Four years ago, Great Plant Picks (GPP), the primary educational program at the Elisabeth C. Miller Botanical Garden in Seattle, presented shade as a theme; gardeners snapped up the posters and handouts. Back by popular demand, Great Plant Picks selections for 2017 focus on plants that do well in shade and are drought tolerant. (You’ll find GPP definitions for various types of shade—light, open, dappled, and deep—on the resources page of the GPP website.)
Indeed, one of the most problematic sites for gardening in the maritime Pacific Northwest is in deep shade with little to no direct sunlight, beneath an almost impenetrable canopy of trees with less than one-quarter of the sky visible during the day. Most often, this canopy consists of native conifers with dense root systems that wick up virtually every drop of moisture during the dry season. Unless planting is strictly limited to natives, this can be a challenging predicament for the gardener who is looking for more variety and wants, or needs, to limit irrigation. Nevertheless, there are a number of great plants to choose from that will provide a captivating landscape in deep shade.
A number of Pacific Northwest native plants are just too exceptional to ignore for deep shade and drought tolerance. Western sword fern (Polystichum munitum) brings year-round evergreen beauty; arching fronds are spring green when they first emerge, then turn dark green by summer. For fetching good looks and edible fruit, there is evergreen huckleberry (Vaccinium ovatum), a three- to six-foot shrub that defines the Pacific Northwest landscape with shiny, forest-green leaves; white urn-shaped flowers in spring; and dark purple-black berries in late summer. A smaller shrub, with growth up to two feet, Cascade Oregon grape (Mahonia nervosa) has holly-like leaves, canary-yellow flowers in spring, and then attractive, waxy blue berries in early autumn that are edible—just not necessarily palatable. Two native perennials from the dark forests are red baneberry (Actaea rubra) and wild ginger (Asarum caudatum). The Actaea features striking clusters of bright fire-engine red, poisonous berries in late summer to early fall; however, the berries are very bitter and it is unlikely that anyone would eat more than one, or enough to cause serious injury. Nevertheless, as with all poisonous plants, educate family and friends. The bold, heart-shaped leaves of wild ginger are less than six inches high, glossy, and evergreen. Be sure to peek beneath the foliage in late winter to see the unusual rusty-brown flowers.
Surprisingly, colorful evergreen foliage is not out of the question for dark, dry situations. The lustrous, hunter-green leaves of Aucuba japonica ‘Mr. Goldstrike’, playfully speckled and splashed with golden yellow, will brighten a shady site. And then there is the evergreen foliage with dark green centers and brilliant gold margins of Elaeagnus ×ebbingei ‘Gilt Edge’, and Osmanthus heterophyllus ‘Goshiki’; the cultivar name means “five colored” in Japanese and refers to the dazzling display of cream, pink, orange, and yellow variegation on the green leaves.
Not quite a shrub or a vine, ×Fatshedera lizei ‘Annemieke’ is an unusual hybrid between Fatsia japonica, a shrub, and Hedera helix, a vine. The ivy-like foliage of this variegated selection is splashed with varying shades of dark to almost golden green. Let ‘Annemieke’ clamber amidst other shade-lovers where it will brighten the way as it goes. With bold, almost tropical-looking foliage and very large palmate leaves, Fatsia japonica should be mentioned in its own right for deep shade and dry conditions. Another Hedera relative, Hedera colchica ‘Dentata Variegata’, is a superb vine to brighten shadowed locations with forest green leaves that have creamy white edges. Plant as a groundcover or on strong permanent supports, although not on a tree or house, where it will create a dense mat of colorful foliage. While it is a vigorous grower, it can be kept in bounds with annual pruning.
There are two distinct types of Oxalis oregana, one has bright green trifoliate leaves, is deciduous, and runs like the devil! Great Plant Picks recommends the other type, which is an evergreen with gray-green leaves that are maroon on the underside and hug the ground at only 2 to 4 inches tall. While the latter plant does spread by underground rhizomes, it is very slow in comparison. Watch for dainty, pink, star-shaped flowers sprinkled above the shamrock foliage in springtime.
The evergreen form of Oxalis oregana, Pachysandra terminalis, and several Mediterranean-type Epimedium are great groundcovers to plant where the sun doesn’t shine. Proven Epimedium performers include E. ×perralchicum, E. ×perralchicum ‘Fröhnleiten’, E. ×rubrum ‘Sweetheart’, and E. warleyense. All have evergreen, heart-shaped foliage, and spread slowly. The petite flowers of the first two hybrids are bright yellow, ‘Sweetheart’ has rosy pink flowers, and the last, coppery orange-red.
For a tall, vertical accent in the shade garden try Carpinus betulus ‘Fastigiata’ or C. betulus ‘Frans Fontaine’, two columnar trees that do well in difficult landscape situations. Both will grow to about 25 feet in ten years and mature to about 50 feet; the width, or spread, of the latter cultivar will be always be less than the former. The magnificent Acer griseum is another small tree for the mid-level of the dimly lit understory that matures at 30 feet in over 20 years. The warm chestnut-brown peeling bark is this plant’s hallmark, and the leaves will develop respectable fall color despite the lack of full sun. Although less commonly planted, its sibling, Acer triflorum, has all the same great attributes as A. griseum and is well worth trying.
One commonly thinks of Cyclamen hederifolium as heralding autumn in September and October, but some tubers begin sending up their bright-pink flowers as early as mid-August. They thrive and bloom for weeks in the shadiest reaches of the garden and are dormant during the dry period. As fall progresses, the ivy-like foliage emerges. The foliage variety that is available now is astonishing; look for intensely mottled dark and light green, patterns of pewter, and gleaming silvery types. Similar, but no less fantastic is Cyclamen coum, which carries the torch of blooming through the winter after C. hederifolium has finished. While the foliage is more rounded on C. coum, there is, again, an array of comparable colors and patterns along with flower colors from magenta to pink to white.
Fragrance is even possible in deep shade. How about the intoxicating perfume of sweet vanilla in wintertime? Several varieties of the handsome shrub, Sarcococca, will provide a delightful scent from tiny white flowers during the chilliest months of the year. All have attractive, evergreen, glossy foliage on arching branches. The larger growing types, which mature from four to six feet tall and wide, are S. confusa, S. hookeriana var. hookeriana, and S. ruscifolia. Sarcococca hookeriana var. humilis is a smaller version at just two feet tall and wide after many, many years.
These are just a few of the outstanding plants that flourish in deep shade and tolerate the dry soil that often exists there. For gardens that receive more sunlight, whether it is dappled, open, or light shade, the choices expand significantly. And if occasional irrigation is feasible, then the possibilities are endless. Please visit the Great Plant Picks website to learn more about these plants and many others that will help create an idyllic shade garden.
To browse a complete list of more than 900 exceptional plants that thrive in the Pacific Northwest, along with complete growing instructions, and sorted by their contribution to the landscape, visit www.greatplantpicks.org.