Astilbe Species The fern like foliage and the showy plume flowers of False Spirea (Astilbe) make them a favorite summer flowering perennial. The flower plumes which appear in June and into July come in a variety of colors ranging from pink, white, red and purple. The most common varieties grow to a height of about a foot and a half, but there are also taller types which may reach five feet for the background, and little 6 inch dwarfs which make nice groundcovers. Even when they are not in bloom, the foliage stays attractive throughout the summer, making them very effective as a border plant, in the shade garden, or at the side of your garden pond. Astilbe are hardy to Zone 6. Although the Astilbe is generally considered to be a partial to full shade plant, they appreciate a little morning sun. They do, however need protection from the hot afternoon sun. They should be planted 15-24 inches apart in good humus soil that is rich in organic matter, and must be kept reasonably moist at all times. Plants may be set in the garden either in the Spring or in the Fall. Be sure to provide good drainage for these plants if your winters are wet, as they are here in the Pacific Northwest Astilbes are heavy feeders and and should receive periodic applications of 5-10-5 fertilizer throughout the summer. They should be divided every 3-4 years to keep them looking their best. In early spring remove the debris from the previous year, before new growth emerges. Astilbes are propagated by division, or they may be grown from seed started indoors in early March, or planted directly into the garden in early Spring. Astilbe, also known as false spirea or meadowsweet, is a native to China, Japan, and Korea. It is a shade tolerant perennial that grows 2 to 3 feet tall although some varieties can grow to a height of 4 feet. Bloom occurs from early June through August depending upon the cultivar. Flowers are available in white and various shades of pink, red, or lavender. The genus Astilbe is composed of approximately 25 species. Astilbe grows best in full sun or partial shade. They require a consistent supply of moisture to prevent browning of the leaf margins. Astilbe also require well drained soils, they do not perform well in heavy, clay. Around the pool they can be bogged or container planted, in a one gallon pot or larger. The pots should be placed so only about the bottom 2 inches of the pot are submerged. Fertilize in the spring with a slow release fertilizer according to label directions. A fertilizer ratio of 3-1-2 is preferred. Astilbe are quite pest free. Although powdery mildew, wilt and spider mites have been reported, control is seldom necessary. In the landscape, astilbe usually need division every 4 years or so.