Invasive Species: Meadow Knapweed

Centaurea pratensis

Ironically, this plant was introduced as livestock forage and now it can displace up to 60% of grazing forage.

Why is it important to control?

Meadow knapweed out-competes grasses and other pasture species and is difficult to control.

Two Meadow Knapweed flowering - showing purple flowers

How can you identify it?

Brown and beige Meadow Knapweed flower headMeadow Knapweed flower showing purple petals
Habitat: Sunny locations including wet meadows and along riverbanks.
Life Cycle: Perennial
Height: Up to 3.5 ft
Leaf Description: Rosette leaves are deeply lobed. Mature leaves are pale green and hairy
Fruit & Flower Description: Pink to purple flowers have light brown bracts. Flowers are solitary
Bloom Time: June to September

How do you control it?

  • Small patches can be dug up or hand pulled.

  • Dispose of plant materials in a tied plastic bag. Put the bag in the trash.

  • Herbicides effectively control meadow knapweed when used according to the label directions.

  • The Oregon Department of Agriculture has released three biocontrol agents for knapweeds.

How to Report it?

There are various ways you can report this noxious weed.

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