For the fourth spring in a row, Pacific Northwest gardeners are able to share in the ruminations of thirty prominent horticulturists as they name outstanding plants for their corner of the continent. Despite occasional head shaking and teasing, especially among the three subcommittees, the Great Plant Picks team members have settled on forty-five plants to highlight for 2004.
Over the past four years, the Great Plant Picks (GPP) program has grown in popularity. Initiated by former Miller Garden director Richard Hartlage and based on the Award of Garden Merit from Britain, it aims not only to help gardeners choose the best plants for their circumstances but to evaluate various species or cultivars within a genus and to make that information available to growers for planning production schedules.
August 2003 saw the GPP staff at the FarWest Trade Show in Portland for the first time. Richie Steffen, Miller Garden coordinator of horticulture, spoke to a full hall about the program. We talked with a never-ending stream of nursery people about the program and the plants. In addition to giving away hundreds of the popular GPP posters, we distributed a “sneak preview” of the 2004 Great Plant Picks to wholesale and retail nurseries with hopes that, come spring of 2004, gardeners will find the Picks without hunting too far or wide. It was also heartening for GPP staff to see how well received the program has become. Many show attendees found it hard to believe that the program is truly philanthropic in nature—a rare treat in any era!
So, on to the plants… As with any gardening advice, take time to reflect on the peculiarities of your own garden before selecting plants. Within the Pacific Northwest region fall the hot, dry pockets of the Willamette River Valley and some rain-drenched spots in Washington and British Columbia. Some areas are cooler, some warmer in winter. And within those broad microclimates are our own particulars of soil, light, and maintenance regimes. For the greatest satisfaction, use the GPP recommendations as a jumping-off point, but always consider your own garden’s needs.
A natural start when planning or evaluating a garden is with the trees. Well chosen and well placed, they determine the mood of a garden and set the traffic flow through the space. Trees screen unwanted views and frame favorite vistas. Large trees can create a feeling of security, forming the vault in a cathedral-like space they define. The leaves of smaller trees hover in midair, catching the dappled light in summer, and igniting the garden in autumn.
The Trees and Conifers subcommittee of GPP is chaired by Douglas Justice, associate director and curator of collections at the University of British Columbia Botanical Garden (and self-confessed “aceroholic”). It is no surprise, then, that three outstanding maples appear on this year’s list.
Acer triflorum, called three-flowered or rough-bark maple, grows on the hills of northern China and Korea. Not only does it have three flowers in a cluster, but it has three leaflets, similar to its close relative, the paperbark maple (A. griseum). Like that species, A. triflorum becomes increasingly handsome in shape and bark as it matures into a small tree. Although fairly common in maple collections, including those at the Washington Park Arboretum in Seattle and at VanDusen and UBC botanical gardens in Vancouver, British Columbia, it is not as readily available as it deserves to be. It is worth seeking out, as it is adaptable to a wide range of garden conditions, including hot locations.
As in past years, the tree enthusiasts have earmarked an exceptional Japanese maple clone. This year’s winner is Acer palmatum ‘Shindeshôjô’. Justice describes this small tree as having “the finest red-emergent foliage that exists,” and Ned Wells, of Wells Medina Nursery in Bellevue, adds “It knocks your socks off.” Young leaf color is most pronounced when the cultivar grows in full sun, and, as with all Japanese maples, it benefits from good air circulation, good drainage and minimal root disturbance or soil compaction.
The closest cousin of Japanese maple is our own vine maple (Acer circinatum), which is native throughout the Pacific Northwest. It was selected as a GPP in 2002, but new this year is its elegant cutleaf selection, A. circinatum ‘Monroe’. Authors van Gelderen and van Gelderen, in Maples for Gardens, write, “Warner Monroe of Portland, Oregon, layered the plant where he found it along the McKenzie River in the Cascade Range of Oregon and brought it into cultivation in 1965; it was named by Brian Mulligan…,” former director of Washington Park Arboretum. A large shrub or small tree reaching only ten to thirteen feet in height, it is noted for leaves that are dissected to the base of their seven lobes. ‘Monroe’ prefers light shade.
Great Plant Picks assembles advisory groups of experts to make recommendations on large groups of plants, and the fern folks have recommended five reliable and easy-to-get ferns for 2004. Two of them, deer fern (Blechnum spicant) and western maidenhair fern (Adiantum aleuticum), are native to the Pacific Northwest.
Deer fern’s small stature and evergreen habit make it particularly effective in mass plantings, where it functions as a handsome groundcover. It is not only easy to grow but easy to combine with other perennials. For that reason, Maurice Horn calls it a “good date” paired with such perennials as Hosta ‘June’ or Brunnera ‘Jack Frost’. It tolerates the poor soil under conifers and can grow in full sun with summer watering. Unlike many other fern genera, species of Blechnum produce two forms of fronds, only one of which is fertile or spore-bearing. Ray Larson, of the Miller Garden, admires the “striking two-tone effect” created by the new fertile fronds of deer fern.
Northwest coniferous forests are also home to western maidenhair ferns, usually growing in wet, rocky seeps. Once grouped with the eastern species Adiantum pedatum, A. aleuticum is now treated as a separate species, characterized in part by deep sinuses in the blade lobes. Maidenhair ferns in general are fairly easy to spot due to the contrast between their black, wire-like stems, and dainty, bright green, almost translucent leaflets. Make the most of those hues by planting them with black mondo grass (Ophiopogon planiscapus ‘Nigrescens’) and golden hostas. Adaptable in nature, maidenhair fern grows in moist or dry shade, or full sun if the soil is not too dry. It is winter deciduous.
A mature specimen of the evergreen soft shield fern (Polystichum setiferum Divisilobum Group) never fails to draw comments from garden visitors due to its tornado-like growth habit. No, it doesn’t whirl around your garden, but the curving fronds appear to whirl around the center of the plant! This effect is especially notable if you can look down into it. Placed near a large rock, the contrast of stillness and perceived motion is heightened.
Two splendid evergreen ferns come to us from Asia, each contributing a bit of foliar color to the garden. The fronds of Japanese painted fern (Athyrium niponicum var. pictum) seem etched with metallic paint. Maurice Horn explains that it “appears to reflect ambient light and brightens up a dark corner.” Team it up with silver or gold lamiums, Cimicifuga ‘Hillside Black Beauty’, Helleborus x sternii, or dark-leafed geraniums. Site it with afternoon shade and be patient: it takes two years to hit full stride. Once established, Japanese painted fern takes a fair amount of drought.
Offering rich russet tones on new growth and on fall foliage, autumn fern (Dryopteris erythrosora) has glossy leaves. It sets off the slender, bronzy leaves of the sedge (Carex flagellifera) or the bare stems of yellow-twig dogwood (Cornus sericea ‘Flaviramea’). Use it en masse for a bold effect or in a mixed border in sun or shade. Pop a plant into a container by the front door in fall, where you can enjoy its fine structure close at hand.
In addition to developing advisory groups, Great Plant Picks staff organize evaluations for some of the larger genera. Evaluation results are posted on the GPP website in the hopes that this shared information will help home gardeners pick the best plants for their garden and that nurseries will propagate the top selections in each genus.
In March 2003, GPP committee members evaluated the genus Erica at VanDusen Botanical Garden. Planted in six locations in the garden, Erica x darleyensis ‘Kramer’s Rote’ caught everyone’s eye. It was admired for its outstanding habit (bushy, upright, and mounding), foliage (dark “spruce” green), and its vibrant reddish purple flowers. The flower clusters are held at varying angles, creating a “busy” texture that I found particularly pleasing.
The genus Pieris was evaluated in January 2001 at the North Willamette Research and Extension Center. A handful of dwarf cultivars (once grouped as P. japonica subsp. yakushimanum) were compared, and ‘Cavatine’ was determined to be the best of the bunch. Richie Steffen, Miller Garden horticulturist, explains that ‘Cavatine’ was selected from a batch of seed-grown plants and is more vigorous than its sister seedling, ‘Nocturne’, yet not susceptible to the leaf spot that ‘Prelude’ exhibits.
While we’ll never rival the splendor of East Coast gardens in autumn, we can assuage our envy with some reliable trees and shrubs that “color up” well. In addition to the maples discussed above, Chinese tupelo (Nyssa sinensis) is an eye-catching tree in the autumn, with dark reds and bronzes, especially if planted in part to full sun. It has a strong structural branching habit, reaching about thirty feet in height, occasionally with multiple trunks. Found growing naturally on swampy ground in China, it is adaptable to a wide range of soil conditions.
As redbud hazel’s common name hints, this is a shrub with heart-shaped leaves, like a redbud (Cercis), but it is more closely related to witchhazels (Hamamelis). When grown in the open, redbud hazel (Disanthus cercidifolius) makes a compact, rounded shrub; in a woodland setting, its habit is more open. In fall, the leaves turn many hues, ranging through yellow, orange, and red, often displaying all these colors at once, even in shade. The flowers appear in mid-autumn, like tiny red starfish but without the lovely fragrance of witchhazel.
From the same family (Hamamelidaceae) comes the witch alder (Fothergilla major ‘Mount Airy’). Horticulturist Michael Dirr spotted this exceptional clone at the Mt Airy Arboretum in Cincinnati, on university field trips. Most clones of witch alder have leaves of gold and yellow in autumn; this one adds red to the mix. The color is more intense if the plant is grown in full sun, where summer water should be provided, but ‘Mount Airy’ is also a good woodlander. Its white flowers are fragrant in spring.
For a guaranteed autumn blaze, provide a sunny spot with a dark green backdrop for a compact burning bush (Euonymus alatus ‘Compactus’). This easy-to-grow shrub has a distinctive branching structure enhanced by small wings that decorate the twigs, carrying fall interest into winter.
For more information on each of the forty-five 2004 Great Plant Picks, with suggestions for using them in attractive and successful plant combinations, visit our website at www.greatplantpicks.org. And, be sure to ask for these selections, as well as those from past years, at your local nurseries this spring.
2004 Great Plant Picks
Perennials and Bulbs
white baneberry, doll’s eyes
Adiantum aleuticum (1-7, 14-21)
western maidenhair fern
Agastache ‘Blue Fortune’ (4-24)
Asarum europaeum (2-6)
European wild ginger
Athyrium niponicum var. pictum (1-9, 14-24)
Japanese painted fern
Blechnum spicant (2b-7, 14-19, 24)
Crambe maritima (2-9, 14-17)
Dryopteris erythrosora (2-9, 14-24)
Eupatorium rugosum ‘Chocolate’ (1-10, 14-17)
white snakeroot, white sanicle
Parahebe catarractae (5, 6, 15-17, 20-24)
Persicaria amplexicaulis ‘Rosea’ (2b-9, 14-24)
(syn. Polygonum amplexicaule ‘Rosea’)
bistort, mountain fleece
(syn. Polygonum polymorphum)
giant fleeceflower, white dragon
Phlomis russeliana (2-24)
sticky Jerusalem sage
Polystichum setiferum Divisilobum Group (4-9, 14-24)
soft shield fern, hedge fern
Sanguinaria canadensis f. multiplex
Shrubs and Vines
Arbutus unedo (4-24)
Buxus sempervirens ‘Suffruticosa’ (3b-6, 15-17)
dwarf boxwood, edging boxwood
Cistus x hybridus (6-9, 14-24)
(syn. C. x corbariensis)
Disanthus cercidifolius (4-7, 14-17)
Erica x darleyensis ‘Kramer’s Rote’ (2-10, 14-24)
Euonymus alatus ‘Compactus’ (2-10, 14-16)
compact burning bush
Fothergilla major ‘Mount Airy’ (2b-9, 14-17)
Hydrangea anomala subsp. petiolaris (2-21)
Hydrangea serrata ‘Beni-gaku’ (3b-9, 14-24)
Laurus nobilis (5-9, 12-24)
Nandina domestica Gulf Stream (4-24)
Osmanthus heterophyllus ‘Goshiki’ (4-10, 14-24)
variegated false holly
Parthenocissus henryana (4-9, 14-17)
Pieris japonica ‘Cavatine’ (2b-9, 14-17)
Syringa pubescens subsp. patula ‘Miss Kim’ (1-9, 14-16)
Trees and Conifers
Abies pinsapo ‘Glauca’ (5-11, 14-24)
blue Spanish fir
Acer circinatum ‘Monroe’ (2b-6, 14-17)
cut-leaf vine maple
Acer palmatum ‘Shindeshôjô’ (2-10, 12, 14-24)
Cornus alternifolia (2-6)
Cornus alternifolia ‘Argentea’ (2-6)
variegated pagoda dogwood
Fagus sylvatica var. heterophylla ‘Aspleniifolia’ (2b-9, 14-21)
Fagus sylvatica ‘Purple Fountain’ (2b-9, 14-21)
columnar weeping copper beech
Magnolia ‘Galaxy’ (3b-9, 14-24)
Prunus x yedoensis Cascade Snow (3-7, 14-20)
Taxus baccata ‘Fastigiata’ (3-9, 14-24)
Taxus baccata ‘Repandens’ (3-9, 14-24)
spreading English yew
Northern Japanese hemlock
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, zone numbers in parentheses refer to Sunset zones in the latest Sunset Western Garden Book (when available) and have been provided as an aid 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.