Onopordum acanthium

Scientific name: Onopordum acanthium

Synonym: Onopordon acanthium


Common names: “Scotch thistle” “cotton thistle” “Argentine thistle” “giant thistle” “musk thistle” “Queen Mary’s thistle” “silver thistle” “star thistle” “thistle-upon-thistle”

Plant Type: Evergreen biennial


Zone: 6-9

Light: Full sun

Exposure: Exposed or sheltered

Soil: Fertile – poorer sites, neutral – slightly acidic best (some sources say slightly alkaline) prefers less clay

Moisture: Well drained


Plant Size: H 9′ W 3′

Leaf and Stem shape: Oblong, spiny, cobwebby grey leaves

Flower: Rounded, thistle-like purple flower heads in summer of second year

Pruning: Minimal

Maintenance: Transplant seedlings when young in fall, can cut out flowers to prevent seedlings

Landscape use: Not in a narrow bed or near pathways, gravel garden, cottage, wildflower meadow

Propagate: By seed, self seeds about

Pests & Disease: None in Victoria

Comments: Prickly and painful, on BC invasive plant list


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