Astilbe Flowers are deceptively delicate with their long, fern-like flowers. These flowers can actually withstand damp soil and shade, while still growing between one to six feet tall. Perfect to add for a pop of color to a garden that typically gets little sunlight.
Their sun requirement is a Full Sun / Partial Shade sun and they require a Well-drained, High fertility soil, they operates on Zones of about 4 – 9 with a Height of about 1.5 – 6 feet tall. They Blooms in Late Spring – Early Fall and are Good for cut flowers.
Astilbe is a perennial with beautiful, showy flowers atop glossy, fern-like foliage. Here’s how to grow and care for astilbes in your garden.
Astilbes’ flower clusters vary in size from 6 inches to 2 feet and their height ranges from 6 inches to 5 feet, depending on the variety.
If you have a shady area, try astilbes. They are a great way to add color and texture to a place where other flowers won’t thrive.
The Basics of Astilbe Flowers
False goat’s beard, false spirea, florist’s spirea
An herbaceous perennial that spreads via underground rhizomes.
3-9 depending on variety
Best in partial shade to shade
Astilbes are typically classified as early, mid, or late season bloomers, depending on the species and cultivar. Early blooming varieties emerge in spring, while late bloomers hold off until July or August.
Because the bloom times vary widely, you can combine plants from each category for an ever-blooming garden from May through September.
Length of bloom:
4 to 6 weeks
8 inches to 4 feet
Characteristics of Astilbe Flowers
Astilbes provide year-round interest, beginning with their foliage in early spring and ending with dried feathery plumes and seedheads in winter. In between, these showy perennials are some of the best plants for summer color, displaying delicately fragrant bottlebrush-shaped blooms in colors ranging from creamy white and soft pink to deep purple and crimson red.
Astilbe flower clusters range in size from 6 inches to 2 feet in length, depending on the species or cultivar. Even when not in bloom, their deeply-cut leaves remain attractive all season and are often enhanced by tones of bronze or burgundy. Some have especially eye-catching foliage in shades such as bright chartreuse, chocolate, and russet red.
Read Also: Artemisia Flowers – All you need to know
Common types of Astilbe Flowers
Hybrid astilbe (Astilbe ×arendsii): This is by far the largest group of garden hybrids and includes more than a hundred varieties. Most are early-season bloomers, emerging in late spring or early summer.
Chinese astilbe (Astilbe chinensis): These fast-spreading, rhizomatous plants are often used as groundcovers. They bloom later than the arendsii hybrids and are more drought and heat tolerant.
Japanese astilbe (Astilbe japonica): An early-to-mid summer bloomer with dense, pyramidal flower plumes.
Star astilbe (Astilbe simplicifolia): A slow-growing, compact plant with shiny leaves and delicate starlike flowers. Like A. chinensis, it blooms late in the season.
Planting of Astilbe Flowers
- Astilbes prefer a site that receives light to moderate shade; they will burn in full sun.
- Astilbes prefer soils that provide average to slightly below average moisture. Make sure your soil drains well and does not puddle or get water-logged in rain. Amend soil, especially clay types, with peat moss, perlite, and coarse sand to improve the drainage.
- You can plant astilbe seeds, but they are short–lived and difficult to germinate. It is easier to plant divisions from other astilbe plants.
- Plant divisions in the spring or fall about 1 to 3 feet apart, depending on the type.
- 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.
- Make sure to plant the divisions in consistently moist, humus-rich soil. Dry soil can be fatal to your plants.
- To prolong the foliage, provide shade from hot afternoon sun. Astilbes can grow in deep shade, but will not flower as much.
Care of Astilbe Flowers
- Remember to regularly check your astilbes to make sure they are moist. Water accordingly if rain does not occur. It’s best to water deeply when you water (not everyday sprinkling).
- Astilbes spread quickly and form broad clumps. Their 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.
- Your astilbes will benefit from a balanced organic fertilizer applied in the spring.
- 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.
- Astilbe do fine as cutting flowers if you wish to clip some blooms to bring inside.
- Removing the flower heads will not promote continued flowering.
- After blooming has finished for the season, feel free to clip off any spent flower stems. Your astilbes will continue to provide attractive foliage until fall.
- After the first frost, the leaves may yellow; trim leaves if you wish and fresh growth will come next spring.
Pests/Diseases of Astilbe Flowers
Rarely bothered by diseases or insects, including the pesky garden slugs that typically nosh on plants grown in a moist environment. They are also Deer and rabbit resistant.
Their pests and diseases include:
- Tarnished plant bug
- Powdery mildew
- Bacterial leaf spots
- Luckily, astilbe are deer-resistant.
- ‘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
Grow your Own Astilbe Flowers
1) When to plant
In spring after the threat of severe frost has passed, or in early-to-mid fall.
2) Where to plant
Best grown in partial shade to shade, tolerating filtered sun. However, they will grow well in full sun in northern zones. “Their best use, however, may be in light shade, since they provide a bright splash of color to banish gloom.”
In warm southern regions, plant astilbes in partial to full shade to prevent scorching of the leaves.
All astilbes, even the more drought-tolerant varieties, prefer cool, moist soil rich in organic matter. Keep the soil evenly damp but not soggy, especially during the winter when plants are dormant.
Avoid planting in heavy clay soils and sites with poor drainage. If necessary, amend the soil with compost or organic matter to improve structure and moisture retention.
4) How to plant
They can be grown from root divisions, nursery-grown plants or seeds, but you’ll have better success planting divisions or potted plants because astilbe seeds have a tendency to rot in the ground before they germinate.
Place the crown of the plant about an inch below the soil surface, and fan or spread out the roots to encourage new root growth. Space plants at least 16 inches apart to allow ample growing room for the attractive foliage.
5) Using in the garden
Good companions for astilbes include other moisture-loving, shade-tolerant plants such as small ferns, hostas, lady’s mantle (Alchemilla mollis), Siberian iris (Iris sibirica), lungwort (Pulmonaria) Siberian bugloss (Brunnera macrophylla), and variegated Solomon’s seal (Polygonatum odoratum ‘Variegatum’).
Care and Maintenance of Astilbe Flowers
1) Water and fertilizer requirements
Astilbes are thirsty plants and heavy feeders during the growing season. Keep your plant well watered, especially during the heat of the summer. A one-time application of a timed-release granular fertilizer before flowering begins in spring should be enough to satisfy their appetite.
Early-flowering astilbe varieties form buds in the autumn for the next season’s flowers, so fertilizing these plants again in October with a high-nitrogen fertilizer will help to stimulate bud formation the following spring.
To help preserve soil moisture, keep them well mulched with leaf mold, compost or another type of organic material.
If you notice that the root crowns are rising above the soil, gently press them back into the ground before top dressing.
To keep astilbes vigorous, divide clumps every three or four years in early spring, using a sharp knife to cut through the heavy, fleshy roots. Separate the clumps into three or four pieces, each with at least one eye.
Don’t bother deadheading because your efforts will not encourage repeat blooming. Leave the flowers and seedheads to dry on the plant for winter interest, or cut the flower heads when fresh to add height and texture to indoor arrangements.
If the foliage shrivels and browns after a prolonged period of drought, it can be cut back to the ground to promote regrowth of new foliage later in the season or the following spring.