The 2002 Great Plant Picks

The February 2001 unveiling of Great Plant Picks, a new plant awards program sponsored by the Elisabeth C Miller Botanical Garden in Seattle, met with enthusiasm and support from all segments of the horticultural community. [See Pacific Horticulture, January 2001] Home gardeners, landscape architects, garden designers, educators, and garden writers downloaded the Great Plant Picks fact sheets from the website, while wholesale and retail nurseries participated in the online nursery directory. This enthusiastic response fueled the selection committee, which has selected over sixty-five Great Plant Picks for 2002.

“There was great debate within the selection committee regarding the number of plants selected for 2002. In the end, I decided that the goal of the program—to create a list of unbeatable plants for the Pacific Northwest garden—required us to ‘up the ante’ this year,” explained Richard Hartlage, director of the Miller Garden.

In this article, we’ll feature this year’s winners in two categories of woody plants: trees and conifers, shrubs and vines. A follow-up article in the April issue of Pacific Horticulture will feature the Perennial & Bulb selections.

Douglas Justice, interim director of the University of British Columbia Botanical Garden in Vancouver, and Tanya DeMarsh-Dodson of Emery’s Garden in Lynnwood, Washington, headed the trees and conifers group. The shrubs and vines group is led by Joe Blue, of Briggs Nursery in Elma, Oregon, and horticulturist Carolyn Jones, from VanDusen Botanical Garden, also in Vancouver, British Columbia.

Foliage and young cones of Korean fir (Abies koreana). Photographs courtesy of Great Plant Picks, except as noted

Foliage and young cones of Korean fir (Abies koreana). Photographs courtesy of Great Plant Picks, except as noted

Evergreens Trees for the Small Garden

Several of the 2002 trees and conifers are narrow or slow growing, making them ideally suited for the small urban garden. The group selected Korean fir (Abies koreana) for its striking bluish-purple cones that are produced on young plants. This compact conifer grows fifteen to thirty feet high in a garden setting and can be used as a specimen or grouped together in the larger garden.

The weeping selection of our native Alaska cedar (Chamaecyparis nootkatensis ‘Pendula’) is a graceful addition to the urban landscape. This conifer’s lush green, pendulous foliage is attractive year-round.

Serbian spruce (Picea omorika) is best known as an elegant columnar tree. Adaptable to a variety of cultural conditions, it is arguably the most beautiful of the spruces commonly available.

Conifers are often used for interesting textural effects. Japanese umbrella pine (Sciadopitys verticillata) is one of the leaders in this category with its large whorled leaf pattern. Extremely slow growing to twenty-five to thirty feet by fifteen to twenty feet, umbrella pine also has shredding orangish brown bark among its outstanding qualities.

The native mountain hemlock (Tsuga mertensiana) offers the home gardener an evergreen tree to anchor the woodland garden. With a slender branching habit and finely textured foliage, this Northwest native figures prominently in both our wilderness and designed landscapes.

Fabulous Fall Foliage and More

Maples are prominent in this year’s Great Plants Picks. Trident maple (Acer buergerianum) is a smaller maple with a graceful rounded habit. A highlight, though, is the foliage. Starting dark, often purple, in spring, the foliage turns a glossy green in summer, and then multiple shades of yellow, orange, and red in fall.

A Northwest native, vine maple (Acer circinatum) was selected for its workhorse status in the garden. Tolerating shade and some drought, this small maple can be grown as a multi-stemmed small tree or as a shrub. Its spreading form, bluish-green foliage, and appealing fall color make the vine maple a garden staple.

Three cultivars of Japanese maple (Acer palmatum) were included in this year’s list. All are small trees ideal for the shady urban garden, and all offer excellent fall color. ‘Katsura’ is known for its appealing orange color in spring; it turns yellow in summer and orange again in autumn. Crimson fall color and a rounded form are hallmarks of ‘Osakasuki’. ‘Seiryu’, a member of the dissected foliage group, was selected for its smaller, vase-shaped form and yellow to crimson fall color.

Sourwood or sorrel tree (Oxydendrum arboreum) is a fifteen- to thirty-foot tree native to the southeastern states; it is an ideal choice for the small Northwest garden. In summer, clusters of fragrant white flowers cover the entire tree. Fall color may be red, yellow, or purple, often all at the same time on the same plant.

One of the selection criteria for a Great Plant Pick is that the plant should have multiple seasons of interest. Cornelian cherry (Cornus mas) is a perfect example, as its yellow flowers emerge before the foliage in late winter. In late summer, the edible fruits become bright red before the leaves turn red and purple in autumn.

Orangebark stewartia (Stewartia monadelpha) and Japanese stewartia (S. pseudocamellia) are relatively unknown to most gardeners. These trees make excellent focal points in the landscape, as they offer mottled brown and gray bark and beautiful saucer-shaped, white flowers in midsummer. Their fall color ranges from bright red to burgundy. Slow growing, both are ideal for the small garden.

The drama of goldenrain tree (Koelreuteria paniculata) is irresistible. Its delicate leaves emerge light red, then turn medium green in summer, and end the year pale yellow. Large, bold panicles of yellow flowers appear in midsummer, maturing into inflated, pinkish red fruits by autumn.

Flowers on layered branches of Chinese witch hazel (Hamamelis mollis) illuminate the garden in a Northwest winter. Inset: backlit flowers of Chinese witch hazel

Flowers on layered branches of Chinese witch hazel (Hamamelis mollis) illuminate the garden in a Northwest winter. Inset: backlit flowers of Chinese witch hazel

Shrubs for the Winter Garden

When fall cleanup is complete, the profuse purple berries of Callicarpa bodinieri var. giraldii ‘Profusion’ always create a surge of excitement in the most weary of gardeners. Early spring foliage is bronze, pale pink flowers appear in midsummer, and the purple fruits remain prominent through early winter.

With hundreds of fine camellias to choose from, the selection committee faced the challenge by highlighting just one cultivar: Camellia x williamsii ‘Donation’. A cross between C. saluenensis and C. japonica, ‘Donation’ was selected for its profuse semi-double, pink flowers that intensify in the shade. ‘Donation’ flowers in late winter and early spring on an upright bush that may reach twenty to twenty-five feet in height.

Evaluations of particular genera are becoming a significant part of the Great Plant Picks program. This year, witch hazels (Hamamelis) were studied at Gossler Farm Nursery in Springfield, Oregon. Five witch hazels were chosen for this year’s list. The first four were selected for their exceptional fall color and for the curious flowers that emerge on bare stems in winter. Four of the selections are cultivars of Hamamelis x intermedia: ‘Diane’ features dark red flowers in midwinter; ‘Jelena’ offers orange flowers in early winter; ‘Pallida’ lights up the midwinter garden with yellow flowers; and ‘Wintr Beauty’ brings dark yellow flowers in mid-winter. Chinese witch hazel (Hamamelis mollis) was added to the list for its fragrant yellow midwinter flowers.

Sweet box (Sarcococca) is a prominent feature of the winter garden; the selection committee chose dwarf sweet box (S. hookeriana var. humilis) for this year’s list. Famed for its intensely fragrant white flowers, dwarf sweet box spreads by stolons and can be treated as a shrubby (to two feet high) groundcover with flowers in early spring.

Initial evaluations of the genus Pieris at the North Willamette Research and Extension Center in Aurora, Oregon, resulted in an early selection: Pieris japonica ‘Valley Valentine’. While P. japonica ‘Mountain Fire’ is one of the most commonly available selections, it has, according to the Aurora trials, a relatively short lifespan in the heavier Pacific Northwest soils. ‘Valley Valentine’, on the other hand, tolerates a variety of soil conditions in addition to producing large panicles of deep red flowers in late winter. Evaluations of pieris will be continuing.

Viburnum tinus ‘Spring Bouquet’ produces dark red buds that open to fragrant white flowers in late winter and early spring. The flowers turn into metallic blue fruits in summer, all on a compact shrub ideal as a specimen or for hedging.

Flowering Shrubs for Spring and Summer

Many gardeners reject reputedly slow-growing plants in favor of instant gratification. Enkianthus campanulatus, while long thought to be a slow grower, in fact produces quite a show at a young age. A member of the rhododendron family (Ericaceae), enkianthus features clusters of bell-shaped, creamy flowers with pink veins in late spring. In autumn, the foliage changes from medium green to yellow, orange, and red. All this, and it does well in partial shade.

Two cultivars of the native flowering currant (Ribes sanguineum) were selected for the 2002 Great Plant Picks: ‘King Edward VII’ and ‘White Icicle’. The first is a compact currant (six feet tall) with deep red flowers in spring. ‘White Icicle’ is an introduction from the University of British Columbia; it produces white flowers on a larger shrub (to eight feet). The two cultivars complement each other when planted together.

Where would the summer garden be without roses? Rosa glauca was chosen for both foliage and flowers. Glaucous blue leaves on arching stems are beautiful all summer long. Single pink flowers appear in late spring and early summer, often with a repeat bloom later in the season. Red hips provide late summer interest.

Clematis viticella ‘Etoile Violette’. Photograph courtesy of Hedgerows Nursery

Clematis viticella ‘Etoile Violette’. Photograph courtesy of Hedgerows Nursery

Vines

The selection committee is fortunate to have Maurice Horn, co-owner of Joy Creek Nursery in Scappoose, Oregon, as a member of the shrubs and vines team. Maurice introduced the committee to Brewster Rogerson, holder of an internationally recognized clematis collection in Hillsboro, Oregon. Evaluations at both Joy Creek Nursery and the Rogerson collection resulted in three outstanding clematis on this year’s Great Plant Picks list: ‘Aljonushka’ is a hybrid between Clematis integrifolia and C. viticella, producing pink, bell-shaped flowers from spring to late summer. ‘Polish Spirit’ is a late bloomer, producing large purple blue flowers from midsummer to late autumn. Another late bloomer, Clematis viticella ‘Etoile Violette’ features large purple flowers with contrasting yellow anthers.


2002 Great Plant Picks

Trees & Conifers

Abies koreana   (3b-9, 14-24)
Korean fir

Acer buergerianum   (2-9, 14-17, 20, 21)
trident maple

Acer circinatum   (2b-6, 14-17)
vine maple

Acer palmatum ‘Katsura’  (2-10, 12, 14-24)

Acer palmatum ‘Osakazuki’  (2-10, 12, 14-24)

Acer palmatum ‘Seiryû’  (2-10, 12, 14-24)

Chamaecyparis nootkatensis ‘Pendula’  (2-6, 15-17)
weeping Alaska cedar

Cornus mas   (1-6)
Cornelian cherry

Koelreuteria paniculata   (2-24)
goldenrain tree

Oxydendrum arboreum   (2b-9, 14-17)
sourwood, sorrel tree

Picea omorika
Serbian spruce

Sciadopitys verticillata   (4-9, 14-24)
Japanese umbrella pine

Stewartia monadelpha   (4-6, 14-17, 20, 21)
orangebark stewartia

Stewartia pseudocamellia   (4-6, 14-17, 20, 21)
Japanese stewartia

Tsuga mertensiana   (1-7, 14-17)
mountain hemlock

Shrubs & Vines

Callicarpa bodinieri var. giraldii ‘Profusion’ (3-9, 14-24)

Camellia x williamsii ‘Donation’  (4-9, 12, 14-24)

Clematis ‘Aljonushka’

Clematis ‘Polish Spirit’

Clematis viticella ‘Etoile Violette’  (2b-9, 14-17)

Enkianthus campanulatus ‘Red Bells’  (2-9, 14-21)

Hamamelis x intermedia ‘Diane’  (3-7, 15-17)

Hamamelis x intermedia ‘Jelena’   (3-7, 15-17)

Hamamelis x intermedia ‘Pallida’   (3-7, 15-17)

Hamamelis x intermedia ‘Winter Beauty’   (3-7, 15-17)

Hamamelis mollis   (2b-7, 15-17)
Chinese witch hazel

Pieris japonica ‘Valley Valentine’  (2b-9, 14-17)

Ribes sanguineum ‘King Edward VII’  (4-9, 14-24)

Ribes sanguineum ‘White Icicle’  (4-9, 14-24)

Rosa glauca    (1-24)

Sarcococca hookeriana var. humilis   (3-9, 14-24)
dwarf sweet box

Viburnum tinus Spring Bouquet’  (4-10, 12-24)

All selections in the Great Plant Picks have been chosen for their suitability in USDA hardiness zones 7 and 8, which covers most of the Pacific Northwest, west of the Cascades. In the list above, numbers in parentheses refer to climate zones in the latest Sunset Western Garden Book and have been provided for readers beyond the Northwest. Plants may not perform equally well in all of the Sunset zones noted.

To learn more about Great Plant Picks, visit our website at www.greatplantpicks.org. There you will find photographs, fact sheets, selection criteria, and current evaluation reports. To join our mailing list, please call (206) 363-4803.