Spiny bear’s breeches

Spiny bear’s breeches: how do you recognise it?

Habit

Broad, clump-forming perennial: a large mound of leaves from which spikes rise to 1.2 m; 90 cm across.

Leaves

Large, deeply cut, glossy dark green, with fine white spines at the tips of the lobes.

Flower

Upright spikes of single-lipped white flowers beneath a purple, hood-shaped calyx and spiny bracts, from June to August.

Fruit

Hard capsules that burst open when ripe and fling out the seeds.

Roots

Deep, fleshy taproots; every piece of root can grow into a new plant.

Flowering: June–August · Plants: March–May and September–October · Pruning: March and August–September

Why grow it?

• A striking structural plant with sculptural leaves and tall flower spikes: a focal point in any border.
• Flowers for three months, from June to August, and draws in bumblebees and other bees.
• Drought tolerant thanks to its deep, fleshy roots: once established it rarely needs watering.
• Grows in sun or part shade and in almost any well-drained soil, from sand to clay.
• The spikes make good cut flowers and keep well when dried.
• Hardier and more free-flowering than soft-leaved bear’s breeches.

Spiny bear’s breeches: where does it grow best?

• Full sun gives the most flowers; it also grows in part shade, but with fewer spikes.
• Any well-drained soil: sand, loam or clay, acid to chalky.
• Dry to moist; it dislikes waterlogged soil in winter.
• Allow 90 cm per plant and choose a permanent spot: it is hard to move.
• Keep it away from paths and play areas because of the spines.

Light

Sun and partial shade

Soil type

Sand, loam or clay

Acidity

Not fussy

Moisture

Dry or normal

Size

1.2 m tall, 0.9 m wide

Hardiness

Hardy (to -20 °C)

Goes well with

• Globe thistle: Blue globes next to the white and purple spikes, and just as drought tolerant.
• Spurge: Fresh yellow-green spring foliage beside the dark acanthus leaves.
• Ornamental grasses: Airy plumes as a contrast to the coarse, spiny leaves.
• Lavender: A low, fragrant edging in front, in the same dry, sunny spot.
• Roses: A classic pairing in a sunny border; the acanthus adds structure.

Spiny bear’s breeches: when and how to plant it?

Plant in March–May and September–October.

1. Plant from March to May or in September–October, when the soil is neither frozen nor waterlogged.
2. Dig a hole twice as wide and deep as the pot and loosen the bottom, so the taproot can go down easily.
3. On heavy clay, mix in some coarse sand or gravel to improve drainage.
4. Set the plant at the same depth as in its pot, firm the soil and leave 90 cm between plants.
5. Water well straight away and keep the soil moist for the first few weeks.
6. Spread a thin layer of mulch around the base in the first autumn.

Care

Water

Water in dry spells in the first year. After that it fends for itself, except in very long droughts.

Feeding

A spadeful of compost in April is enough: it needs little feeding.

Spent flowers

Cut the flower stems off at the base after flowering, or keep a few to dry.

Old leaves

Remove brown, withered leaves; most of the foliage dies down in autumn.

Gloves

Wear sturdy gloves and long sleeves for every job on the plant.

Tip: Get the spot right first time: moving an acanthus rarely works, because every piece of root left in the ground grows into a new plant.

Spiny bear’s breeches: when to prune it?

Pruning months: March and August–September.

When: After flowering, in August–September, and again in March to clear away the old leaves.

How:

• Cut the faded flower stems off at the base, just above the leaves.
• In March remove last year’s dead foliage before the new leaves appear.
• In summer remove leaves with powdery mildew to keep the plant looking fresh.

Caution: Wear sturdy gloves: the spines on the leaves and bracts go straight through thin fabric.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Root cuttings

From December to February: dig up a thick root at the edge of the clump, cut it into 5–8 cm pieces and push them upright into a pot of sandy cutting compost, the top just below the surface. They sprout in spring.

Division

In March–April or in October: slice off a piece of the clump with roots and buds using a sharp spade, and replant it straight away in its final spot.

Spiny bear’s breeches: how does it get through the winter?

Hardy to −20 °C.

• Hardy to about −20 °C: in Belgium it survives the winter outdoors without any trouble.
• Most of the foliage dies down in autumn; the plant regrows from the roots in spring.
• In their first winter, cover the base of young plants with a layer of leaf mould or straw.
• Waterlogged soil in winter is more dangerous than frost: make sure drainage is good.

Diseases and pests

• Powdery mildew: White powder on the leaves, especially in dry summers. Cut off affected leaves: new ones will follow.
• Slugs and snails: They make holes in the young leaves in spring. Pick them off in the evening and put a ring of coarse grit around the plant.
• Root rot: Yellow, limp leaves on heavy, wet soil. Improve drainage with sand or gravel.
• Few flowers: Young plants often only flower from their second or third year; too much shade also means fewer flowers. Patience and a sunnier spot help.

Through the year

• January: Take root cuttings.
• February: Take root cuttings.
• March: Clear the old leaves. Plant or divide. Add compost.
• April: Plant. Watch for slugs on the young leaves.
• May: Plant. Water young plants in dry spells.
• June: Flowering begins. Bumblebees visit the flowers.
• July: Full bloom. Cut spikes for a vase or for drying.
• August: Cut off faded stems. Watch for powdery mildew.
• September: Cut off the last stems. Plant or divide.
• October: Plant. The foliage starts to die down.
• November: Cover young plants with leaf mould.
• December: Rest. Take root cuttings.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• The acanthus leaf was the model for the decoration of the Corinthian capital in Greek architecture.
• Mainly bumblebees are strong enough to push between the bracts to reach the nectar.
• When ripe, the capsules burst open and fling the seeds some distance from the plant.