Great Plant Picks for the Pacific Northwest

Credit: Richie Steffen, Elizabeth Miller Garden

Trees for Small-Space Gardens

Whether we truly garden in a small space, or simply want to squeeze in more plants, it seems we’re always keeping an eye open for a good small tree. Threeflower maple or roughbark maple (Acer triflorum) is just such a tree, as it grows slowly to about eight metres high, with a rounded crown that reaches seven metres wide. It is similar to paperbark maple, with its three-part leaves, but reaches a smaller ultimate size and flushes into leaf much earlier in spring. The bark of Acer triflorum also peels, but it creates a rugged effect that is not as red-brown as that of paperbark maple. A. triflorum provides dependable fall colour that ranges from light orange to scarlet, and is generally a very tough disease- and pest-resistant tree suitable for a wide variety of garden conditions. One of my favourite trees is the wedding cake tree, Cornus controversa ‘Variegata.’ I’ll never forget the sight of the one at Butchart Gardens – dramatic tiers of horizontal branches lit up with variegated leaves, framed by the dark conifers that flourish around it. It remains one of the most-asked-about trees at Butchart. It is too large for many home gardens, but its junior version is found in the 2004 Great Plant Picks’ Cornus alternifolia ‘Argentea,’ commonly called the variegated pagoda dogwood. This spectacular small tree brings a strong architectural element to any garden, thanks to its horizontal branching structure. It has white flowers in late spring and bluish-black berries, set off by striking white-edged green leaves. At the Miller Garden, one is set at the end of a path, in front of dark evergreens, creating a natural sculpture, a luminescent focal point. Here, the lower branches are given room to spread—pruning them up to permit passing traffic would ruin the tree’s overall shape. Variegated pagoda dogwood is truly a four-season tree, providing elegance and interest throughout the year.

Shrubs for Containers

Many of the 2004 Picks are wonderful in containers. “Box balls”—that is, dwarf boxwood sheared into perfect spheres—are all the rage in England. They are a guaranteed fit for the formal garden or to accent a front entrance, but they also meld surprisingly well into a naturalistic garden, where they add a touch of whimsy. The best cultivar to use for this treatment is Buxus sempervirens ‘Suffruticosa,’ which readily retains its compact shape. Variegated false holly (Osmanthus heterophyllus ‘Goshiki’) is a very compact evergreen shrub. Its new leaves emerge tinted with pink and orange, maturing to creamy-yellow variegation on a dark-green background. The leaves have spiny margins, much like English holly. Planted in an oxblood ceramic pot, bedecked with tiny white lights, this easy-to-grow shrub adds a festive note at any time of year and is adaptable to sun or shade. It isn’t reputed to bloom, but as the clone is still relatively new, I am hopeful! Nothing compares to the sweet perfume of Osmanthus heterophyllus floating through the garden on a sunny October day. Last April, Great Plant Picks committee members were invited to VanDusen Botanical Garden to study the heath collection. There, Erica x darleyensis ‘Kramer’s Rote’ caught everyone’s eye. Its habit is simultaneously bushy, upright and mounding—hard to imagine!—with dark, spruce-green leaves and vibrant reddish-purple flowers. The flower clusters are held at varying angles, creating a “busy” texture that I found particularly pleasing. Add it to a sun or shade container for months of winter colour. Once the flowers have faded, shear the plant to keep it compact.

Woodlanders

Many gardeners bemoan the fact that they are faced with shady gardens, but there are many wonderful perennials to grow beneath trees. The Miller Garden in Seattle is famous for its woodland, where tall Douglas firs shelter fine Japanese maples underplanted with a tapestry of native shrubs and rare and exotic perennials. Visitors praise this part of the garden as a wonderland and tell us that it makes them feel cozy and safe.

In our woodland, we grow Actaea pachypoda (synonym A. alba), white baneberry or doll’s eyes. This unusual but easy-to-grow, drought-tolerant perennial has a long season of interest. Fragrant white flowers are held above dissected leaves in spring, ripening into spherical white berries, each with a black eye, held on red stalks. In the shaded woodland, the effect is quite dramatic as the overall height of the plant is up to a metre tall. Plants spread gradually to form a clump. Be careful not to plant this perennial where children might be tempted by the fruit, which is highly poisonous. Combine baneberry with deer fern (Blechnum spicant), which is native to B.C. and similarly easy to grow and drought-tolerant once established. The Eastern North America collection at VanDusen Botanical Garden is home to many woodland perennials. Among them is a lovely spring bloomer that produces white flowers as the bluish-grey leaves unfurl. Sanguinaria canadensis, which, as its name suggests is also native to eastern Canada, spreads gradually to form a patch and its leaves may disappear by late summer. The GPP committee has chosen bloodroot’s double form (S. canadensis f. multiplex) for an award this year. This plant’s curious common name refers to the fact that the rhizomes exude red sap when cut. For more information, including nurseries that sell the plants recognized in the program, visit the website at www.greatplantpicks.org

Great Plant Picks Plants for the Pacific Northwest.

Perennials and Bulbs

Actaea pachypoda (white baneberry, doll’s eyes) — zone 4 Adiantum aleuticum (western maidenhair fern) — zone 3 Agastache ‘Blue Fortune’ (hybrid hyssop) — zone 6 Asarum europaeum (European wild ginger) — zone 4 Athyrium niponicum var. pictum (Japanese painted fern) — zone 5 Blechnum spicant (deer fern) — zone 5 Crambe maritima (sea kale) — zone 6 Dryopteris erythrosora (autumn fern) — zone 6 Eupatorium rugosum ‘Chocolate’ (white snakeroot, white sanicle) — zone 4 Parahebe catarractae — zone 8 Persicaria amplexicaulis ‘Rosea’ (bistort, mountain fleece) — zone 5 Persicaria polymorpha (giant fleeceflower, white dragon) — zone 5 Phlomis russeliana (sticky Jerusalem sage) — zone 4 Polystichum setiferum Divisilobum Group (soft shield fern, hedge fern) — zone 5 Sanguinaria canadensis f. multiplex (double-flowered bloodroot) — zone 3

Shrubs and Vines:

Arbutus unedo (strawberry tree) — zone 7 Buxus sempervirens ‘Suffruticosa’ (dwarf boxwood, edging boxwood) — zone 5 Cistus x hybridus (white rockrose) — zone 7 Disanthus cercidifolius (redbud hazel) — zone 5 Erica x darleyensis ‘Kramer’s Rote’ (Darley heath) — zone 6 Euonymus alatus ‘Compactus’ (compact burningbush) — zone 4 Fothergilla ‘Mount Airy’ (witch alder) — zone 4 Hydrangea anomala subsp. petiolaris (climbing hydrangea) — zone 4 Hydrangea serrata ‘Beni-gaku’ (mountain hydrangea) — zone 6 Laurus nobilis (bay laurel) — zone 8 Nandina domestica ‘Gulf Stream’ (heavenly bamboo) — zone 6 Osmanthus heterophyllus ‘Goshiki’ (variegated false holly) — zone 7 Parthenocissus henryana (silvervein creeper) — zone 7 Pieris japonica ‘Cavatine’ (lily-of-the-valley shrub) — zone 4 Syringa pubescens subsp. patula ‘Miss Kim’ (dwarf Korean lilac) — zone 5

Trees and Conifers:

Abies pinsapo ‘Glauca’ (blue Spanish fir) — zone 6 Acer circinatum ‘Monroe’ (cutleaf vine maple) — zone 6 Acer palmatum ‘Shindeshôjô’ (Japanese maple) – zone 6 Acer triflorum (threeflower maple, roughbark maple) — zone 5 Cornus alternifolia (pagoda dogwood) — zone 4 Cornus alternifolia ‘Argentea’ (variegated pagoda dogwood) — zone 4 Eucryphia glutinosa — zone 8 Fagus sylvatica var. heterophylla ‘Aspleniifolia’ (fernleaf beech) — zone 4 Fagus sylvatica ‘Purple Fountain’ (columnar weeping copper beech) — zone 4 Magnolia ‘Galaxy’ — zone 6 Nyssa sinensis (Chinese tupelo) — zone 7 Prunus ‘Berry’ cascade snow(tm) (Japanese flowering cherry) — zone 5 Taxus baccata ‘Fastigiata’ (Irish yew) — zone 6 Taxus baccata ‘Repandens’ (spreading English yew) — zone 5 Tsuga diversifolia (northern Japanese hemlock) — zone 5 With more than 30 years experience in horticulture in B.C.—in wholesale, retail and at VanDusen Botanical Garden for a decade—Carolyn Jones brings a wealth of knowledge and expertise to GardenWise and www.gardenwiseonline.ca as staff horticulturist.