Astilbe: Bare Root or Potted Plant Perennial
How to Plant
Planting Bare Root Plants:
- Choose a location in full shade or part shade, with moist, well-drained organic soil. Astilbe can tolerate sun, but only if the soil is moist.
- Prepare the bed by turning the soil under to a depth of 6-12, inches removing any debris, and lightly raking as level as possible.
- The addition of organic matter (leaf mold, compost, well-rotted manure) benefits all gardens and is essential in recently constructed neighborhoods.
- Dig a hole deep and wide enough to accommodate the bare root.
- Set the plant such that the crown is at or just slightly below the ground level
- Cover the roots with soil and tamp down firmly to get rid of air pockets. Fill the soil to just below the crown, where the top growth and leaves will emerge. Make sure all the roots under the crown are in good contact with the soil.
- Water well to fully saturate the roots and soil.
- Wait until new growth starts to appear before applying a layer of mulch.
Planting Potted Plants:
- Choose a location in full shade or part shade, with moist, well-drained organic soil. Astilbe can tolerate sun, but only if the soil is moist.
- Prepare the bed by turning the soil under to a depth of 6-12, inches removing any debris, and lightly raking as level as possible.
- The addition of organic matter (leaf mold, compost, well-rotted manure) benefits all gardens and is essential in recently constructed neighborhoods.
- Plant on a cloudy day or in late afternoon to reduce transplant shock.
- Dig a hole for each plant large enough to amply accommodate the root ball.
- Unpot the plant and gently loosen the root ball with your hands to encourage good root growth.
- Place the top of the root ball even with the level of the surrounding soil. Fill with soil to the top of the root ball. Press soil down firmly with your hand.
- Use the plant tag as a location marker.
- Thoroughly water and apply a light mulch layer on top of the soil (1-2 inches) to conserve water and reduce weeds.
How to Grow
- Keep weeds under control during the growing season. Weeds compete with plants for water, space and nutrients, so control them by either cultivating often or use a mulch to prevent their germination.
- Mulches also help retain soil moisture and maintain even soil temperatures. For perennials, an organic mulch of aged bark or shredded leaves lends a natural look to the bed and will improve the soil as it breaks down in time. Always keep mulches off a plant’s stems to prevent possible rot.
- Careful watering is essential in getting perennials off to a good start. Water thoroughly at least once a week to help new roots grow down deeply. Soil should be damp at about 1 inch below the soil surface. You can check this by sticking your finger in the soil. Water early in the morning to give all leaves enough time to dry. One inch of rain or watering per week is recommended for most perennial plants. You can check to see if you need to add water by using a rain gauge.
- After new growth appears, a light fertilizer may be applied. Keep granular fertilizers away from the plant crown and foliage to avoid burn injury. Use low rates of a slow release fertilizer such as Garden-tone, as higher rates may encourage root rots.
- Remove and discard foliage after a hard frost in fall.
- Divide in early spring every 4 or 5 years if plants become overcrowded.
Growing Tips
- Many gardeners do not cut back perennial flower seed heads in the fall, but wait until early spring before the new foliage appears. This provides food for wildlife over the winter.
- Flowers are great for cutting for fresh or dried arrangements. Foliage is also attractive in arrangements.
- Astilbe naturalizes well in woodlands.
Common Disease Problems
Cercospora Leaf Blight: Small flecks which develop a yellowish halo appear on the leaves and turn brown and coalesce. They cause the leaves to wither and die. Burpee Recommends: Remove infected plants and destroy all plant debris. Rotate crops.
Leaf Scorch: The margins of the leaves turn red to brown and appear burnt. Burpee Recommends: This is not a disease but comes from hot, dry, windy conditions. Make sure the plants are properly sites in partial shade in moisture retentive soil.
Powdery Mildew: This fungus disease occurs on the top of the leaves in humid weather conditions. The leaves appear to have a whitish or greyish surface and may curl. Burpee Recommends: Avoid powdery mildew by providing good air circulation for the plants by good spacing and keeping weeds under control. Contact your Cooperative Extension Service for fungicide recommendations.
Root Knot Nematodes: Microscopic worm-like pests that cause swellings (galls) to form on roots. Plants may wilt or appear stunted. Burpee Recommends: Remove infected plants and do not plant in the soil for at least a year. Try planting in containers.
Virus (Various causes): Plants may have a yellowish tone and become stunted. Burpee Recommends: Remove infected plants.
Common Pest and Cultural Problems
Aphids: Greenish, red, black or peach colored sucking insects can spread disease as they feed on the undersides of leaves. They leave a sticky residue on foliage that attracts ants. Burpee Recommends: Introduce or attract natural predators into your garden such as lady beetles and wasps which feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.
Asiatic Garden Beetle: Velvety, cinnamon-brown beetle that looks like a coffee bean. The grubs eat the roots and the adults attach the foliage and blossoms. Burpee Recommends: Night time picking. Prevent by cleaning up fall debris. Check with your Cooperative Extension Service for pesticide recommendations.
Slugs: These pests leave large holes in the foliage or eat leaves entirely. They leave a slime trail, feed at night and are mostly a problem in damp weather. Burpee Recommends: Hand pick, at night if possible. You can try attracting the slugs to traps either using cornmeal or beer. For a beer trap, dig a hole in the ground and place a large cup or bowl into the hole; use something that has steep sides so that the slugs can’t crawl back out when they’re finished. Fill the bowl about ¾ of the way full with beer, and let it sit overnight. In the morning, the bowl should be full of drowned slugs that can be dumped out for the birds to eat. For a cornmeal trap, put a tablespoon or two of cornmeal in a jar and put it on its side near the plants. Slugs are attracted to the scent but they cannot digest it and it will kill them. You can also try placing a barrier around your plants of diatomaceous earth or even coffee grounds. They cannot crawl over these.
Tarnished Plant Bug: These insects cause distorted leaves and flower buds. The adults are about ¼ inch long, oval shaped and flat. They are greenish brown with reddish brown markings on their wings. There is a small but distinct yellow tipped triangle in the center of the back behind the head. Burpee Recommends: Introduce beneficial insects to your garden. Traps are available. Try insecticidal soap.
Vine Weevil: This insect cuts irregular notches in leaf margins and grubs feed on plant roots, sometimes causing the death of the plant. Adults are approximately 5/16 inch long, dull black with dirty yellow marking on the wing cases. The grubs are c-shaped, 3/8 inches long, with light brown heads. Burpee Recommends: Handpick adults at night, shake the plants over newspaper to dislodge them. Check under pots where they hide during the day. Check with your Cooperative Extension Service for pesticide recommendations.
Astilbe FAQs
Can I grow astilbe in a container? Yes astilbe is fine for containers. Be sure to use a commercial potting mix and do not allow it to dry out.
Is astilbe deer resistant? Yes, astilbe tends to be resistant to deer and rabbits.
What are some good plants to combine with astilbe? Astilbe looks great with other shade loving perennials such as heuchera, hosta and hakonechloa, which contrast with its ferny foliage.
Can I grow astilbe under a black walnut tree? Astilbe is more resistant than other plants under a black walnut, but if planted too close to it the area may be too dry.
Does astilbe attract pollinators? Yes, astilbe attracts bees, butterflies and moths.