Acanthus spinosus (Acanthus)

A popular architectural herbaceous plant with very large distinctive, glossy, but spiky leaves which resemble those of a thistle. From mid to late summer it produces tall spikes of hooded two tone flowers in purple or mauve and white.  

History

Acanthus comes from the greek word for 'thorn' or 'spine' and refers to the leaves of Acanthus spinosus which are like those of the thistle. Acanthus have been popular since Greek and Roman times, infact it is thought by historians that the leaves of this plant were the inspiration for Corinthian column captials. It is a native plant of southern Europe and northwest Africa, found in woodland scrub and on stony hillsides.  It has now naturalised in parts of Great Britain and is considered a wildflower, but it was actually one of the earliest cultivated species of garden plants.

Planting

Once the plant has become established it is very difficult to move, so it is vital to chose the position with care. Dig a hole and loosen the surrounding soil with a fork, especially at the base and mix in some well rotted organic material or compost. Place the plant in the hole so that the roots are just below the level of the surrounding soil. Backfill in around the plant and firm in the roots tomake it secure.  Water after planting.

Propagation

Seeds (plant March-April),Division (February-April), Root Cuttings (during winter). 

Cultivation

Will grow well in any reasonably fertile, deep, moist, but well drained soil in dappled shade. It will survive in full sun and it is drought tolerant, but the leaves may wilt or scorch.

Aftercare

Protect new and young leaves from attack by slugs and snails. To minimise the risk of powdery mildew, ensure the plant is watered well during hot, dry spells. Feed by applying an annual mulch of well rotted organic material or manure. To rejuvenate the plant and avoid congestion lift and divide large clumps in autumn or spring. Cut back old foliage once it has died back in autumn. 

Pests

Slugs and Snails.

Diseases

Trouble free.

Other information

The Royal Horticultural Society has given this plant its prestigious Award of Garden Merit (AGM). Makes good cut flowers. Although the spines on the leaves are a good deterrent for unwanted visitors they can also be a problem for young children.

Height/Spread

A hardy herbaceous perennial that can grown up to 1.5m in height making it a popular architectural plant.  It is a clump forming plant, which makes large mound shaped rosettes of deep green, glossy, arching leaves that are 90cm long. These large leathery leaves are deeply divided with spines at the edges. From May to June it produces spectacularly tall spikes of hooded two-tone flowers in Purple and white; that last for quite a few weeks. Once the plant has become established it is difficult to move, so correct positioning is vital.

Annual care

March

Feed by applying an annual mulch of well rotted organic material or manure. Lift and divide any congested plants.

October

Cut back old foliage once it has died back.  Lift and divide congested plants.

November

Take root cuttings to propagate