1 / 14

Carduus crispus

welted thistle

Asteraceae Europe and temperate Asia

Attracts Pollinators Attracts Butterflies

SunFull Sun – Part Shade

WaterMedium

HardinessZones 4–8

Overview

Carduus crispus is a biennial growing 16-47 inches (40-120 cm) tall, forming a leaf rosette in its first year and an erect, branched flowering stem in its second. The stems carry continuous spiny wings along their length, broken just below the flower heads. The leaves are deeply lobed, 4-10 inches (10-25 cm) long, green above and grey-woolly beneath, with spine-tipped margins. Red-purple flower heads 0.4-0.8 inch (10-20 mm) across cluster in groups of two to five at the stem tips from early summer, each head ringed by narrow spiny bracts. The flowers are followed by seeds tipped with a parachute of unbranched hairs, dispersed by wind. The plant dies after setting seed in its second year. It grows as scattered plants on disturbed and nutrient-rich ground rather than dense stands. The spiny stems and leaves deter grazing animals.

Native Range

Native to Europe and temperate Asia, from the British Isles east to Siberia, and naturalised in North America. Grows on roadsides, hedge banks, riverbanks, waste ground, and field margins, on damp, fertile, disturbed soils.

Suggested Uses

Grown occasionally in wildlife and conservation plantings for its nectar-rich heads and seed, which feed insects and birds. Suited to rough grassland and naturalistic areas rather than borders. Its spiny growth and self-seeding habit limit its use in cultivated gardens, where it is more often treated as a weed.

How to Identify

Identified by continuous spiny wings running along the stems, broken just below the flower heads, and red-purple heads 0.4-0.8 inch (10-20 mm) across in clusters of two to five. Leaves are green above and grey-woolly beneath with spiny margins. The small clustered heads and narrow stem wings separate it from the larger-headed spear thistle Cirsium vulgare.

Appearance

Size & Dimensions

Height1'4" - 3'11"

Width/Spread1' - 2'

Colors

Flower Colors

purple

red

Foliage Colors

green

Bloom Information

Bloom Period

~8 weeks

Summer

Flower heads open from June to September, with peak bloom in July and August. Individual heads flower for one to two weeks, and a plant flowers over several weeks as new heads open. Bees and other insects visit the heads for nectar. Seed ripens from late summer and disperses on the wind.

Detailed Descriptions

Foliage Description

green above, grey beneath

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 5-10 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

Soil Requirements

pH Range6.0 - 7.8(Neutral)

357912

Soil Types

loam clay silt

Drainagemoist

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

Flowers in its second year

Care & Maintenance

Care Guide

Grows in full sun to light shade on damp, fertile, disturbed soils and tolerates a range of conditions in its native range. As a biennial it grows from seed, forming a rosette in the first year and flowering in the second before dying. It needs no watering once established in temperate climates. It self-seeds freely on bare, fertile ground and can spread where soil is regularly disturbed. The wind-blown seed lets it colonise new ground quickly. It is treated as a weed of pasture and waste ground in many areas.

Pruning

No pruning is required. Cutting or removing the flower heads before seed sets prevents self-seeding and spread. As a biennial, the whole plant dies after flowering and can be cleared in late summer or autumn.