False Spirea, False Goat's Beard 'Amethyst'

Astilbe x arendsii

Family: Saxifragaceae (saks-ih-frag-AY-see-ee) (Info)
Genus: Astilbe (a-STIL-bee) (Info)
Species: x arendsii (ar-END-see-eye) (Info)
Cultivar: Amethyst



Foliage Color:

Unknown - Tell us

Bloom Characteristics:

Unknown - Tell us

Water Requirements:

Average Water Needs; Water regularly; do not overwater

Where to Grow:

Unknown - Tell us


18-24 in. (45-60 cm)


15-18 in. (38-45 cm)


USDA Zone 3a: to -39.9 C (-40 F)

USDA Zone 3b: to -37.2 C (-35 F)

USDA Zone 4a: to -34.4 C (-30 F)

USDA Zone 4b: to -31.6 C (-25 F)

USDA Zone 5a: to -28.8 C (-20 F)

USDA Zone 5b: to -26.1 C (-15 F)

USDA Zone 6a: to -23.3 C (-10 F)

USDA Zone 6b: to -20.5 C (-5 F)

USDA Zone 7a: to -17.7 C (0 F)

USDA Zone 7b: to -14.9 C (5 F)

USDA Zone 8a: to -12.2 C (10 F)

USDA Zone 8b: to -9.4 C (15 F)

Sun Exposure:

Sun to Partial Shade

Light Shade


Unknown - Tell us

Bloom Color:


Bloom Time:

Mid Summer



Other details:

Unknown - Tell us

Soil pH requirements:

5.6 to 6.0 (acidic)

6.1 to 6.5 (mildly acidic)

6.6 to 7.5 (neutral)

Patent Information:


Propagation Methods:

By dividing the rootball

Seed Collecting:

N/A: plant does not set seed, flowers are sterile, or plants will not come true from seed


This plant has been said to grow in the following regions:

Eureka, California

Seaford, Delaware

Mount Prospect, Illinois

Lancaster, Kentucky

West Friendship, Maryland

Foxboro, Massachusetts

Weymouth, Massachusetts

Pinconning, Michigan

Buffalo, New York

Ithaca, New York

Raleigh, North Carolina

Canton, Ohio

North Ridgeville, Ohio

Knoxville, Tennessee

Leesburg, Virginia

Bainbridge Island, Washington

Kalama, Washington

show all

Gardeners' Notes:


On Jan 13, 2009, catcollins from West Friendship, MD (Zone 6b) wrote:

I have used astilbe to fill in the shady space under my decks for many, many years. Amethyst is excellent for this purpose. I does not get as full as it would with more light, but it blooms reliably year after year. These thrive where ferns struggle.


On Jul 1, 2007, Crimson from Clarksville, TN (Zone 6b) wrote:

If kept moist and well mulched it blooms nicely. Do not allow to dry out or the leaves will brown. Needs well draining soil, heavy clay soils cause stunted growth.

The label that came with the plant states:
"A mid season bloomer with deep lilac plumes."
"Tall, with spires that reach almost 3 feet, Amethyst is a full-leafed variety that fills a space nicely and never looks sparse."
"Select a site with light to full shade and humus-rich soil. Loosen the soil to a depth of 2-3 inches, cover root with soil, leaving the crown and new growth eyes above the soil line. Apply a layer of mulch over the top."
"Keep well-watered until shoots appear, then keep soil moist but not soggy."
"End of Season apply a thin layer of compost each fall, followed... read more


On Mar 19, 2007, berrygirl from Braselton, GA (Zone 7b) wrote:

Medium to tall - plant 18" apart. zone 4-8. Many strong plumes of lavender in early summer. Excellent fern-like foliage. 14-18". Effective anywhere with rich moist soil and partial shade. Deer resistant.


On Jun 14, 2006, Sherlock221 from Lancaster, KY wrote:

This is a gorgeous Astilbe -- my favorite of all the colors I have! It grows very well in central Kentucky and gets quite large. I've had it grow nearly 3 feet tall. You need to leave lots of room for it to spread as well. It takes up quite a large space in the garden. I have two of this particular Astilbe and both are in part sun. The flowers are a stunning violet-pink color and the leaves are delicate and fern-like. In fact, it pairs quite well with ferns -- as you can see if you view the photo I uploaded. As the reviewer in NY said, this is a plant that is easily moved if it outgrows the space you plant in it. I have moved some of mine several times and it hasn't bothered them at all. I have even moved a very large one with no damage to the plant at all. It happily bloo... read more


On Nov 12, 2004, lmelling from Ithaca, NY (Zone 5b) wrote:

I started the Amethyst Astilbe out in two locations. One clump in my pond area where it gets full sun and constantly moist to wet soil. This plant gets little to no extra fertilizer other than what washes down in soil through the springs in the hill behind it, but does extremely well, growing at a moderate pace. The lavendar blooms each June are a beautiful sight against the rocks and other plants around it.

The other plants were planted in semi shade in a corner garden near the house foundation, where they grew so rapidly that they had to be moved to other locations. I have since successfully moved them to other area's in the hillside and shade gardens where the grow contentedly.

Astilbe is such an easy plant! Deer resistant as well and divdes and tran... read more