With their graceful plume-like blooms dancing above airy fern-like foliage, astilbe are the quintessential shade loving perennials. These hardy plants flourish in shady garden beds and borders, providing elegant texture and months of colorful flowers.
In this in-depth guide, you’ll discover everything you need to know about successfully planting, growing, and caring for astilbe. Read on to learn how to incorporate these striking perennials into your own shade garden.
What is Ornamental Astilbe Plants
Astilbe are herbaceous perennials prized for their showy, feather-like blooms borne on tall slender stems above mounds of lacy compound leaves. They belong to the Saxifragaceae family and are closely related to popular shrubs like hydrangea and mock orange.
There are 18 wild astilbe species, the majority native to mountain stream banks and ravines in Asia and North America where they thrive in damp, shaded conditions. But most types grown today are hybrid cultivars bred for fuller, longer-lasting plumes and vibrant flower colors like red, pink, purple, white, and salmon.
Astilbe plants form bushy mounds or clumps reaching 1-3 feet tall and wide when mature. Their fern-like leaves and arching bloom plumes provide beautiful fine texture. The feathery flower heads appear in late spring through early summer depending on the variety.
While exotic in appearance, astilbe are relatively easy to grow perennials. They flourish with minimal care as long as their preference for rich, moist soil and cool partial to full shade is met. Read on for tips on successfully incorporating astilbe into shady garden beds, borders and containers.
Providing the Best Growing Conditions for Astilbe
While adaptable to various site conditions, astilbe thrive best when grown in a location that provides:
- Partial shade – Dappled or filtered sunlight is ideal, such as that beneath high tree branches or a porch overhang. Morning sun with afternoon shade also works well. Avoid hot direct midday sun.
- Consistently moist soil – Enrich soil with several inches of compost or other organic material to improve moisture retention. Fertile loam that holds water works better than dry, sandy soils.
- Even moisture – Ensure soil stays moderately moist but not soggy wet. Add peat moss if needed to improve drainage on heavy clay soils. Use mulch to conserve moisture.
- Cool temperatures – Site astilbe away from areas that collect heat like paved surfaces or walls that radiate warmth. Shade helps keep roots cool.
- Slightly acidic pH – Test soil pH and amend if needed to fall between 6.0-7.0 which is ideal for astilbe. Aluminum sulfate can help lower pH.
With their preference for the cool, humid conditions found in forest understories and along shaded streambanks, astilbe are right at home in woodland gardens and shady perennial or fern borders. They combine beautifully with other shade-loving plants like hosta, coral bells, lenten rose, and ferns.
When and How to Plant Astilbe for the Best Success
Astilbe are easy to plant in either spring or fall. Here are some tips for adding them to your landscape:
- Spring planting – Set out nursery-grown potted astilbe in early spring once the threat of hard frost has passed and soil has warmed up a bit. Avoid transplanting too early while soil is still freezing cold.
- Fall planting – Late summer into early fall is also an excellent time to plant or transplant astilbe so they can establish roots before winter dormancy sets in.
- Prepare soil – Mix 2-3 inches of compost or well-rotted manure into the soil to improve fertility, moisture retention, and drainage. Astilbe prefer consistently moist but well-aerated soil.
- Allow enough room – Space astilbe plants 18-24 inches apart so they have room to reach maturity and spread. They dislike being overcrowded.
- Plant at proper depth – Ensure the crown where the roots meet the stems sits right at soil level when planting astilbe. Plant only as deep as the roots sit in the pot.
- Water well – Water thoroughly after planting to soak soil and mist regularly for the first few weeks until plants are established.
- Apply mulch – Spread 2-3 inches of shredded bark, pine needles, leaves or other organic material around plants to conserve soil moisture and inhibit weeds.
Follow these simple tips for planting astilbe, and you’ll have lush, healthy specimens growing in your shade garden in no time.
Caring for Astilbe Plants: Watering, Fertilizing, and Pruning
While relatively low maintenance once established, astilbe do require some regular care and attention throughout the seasons to keep them looking healthy and floriferous. Here are the key aspects of astilbe care:
- Consistent watering – Maintain even soil moisture by providing around 1 inch of water per week from rain or supplemental irrigation. Water more frequently during hot, dry spells. Use mulch to preserve moisture.
- Regular fertilizing – Apply a balanced flower fertilizer or one formulated for perennials in early spring just as new growth emerges. Fertilize again midway through summer. Avoid high nitrogen formulas that spur leggy growth.
- Annual pruning – After flowering ends in summer, cut back spent flower plumes to prevent self-seeding. Remove any dead or damaged foliage before new leaves emerge in spring.
- Occasional division – Congested astilbe clumps should be divided every 2-3 years in early spring, replanting divisions to rejuvenate and expand plantings.
- Winter protection – Cut back dead foliage in late fall once it has been damaged by frost. Mulch around the crown with leaves or evergreen boughs in cold climates for insulation. Avoid fertilizing late in the year.
With the right care in terms of water, nutrients, pruning, and protection, an astilbe planting can thrive for many years in the shade garden.
Troubleshooting Astilbe Care Issues: Diseases and Pests
While generally quite hardy when their preferred growing conditions are provided, astilbe can be affected by some fungal diseases, pests, and cultural issues:
- Poor flowering – Lack of sun, overcrowding, excessive fertilizer, or drought stress can all inhibit astilbe from blooming well. Ensure proper siting and growing conditions.
- Leaf scorch – Dry soil, excessive sunlight, or hot desiccating winds can cause leaf tips and margins to brown. Improve site conditions and moisture retention.
- Powdery mildew – This fungal disease coats leaves in a telltale white powdery substance. Improve air circulation and avoid wetting foliage.
- Rust – Reddish bumps appearing on the leaf undersides indicate rust fungus. Remove and destroy affected leaves. Space plants out for better air movement.
- Slugs and snails – Use traps and iron phosphate baits to control these pests that chew ragged holes in astilbe foliage. Avoid wetting leaves. Handpick at night.
Catching problems early and adjusting care practices can help prevent further issues and keep your astilbe looking healthy.
The Best Astilbe Varieties to Grow in Gardens
Between the many species and countless cultivated hybrids, there are numerous excellent astilbe varieties to choose from. Here are some of the best types to grow:
- Astilbe x arendsii ‘Bridal Veil’ – Elegant pure white plumes on 30 inch scapes bloom early summer. Good cut flower with excellent vigor.
- Astilbe chinensis ‘Visions in Red’ – Vibrant glowing cherry-red blooms arise from bronze-green foliage. Grows 18-24 inches tall.
- Astilbe chinensis ‘Pumila’ – A compact dwarf variety reaching just 10-12 inches tall but with full feathery bright pink blooms.
- Astilbe japonica ‘Deutschland’ – Huge showy white plumes on 18 inch stems appear in early summer. Grows 2-3 feet tall when mature.
- Astilbe x arendsii ‘Fanal’ – Deep red flowers on glossy foliage. Blooms mid to late season. Mature height of 2-3 feet.
- Astilbe chinensis – Features light lilac-pink plumes on attractively bronzed foliage. One of the earliest to bloom.
With so many astilbe cultivars to pick from, it’s easy to find more than one variety to incorporate into your shade garden for a succession of flowers from spring through summer.
How to Plant and Grow Astilbe for Months of Graceful Color
With their elegant plumes dancing above airy, fern-like foliage, astilbe beautifully combine fine texture with months of color in shaded garden beds and borders.
By choosing an appropriate shady site and providing ample moisture along with yearly feeding and pruning, astilbe are easy to grow perennials that need minimal care while brightening even the darkest corners of a garden with their graceful flowers and foliage.
So be sure to reserve a spot for these striking hardy perennials this year as you plan out and plant your own shade garden display.