Astilbes, also known as Florist's Spirea or False Goat's-Beard, come to us from Asia. The various hybrid forms of this versatile perennial plant are easy to grow and, as their feathery flowers dry, are attractive well into the winter. They are excellent low-maintenance plants as long as their soil is moist. The reliable hybrid astilbes flower at various times over the season and are available in white and a wide range of pinks and reds. In addition to the hybrid astilbes, there are several individual species that resemble them. Because they all are similar with regard to their care, this information is appropriate for most of the astilbes commonly available from nurseries and garden centers.
Astilbes are fairly hardy perennials and the range of most extends into New York state and up into New England and along the Great Lakes (zone 4). They survive comfortably in northern areas where it seldom gets colder than -20°F. They are not suitable for the deep South.
Size: Various hybrid astilbes grow from 2 to 3 feet tall at maturity. Over several years their shallow, fibrous roots form clumps that are 1 to 3 feet wide.
Foliage: Astilbe leaves resemble ferns, delicately divided into small toothed, oval leaflets on stiff stems. They are typically 1 to 1 1/2 inch long. They are usually dark green, but some have reddish or bronzed foliage. Red-flowered astilbes usually have the darkest foliage. New young leaves are glossy, but they gradually lose their shine as they mature. Eventually they turn brown and drop off in the fall.
Flowers: Astilbes bloom in white, pink, red to raspberry or purple for about 4 to 6 weeks. The individual flowers are small and densely arranged in fluffy sprays up to 6 inches or more long at the ends of tall stems. Depending on the variety, blooms may be stiffly upright or airily open and plume-like. Some varieties have a subtle scent. There are early bloomers (June), mid-season bloomers (July) and late bloomers (September).