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Acanthus Plant Growing & Care Guide for Gardeners

In this Gardener's HQ guide, we'll explore cultivating Acanthus plants in your garden, indoor spaces, and other settings.

Bear's Breeches, and Mountain Thistle: Cultivation & Garden Use

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

It typically flowers from late spring and throughout the summer.

Acanthus

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.

Common Questions

How many members does the Acanthus genus have?

The Acanthus genus consists of about 30 species, although the exact number can vary based on different taxonomical classifications.

Do members of Acanthus make a good garden or landscaping plant?

Yes, Acanthus species are highly regarded in horticulture. Their decorative, deeply cut leaves and tall, flower spikes make them excellent choices for garden or landscape design.

Which Acanthus species are most frequently grown by gardeners?

Two of the most popular species grown by gardeners are Acanthus mollis (Bear's Breeches) and Acanthus spinosus (Spiny Bear's Breeches).

Are members of the Acanthus fragrant?

Members of the Acanthus genus are not typically known for fragrance. Their appeal lies in their unique foliage and striking flower spikes.

What is the perfect location to grow Acanthus?

Acanthus plants thrive best in partial shade with well-drained soil. However, they can tolerate a wide range of conditions and are quite adaptable.

Is Acanthus invasive in the USA, if so in which states?

While Acanthus is not typically classified as invasive in the USA, it can spread quickly in suitable conditions. However, it's best to check with local guidelines as this can vary by region.

How do I remove Acanthus from my garden?

To remove Acanthus from your garden, dig up the plant ensuring to remove all root fragments. It's important to note that any remaining root pieces can potentially sprout new plants.

Summary

Acanthus Genus: Growth and Habitat

The Acanthus genus consists of perennial plants known for their architectural foliage and ornamental flowers. Native to the Mediterranean region, they can thrive in various climates. Acanthus plants prefer well-drained soil and partial shade but can tolerate full sun. They require regular watering and benefit from organic mulch. These plants are appreciated for their attractive, deeply lobed leaves and tall flower spikes. Acanthus is commonly used in landscaping and gardens for its dramatic, sculptural appearance.

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