Although astilbes are relatively easy to grow, they are a little different than some other varieties of perennial flowers. The ways that astilbe flowers differ from other perennials tends to cause many gardeners to make common mistakes when planning and caring for them.
Avoid Direct Sunlight
Unlike many other perennials, astilbes generally grow and thirve better in shaded areas rather than in direct sunlight. The astilbe flowers have above average water requirements for a perennial, and too much direct sunlight may cause the soil to dry out and cause your astilbe to wilt or die.
No Deadheading Required
Deadheading astilbe flowers has no positive effect at all and produces no new blooms or flowers. While many other perennials benefit from clipping faded blooms (deadheading) by actually encouraging new bloom and flower growth., your astilbe flowers will not benefit from this practice.
Astilbe flowers are relatively resistant to most types of diseases; however, spacing your astilbe flowers too close together may result in powdery mildew being caused by fungi that thrive in overcrowded plant environments. So, make sure to space the astilbe flowers about 1 to 3 feet apart depending on the variety.