Acanthus mollis, bear's breech
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Perennials

Acanthus mollis

bear's breech

AcanthaceaeMediterranean region

At a Glance

TypePerennial
HabitClumping
FoliageSemi-evergreen
Height3-5 feet (90-150 cm)
Width3-4 feet (90-120 cm)
Maturity3 years

Growing Zones

USDA Hardiness Zones

5 - 9
Zone 5
Zone 6
Zone 7
Zone 8
Zone 9
These zones indicate the coldest temperatures this plant can typically survive.
Frost Tolerancehardy

Key Features

Attracts Pollinators
Deer Resistant
Drought Tolerant
Maintenancemoderate

Overview

Acanthus mollis is a clump-forming herbaceous perennial in the Acanthaceae family, reaching 3-5 feet (90-150 cm) tall in bloom and 3-4 feet (90-120 cm) wide. Basal leaves are large, deeply pinnately lobed, and glossy dark green, measuring 18-24 inches (45-60 cm) long and 12-18 inches (30-45 cm) wide. Leaf lobes are rounded with shallow sinuses and spiny-tipped. Flower spikes emerge in late spring to early summer, rising 3-5 feet (90-150 cm), each bearing tubular two-lipped flowers with white lower lips and hooded purple-green upper bracts. Individual flowers are 1.5-2 inches (4-5 cm) long. Plant spreads by creeping rhizomes and fleshy roots; once established, removal is difficult because root fragments regenerate. In zones 7 and warmer, the plant is nearly evergreen; in zones 6 and colder, foliage dies back in winter. Clumps expand slowly during the first 1-2 years, then spread more rapidly once roots are established. Siting in afternoon shade in zones 8-9 reduces leaf scorch in summer.

Native Range

Native to the Mediterranean region, including the Iberian Peninsula, southern France, Italy, the Balkans, and North Africa. Grows in rocky hillsides, forest margins, and disturbed ground in well-drained soils at low to moderate elevations.

Suggested Uses

Commonly planted as a specimen in perennial borders or woodland garden edges at 3-4 foot (90-120 cm) spacing. The large leaf form provides strong textural contrast to fine-textured or small-leaved plants. Spreading rhizomatous habit makes it unsuitable near small or slow-growing plants it may overwhelm; more suitable at the back of borders or in isolated planting beds where spread can be managed.

How to Identify

Identified by its very large, deeply lobed, glossy dark green leaves, 18-24 inches (45-60 cm) long, with rounded lobes and spiny teeth. Tall flower spikes, 3-5 feet (90-150 cm), bear tubular white flowers enclosed in spiny purple-green bracts. The combination of large, architectural basal rosette and tall, densely packed flower spike is distinctive. Rhizomatous spreading habit causes the plant to form dense clumps over time.

Appearance

Size & Dimensions

Height3' - 5'
Width/Spread3' - 4'

Reaches mature size in approximately 3 years

Colors

Flower Colors

white
purple

Foliage Colors

dark green

Fall Foliage Colors

no change

Bloom Information

Bloom Period

~4 weeks
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SpringSummer
Blooms late May through July in zones 7-8; late June through August in cooler zones 5-6. In zones 9-10, bloom may begin in April. Individual flower spikes remain attractive for 3-4 weeks. Plants may not bloom in the first 1-2 years after establishment; foliage-only growth is common until the root system matures.

Detailed Descriptions

Flower Description

White with purple-green hooded bracts

Foliage Description

Deeply lobed, glossy dark green

Growing Conditions

Sun Requirements

Full Sun
Partial Shade
Requires 3-6 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 7.5(Neutral)
357912
Soil Types
loamclaysand
Drainage
well drained

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

2-3 years

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Plant in well-drained soil; waterlogged conditions, especially in winter, cause crown and root rot. Water weekly during the first growing season; established plants tolerate dry periods of 3-4 weeks but may drop lower leaves and temporarily wilt. In zones 6 and colder, apply 3-4 inches (8-10 cm) of mulch over crowns after hard frost to protect roots. Rhizomatous roots are difficult to eradicate once established; siting carefully before planting reduces future management problems. Remove any root fragments when dividing, as fragments as small as 1 inch (2.5 cm) can regenerate into new plants. Slugs and snails feed on new foliage in spring; damage is cosmetic but can be significant in wet seasons.

Pruning

Remove dead or damaged foliage in early spring before new growth emerges, cutting stems to ground level. After flowering, cut spent flower spikes to the base; the plant will not rebloom but removing spikes prevents energy diversion to seed production. In zones 7 and warmer where foliage persists through winter, remove any tattered or frost-damaged leaves in late February or early March. Divide in fall or early spring every 5-7 years to manage spread.

Pruning Schedule

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early spring

Maintenance Level

moderate

⚠️ Toxicity Warning

Toxic to pets and humans