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, AZ, CA and 44 more states, per the World Checklist of Vascular Plants (Kew).

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: August 2026

Toxicity unknown

Horseweed (Conyza canadensis) is not listed by the ASPCA Animal Poison Control Center (opens in new tab) or the other sources we check, so we have no verdict for it either way. Absence from those lists is not a clearance. If your pet shows symptoms after eating any plant, call the ASPCA at (888) 426-4435.

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, AZ, CA and 44 more states

Pollinators

bees, butterflies, beetles

Before you buy

Your city may pay you to plant this

Cities and water utilities offer rebates for replacing lawn with native and water-wise plants. We track 452 programs across 44 states, each with a link to the provider and the date we last checked it.

Find rebates in your area

Browse plants for this ecoregion

Coast Range Puget Lowland Marine West Coast Forest Northwestern Forested Mountains Sierra Nevada Central California Foothills and Coastal Mountains Central California Valley Southern California Mountains North American Deserts Central Basin and Range Mojave Basin and Range Southern Rockies Arizona/New Mexico Mountains Chihuahuan Deserts High Plains Southwestern Tablelands Central Great Plains Great Plains Cross Timbers Edwards Plateau East Central Texas Plains Western Gulf Coastal Plain South Central Plains Eastern Temperate Forests Ozark Highlands Central Irregular Plains Northwestern Glaciated Plains Northwestern Great Plains Piedmont Northern Glaciated Plains Western Corn Belt Plains Northern Forests Northern Lakes and Forests North Central Hardwood Forests Driftless Area Southeastern Wisconsin Till Plains Central Corn Belt Plains Eastern Corn Belt Plains Southern Michigan/Northern Indiana Drift Plains Huron/Erie Lake Plains Northeastern Highlands Northeastern Coastal Zone Northern Allegheny Plateau Erie Drift Plain Middle Atlantic Coastal Plain Northern Piedmont Southeastern Plains Blue Ridge Ridge and Valley Central Appalachians Western Allegheny Plateau Interior Plateau Interior River Valleys and Hills Mississippi Alluvial Plain Mississippi Valley Loess Plains Southern Coastal Plain Southern Florida Coastal Plain Madrean Archipelago Sonoran Basin and Range Acadian Plains and Hills Eastern Great Lakes Lowlands Atlantic Coastal Pine Barrens Southern California/Northern Baja Coast

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, AZ, CA and 44 more states, per the World Checklist of Vascular Plants (Kew).
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 World Checklist of Vascular Plants (Kew). Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.

If something looks wrong

Common plant problems, and what to check first

These come up on almost any plant. Each guide lists the likely causes in the order they are worth ruling out, with one thing to check before you act on any of them, and links to the source it came from.

See all plant problem guides

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