Cirsium rivulare ‘Trevor's Blue Wonder'
A clump-forming thistle with upright stems carrying rich purple, button-like flowers over a long season from late spring into summer. Despite the name, the flowers read clearly as purple rather than blue. Sterile seed and a tidy habit keep the plant contained, while cutting back spent stems after the first flush encourages continued flowering. Best grown in full sun with moisture-retentive soil, where it remains robust without becoming unruly.
Growing Conditions
Light: full sun
Moisture: average to moist
Soil: moisture-retentive garden soils
Hardiness zone: 5
Maintenance: low to moderate
Size & Habit
Height (cm): 120
Spread (cm): 70
Habit: upright clump
Seasonal Interest
Flowering period: May–Sept
Seasonal interest: late spring through summer flowering
Foliage: green
Flower: purple
Ecology & Notes
Wildlife value: pollinators
Deer/Rabbit resistance: moderate
Habitat: perennial borders; mixed borders; moisture-retentive sites
Features: clump-forming; long flowering season; sterile seed; upright habit
Notes: a well-behaved, clump-forming thistle with sterile seed; flowers appear over a long season and respond to cutting back after the first flush; considered slightly more vigorous than the red form, with less frequent need for division to maintain strength