Also called false spirea, false goat’s beard and meadowsweet, the astilbe perennial shrub grows and flowers in full shade, making it desirable as an understory plant to add color and interesting, fern-like texture to landscape areas with tall shade trees.
There are several varieties of astilbe for home landscapes. They range in size from 6 inches to 4 feet. Before selecting a plant, check the descriptive tag or talk with your nursery professional about the specific cultivar you are considering. A popular cultivar is Astilbe x arendsii. The feathery flowers may bloom in white, pink, rose, red or lavender bloom in spring to mid-summer.
Astilbe grows well in USDA Hardiness Zones 4 through 8, if given moist, fertile soil. Purchase container grown cultivars and plant at the same depth as in the container. Cover roots with a shallow layer of soil. If growing from seed, wait until soil has warmed before planting. Amend soil with a balanced 5-10-5 fertilizer and propagate by root division in spring or fall every three to four years. Adding a protective layer of mulch around, but not touching the trunk, helps maintain soil moisture and adds winter protection. Water frequently until plants establish in their new location. Multiple plants should be spaced 1 to 2 feet apart.
Astilbes are generally healthy plants, although they may experience problems from slugs and powdery mildew. Fusarium wilt and spider mites may attack astilbe. Treat these problems with insecticidal soap for mites and fungicides or water spray for wilt and mildew, especially on young, vulnerable plants. To reduce pest attacks, clear the area directly under the shrub of debris in early spring.