, Judith Jones, Peter Ray, and Jean Emmons are some of the Northwest gardeners and nursery owners that fall into the categories of Hunters, Missionaries, Specialists, and Aesthetes by which Druse, rather arbitrarily, divides the gardeners he profiles. He claims there is an “insider’s network” of these passionate gardeners, and we are lucky enough to be taken on a tour of their gardens and hear about their successes and failures, as well as favorite plants and where to find them. And if many of the rare and unusual plants mentioned are quite famil- iar here in the Northwest, we can feel a bit smug about being well represented by some of the best of the plant addicts. Elliott, Brent. The Country House Garden: From the archives of Country Life 1897-1939. London: Mitchell Beazley, 1995. We missed them — the great decades of garden design, and there is no question that gardening on this scale is over. The haughty magnificence of these huge estate gardens was chronicled in Country Life , however, and reproduced here in an oversized format and stunning black-and-white photog- raphy. From the frontispiece of a live peacock standing on the rim of a lichen-covered urn placed along the central axis of a formal gar- den, to the chapter on topiary variation, these grand and stately gardens seem as remote from our own modest plots as do Inca ruins rising out of a steamy jungle. The scale of the gardens — the stone, water, and hedges — is breathtaking. Obviously people lived in these grand houses (often calling them cottages!) and loved these gardens, and it showed despite the grandeur. Arts and Crafts designs, rock and woodland gardens, and styles such as neo-Georgian and interwar baroque are varied and elaborate, all surrounding huge and elegant houses, in the British countryside. To read this book is to learn about the very best and most impressive design, as well as to suc- 14 Washington Park Arboretum Bulletin cumb to a longing for elegant white dresses, pic- ture hats, and tea on the lawn during a perfect, Joycian summer afternoon. Kingsbury, Noel. The New Perennial Gar- den. New York: Henry Holt, 1996. While books on perennials abound, few talk about how to combine perennials with other plantings to cre- ate a naturalistic garden. Kingsbury advocates planting schemes that work with nature and take advantage of existing garden conditions rather than fighting against them. Plentiful and artful color photographs show a lush mix of mostly perennials, along with some ornamental grasses, ground covers, and shrubs, in lush, informal, and well-blended sweeps of color. Here is confirma- tion that dry gardens can be excitingly varied, and that damp heavy soils can be planted with more than gunnera and ligularia. How to design, plant, and establish plant communities in tune with nature, weed and pest control, growing from seed, and planning for year-round interest are just a few of the topics covered. Especially useful are chapters on how to deal with such difficult garden situations as deep shade, hot sun, and seaside winds. Exten- sive plant lists are included for each. And Kingsbury promises that the payoff for keeping your own garden’s environment in mind while planning and planting is far less maintenance, water, and fertilizing in the future. The books reviewed above are at the Miller Library and can be purchased at the Arboretum Gift Shop. Also New Engel, David H. A Thousand Mountains , a Million Hills: Creating the Rock Work of Japanese Gardens. Tokyo: Shufunotomo/ Japan Publica- tions, Kodansha, 1995. Gildenmeister, Heidi. Mediterranean Gardening: A Waterwise Approach. Mallorca, Spain: Editorial Moll, 1995. Hill, Mary Brawley. Grandmother’s Garden: The Old-Fashioned American Garden , 1865-1915. New York: Abrams, 1995. Lord, Tony. Gardening at Sissinghurst. New York: Macmillan, 1995. Raver, Anne. Deep in the Green: Country Pleasures. New York: 1995. Valerie Easton is the book Arboretum Bulletin , a librarian at ban Horticulture, and a freelance writer. Rock Garden Plants of North America . Jane McGary , editor. Portland , Oregon: Timber Press, 1996. $49.95. Fifty years of publication of the Bulletin of the American Rock Garden Society (now the Rock Garden Quarterly) has been commemorated with the publication of this anthology. Editor Jane McGary stated, “Many of the most noted American horticulturists and botanists contrib- uted to the Bulletin over the years, as they con- tinue to do today. It is fitting that the first anthology drawn from its pages takes as its or- ganizing principle the native plants of North America and their cultivation.” The articles have all been edited, some were revised by the authors, and plant names are brought up to date. The text is divided geo- graphically, with areas and their plants described, and some discussions on their cultivation, en- hanced by over 100 color photographs. Plantsman J.C. Raulston of North Carolina State University once jokingly called rock gar- deners “the horticultural deviants” of the plant world, because they are interested in only the smallest plants — generally under one inch — the smaller the better. But these plants, many of which offer interesting challenges to dedicated gardeners, are ideal for today’s smaller gardens and for pots and troughs. Gardeners who are tired of the same old plants will find a whole new world opening up on reading this book. From discussions of key American genera and from descriptions of some of the USA’s richest plant sites, gardeners can learn of new plants, how to grow them, and where to see natives growing in the wild. The book is not only valuable as a refer- ence to seldom-encountered plants and where they can be seen but for the articles themselves, written by people who take great joy in the plants discussed. Seed of many of the plants referred to in this book is available to members of the North American Rock Garden Society through its seed exchange. A membership application is included with each book. — reviewed by Alice Lauber Alice Lauber gardens in Lake Forest Park, north of Seattle. She is currently the national record- ing secretary of the North American Rock Garden Society and president-elect of the northwest chapter. Vol. 59:1 15 North American Landscape Trees. Arthur Lee Jacobson. Berkeley , California: Ten Speed Press , 1996. Paper ; $39.95; hardcover, $70. Gardeners in the Puget Sound region have long been the beneficiaries of Arthur Lee Jacobson’s horticultural interests. In the early 1980s, Lee Jacobson was re- nowned for making salad-collecting trips through Seattle’s neighborhoods. In recent years, writing has been the focus of his interest in horticulture, resulting in Trees of Seattle and Pnrpleleaf Plums. Perhaps most of all, Lee is known for his passion for trees and their ex- tremes— the biggest, smallest, oldest, most un- usual. His focus has delighted readers and listeners for years. Jacobson’s new book, North American Landscape Trees , is his most ambitious under- taking to date. In it, he covers both native and exotic ornamental trees growing in temperate North America north of Mexico, hardy to at least 30°F. The book covers 72 families, 198 genera, 950 species, 36 subspecies, 159 varieties, 95 forms, and 3,540 cultivars. Entries are made ac- cording to scientific name, and they are supple- mented by an excellent in- dex ordered by common name. Each entry pro- vides the common names, a brief description of the tree, its year of discovery or selection, any botanical synonyms, and the size of the largest individuals. For cultivars, the date or loca- tion of introduction is noted as well as the dis- tinguishing character(s). Despite the book’s title, the area covered is not truly national. Though the geographic range is extensive, for some reason, Lee decided to exclude the warmer areas of the United States, including most of California and Florida. A reader in San Francisco, for example, would be unable to locate such common trees as carob or camphor. However, readers from Seattle to Bos- ton will find the native and exotic trees com- mon to their region represented, and in those areas, the level of detail is high. Not only does the reader learn about big-leaf maple but about the form rubrum and the cultivars "Seattle Sen- tinel’ and ‘Kimballiae’, as well. The main text is supplemented with excel- lent introductory and supplemental material. The basics of nomenclature are reviewed, with a good summary of hybrids, cultivars, patents, and trademarks. The appendix provides a location for the author’s passion for numbers. It details the im- portant statistics (Acer is the genus with the most taxa, 446) and also provides a list of families and genera, a glossary, and a reference list. For all of its strengths, this volume has some limitations. First and foremost, one must know the plants in order to use it. There are a limited number of drawings and photographs, and these supplement rather than illustrate. Second, there is limited cultural information. Details of envi- ronmental tolerances, pest issues, etc., are not included. Moreover, as a taxa-oriented publica- tion, there are no comparative tables or lists. Most lacking, however, is any sense of where in the United States these plants will perform well. For these reasons, the book does not replace such publications as Perry’s Landscape Plants for West- ern Regions, Sunset’s West- ern Garden Book , or Elias’s Trees of North America. North American Land- scape Trees is valuable for two reasons. First, it is sim- ply a superb compilation of the taxonomic information. It is already my resource for correct nomenclature, par- ticularly related to correct form and cultivar names. Second, the book provides Arthur Lee Jacobson’s per- spective on trees. Once again, we benefit from his knowledge, humor, and passion — Jim Clark Jim Clark co-owns HortScience, Inc., Pleasanton, California, where he writes about and consults on trees. He is a former faculty member of the Center for Urban Horticulture, University of Washington. 16 Washington Park Arboretum Bulletin sing Woody Plants in I will grow anything in a pot, from annuals, tender and hardy perennials, and bulbs to tropical, subtropical, and temperate woody plants — all are fair game. Though flowering herbaceous plants are the most popular sub- jects for containers, woody plants can add a whole new dimension. Extraordinary effects can be achieved, depending on your goals. Why am I fond of container gardening? I use potted plants to accessorize the garden, and more often than not, to soften and enliven the garden’s architecture. Patios, terraces, and courtyards can be made much more appealing and hospitable with container gardens. PHOTOS C^TEXT BY RICHARD W. HARTLAGE Gardening in containers has become very popular over the last several years. Yet, because containers are photogenic and seen as easy to prepare, glossy books often over-simplify the subject. When executed well, however, container gardening is wonderfully satisfying. Until moving to Seattle in 1995, 1 managed the Frelinghuysen Arboretum in Morristown, New Jersey. There, I created more than 250 containers annually. What fun! The amazing thing is that I feel as if I have only begun to scratch the surface of the topic. Below, I’ll share some of my experiences, specifically my successes with trees and shrubs in pots. Why Container Gardens? PHOTOS top: wave hell, a source of inspiration, above: containers of buxus ‘KINGSVILLE dwarf’ WITH HOLLY (ILEX ‘GREEN DRAGON5). Vol. 59:1 17 Preparing the Pot I tend to use terra-cotta and glazed ceramic containers, but you can use anything that holds potting mix and has adequate drainage holes. After trial and error I have developed sev- eral potting mixes for the range of different plants I like to grow. My general workhorse mix is as follows (by volume, per wheel barrow of fin- ished mix): Use three parts of a peat-based pot- ting mix, one part medium-grade perlite, one part honest-to-goodness garden soil, and last, a handful of dolomitic limestone. The garden soil gives the mix body over time (i.e., one to three years), helps to hold nutrients, and increases the water-holding capacity. It also gives weight to the pot and acts as ballast for tall plants. Any reasonable garden soil will do; however, if clay is stiff enough for ceramics, it is not good as a potting mix component. Also avoid soils that are too sandy; they have little or no nutrient- holding capacity. Contrary to popular practice, do not put gravel or shards in the bottom of a container; this is not needed and does not improve drain- age. Also, under no circumstances use surfac- tants, gels, or water-holding pellets, which by any name are a disaster. They hold water as the manufacturers claim, but they hold it so tight the plant cannot use it. This is a tug of war your plants will not win. Even with the surfactant moist, I have seen plants completely wilted. Planting Pots for Effect Now the fun part — planting. I generally like to grow one kind of plant per pot and prepare many different containers. This allows me to ar- range and rearrange pleasing vignettes. Pots planted in a more simple fashion are more ver- satile and have greater impact in the garden, particularly if the garden itself is richly planted. Using complex plant combinations in a single pot can be like putting a polka-dot throw pillow on a chintz couch. Too much pattern! Planters of rich combinations are most effective when used in highly architectural garden spaces where the backdrop is clean and crisp; then the exuberance can be fully appreciated. Another trick I like is to use hardy plants for only a limited number of years and then plant them in the garden. This enables you to buy S9me very choice trees or shrubs in smaller sizes and grow them to a larger size before installing them in a permanent location. Meanwhile, you can use them in a very exciting and unique way. Blossoming Plants For summer bloom, there is nothing more voluptuous than hydrangeas. There are plenty of hydrangeas from which to choose in blue, purple, rose, pink, and white with much varia- tion between, and even several variegated vari- eties. These full-figured beauties look great in a shady nook with a backdrop of blue-leaved hos- tas, such as the old standby, Hosta sieboldiana ‘Elegans’, which is itself an excellent subject when delegated to a planter. If you lack space, Hydrangea serrata ‘Preziosa’, at four feet, is more diminutive than some of her cousins. Mops of dusty rose progress to claret with the season ending up garnet come autumn. ‘Mme. Emile Moulliere’ is a good white. She is large, requiring a tub at least two feet in diameter, with whisky- barrel size being best. Her petite sister, ‘Lanarth White’, how- ever, could fit happily in an eighteen-inch Chi- nese green bowl and look fine. In winter, protect hydrangeas that are in pots from the most severe cold, say anything below 25°F; however, to be safe, start protecting them between 30°F and 40°F. Turn-of-the-century English gardener Gertrude Jekyll often em- ployed hydrangeas planted in white wooden tubs for summer displays. I love the idea and have tried it with success, but seldom see others tak- ing advantage of such a good thing. Occasionally I like to underplant trees in containers with a complementary ground cover. I will never forget the strong image of an Exbury azalea the color of Kraft macaroni and cheese, which was pruned like a bonsai, with a skirt of the cobalt-flowered Pulmonaria longifolia ‘Batrum Anderson’, and handsomely displayed in a stately Italian rolled- rim pot. This scene was on a friend’s terrace. In spring he would pool lavender violas and raspberry pansies, also in terra-cotta, around the base of the azalea, and in summer, gauzy mounds of southern maidenhair ferns were the attendants. Exbury azaleas are deciduous, so when the foliage turned tawny the maidenhairs were relieved by silver- lavender Crocus goulimii, the best of the fall-blooming crocuses. Garden- ing in pots gives flexibility and diversity through- out the gardening year. 18 Washington Park Arboretum Bulletin Non-Flowering Trees and Shrubs Flowering trees and shrubs are not the only possibility for containers. In fact, I tend to pre- fer non-flowering woody plants, which make better foils for a floral display. Boxwoods are excellent candidates. If you like a less formal approach, use the free-form cultivar ‘Kingsville Dwarf’, which is quite elegant when grown in a low pot to accentuate its mounding habit. Marco Polo Stufano, director of Wave Hill in New York, has a striking old specimen of this boxwood that he often uses on the front step of the Conservatory. He also has a fine old plant of Ilex even at a ‘Green Dragon’, a dwarf holly cultivar that is most of- ten seen as a rock garden inhabitant. It grows upright with a very loose constitution impart- ing a Japanese effect. The dwarf Hinoki cypress, Chamaecyparis obtusa ‘Nana Gracilis’, is another evergreen shrub for a container. With very dark emerald- green fern-like texture, it is very nice in an informal setting and a fine companion to the dwarf trees mentioned above. I would flesh out a composi- tion with these plants by adding shallow pots planted with Ajujya, such as ‘Catlin’s Giant’, whose foliage would be a good contrast to the fine texture of the shrubs. Liriope could take the place of ajuga as a ground cover, especially the white variegated ‘Silver Dragon’. Black-leafed mondo grass, Ophiopojyon , is another grass-like ground cover that provides a subtle variation of color. Boxwoods also have a formal connotation good for potted plants. If you have ever visited gardens in Virginia you will recall the miles of hedges creating the highly geometric hearts of many a colonial garden. It is a favorite building block along with Irish yews in many English gar- dens, and I would hate to calculate linear dis- tances of boxwood used to articulate French parterres. Again at Wave Hill, Marco Polo has spent many years growing Buxus sempervirens ‘Elegantissima’ into bullet-like form. Four plants used at the cross axis in the Flower Garden make the perfect counterpoint to the billowing ca- cophony of herbaceous perennials, which are the theme of this garden. They are clipped two or three times a year to create highly stylized ex- clamation points to underscore the classic lay- out of the space. For a dramatic change in scale you could use the staghorn sumac, Rhus typhina , in a tub. This plant always looks so tropical to me despite knowing its native range, which encompasses most of eastern North America. Sumac is du- rable, so a missed watering won’t mean its de- mise. Its dramatic form has a wildly expressive habit, and crimson fall color so luminous and intense that everything pales in comparison. This plant is strong enough to use alone in a court- yard because of its commanding presence. Com- panions would only lessen the impact, a definite case of less being more. In the same vein of plants with impressive stature is Mahonia lomariifolia. Pinnately com- pound leaves have fifteen to nineteen pairs of spiny sea- blue leaflets ranking rigidly down the midrib rachis. Reaching ten feet — up to eight feet in a pot — it reminds me of a surrealistic palm. This grape holly of western China and Burma is seldom hardy here in the Northwest, so you will need room to store this monster in the win- ter. I was fortunate enough to have a cool green- house heated to 35°F. Your efforts are rewarded in January by eighteen-inch flares of flower spikes exploding from the top of the plant — a bonus, as I love it for the striking foliage. Another temperate plant that is not always hardy, therefore better delegated to an urn, is cordyline. Cordyline australis, commonly known as the cabbage tree, is native to New Zealand. The green-leafed form is ubiquitous and is of- ten used for the axils of a wheel of scarlet gera- niums in the front yard. I prefer the cultivars with burgundy and variegated foliage, Cordyline australis ‘Atropurpurea’ and ‘Albertii’, respec- tively. The heads of spiky leaves are reminiscent of yuccas. Extremely versatile, a couple of pots look great on either side of a gate, and appear rather imposing as sentinels. Grow Pots in the Mixed Border Another good use of containers is as a point of interest, pot and all, in the mixed border. You need not look abroad for dramatic botanical punctuation, though. One of the most beauti- ful tree yuccas, Yucca rostrata , is from Arizona. Mace-like heads of incredible steel gray are truly striking in the garden. It is hardy in the North- west, and I have seen small plants growing at the Arboretum. I think it looks too exotic to be planted in most gardens and prefer it as a con- tainerized focus on a terrace. It is slow growing, can reach six feet after many years, and can eas- ily live a couple hundred years, outlasting you. Vol. 59:1 19 PHOTOS top: buxus sempervirens ‘elegantissima’ with cordtline australis ‘albertiT left: cordtline australis ‘ at ro purpurea’ right: RHUS TTPHINA (SUMAC) 20 Washington Park Arboretum Bulletin A final plant to consider potting is a sub- tropical tree, the Chinese rice-paper plant. A native of Taiwan, Tetrapanax papyrifera has been grown on mainland China for centuries; its fibrous white pith is scraped from split stems to make a high quality rice-paper. Though it is a tree, I cut the rice paper plant back to soil level yearly or every other year to keep it between three and four feet. It suckers, so a multitude of new shoots are produced by this treatment. The eighteen-inch felted palmate leaves are really incredible, and the olive green looks great with a cream-colored glazed ceramic pot. The large scale of this plant gives a lush im- pression, and being extremely adaptable can be grown in full sun or shade. I have used it in ar- rangements of monumental proportions with giant pots of purple-leafed cannas and elephant ears, and in a shadier location with Hosta "Hal- cyon’; the gold spotted cast-iron plant, Aspidis- tra elatior "Milky Way’; or the Japanese painted fern. There are not many plants as versatile. Caring for the Container Garden Now for the rudiments of care. Fertilizing is essential, and I believe in the double-whammy approach to potted plants. In early April, for woody plants or perennials that have been held from the previous year, I apply an evenly bal- anced slow-release fertilizer, as recommended by the label. I use the three-month formulation, then apply again three months later to get through the entire growing season. To really get the plants off to a good start, use a water-soluble fertilizer every other week for six weeks. I am impatient! After six weeks I try to hit them once a month with a little water- soluble fertilizer, with a formulation of 20-20- 20. This sounds excessive, but trust me: Your containers will be the envy of the neighborhood. Now comes the real commitment: Water- ing! Containers in full sun need watering every day in the warmest months and every other day during the milder ones. Water containers in bright shade every two to four days, depending on the plants used and the light levels. Hoses with a Dramm watering wand and water breaker work well, especially with a ball valve installed below the wands. When watering use the opportunity to check each plant’s progress and groom the containers. Winter Protection Logistics is always an issue. What about winter protection? If the plants are bone hardy like the sumac or conifers they can be left to the elements, assuming that the container is imper- meable to frost and not subject to breakage from freezing and thawing. Terra-cotta must be brought in for winter and stored no lower than freezing; all of the plants are fine at 32°F or above, including the subtropical trees and shrubs. A garage is an excellent place for winter storage for the average home gardener. Water to keep the stored pots moist but not wet. Add a new dimension to your garden by growing a wider range of plants in containers. If you are a plant junky, you increase the range of plants by using less hardy varieties. For those lacking in patience, the plants usually grow faster because of the impeccable growing conditions. You will find, as I have, that it is fantastic to be able to change a garden scene instantly by just adding or subtracting a potted plant. Richard W. Hartlage is a recent transplant from New Jersey, though a Southerner by birth. He is the new director of the Elisabeth C. Miller Botanical Gar- dens, and lectures widely on container gardening and other gardening topics. Where in the Arboretum? '^A^ind specimens suitable for container gardening throughout the Arboretum. Volunteers at the reception desk at the Graham Visitors Center will help you map a route, using the coordinates designated after each specimen. Buxus semper virens "Elegantissima’, 5-B B. ‘Kingsville Dwarf’, JG Cordyline australis (cabbage tree), 13-6E (the New Zealand Garden) Chaemaecyparis obtusa ‘Nana Gracilis’ (Hinoki cypress), JG Hydrangea "Lanarth White’, 12-6E H. ‘Mme. Emile Moulliere’, 41 -3W H. serrata ‘Preziosa’, UB Ilex crenata, 4-3E, 5-3E, JG Vol. 59:1 21 In the > '.■U Washington Park Arboretum BY JOHN A. WOTT A L Planning the Best Arboretum The most exciting event in the recent his- tory of the Arboretum is the develop- ment of a master plan, which will pro- vide overall guidance for WPA. The plan will assess the current conditions of the Arboretum plant collections, then determine how to best manage and display them in the future. In addition to creating better displays, the plan will coordinate improvements to WPA grounds (such as pathways) and decide how to approach education, research, and other pro- grams in the next century. To help the lead consultants to the plan- ning process, The Portico Group, University of Washington WPA staff completed a 1000-page loose-leaf notebook of facts, figures, and dreams. Since June 1996, Portico Group planners Becca Hanson, Dennis Meyer, and Kate Day have shared their initial thoughts about plan- ning at open houses and during meetings with students, citizens, and the three cooperating overseers — the University of Washington, the City of Seattle, and The Arboretum Founda- tion. Help WPA Run When you come to the Arboretum for a lecture, a tour, or a stroll, chances are that vol- unteers have helped make it possible. From July 1995 to June 1996, Education Coordinator Dana Kirley reports that a larger- than-ever group of volunteers was busy: 52 guides, 52 leaders of Saplings (for third- to fifth- graders), 28 Family Festival volunteers, and 22 special project leaders. They “clocked in” 2,564 hours, on 300 tours, and worked with 4800 stu- dents in the Saplings educational program. To volunteer call (206) 543-8800. Programs for Tomorrow’s Leaders Leadership Tomorrow, a joint project of United Way and the Seattle Chamber of Com- merce, helps develop the potential of young people that are tomorrow’s leaders. Two volun- teer teams of Leadership Tomorrow have been working with WPA’s education coordinator, Dana Kirley. Kirsten Bilodeau has been hired as Dana’s part-time education program assistant for the youth and outreach education programs. Street Smart Art. One team working with the Street Smart Art program brought students from Saint Therese Elementary, Garfield Com- munity Center, and Yesler Community Center to paint murals on the Arboretum greenhouse’s interior walls. They have made the greenhouse a more fun place for children’s activity programs. Branching Out. The second Leadership Tomorrow team helped set up an after-school program, Branching Out, with two community centers in the Central District. The Wallingford Unit of The Arboretum Foundation is provid- ing the monthly volunteer support to introduce children to what the Arboretum has to offer. Where in the Arboretum? Visit the Conservation Trees WPA has recently added to the collections several plants that need to.be preserved and con- served, due to being threatened in the native state: Pterostyrax psilophylla (47-93), the epau- lette tree, is a small native of China. This plant came to WPA as seed from the Shanghai Botanic Garden, having been collected from a wild popu- lation in Szechuan. It is planted about 100 feet north of the Lookout on the west side of the upper trail. ( continued, page 25 ) 22 Washington Park Arboretum Bulletin PARTICIPANTS IN LEADERSHIP TOMORROW DECORATE THE INTERIOR OF THE GREENHOUSE AT THE ARBORETUM. THE GREENHOUSE CURRENTLY IS BEING USED TO HOUSE EDUCATION ACTIVITIES AND OTHER SPECIAL PROJECTS. PHOTOS BY RICK HASSELBLAD Vol. 59:1 23 KEN KELLEY INSTALLED THE STREAMBED THROUGH RHODODENDRON GLEN DURING THE 1930s; THIS VIEW IS LOOKING EAST TO WEST (photo COURTESY OF KELLEY family). Inset: the east end of the creek in summer 1995, before clean-up began (polly HANKIN PHOTO). OPPOSITE PAGE: SUMMER 1996, AFTER CLEAN-UP WAS WELL UNDERWAY AND EROSION NETTING WAS INSTALLED. 24 Washington Park Arboretum Bulletin Podocarpus andinus( 62-89) is a rare coni- fer from Chile, grown from seed collected in Chile by Jan Pirzio-Biroli. Two of these plum- fruited yews are now planted in the Rock Gar- den at the south end of the Arboretum, south of Loderi Valley. Picea mexicana (73-90) was collected as seed in the mountains near Guadalupe, Mexico, and distributed by the International Dendrol- ogy Society. Find WPA’s first viable plant of this species, which is closely related to the Englemann spruce, near the south end of the legume sec- tion. Better Rhododendron Collections Rhododendron Glen. Although WPA has rhododendrons in blossom eleven or twelve months of the year, many enjoy walks in spring through WPA’s collections. Since early summer, renovation has been done along the gently am- bling stream through Rhododendron Glen. Removal of overgrown vegetation and pruning of large trees revealed the beautiful rock work laid out by Ken Kelley in the late 1930s. Historic photos are helping us immensely in un- derstanding the original intent. Generously funded by Mrs. Ruth Ellerbeck, WPA also will improve the function of the stream and add ap- propriate rocks in order to reduce the silt run- off. Landscape architect Polly Hankin is the design consultant for the project. Rhododendron Hybridizers’ Garden. Assistant Curator Tracy Omar works closely with the Puget Sound Rhododendron Hybridizers, spearheaded by Jack Root, to renovate plants for the Rhododendron Hybridizers’ Garden, funded by The Arboretum Foundation with memorial funds. Enjoy the new plants gener- ously donated by several participating hybrid- izers. The garden is located above Azalea Way. Won’t You Be Our Neighbor? Neighborhood volunteers attacked and removed invasive ivy during the first neighbor- hood volunteer day in the Arboretum, held in June 1996. Marilyn Fite, a Madison Park resi- dent, led a dozen other enthusiastic neighbors to assist WPA staff members Christina Pfeiffer, Paul Smith, and Annie Bilotta in removing the invasive ivy and other troublesome weeds along the west portion of the Arboretum. To join future work parties, contact Christina Pfeiffer, or watch for upcoming “Neighbor’s Day” events in 1997. Find WPA Brochures in the Lobby If you are trying to find Arboretum pam- phlets or brochures, check the new informa- tion display in the Graham Visitors Center lobby, generously funded by The Arboretum Foundation. fohn A. Wott, Ph.D., is the director of Wash- ington Park Arboretum, and professor of Urban Horticulture, CUH. The UW manages the collec- tions and the associated arboretum programs and works cooperatively with City of Seattle and The Ar- boretum Foundation. Vol. 59:1 25 ‘Shining Scepter ’ Lilies for All Seasons PHOTOS e^TEXT BY ROGER PlERCE Among perennials are a select few gen- era that bloom in all four seasons of the year, including viola, iris, primula, and erysimum. During very cold years, some of these might not make it. In a mild, more typical year, all four have species and cultivars that to- gether provide bloom from January through De- cember. In addition to these familiar perennials, add a surprising name to the list of year-round per- formers: the torch lily — Kniphofia. It is surprising to find that kniphofias actu- ally do flower in the Northwest’s winter climate. What also is surprising and little appreciated is that many other kniphofias will flower in all of the other seasons, too. Torch lilies are most often thought of as having colors of brassy orange-red, as repre- sented by the familiar red-hot poker plant; how- ever, there are more subtle colors of cream, pale yellow, apricot, soft coral, and tangerine. Individual inflorescences last for several weeks. During this time they undergo a gradual metamorphosis of color, looking different over a period of several days. Color variations are also related to the sea- sons’ temperatures. For instance, kniphofias that bloom early in summer often rebloom in fall with subtle differences in color. The explanation for this may be that the climate is often much cooler early, and then hotter at summer’s end. When a plant has grown into a crowded clump, the flowers will be reaching their full heights. For example, ‘The Rocket’ will flower at three feet its first couple of years and will sur- prise you by the fourth year with stems over six feet. Heights are given below for older plants, of three or four years of age, because younger plants have considerably shorter flowers. Winter The two species that flower during winter in their native range are also winter hardy in the Pacific Northwest: Kniphofia sarmentosa and K. rooperi. 26 Washington Park Arboretum Bulletin PHOTOS right: ‘Percy’s pride’ below: ‘primrose mascotte’ bottom: ‘glow’ with BACKDROP OF ‘royal standard’ Kniphofia sarmentosa , which reaches two feet in height, begins to flower for me in De- cember and may continue showing color all win- ter. More often than not, frost ends the season early in our climate. During winter of 1995-96, the flowers were blackened by frost in mid-Janu- ary. While they last, however, their color is a soft salmony pink at the top of the inflorescence and a pale, creamy yellow below. The leaves are glau- cous green, very similar in color to a larger fall- blooming species, Kniphofia caulescens. The species name, sarmentosa , means “hav- ing or bearing runners,” and in time plants form a widely spreading colony, rather than the tight clumps formed by other kniphofias. Late Winter to Spring My collection of kniphofias includes more cultivars than species, many of which are spring flowering. ‘Robin Hood’, however, showed color on Valentine’s Day in 1995. Usually it does not be- gin until May, 1995 being the exception, and even then is the first spring bloomer. It grows to four feet in height with flowers of a solid coral - red. Other spring bloomers are ‘Apricot’, in a pale, soft tint, and ‘Earliest of All’ (which isn’t), with three- to four- foot spikes of coral. Two of my own introductions also bloom during this time: ‘Bleached Blonde’ is a creamy tannish blonde with a touch of auburn at the very top, and grows to four feet. The citron-yellow flow- ers of ‘Elizabeth Pierce’ fade to golden. Vol. 59:1 27 Summer Many kniphofias flower in mid-summer, in a range of striking color combinations. ‘Glow’ is a solid deep coral-red, the closest I have seen to true red, growing to two and a half feet. ‘The Rocket’ has fiery scarlet flowers and dark stems, reaching over six feet. ‘Springtime’ blooms clear red on top and white below, to three feet. ‘Shin- ing Scepter’ is at the tangerine end of the spec- trum, also reaching three feet. Among different yellows, kniphofia offers a diversity. Flowers of ‘Primrose Mascotte’ are am- j ber-yellow, to three feet; ‘Little Maid’ boasts slender spikes of green, pale yellow, and cream to two feet; and ‘Royal Standard’ is clear lemon- yellow and red to four feet. ‘Vanilla’ is an ap- propriate choice when a very pale yellow flower is needed, to four feet. Fall Some of the choicest torch lilies wait to flower until late summer and into fall. A few sources may list fall-blooming culti- vars as spring bloomers, because plants occasion- ally flower in spring from buds set too late in fall to mature. They are easily mixed up when not in flower, which is all too common in nurs- eries. ‘Bressingham Comet’ is a miniature at eigh- teen inches with two shades of fiery orange flow- ers. The species, K. caulescens , has pinkish red and cream flowers, growing to four feet. English plantsman Graham Thomas refers to its stout stems as being “like elephants’ trunks.” The spe- cies K.galpinii has a single tone of orange flow- ers reaching two and a half feet on older plants. ‘Parmentier’, a pure salmon to three feet, gains a creamy edge on its oldest florets, in slender and long heads. ‘Ice Queen’, also a fall bloomer, has lime green opening to white flowers, reaching four feet; ‘Percy’s Pride’ has about the largest inflo- rescence of any lime, opening palest yellow to four feet. Versatile Mixers and Growers Torch lilies mix well with other flowers in group plantings. Cloudy days in the Northwest complement warmer colors of orange and salmon. Their arching leaves and vertical flow- ers are also counterpoints to the more common billowy shapes of perennial flowers. Most are evergreen, so could be used as a ground cover if planted in mass, a technique that is rarely seen. Kniphofias can take neglect and stand up to weedy neighbors, so they are often relegated to inhospitable conditions. In their native habi- tat they are found in damp seepages or marshy swampland, frequently at higher elevations. The acreage where I grow kniphofias is quite swampy in winter, and they thrive. Here they happily withstand winter temperatures down to 6°F. Once settled in, many can with- stand winter lows of-25°F, and in gardens that get this cold, transplanting in early summer is best. Their homeland spans several thousand miles, with species occurring in such surprising locations as Madagascar and southern Arabia. There are species in tropical Africa, so not all kniphofias are winter hardy. Finally, a word concerning hummingbirds and bees. Many kniphofias produce so much nectar that it fairly drips from the flowers, and this attracts these winged garden visitors, as well as finches and evening grosbeaks. Humming- birds consider beds of torch lilies to be prime real estate, and being territorial, will fight brief skirmishes over them throughout the summer. Deer do not eat the leaves or flowers. Spring, summer, fall, and winter are times for torch lilies. Take advantage of the fact that the Pacific Northwest climate allows us to have the colors, design value, and wildlife use of kniphofias during all four seasons. Sources Olympic Coast Garden, 84 Eaton Lane, Sequim, WA 98382. Descriptive catalog of plants, $1. Silverhill Seeds, 18 Silverhill Crescent, Kenilworth, 7700 Republic of South Africa. Seed catalog, $2 (US funds). Roger Pierce owns Olympic Coast Garden, in Sequim, Washington, where he raises Kniphofia and other perennials. 28 Washington Park Arboretum Bulletin Recognize family and friends at special times — birthdays, holidays, weddings, personal accompl ishments, anniversaries, and as expressions of sympathy — with a gift to The Arboretum Foundation. Adopt a Tree $ 1,000 Select from several varieties. Arboretum staff will locate and care for your tree. Plant Conservation Fund $50 or more Gifts will go toward plant conservation and research in the Arboretum Call 206-325-4510 for details Growing Strong for 25 Years. “When horticultural luminaries are in town, this is where they are taken for a look-see. I can count on Wells-Medina year round to be in top form, so I often stop for a horticultural pick-me-up.” “Many of the unusual plants or varieties you’ve been searching for they have found first and have awaiting your arrival. I often find other plant aficionados who have traveled as far as I have come to enjoy a look around.” -Stephanie Feeny The Northwest Gardener’s Resource Directory, 1995 WellsAVed INA NURSERY Growing Strong for 25 years. 8300 Northeast 24th Street • 454-1853 DRIVING DIRECTIONS: FROM 405: Take the exit onto 520 westbound toward Seattle and exit at 92nd St. Go over the freeway heading south on 92nd St. to 24th St. Turn right and watch for the nursery 1/2 block past the stop light at 84th St. (mind the 25 mph speed limit!) FROM 1-5: Take Hwy. 520 eastbound towards Bellevue. Take the first exit after crossing the bridge and turn right onto 84th St. At 24th St. turn right 1/2 block. THE ARBORETUM FOUNDATION Invites you to visit our unusual jjift & book shop in the DONALD G. GRAHAM VISITORS CENTER 2300 Arboretum Drive East Weekdays: 10 a.m.-4:00 p.m. Weekends: noon-4:00 p.m. Eucryphia x nymansensis ‘Nymansay’ ^GTOyy ARBORETUM Nonprofit Org. US Postage PAID Seattle, WA Permit No. 126 V' Washington Park Arboretum University of Washington ^ 2300 Arboretum Drive East Seattle, WA 98112 (206) 325-4510 > * .w‘ 10515 *5/1 \ v NE ,vA 98115 Arboretum * a living museum of woody plants for research, education, conservation, and display. I