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How to grow acanthus

Val Bourne / 24 August 2020

Acanthus, or bear's breeches, are tall architectural perennials that were originally popularised in ancient Greece. Read our growing guide to choose a good variety and find out how to grow it.

Acanthus Mollis Latifolius
Acanthus Mollis Latifolius

Acanthus, otherwise known as bear's breeches. is one of the most architectural garden plants of all, both in leaf and flower. The lobed foliage of Acanthus mollis was commonly used to adorn Greek graves in centuries past, because it represented immortality and enduring life. It’s thought that Callimachus, a Greek architect and sculptor working in the 5th century BC, was the first to carve acanthus foliage on stonework. He had been inspired by seeing a simple basket of acanthus leaves placed on the grave of a young girl.

The Temple of Apollo Epicurious at Bassae, built between 450 - 420 BC, has columns decorated with the foliage of Acanthus mollis, a species found in poor soil across the western Mediterranean. Acanthus foliage has remained a popular motif and it was used by the Romans and in Italian Renaissance art. William Morris designed an iconic acanthus-leaf wallpaper in 1875. It’s one of his best-known designs.

There are 22 species of acanthus, but most are tender plants found in North Africa, Australia and Asia, so not suited to British gardens. Our hardy garden plants are derived from species found in southern Europe, mostly from Acanthus mollis and Acanthus spinosus. These easily grown perennials have been cultivated in Britain for centuries and they were called spiny bear’s breeches, although it’s not known why. However the name Acanthus is derived from the Greek word akantha meaning spiny and A. spinosus is definitely prickly. A. mollis is a kinder plant with softer foliage. Both aren’t fussy about soil, but they do enjoy warmth so they’ll need a hot spot in a prominent place.

How to use acanthus in the garden

These taller noble acanthus need a star position, close to steps perhaps, or on the corner of a border. Their habit of running makes it hard to integrate them into traditional borders and the pricklier ones need careful placing, because their thorny foliage can do some damage to the gardener’s hands. Bumblebees love them and shiny round chestnut-brown seedpods follow. These can stand through winter, to form silhouettes. In warmer parts of the country, seeds might explode from them!

Acanthus varieties to grow

Acanthus mollis Latifolius Group ‘Rue Ledan’

This is undoubtedly the best garden acanthus and the only one to have been awarded an AGM (Award of Garden Merit) by the RHS. The bright-green, non-prickly high-gloss foliage and green-hooded, pure-white flowers add a touch of coolness to any summer’s day. It was discovered in France and originally propagated by Jean- Pierre Jolivot, a nurseryman from St Malo in France.

This enormous plant can reach five feet in height and the same across, so space in definitely needed. However ‘Rue Ledan’ produces far more scented flower spikes than any other acanthus, without setting seeds. The foliage doesn’t suffer from mildew, as many do, and it rarely runs. In most winters it keeps its handsome, glossy green foliage. In colder winters, it retreats underground and then reappears in late spring.

Acanthus mollis

Grown in English gardens since1548, this handsome perennial has glossy green, attractively lobed, non-prickly leaves and spires of purple-pink hooded white flowers that open over many weeks. A. mollis dies down in cold winters, but stays above ground in warmer ones, thriving in dappled shade or full sun. On the debit side, the foliage can be marred by mildew, in dry summers, and it runs rather aggressively. Think, before you plant! 1.2m.

Acanthus spinosus

Introduced into English gardens in 1629, this much pricklier species has deeply cut leaves which are more or less deciduous and tend to form a dense carpet. It covers an area of about 90cm, and can get to 120cm tall. It produces dramatic, purple-hooded white flowers, far more willingly than A. mollis.

Acanthus spinosus Spinosissumus Group

Introduced into English gardens in 1629, and thought to be a hybrid between A. mollis and A. spinosus, this extremely prickly acanthus is more difficult to grow. It’s generally used as a foliage plant, because its often fails to flower. The foliage is very finely cut, but this acanthus takes time to grow.

Acanthus Whitewater
Acanthus 'Whitewater', bred by Terra Nova Plants.

Acanthus ‘Whitewater’

Raised by Terra Nova Plants in Oregon USA, this variegated acanthus has white-splashed green foliage and pink stems and pinkish flowers. You’ll love it or hate it, but it thrives in the hot, humid summers and cold winters found in America. A shadier position will make the foliage look less brash. 1.2 m- 1.5m/ 4 - 5ft.

Acanthus hungaricus

This shorter Balkan acanthus has scented lilac-pink and white flowers and greyer foliage. It’s more diminutive, reaching only 3 feet in height (90cm), but difficult to find. It will also need good drainage. From Beth Chatto - www.bethchatto.co.uk

Acanthus hungaricus ‘White Lips’

This Dutch-raised from of A. hungaricus has flower spikes with crisper, contrasting reddish purple and pure-white flowers. 2-3ft/ 90 cm Hayloft Plants.

Acanthus dioscoridis var. Syriacus

A Southern Turkish acanthus that will only survive if very well-drained and in a very warm, sunny position. Narrow grey-green foliage and pale-pink flowers. 30cm/1ft

Acanthus hirsutus subsp. Syriacus

The showy spires consist of many creamy-yellow flowers held between purple-red bracts in midsummer. The grey-green foliage is narrow and prickly. 45cm/18in

Acanthus sennii

This exotic-looking, red-flowered Ethiopian acanthus has prickly, holly-like green leaves, with prominent white midribs, and scarlet flowers. It is hardy, given good drainage, but could also be grown in a pot. Take the container into a dry, frost-free place in late-autumn and then bring it out again in late Spring. From Beth Chatto and Hillview Hardy Plants. 1m /3ft

Acanthus dioscoridis var. Perringii

This slow-growing diminutive acanthus, from Southern Turkey, needs heat and good drainage. The highly cut silver-green foliage flatters pink flower that appear in June and July. In the wild it grows on stony hillsides, but it should survive in a garden hotspot. From Beth Chatto and Hillview Hardy Plants. 30cm/ 1ft.

Where to plant acanthus

Acanthus is a Mediterranean plant that prefers a sunny well-drained position, but they don’t like rich soil so avoid over-feeding or you will not get flowers. Likewise a shady spot will produce less flowers.

Can you grow acanthus in pots?

Some smaller varieties of acanthus, such as the exotic Acanthus sennii can be grown comfortably in pots. Some varieties will need to be brought in to a frost-free place over winter.

When to plant acanthus

Plant acanthus in spring or autumn when the weather is mild so it has time to establish before a period of hot or freezing temperatures. Dig a large hole and add some rotted manure or compost.

Powdery mildew on acanthus

Don’t panic, this white powdery mildew is specific to acanthus and won’t travel to other plants. Although unsightly, plants recover. It’s caused by lack of moisture and air flow. Remove badly affected leaves, water well and thin out the leaves to allow better airflow.

Why isn’t my acanthus flowering?

These are plants adapted to poor soils. If your garden soil is rich, or you are over-feeding, you may well get lovely foliage but few flowers. If it’s too shady, it will not flower well either. Warm positions work best.

Can you move acanthus?

Acanthus resent being split up and this may cause plants to travel and pop up somewhere else. Once planted, leave well alone!

Where to buy acanthus

Beth Chatto - www.bethchatto.co.uk
Hillview Hardy Plants - www.hillviewhardyplants.com
Hayloft - www.hayloft.co.uk

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