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Spiny bear's breeches

Spiny bear's breeches in flower.

Spiny bear's breeches is a bold, 3 to 4 foot high perennial with large, shiny, thistle-like leaves. Spikes of white with mauve color flowers tower above the foliage in early summer. A good back of the border plant or use as a specimen. Plants grown in northern climates benefit with a layer of winter mulch.

Botanical name:

Acanthus spinosa

All Common Names:

Spiny bear's breeches, spiny acanthus, spiny bears breeches, bear's breeches, spiny bear's-breeches

Family (English):


Family (Botanic):


Tree or Plant Type:

  • Perennial

Native Locale:

  • Non-native

Landscape Uses:

  • Foundation,
  • Mixed border,
  • Specimen

Size Range:

  • Large plant (more than 24 inches)

Light Exposure:

  • Partial sun/shade (4-6 hrs light daily)

Hardiness Zones:

  • Zone 5 (Chicago),
  • Zone 6,
  • Zone 7,
  • Zone 8,
  • Zone 9

Soil Preference:

  • Moist, well-drained soil


  • Dry sites,
  • Clay soil

Season of Interest:

  • Early summer

Flower Color & Fragrance:

  • Purple

Shape or Form:

  • Arching,
  • Mounded,
  • Upright

Growth Rate:

  • Slow

More Information:


3 to 4 feet high and 3 feet wide; mounded plant

Plant Care

Best in part shade in well drained, organic rich soil; will tolerate clay soil provide there is good drainage.
Plants benefit with morning sun and afternoon shade
In cool summers plants will tolerate more sun and drier conditions
In northern climates add a layer of mulch to protect root system in winter
Wait to cut back dead foliage until spring
Deadhead flower stalks by cutting back to the ground
Can be aggressive in sandy soils

Disease, pests, and problems

Slugs and snails, root rots in wet soil; powdery mildew

Native geographic location and habitat

Eastern Mediteranean; Italy to Greece, Turkey and Algeria

Leaf description

Large, deeply cut, pinnately compound leaves; thistle-like with a sharp spine at the tip. Each leathery leaf is 18 to 24 inches long and shiny. Most foliage is mounded at base.

Flower description

The mauve-purple and white, trumpet-shaped flowers are born on a 2 to 4 foot high flower stalk in early summer

Fruit description

not showy

Location of Acanthus spinosa (Spiny bear's breeches) at the Arboretum

We do not seem to have this in our living collection.