Giant Sumpweed
Cyclachaena xanthiifolia
Last reviewed: June 2026
Light
full sun
Water
medium
Size
24"–60" H × 12"–24" W
Bloom
Jul, Aug, Sep
Native to
VT
Pollinators
bees, beetles, flies
Browse plants for this ecoregion
Giant ragweed is a tall, fast-growing annual wildflower with large, deeply lobed leaves that can reach 5 feet in height. It produces small, inconspicuous greenish flowers from July through September and thrives in sunny locations with average moisture. This native plant self-seeds readily and can form substantial colonies in favorable conditions.
In an HOA neighborhood
Giant Sumpweed takes more care to keep looking intentional in a front yard. Maintenance level: low. Consider it for backyard or mid-zone beds rather than the street edge.
Works well in: backyard only.
- Very tall and can appear weedy
- Aggressive self-seeding habit
- May trigger allergies in sensitive individuals
Wildlife value
The flowers attract various pollinators including native bees, beetles, and flies during its long summer blooming period. Seeds provide food for birds, particularly finches and other seed-eating species in 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 Giant Sumpweed fit your yard? Open it in Pollinator Patch to check it against your sun, soil, and HOA-conscious filters.