Musk thistle

Carduus nutans

At a glance
Type	Broadleaf
Life cycle	Biennial
Family	Aster family (Asteraceae)
Origin	Introduced from elsewhere
Most common in	Great Plains

About

Musk thistle is a tall, spiny biennial from Europe and Asia with big nodding purple flower heads. It is a state noxious weed in many places and can take over pastures, roadsides and weedy lots.

Also called nodding thistle, nodding plumeless thistle

How to identify it

Look for

First-year rosettes have dark green, deeply lobed, spiny leaves with a light-colored midrib. The second year, spiny-winged stems grow 2 to 7 feet tall and carry large single flower heads up to about 3 inches across that droop, with broad spine-tipped bracts underneath.

Look-alikes

Bull thistle has smaller upright heads and woolly leaf undersides; Canada thistle has small clustered heads and spreads in patches from roots.

Where it grows

Pastures, rangeland, roadsides, ditch banks, hayfields and disturbed ground.

When

Rosettes form in the first year (or from fall sprouts), bolt the next spring and flower from about June into summer before dying.

How it spreads

Only by seed: a plant may carry 50 to 100 flower heads and 10,000 or more seeds, most landing within about 160 feet.

Most common in

Northeast	Occasional here
Southeast	Common here
South Central	Common here
Midwest	Common here
Great Plains	Very common here
Mountain West	Common here
Southwest	Occasional here
Pacific Northwest	Occasional here
California	Occasional here
Alaska	Not found here
Hawaii	Not found here

Where it is regulated

Listed as a noxious weed in Colorado (List B), Washington (Class B), Nebraska and Oklahoma.

What to do, gentlest first

Start at the top. Weed killers are a last step; always read and follow the label.

Keep ground covered Prevent
Thick grass or planting keeps seedlings from getting started; cultivation kills young seedlings.
Dig or cut below the crown By hand
Cut rosettes or bolting plants off below the soil line with a spade or hoe. If flowering, cut plants when the first heads are in bud or early bloom and bag the heads.
Wear heavy gloves; plants cut too early may regrow, so check back.
Spray rosettes spring or fall Conventional spray
Herbicides such as 2,4-D, dicamba, triclopyr, clopyralid or aminopyralid work best on rosettes before bolting, in spring or fall.
Read and follow the label; many lawn and brush herbicides also kill garden plants.

Uses, wildlife and pets

Pets

Not listed by the ASPCA.

Sources

Photo: Photo: Robert Flogaus-Faust / Wikimedia Commons, CC BY 4.0 (CC BY 4.0). Photo resized for the web.

Planting dates and advice are general guidance; check with your local Cooperative Extension office for your area.