How to Grow Acanthus Plants in your Garden

Gardener's HQ Guide to Growing Bear's Breeches and Mountain Thistle

The common name for the Hardy perennial Acanthus is Bear's breeches.

It typically flowers from late spring and throughout the summer.


Description of Acanthus

Bear's breeches and related plants may be either deciduous or evergreen. Acanthus are large plants of between 30 and 120 cm (1 to 4 feet) and are often used as border plants.

Acanthus have spiky leaves and purple flowers.

Photographs of Commonly Grown Acanthus Plants such as Acanthus mollis, Acanthus spinosus and Acanthus hungaricus

Acanthus mollis

Acanthus mollis
Acanthus mollis by Endless Autumn.

Acanthus spinosus

Acanthus spinosus
Acanthus spinosus photograph by Leonora Enking.

Acanthus hungaricus

acanthus hungaricus
Acanthus hungaricus (Long-leaved Bear's Breach) photograph by Patrick Standish

How to Grow the Acanthus Plant

It is best to plant Acanthus mollis and other members of the genus at a depth of 1/2 cm (1/4 inch), with a planned spacing of about 90 to 120 cm (3 to 4 feet) apart

This should be done after the last frost of spring or in the autumn.

Acanthus plants enjoy light and can be grown in full sunlight or in partly shady conditions.

The soil should be deep and well drained, ideally at a pH between 6 and 7. Acanthus plants are unlikely to survive in wet areas.

If growing the plant indoors, then it should be sown in late winter to early spring in peat pots. They require 20 to 25 days for germination at a temperature of 10 to 15 degrees Celsius (50 to 59°F).

Transfer outside in the early spring.

Caring for Acanthus in the Garden

Acanthus is a very easy plant to care for, it requires watering until flowering begins, but only when conditions become too dry. DO not overwater as plants do not like wet soils.

Acanthus Growing and Care Guide

Common Names: Bear's Breeches, Mountain thistle, Brank ursine.
Common Names: Acanthus mollis, A. spinosus, A. longifolius and Acanthus hungaricus.
Life Cycle: Hardy Perennial.

Height: 12 to 48 inches (30 to 120 cm).
Native: Europe, Western Asia.
USA: Zones 5 to 10.

Flowers: Late Spring and Summer.
Flower Details: Purple, pink, white. (Beware of spikes beneath flowers)
Foliage: Sharp spiky leaves. Variegated. Evergreen. Herbaceous.

Sow Outdoors: 1/4 inch (5mm). Following last frost or Autumn. Spacing 36 to 48 inches (90 to 120cm).
Sow Indoors: Use Peat pots. Germination time: 3 to 4 weeks. Temperature 50 to 60°F (10 to 15 °C). Sow in late winter, transplant outdoors following the last frost.
Requirements: Full Sunlight or light shade. Soil pH 6 to 7 for best results. Good drainage. Deep soils. Water during prolonged dry spells. Propagate by root cuttings in the autumn.

Family: Acanthaceae.
Closely related plants to Acanthus: Wild Petunia; and Black eyed Susan Vine.

I hope that you enjoyed this guide on how to grow Acanthaceae plants. You may also enjoy the following similar perennial plant growing guides: How to grow Foxglove and Lupins.