The small flowers of astilbe form in tall clusters.
image by Unforth: Flickr.com
Astilbe is a genus of flowering perennials that consists of about 18 different species. Astilbe plants are native to Asia and North America and are commonly known as false goat's beard or false spirea, due to their appearance. The flowers are small in size but grow in clusters up to 6 inches in length. Astilbe plants bloom during the summer and can grow up to 4 feet in height. They are easy to grow but require adequate fertilization and moisture to thrive.
Harden astilbe by leaving seedlings outside for several hours each day for a week before planting in the ground. This will allow the plant to acclimate to the environment. Choose a planting location that has well-drained soil and receives full morning sun and shade in the afternoon when temperatures peak.
Dig a hole slightly larger than the root ball to allow plenty of room for the roots. Remove the astilbe from the pot and gently spread the roots out without damaging them. Place directly into the hole and cover with soil. Water thoroughly to compact the soil around the roots.
Water astilbe when the top 3 to 4 inches of soil are slightly dry and crumbly. Use enough water to thoroughly soak the soil around the plant. Do not water during the winter, as the plant will not require the supplemental moisture.
Spread a 1- to 2-inch layer of mulch over the soil around the astilbe to suppress the growth of weeds and conserve moisture. Feed twice a year---once in early spring and again in fall---using a slow-release fertilizer that is low in nitrogen.
Trim dried flower spikes in late fall, if desired. The spent spikes are considered ornamental during winter, but flowering will be reduced the following season if they are not removed. Do not remove dead flowers during the blooming season; doing so will not force new blossoms.