American Arnica
Arnica chamissonis

Family: Asteraceae (ass-ter-AY-see-ee) (Info)
Genus: Arnica (ARN-ee-kuh) (Info)
Species: chamissonis (kam-ISS-oh-nis) (Info)

Category:

Herbs

Perennials

Height:

6-12 in. (15-30 cm)

Spacing:

15-18 in. (38-45 cm)

Hardiness:

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)

USDA Zone 9a: to -6.6 C (20 F)

USDA Zone 9b: to -3.8 C (25 F)

Sun Exposure:

Full Sun

Danger:

Parts of plant are poisonous if ingested

Bloom Color:

Bright Yellow

Bloom Time:

Late Winter/Early Spring

Mid Spring

Foliage:

Herbaceous

Other details:

This plant is attractive to bees, butterflies and/or birds

Average Water Needs; Water regularly; do not overwater

Soil pH requirements:

4.6 to 5.0 (highly acidic)

5.1 to 5.5 (strongly acidic)

5.6 to 6.0 (acidic)

6.1 to 6.5 (mildly acidic)

Patent Information:

Unknown - Tell us

Propagation Methods:

By dividing the rootball

From seed; direct sow outdoors in fall

From seed; winter sow in vented containers, coldframe or unheated greenhouse

From seed; stratify if sowing indoors

Seed Collecting:

Bag seedheads to capture ripening seed

Allow seedheads to dry on plants; remove and collect seeds

Seed does not store well; sow as soon as possible

Regional

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

Minneapolis, Minnesota

Gardeners' Notes:

1
positive
2
neutrals
1
negative
RatingContent
Positive

On Oct 19, 2009, bonehead from Cedarhome, WA (Zone 8b) wrote:

Spreads quickly by rhizomes, looks scrappy in late summer, so suggest planting it below something to cover it. Nice herb.

Negative

On Oct 30, 2002, HelenIble wrote:

When used externally, this plant may cause a severe reaction in people with a sensitivity to sesquiterpenes of the helenalin type. Arnica should not be applied to broken skin. I suffered severe blistering of my forearm when I applied it to reddened skin.

Neutral

On Jul 30, 2002, smiln32 from Oklahoma City, OK (Zone 7a) wrote:

Can also be used to treat diaper rash.

Neutral

On Nov 2, 2001, poppysue from Westbrook, ME (Zone 5a) wrote:

This medicinal herb has small, aromatic, orange-yellow daisy-like flowers. Its very similar in appearance and active ingredients to the more well known Arnica montana, but its hardier and easier to grow. It has more blossoms and somewhat larger, hairy leaves. It prefers full sun and a well-drained soil. It will bloom from June until August if spent blossoms are removed.

Its used medicinally in liniments and creams for external treatment of all types of injuries. Im sure many of you have used arnica cream on bruises and sprains before. Its also used in homeopathic dilutions as an immune system stimulant. Use cautiously! It can be toxic when taken internally.