Looking South For New Ideas
I’ve been asked a lot lately about which plants might work best as our climate changes. Clearly, climate change is having enormous impacts on our forests as well as our gardens; firs, hemlocks and cedars are dying throughout the Northwest, as are bigleaf maples, salal, and sword ferns. As our iconic flora struggles, we gardeners are also struggling to understand how best to work with the changing landscape. So far, our foresters and scientists are leaning to drought as the biggest stressor for our noble natives. Stressed plants are always more susceptible to pests and diseases and our beloved woody plants are being attacked by a determined little army of enemies.
Accustomed to cool, damp conditions for much of the year, maritime Northwestern natives suffer when snowmelt and seasonal rains are scanty. Even in hotter, drier regions, increased heat and drought put natives and exotics at risk, especially as water prices rise and watering restrictions are put in place. Though my corner of the world didn’t heat up this summer, heat surely happened elsewhere. Soaring temperatures and altered rain distribution, sudden snow and hellacious hail are hard on gardens. What’s a gardener to do?
Answering that will take some thought and experimentation. As the worldwide weather shifts continue, many folks in the horticulture business are rethinking their plant palettes. Everyone, from growers to nursery retailers to garden designers, is looking for more adaptable plants. There’s a growing movement to find tougher replacements for old standards that no longer thrive where they were once were tried and true. Fortunately, skillful folks everywhere are experimenting with plants that historically do best a zone or two south. For instance, growers from Washington, Oregon and California are working to develop a broader palette of garden-worthy Oregon and California natives.
Like what? Like the lovely manzanitas (Arctostaphylos), a family of evergreen shrubs and small trees. Though manzanitas have rarely been successful garden plants in coastal Washington gardens, they’re now are enjoying new popularity up and down the coast. Once a hobby relegated to native plant hunters and native plant enthusiasts, these days, nursery buyers and garden designers alike are seeking out handsome, reliable evergreens that tolerate heat, drought, and winter cold. Like the lovely native madrones, many manzanitas have peeling, ruddy bark and leaves of shimmering blue-grey or deep or silvery green. The clustered, bell shaped flowers (usually pink or white) are highly attractive to native bees, and the subsequent fruit feeds critters galore, from birds to bears.
More Great Choices
Many perennials will thrive in difficult conditions, once well established. Most plants that like it hot are actually fairly thirsty until well established, including many native prairie perennials such as rudbeckias and echinaceas. Though summer rain is rare on most American prairies, prairie plants develop extremely deep root systems that help them survive high heat and dry soils. Sold as drought tolerant (which they are, eventually), they can die for lack of water for the first several years. Like Pacific Northwest natives, most dryland plants do much of their root building in winter. To encourage root production, offer slow, steady organic fertilizers such as compost mulches. To keep those roots on track, avoid using commercial fertilizers from late summer until mid spring.
Among my favorite heat lovers are the Agastaches, called anise hyssop (though related to neither). These long blooming perennials are excellent performers in hotter, drier climes, where they attract all sorts of bees, hummingbirds and other pollinators from midsummer well into autumn. Thriving in open, sandy soils, anise hyssops do far better in large containers than in heavy clay soils, especially if drainage is less than optimal. Among the sturdiest classic varieties are Blue Fortune, with spires of dreaming blue, and Purple Haze, which produces cloudy spikes in thunderhead shades. Many recent hybrids involve high desert species with warm apricot and deep orange tints, notably the Arizona series, in shades of terra cotta, peach, and gold, and the tawnier Summer series, including coppery Summer Sunset and gentle peach Summer Glow.
Great Performers With Stamina
Modern yarrow (Achillea) hybrids are both mannerly and long blooming and take heat and drought in stride. Architectural in form, these deserving newcomers include lemon-ice Moonshine, with grey-green foliage, an especially effective blender for blues and purples. Where pastels are preferred, Appleblossom blooms in gentle shades of pink, from baby ribbon to delicate rose. Spunkier Paprika runs from smoky to sparky shades of red, while Ortel’s Rose creates a complex run from cool lavender to vivid magenta-rose.
The spurge family (Euphorbia) is deer proof, hardy, and handsome, and includes many excellent garden plants as well as a few rogues. I’m a sucker for wood spurges like Euphorbia amygdaloides Ruby Glow, a smoldering beauty with dusky purple foliage set aflame by ember red new growth. It grows happily in shade or sun and seeds itself about in a mild sort of way, never a pest since the plants are fairly short lived. Sculptural E. characias is a noble creature with many fabulous variations, such as Black Pearl, with tall stalks of green blossoms with snapping black eyes. Glacier Blue offer frosty foliage in silver and blue, while Silver Swan is even cooler in soft jade trimmed in ice. E. x martinii Ascot Rainbow makes a delectable, almost shrublike two-foot mound with foliage like frozen fireworks in delicate rainbow shades. Onward!