Spiraea serves as foundation of woodland gardens

Birch-leaf Spiraea (Spiraea betulifolia) — sometimes spelled Spirea — is a small, deciduous shrub native to the Northwestern U.S., east to include the Intermountain West and the Black Hills of South Dakota, as well as southern parts of Canada's western provinces. It is a common understory plant in dry open forests and on east- and south-facing rocky slopes where it enjoys full sun, rich soil and light to moderate moisture.

Rarely growing more than two to three feet high and equally as broad, Birch-leaf Spiraea has cinnamon-colored bark, which is scaly when mature. Its relatively sparse branches are covered with broadly oval, bright green leaves ranging from one to three inches long. Leaf margins are smooth on the stem end and serrated near the tip. Their resemblance to birch leaves is reflected in the species name “betulifolia.” “Betula” is the genus name for birch and “folia;” is Latin, meaning leaf. The genus name “Spiraea” is Greek for a plant used for garlands.

A member of the Rose family, Birch-leaf Spiraea blooms in early to mid-summer, depending on elevation, with abundant two-to-five-inch flat clusters of flowers. Individual blossoms have five creamy white to slightly pink petals and up to 60 delicate stamens extending beyond the petals, giving the flowers a soft, lacy look. While the spring bloom is showy, in the fall the entire shrub bursts into autumnal flame with shades of red, orange, gold, and burgundy.

Following bloom, inconspicuous seed heads form, though the plant most usually reproduces asexually from underground rhizomes. Birch-leaf Spiraea is a moderate spreader forming patches of lovely, low-mounded shrubs. It is easily pruned, best in late winter or early spring while branches are still dormant. Although it is considered poor forage, deer may browse the winter stems. It recovers this natural pruning nicely, making it a good choice for low hedges or borders.

Native people used branches, leaves, or roots to make a tea for abdominal and menstrual pain. Plants in the Spiraea genus contain acetylsalicylic acid, the pain-relieving substance we know today as aspirin. In fact, the word “aspirin” was derived by adding the “a” from “acetylation” to “spirin” from a German reference to Spiraea.

In the garden, Birch-leaf Spiraea serves well as a foundation planting, border, or understory groundcover in a woodland garden. Its small, compact form fits nicely into perennial beds where a larger shrub would be too much. When in bloom, it attracts butterflies and other native pollinators. It loves the sun but adapts to some shade and is drought-tolerant once established. Occasional summer watering will encourage additional summer blooms, but don't let it become oversaturated. Birch-leaf Spiraea is relatively disease- and pest-free and easy to grow from cuttings.

If you're purchasing Birch-leaf Spirea from a nursery, look for Spiraea betulifolia var. lucida. This is the name most commonly given to the American Northwest native. Others named Spiraea betulifolia may be native to Asia and will be much larger and less hardy than our variety.

Birch-leaf Spiraea grows in the Meadow/Moist Forest Habitat of the North Idaho Native Plant Arboretum, 611 S Ella St. in Sandpoint. Pictures and a description are found in “Landscaping with Native Plants in the Idaho Panhandle,” a KNPS publication available at local bookstores and the Bonner County History Museum.

Native Plant Notes are created by the Kinnikinnick Native Plant Society. To learn more about KNPS and the North Idaho Native Plant Arboretum, visit www.nativeplantsociety.org.