By Dan Milhollin, Sonoma County Master Gardener
Of the hundreds of species in the Artemisia family, only a few are used in Sonoma County landscape design; many of the most useful were produced by hybridization. (See specific listings below.) A. “Powis Castle,” the best known and most available in local nurseries, has been called the “Gardener’s Dream Plant”. “Powis Castle” is ideal for the very casual, low maintenance, arid garden. Deer do not like the fragrance but aphids do like to dine on early spring growth; otherwise this rugged plant is quite pest resistant and not prone to any diseases.
I’ve used “Powis Castle” for about seven years in various locations throughout my landscape: as foundation planting along with Euphorbia, Arctostaphylos (manzanita), Kniphofia and Achillea (yarrow) in my public spaces -- next to a very yellow-colored house. I’ve moved some of the plantings several times, from well-amended soil to the native rocky clay of this valley setting. It has always transplanted easily and adapted to its new home despite soil conditions. Artemisia dislikes both water and fertilizer. Some water is necessary to help establish the shrub, then occasional -- maybe monthly.
Artemisia’s color variations, sizes, sculpted shapes and tolerance of both cold and wet winters invite many uses in the Sonoma County garden; in full sun the silvery gray color enhances both light and deep-colored companion plants. The chartreuse of the Euphorbia in my front yard is complimented by “Powis Castle”’s gray hues; in part shade, in another part of the garden, “Powis Castle”’s gray-green lace texture compliments a reddish brown Carex and a potted palm. I wanted limited color use next to the yellow house along with limited maintenance, and “Powis Castle” met both these needs while also softening the appearance of the hard-surfaced blue paver walkway.
Other possible companion plants include Ceanothus, Cotoneaster, Cistus, the larger and more dramatic Agaves (Americana for example), Arctostaphylos, Rosmarinus and Nandina. Artemisia also shines when planted near deep maroon or red-hued plants, such as Cotinus coggygria (smoke bush) or dark-leaved Phormiums. Variations in both color and texture are pleasing to the eye but take care to group only those plants with similar care needs: no fertilizer, very little water, full to part sun and good drainage for our wet winters.
My recent survey of Sonoma County nurseries revealed six selections of this plant family that are usually available locally. While having similar general characteristics these have variety in size, shape, use and color: each is worthy of consideration for your garden. Note: two of these like regular water.
A. “Powis Castle”: Airy, gray-green, lacey foliage, sculptural, 3’ x 3 - 5’ wide from woody stems, easily shaped. Takes severe pruning, is tough and versatile in low-water landscapes while enhancing most other plants. In part or filtered sun the foliage becomes more gray green; in full sun the silver hues dominate. It is the most widely available Artemisia here in Sonoma County.
A. stelleriana “Silver Brocade”: White, silver groundcover. 6-10”x 20.” Sun. Little water. Softens edges of walkways, contrasts easily with agaves or other plant colors: white, yellow, blue, reds, and maroon. The leaf is similar in size and shape to flat leaf parsley, but is silver white.
A. lactiflora “Guizhou Group”: Native of western China. White mugwort. 3-5’ x 2’, clump-forming with airy clusters of fragrant creamy flowers on purple stems late summer to mid autumn. Purple, deep lobed leaves changing to green. Border plant for cut and dried flowers. Rich, moist, well-draining soil in full sun.
A. schmidtiana “Silver Mound”: dwarf mounds (12’ - 24”x 12” x 24”) of soft, silky silver gray fragrant foliage; small white or yellow flowers for rock gardens, front of border, containers. Slightly dry, average soil. Pairs well with Echinacea ‘Purple Coneflower’ or Rudbeckia ‘Black-eyed Susan.’
A. vulgaris “Oriental Limelight”: variegated green-yellow, flat, lobed leaves on stalks to 2’. This variety likes regular water - the most dissimilar of the Artemisias but also more versatile. Especially attractive with yellow flowered plants (Coreopsis, Achillea, and Kniphofia)
A. pycnocephala “David’s Choice.” A native from Pt. Reyes but thrives inland. Rounded, compact form in blue-gray, cedar-like but delicate foliage. 3’x3’. Same easy care as other Artemisias: good drainage, very little water after established, loves neglect. Contrasts well in shape and texture with larger boulders in landscape and California fuchsias (Zauschneria), orange-hued tubular flowers that attract hummingbirds.
Artemisias may be found locally at Cottage Gardens, Emerisa, Harmony Farms, King’s, Pricketts and Sonoma Mission Gardens.