Astilbe requires humus-rich soil that retains moisture yet is fast draining. Some varieties are more drought tolerant than others, but all must have adequate moisture in either sun or shade or their foliage will shrivel and brown. Avoid planting astilbe in boggy conditions; it will succumb to rot in too much water, especially while dormant in winter. Incorporate ample amounts of well-decomposed compost, aged manure, or leaf mold into the soil before planting. After planting, add a 2- to 3-inch layer of mulch—pine needles or shredded bark—over the surface to hold in moisture. The browned flower spikes remain attractive in autumn, but your astilbes will look tidier and bloom more heavily the next year if you trim off the dried flower stalks.
Astilbe puts on the most spectacular show of any shade-loving plant. When in bloom, 12-to 24-inch-long, many-branched flower spikes shine brilliantly in lavender to rose-pink, in blood red to salmon and magenta, and in creamy, rosy, and snowy white. The lacy, fernlike foliage grows in clumps 2 to 4 feet high and nearly as wide. It remains attractive from its first appearance in spring until it is covered by winter frost or snow. Some selections have stunning bronze leaves.
ZONES: 4–9
BLOOM TIME: Summer
LIGHT: Part shade
HEIGHT: 22–48 inches
INTEREST: Plumes of flowers in many shades of pink, red, or white; one of the most rugged garden plants
Hybrid astilbe belongs in every border with moist soil. Its glossy foliage adds refinement to any planting all season long. Enjoy months of color by selecting those with early, midseason, and late bloom periods. When introducing astilbes into a woodland habitat, choose varieties with a loose, arching habit; reserve the stiffly upright growers for more formal locations in borders or along foundations.