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Northwest Prairie Plants

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Oh, my aching muscles...

By Deborah Horn

Much of the landscape we know today was created by what a glacial ice sheet left behind when it retreated 15,000 years ago: the Puget Sound, lakes and rivers, and south from Olympia to the Columbia River (and beyond), deep, gravelly soils that became open prairies. Colonized by grassland steppe plants from the east and oak woodlands from the south, prairies covered only 10% of the post-glacial landscape. They were preserved by Native Americans with controlled fires so that they might harvest the bulbs and forbs (herbaceous flowering plants) that grow in fire’s wake. Today, only 3% of the original prairies and oak woodlands remain.

Many plants native to the prairie are found in other areas in the Northwest, so may be familiar garden plants. Columbine (Aquilegia formosa) and camas (Camassia spp.) are garden favorites, as are yarrow (Achillea millefolium) and chocolate lilies (Fritillaria affinis). Native Americans steamed chocolate lily roots and camas bulbs in pits. They also relied heavily on biscuit-root (Lomatium utriculatum and others), and actually distinguished between a greater number of species of lomatium than modern botanists did until molecular analysis verified the First Peoples’ intimate knowledge of the plants.

For those interested in growing Northwest native plants, species from the south Puget Sound prairie are perfect for that sunny, gravelly, drought-prone patch that is all too often sacrificed to the weeds. For that hard-to-water “hellstrip” between your sidewalk and the street—a prairie garden might be just the thing. And who knows? You might attract the endangered Taylor’s checkerspot butterfly (www.xerces.org/Endangered/taylorscheckerspot.htm) as well as interest and admiration from your neighbors.

Plant Portraits

The south Puget Sound prairie ecosystem is dominated by Roemer’s fescue (Festuca idahoensis subsp. Roemeri). Fescue grass makes a natural-looking matrix within which to plant flowering herbs and bulbs in your prairie garden. It is a long-lived, cool-season grass which grows through the winter, so is important as a space-holder, and is attractive in its own right with bluish blades forming dense tufts to 12 inches. It does not spread by runners.

Wild strawberry (Fragaria virginia) and kinnikinnik (Arctostaphylos uva-ursi) are also ground-covering plants that can form the background from which the taller plants arise.

Two camas lily species offer sequential flowering: common camas (Camassia quamash) and great camas (Camassia leichtlinii). The first blooms in early May, followed by the second two weeks later. Cultivars include Camassia quamash ‘Orion’, with deep violet-blue flowers.

Blooming at the same time as common camas is Henderson’s shooting star (Dodecatheon hendersonii). The rocket-shaped corolla is pink, with a yellow base and dark stamens. This prairie-adapted shooting star goes dormant in summer, so it is drought-tolerant.

A new plant for me is cut-leaved microseris (Microseris laciniata). The jagged-edged succulent leaves have a very distinctive look, with yellow daisy flowers hanging on nodding stems.

Showy fleabane (Erigeron speciosis) is definitely showy. If you cut the blue flowers back after it finishes blooming in spring, it will flower again through the summer and offer a third flush in autumn. The foliage forms a dense 12” tall tuft of narrowly spatulate leaves.

Delphinium nutallii is one of my favorites. It has one the deepest violet flowers that I have ever seen. I am told that it is slow to establish, so be careful not to weed it out!

Oregon sunshine (Eriophyllum lanatum) is a wonderful, low-growing yellow daisy whose narrow, silver leaves provide a foil to the blue flowers of the erigeron mentioned earlier. It is one of the easiest prairie plants to grow. This tough groundcover takes drought in stride.

Slender cinquefoil (Potentilla gracilis) is a small shrub with buttercup-yellow flowers summer through fall.

If You Like a Challenge…

And there are some harder-to-grow species for those who like a challenge:

Balsamroot (Balsamorhiza deltoida) is a big, beautiful perennial with soft gray-green “mules ears” and huge yellow daisies. It needs a deep root run because of its taproot, so plant it high and dry!

Harsh paintbrush (Castellija hispida) is rarely grown in cultivation, but it is possible. It usually grows with a “host” which enables the paintbrush to derive more nutrients and water. This extra requirement does make it a challenging plant to propagate, so few nurseries carry Indian paintbrush at this time.

Home of the Golden Indian Paintbrush

This rare yellow flame is a charismatic ambassador (as much as a non-mobile species can be) for Northwest prairie ecosystems. Golden indian paintbrush (Castillija levisecta), is listed as a threatened species in Washington and British Columbia. It is extirpated from the Willamette Valley, but there are plans to reintroduce it to selected sites later this year. Populations in under a dozen sites in Washington and British Columbia comprise from 10 to around 1000 individuals.

The special attention given to protecting the golden indian paintbrush has fueled restoration efforts in prairies throughout the region. Such activity provides a good example of the cross-over benefits that can occur when the world of gardening and the world of restoration ecology meet.

Conservation of prairie plants

I recently toured The Nature Conservancy’s (TNC) Glacial Heritage Preserve near Little Rock, about 10 miles south of Olympia, WA. My guides, Dan and Pat Montague, are dedicated volunteer coordinators who spend their Tuesdays (and many other days) at the preserve pulling invasive Scotch broom (Cytisus scoparius), collecting seed, and planting native prairie seedlings. I was fortunate to see Castilleja levisecta in bloom—and felt guilty for not having earned the privilege by pulling Scotch broom.

The Montagues are members of the Northwest chapter of the North American Rock Garden Society, and have created a beautiful rock garden featuring native plants and dwarf conifers at their home north of Olympia. As Dan led me over to the open, mounded area where they grow a prairie garden in miniature, featuring Roemer’s fescue, showy fleabane, lupines, camas, lomatium, shooting star (in bloom) and Oregon sunshine, Pat explained, “Prairie restoration efforts are relatively new. When we first became involved about 10 years ago, there wasn’t much known about propagation or reintroduction of these plants.” Yet here were all these species thriving in a garden situation.

Later, as I toured TNC’s Shotwell Nursery, run by horticulturist Daeg Byrne, it was obvious that propagation efforts were paying off. Raised beds were filled with a single species in each box, while rows of seedlings filled covered benches. Harsh paintbrush was in full bloom, filling one raised bed for 30 feet in shades from yellow to orange. They were grown with Oregon sunshine, the host, for transplanting out or seed collection. Such a gorgeous sight makes one wonder: where can I buy these for my home garden? Indeed, Pat told me that they sometimes get a visitor who inquires whether the nursery would sell to a retail customer. And sometimes they do. It’s all very new.

The Hunt for Prairie Gems

Just as it was once difficult to find Northwest native woodland plants at retail nurseries, it is a challenge to find nurseries that sell prairie plants. Wholesale nurseries are selling great numbers of these plants for restoration projects. My best advice is to ask your local native plant retailer to put an order in for you with their next wholesale order. Once the word gets out, nurseries will stock more prairie gems for their demanding customers. In the meantime, you could volunteer at one of the south Puget Sound prairie preserves to get your prairie plant fix.

To volunteer:

The Nature Conservancy 206-343-4345

Washington Native Plant Society 888-288-8022 (inside Washington)

Prairie Plant Sources:

In Washington (this site also lists nurseries in Oregon) http://www.wnps.org/landscaping/nurserylist.html

Defenders of Wildlife webpage has an appendix listing native plant nurseries in the Willamette Valley and beyond: www.biodiversitypartners.org/pubs/Campbell/07af.shtml

A Seattle “native” since 1981, Deborah Horn owns Artemis Gardens Landscape Design, and works in North Seattle, Edmonds, Shoreline and Lake Forest Park.

 

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