1 / 3
Acanthus spinosus
Spiny Bear's Breeches
Eastern Mediterranean (Italy, Balkans, Greece, Turkey, western Asia)Learn more
At a Glance
TypePerennial
HabitClumping
FoliageSemi-evergreen
Height3–5 feet (90–150 cm)
Width2–3 feet (60–90 cm)
Maturity3 years
Overview
Acanthus spinosus is a clump-forming perennial reaching 3–5 feet (90–150 cm) tall in bloom with a spread of 2–3 feet (60–90 cm). Leaves are deeply pinnately cut, 12–24 inches (30–60 cm) long, dark glossy green, with narrow lobes terminating in sharp white spines. The leaf texture is firmer than that of A. mollis, and the deeply dissected outline is distinctive among garden perennials. Flower spikes, 3–5 feet (90–150 cm) tall, bear tubular white flowers subtended by spiny purple-green bracts from June through August. The spines on both leaves and bracts can cause skin punctures on contact. The plant spreads by fleshy rhizomes; root fragments left in soil produce new shoots and established clumps are difficult to fully remove. In prolonged summer drought, foliage may go partially dormant by late August. Not reliably hardy below zone 5 without mulch protection; in zone 5 stems die back to the ground in winter and may not re-emerge reliably after severe winters.
Native Range
Acanthus spinosus is native to the eastern Mediterranean, including Italy, the Balkans, Greece, Turkey, and western Asia. It grows in rocky, well-drained sites including hillsides, woodland margins, and disturbed ground, typically in thin soils in a Mediterranean climate with dry summers and mild, wet winters.Suggested Uses
Planted in perennial borders, gravel gardens, Mediterranean-style plantings, and dry slopes at 2–3 foot (60–90 cm) spacing. The spiny foliage and bracts deter browsing by deer and rabbits in most conditions. The spreading habit requires management near paths, patios, and lawn edges. Not suited to small formal gardens where containment of rhizomes is difficult.How to Identify
Appearance
Size & Dimensions
Height3' - 5'
Width/Spread2' - 3'
Reaches mature size in approximately 3 years
Colors
Bloom Information
Flower spikes emerge in June and bloom through August in zones 6–9. Individual spikes last 4–6 weeks; plants may produce 3–5 spikes per clump in a season. In cool Pacific Northwest summers, flowering may begin in late May. In hot, dry summers, plants may enter partial dormancy before the bloom period ends.Detailed Descriptions
Flower Description
white with purple-green spiny bractsFoliage Description
dark glossy greenGrowing Conditions
Sun Requirements
Requires 3-8 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Plant in well-drained soil; A. spinosus tolerates dry, poor, or rocky soils better than A. mollis once established. Water weekly during the first growing season. Established plants tolerate dry spells of 2–3 weeks and perform in dry-summer Mediterranean-climate regions. The rhizomatous root system spreads in moist, fertile soils; root fragments left during removal regenerate new growth. Leaf and bract spines cause skin punctures on contact. Slugs and snails feed on new spring growth. In zone 5, mulch the root zone with 4–6 inches (10–15 cm) in fall to improve winter survival. Divide every 5 years or when flowering decreases.Pruning
Cut flower spikes to ground level after bloom in August–September to prevent self-seeding. Remove dead or yellowed leaves at any time. In climates where foliage dies back in winter, leave stems until new growth appears in spring, then cut old growth to the ground. In zones 8–9 where foliage persists, remove old leaves in early spring before new growth begins.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
summerearly spring