Astilbe (Astilbe spp.) produces spikes of showy flowers atop glossy, fern-like foliage. This perennial adds color and texture to a shady place. Here’s how to grow and care for astilbe in your garden.
Deceptively delicate in appearance this moisture- and semi-shade-loving perennial is hardy to Zone 4. Depending on the variety, astilbe will provide blooms from late spring to late summer. A few selections are even fall flowering. With proper moisture, the foliage remains attractive throughout its blooming period.
Astilbes are clump-forming perennials that belong to the saxifrage family and arise from a stout rootstock. The upright stems—typically 1.5 to 3 feet tall—bear fern-like green foliage and feathery plumes extending above the foliage in shades of pink, red, purple or white. The flower clusters vary in size from 6 inches to 2 feet, and the plant height ranges from 6 inches to 5 feet, depending one variety.
Astilbe prefer shady and moist sites. They’ll add a splash of color to a shady place, perennial borders, woodlands, wet sites, containers, and groundcovers. The plant attracts butterflies and is resistant to rabbits and deer. The showy flowers are excellent for floral cuttings or use in a dried arrangement.
Astilbes prefer light to moderate shade. Deep shade will result in few and/or poor flowers. The plant requires well-draining fertile soil with compost or aged mature added compost. Also, ensure this plant gets constant moisture (without puddling). In summer, damp conditions are important. Plants that are stressed for water will have burned summer foliage and disappear in a season or two. They prefer a soil pH of slightly acidic to neutral.
When to Plant Astilbe
Pots of astilbes are available at garden centers in spring and early summer and should be planted as soon as possible.
Divide existing astilbe plants in early spring as soon as you see new growth.
When started from seeds, astilbes can be difficult to germinate. The resulting plants tend to be short-lived. Division is recommended to keep the plants producing.
How to Plant Astilbe
If you are planting bare-root plants, make sure the holes are twice as wide as the plants and 4 to 6 inches deep. Place the plants so that the roots are fanned slightly and pointing downwards, with the crown planted 1 to 2 inches below the ground level. Cover the roots with soil and press firmly. Water well.
For plants already growing in nursery pots at garden centers, loosen the soil to about 10 to 12 inches deep. Mix in a handful of compost. The crown (where roots and plant connect) should be just below the soil line. Back fill with soil removed from hole. Water well after planting.
Remember to check that astilbes are moist. If rain does not occur, water deeply and regularly. Do not sprinkle frequently.
Astilbes are a bit slow to establish. Flowers should be better the second year.
Astilbes crowns often rise above the soil as they grow, so make sure to cover them with humus-rich soil or lift and replant the clumps.
As astilbes establish, they form clumps.
Be sure to divide the overgrown clumps every 3 to 4 years in the spring. You can either replant the divisions immediately or put them in pots to be planted out in the early summer when they are re-established.
Astilbes do fine as cutting flowers, if you wish to clip some blooms to bring inside.
Dead heading, or removing spent flowers, does not encourage the plant to promote continuous flowering.
After the bloom period, clip off any spent flower stems. The foliage will hold visual appear until fall.
To prolong the foliage, provide shade from hot afternoon sun. Astilbes can grow in deep shade, but will not flower as much.
After the first frost, the leaves may yellow. Trim them, if desired. Fresh growth will return in spring.
‘Fanal’, for its dark green foliage and dark crimson flowers
‘Irrlicht’, for its dark green foliage and elegant white flowers
‘Venus’, for its bright green foliage and bright pink flowers
‘Visions’ has strong stems, green leaves, thick raspberry flowers, and is more drought tolerant.
Astilbes are wonderful cut flowers. Put them in a vase with fresh water. They last 4 to 12 days in a vase. Cut the main stem, which frees up the side shoots to develop. Cut the side shoots as desired.