Acanthus Species, Armed Bear's Breeches, Spiny Bear's Breeches, Oyster Plant

Acanthus spinosus

Family: Acanthaceae (ah-kanth-AY-see-ee) (Info)
Genus: Acanthus (a-KANTH-us) (Info)
Species: spinosus (spy-NO-sus) (Info)
Synonym:Acanthus caroli-alexandri
Synonym:Acanthus spinosus subsp. spinosissimus
View this plant in a garden



Water Requirements:

Average Water Needs; Water regularly; do not overwater

Sun Exposure:

Sun to Partial Shade




Foliage Color:

Unknown - Tell us


36-48 in. (90-120 cm)


24-36 in. (60-90 cm)


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)

USDA Zone 10a: to -1.1 C (30 F)

USDA Zone 10b: to 1.7 C (35 F)

USDA Zone 11: above 4.5 C (40 F)

Where to Grow:

Unknown - Tell us


Plant has spines or sharp edges; use extreme caution when handling

Bloom Color:


Medium Purple

White/Near White

Bloom Characteristics:

Unknown - Tell us

Bloom Size:

Unknown - Tell us

Bloom Time:

Late Spring/Early Summer

Mid Summer

Other details:

Unknown - Tell us

Soil pH requirements:

6.1 to 6.5 (mildly acidic)

6.6 to 7.5 (neutral)

7.6 to 7.8 (mildly alkaline)

Patent Information:


Propagation Methods:

From seed; direct sow outdoors in fall

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

From seed; sow indoors before last frost

From seed; direct sow after last frost

Seed Collecting:

Bag seedheads to capture ripening seed


This plant is said to grow outdoors in the following regions:

Clovis, California

San Leandro, California

Santa Monica, California

Boise, Idaho

Washington, Illinois

Shawnee Mission, Kansas

Kennebunkport, Maine

Silver Spring, Maryland

Leeds, Massachusetts

Roslindale, Massachusetts

South Deerfield, Massachusetts

Ludington, Michigan

Boone, North Carolina

Greenville, North Carolina

Cincinnati, Ohio

Columbus, Ohio

Hamilton, Ohio

Springboro, Ohio

Clackamas, Oregon

Sunnyside, Oregon

Haverford, Pennsylvania

Norristown, Pennsylvania

Wilkes Barre, Pennsylvania

Donna, Texas

Fort Worth, Texas

Leesburg, Virginia

Quilcene, Washington

Seattle, Washington

Charleston, West Virginia

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Gardeners' Notes:


On Feb 20, 2014, coriaceous from ROSLINDALE, MA wrote:

A superb garden perennial that deserves to be better known and more often grown. If it didn't bloom, it would be worth growing for the glossy, statuesque foliage alone.

The flower stems are showy and look good in arrangements. Though the white petals fade quickly, the showy green-and-purple bracts stand up well in the garden for months. They also dry well.

It's only the flower stems and bracts that have sharp spines. The spiny-looking projections on the leaves are soft. Acanthus spinosus var. spinosissimus (AKA Acanthus spinosissimus, Acanthus 'Spinosissimus') is spiny as a porcupine. It helps, when shopping, to remember that "spinosus" means "spiny", but "spinosissimus" means "spiniest". It also helps to check out the tips of the leaves, gently.

... read more


On Jun 15, 2011, janaestone from (Di) Seven Mile, OH (Zone 6b) wrote:

Absolutely beautiful, unique plant. The flowers are a very pretty dusky purple with white. This plant has survived extremely cold winters here with no problem. I've been told this is a shade plant but I have three of them in full sun in different parts of my yard and I've never had any problems with them. The only it hates is being moved. It wilts almost immediately upon being taken out of the ground and will appear dead until the following spring. Once I moved mine it took two years before it bloomed again. It is definitely a 'showcase' plant as it will be the center of attention once it blooms!


On Jun 19, 2010, budstockwell from Leeds, MA (Zone 5b) wrote:

It's taken several years but now my plant has produced it's first bloom. Very different plant, it has survived some very cold winters (-20F)


On Oct 4, 2005, lmelling from Ithaca, NY (Zone 5b) wrote:

I was given several starts of this plant 2 years ago and told that it was A.'Mollis'. Of course I found out that it is actually A. 'spinosus'. Neither type of Acanthus, according to plant guide I have, can grow in our zone, however, it grows here fine and at several friends' homes as well. I had my first bloom this July.

Ours is planted in our shade garden under white pines. The shelter keeps this area a little warmer in winter and may be the reason it survives for us here. According to an encylcopedia of plants the zone for this type (and A.'mollis' as well), is zone 7-10. Of course, because of the spines, this plant and it's blooms are quite deer resistant!

Blooms can be dried by hanging upside down and keep quite well for a year or so. Cut at the heig... read more


On Apr 2, 2005, SalmonMe from Springboro, OH (Zone 6a) wrote:

Likes morning sun in zone 6. Well-draining soil is of high importance, and may need a winter mulching in cooler zones. Divide in spring every 5 years or so to maintain vigor. 'Spinossisimus' is very spiny and unpleasant to handle, but other forms are much less so.


On Sep 3, 2004, pokerboy from Canberra,
Australia (Zone 8b) wrote:

This plant is less common than acanthus mollis. Its leaves are more deeply divided than acanthus mollis. They produce flower stalks that resemble each other. pokerboy.


On Aug 1, 2002, smiln32 from Oklahoma City, OK (Zone 7a) wrote:

Bear's Breeches is a relatively uncommon shade perennial that is becoming increasingly available in the nursery trade, prized for its large, arching, bold-textured foliage, unusual floral spikes, and ability to cover large areas of ground when mature.