How much sun does Horseweed need?

Horseweed grows best in full sun conditions.

When does Horseweed bloom?

Horseweed blooms in July, August, September, and October.

Where is Horseweed native?

Horseweed (Conyza canadensis) is native to AL, AR, CA, CO and 40 more states, per the USDA PLANTS Database and regional native plant society lists.

Is Horseweed toxic to livestock?

The USDA PLANTS Database does not flag Horseweed as toxic to livestock.

What butterflies or moths does Horseweed host?

Horseweed is a larval host plant for American Lady and Painted Lady.

Is Horseweed HOA-friendly?

Horseweed takes more care to look intentional in a front yard. Consider it for backyard or mid-zone beds rather than the street edge.

Horseweed

Name: Pollinator Patch
Author: Pollinator Patch

Conyza canadensis

Last reviewed: July 2026

The USDA PLANTS Database (opens in new tab) does not flag Horseweed as toxic to livestock.

Light

full sun

Water

low

Size

12"–60" H × 6"–24" W

Bloom

Jul, Aug, Sep, Oct

Native to

AL, AR, CA, CO and 40 more states

Pollinators

bees, butterflies, beetles

Browse plants for this ecoregion

Coast Range Sierra Nevada Central California Valley Central California Foothills and Coastal Mountains Southern California Mountains Central Basin and Range Mojave Basin and Range Chihuahuan Deserts Central Oklahoma/Texas Plains Edwards Plateau East Central Texas Plains Western Gulf Coastal Plain South Central Plains Sonoran Basin and Range

Horseweed is a tall annual wildflower that produces clusters of small white to greenish flowers from summer through fall. This native plant can reach up to 5 feet tall and readily self-seeds, often appearing in disturbed soils and open areas.

In an HOA neighborhood

Horseweed 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.

Aggressive self-seeder often considered weedy
Tall growth habit can appear unkempt
Common in vacant lots and disturbed areas

Wildlife value

Host plant for American Lady, Painted Lady.

The small flowers attract various pollinators including bees, butterflies, and beetles during its extended blooming period. Seeds provide food for birds, particularly finches and sparrows.

Common questions

How much sun does Horseweed need?: Horseweed grows best in full sun conditions.
When does Horseweed bloom?: Horseweed blooms in July, August, September, and October.
Where is Horseweed native?: Horseweed (Conyza canadensis) is native to AL, AR, CA, CO and 40 more states, per the USDA PLANTS Database and regional native plant society lists.
Is Horseweed toxic to livestock?: The USDA PLANTS Database does not flag Horseweed as toxic to livestock.
What butterflies or moths does Horseweed host?: Horseweed is a larval host plant for American Lady and Painted Lady.
Is Horseweed HOA-friendly?: Horseweed takes more care to look intentional in a front yard. Consider it for backyard or mid-zone beds rather than the street edge.

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.

Ready to grow Horseweed? Add it to your garden in Pollinator Patch to track it and get season-by-season care guidance.

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