The Astilbe plant, also known as false spirea, is an herbaceous perennial native to both North America and Asia. The plant is valued for its attractive fern-like foliage and large plumes of flowers that appear in early to mid-summer. Astilbe flowers can be purple, pink, white or red in color and the entire plant can reach up to 5 feet in height. Astilbe is hardy in zones 4 through 8 and requires only basic care to thrive in the home garden.
Plant astilbe during early spring in a location that receives partial shade throughout the day. Ensure the planting site is composed of well-drained, fertile soil for optimal growth. Space astilbe plants about 16 inches apart.
Cover the soil surrounding your astilbe plants with a light ½-inch layer of mulch to prevent the root ball from drying out too quickly. Add more mulch to the layer when necessary to replenish as the mulch decomposes.
Water astilbe once per week during the first year of growth. Reduce frequency of watering to once every 10 days for the remainder of the plant's life. Do not allow the soil to dry out completely at any time or the foliage will wither and die.
Feed astilbe plants twice per year, once during late spring and again in late summer. Use a 5-10-5 NPK fertilizer to increase the production of flowers. Apply following the manufacturer's directions for the best results.
Remove dead or wilted astilbe leaves whenever possible to encourage the growth of new foliage. Cut astilbe to the ground if most of the plant becomes wilted during extremely hot weather and the plant will go dormant until the following spring.