Cotton Thistle
Onopordum acanthium
Last reviewed: June 2026
Light
full sun
Water
low
Size
36"–72" H × 24"–48" W
Bloom
Jun, Jul, Aug
Native to
UT
Pollinators
bees, butterflies, beetles
Browse plants for this ecoregion
Cotton thistle is a tall, imposing biennial with large, spiny silver-green leaves and purple thistle flowers that bloom through summer. This dramatic plant can reach 6 feet tall and forms a striking architectural presence in the landscape. It self-seeds readily and tolerates drought conditions once established.
In an HOA neighborhood
Cotton Thistle takes more care to keep looking intentional in a front yard. Maintenance level: moderate. Consider it for backyard or mid-zone beds rather than the street edge.
Works well in: backyard only.
- Extremely tall and can appear weedy
- Sharp spines pose safety concerns
- Self-seeds aggressively and may spread
Wildlife value
The large purple flowers attract bees, butterflies, and beetles during the summer blooming period. Seeds provide food for finches and other birds in late summer and fall.
Native range data from the USDA PLANTS Database and regional native plant society lists. Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.
Does Cotton Thistle fit your yard? Open it in Pollinator Patch to check it against your sun, soil, and HOA-conscious filters.