Horseweed
Ambrosia trifida
Last reviewed: June 2026
Light
full sun
Water
low
Size
12"–60" H × 6"–24" W
Bloom
Jul, Aug, Sep
Native to
AL, AR, AZ, CA and 43 more states
Pollinators
bees, beetles, flies
Browse plants for this ecoregion
Giant ragweed is a tall annual wildflower that can reach up to 5 feet in height with distinctive three-lobed leaves. It produces small greenish flowers in late summer and is well-adapted to disturbed soils and full sun conditions. This native plant self-seeds readily and can form large colonies in suitable locations.
In an HOA neighborhood
Horseweed takes more care to keep looking intentional in a front yard. Maintenance level: high. Consider it for backyard or mid-zone beds rather than the street edge.
Works well in: backyard only.
- Aggressive self-seeding can appear weedy
- Very tall growth may violate height restrictions
- Common ragweed appearance triggers allergy concerns
Wildlife value
The flowers attract bees, beetles, and flies during late summer blooming period. Seeds provide food for birds, particularly finches and sparrows 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 Horseweed fit your yard? Open it in Pollinator Patch to check it against your sun, soil, and HOA-conscious filters.