Astilbe is best planted in spring or fall. Avoid planting it in the summer due to the hot weather that tends to dry it out. If you must plant in the summer, keep the plant well-watered until you begin to see new growth emerging...
Astilbes grow well in moist, well-drained soils with slightly low moisture. Do not grow these flowers on waterlogged soils. Amend clay soil or soils that don’t drain well with peat moss, perlite, and coarse sand to improve drainage...
Every 3 to 4 years, it’s time to divide your plant’s roots. Dividing prevents them from becoming overcrowded.When Astilbe plants become overcrowded, they stop growing and do not flower well...