After astilbes have finished flowering, there are a few steps you can take to care for them and ensure their continued health and beauty. First and foremost, it’s important to resist the urge to deadhead the flowers. Unlike some other flowering plants, astilbes do not require deadheading. Instead, allow the flowers to go to seed, as this will help the plant propagate and produce new plants.
Once the flowers have faded and the seed heads have formed, you can begin the process of cutting back the astilbe plants. Using a pair of sharp pruning shears or scissors, carefully trim the spent flower stalks down to the base of the plant. This not only helps to tidy up the appearance of the plant, but it also allows the plant to redirect its energy towards growing new foliage and preparing for the next season.
After cutting back the spent flowers, it’s a good idea to give the astilbe plants a thorough watering. This will help to replenish any moisture that may have been lost during the flowering period and promote healthy growth. Be sure to water at the base of the plant rather than from overhead, as this can help prevent the development of fungal diseases.
Dividing astilbes every three or four years is another important step in their care. Over time, astilbes can become crowded and their growth may become stunted. Dividing the plants helps to rejuvenate them and encourages healthier growth. The best time to divide astilbes is in early spring or early fall, when the weather is cool and the plants are not actively growing. Simply dig up the clumps of astilbes and use a sharp knife or garden spade to divide them into smaller sections. Replant the divided sections in a well-prepared soil and water them thoroughly.
In terms of general care, astilbes prefer moist, well-draining soil and partial shade. They are not particularly fussy about soil pH, but adding organic matter such as compost or well-rotted manure to the planting area can help improve soil fertility and drainage. Mulching around the base of the plants can also help retain moisture and suppress weeds.
As with any plant, it’s important to keep an eye out for any signs of pests or diseases. Common pests that may affect astilbes include slugs and snails, which can be controlled by various methods such as handpicking or using organic slug pellets. Fungal diseases such as powdery mildew or leaf spot can be prevented by ensuring good air circulation around the plants and avoiding overhead watering.
Caring for astilbes after flowering involves cutting back the spent flowers, dividing the plants every three or four years, providing adequate water and drainage, and monitoring for pests and diseases. By following these simple steps, you can enjoy the beauty of astilbes in your garden for years to come.