Spotted knapweed (Centaurea stoebe spp. micranthos)


Appearance: Biennial or short-lived perennial herbaceous plant, 2 - 3' high. Basal leaves form a rosette the first year from which grow 1- 20 wiry, hoary, branched stems during the second year.

Leaves: Alternate, grayish, hoary, and divided into lance-shaped lobes decreasing in size at the top.

Flowers: Thistle-like pink to purple flowers sit at the tips of terminal and axillary stems, bloom from July through September.

Seeds: Brownish, 1/4" long with small tuft of bristles, dispersed by rodents, livestock and commercial hay. Seed viable in the soil for 7 years.

Roots: Stout taproot. Lateral shoots form new rosettes near the parent plant.

Caution: Wear long sleeves and gloves, can be a skin irritant to some people.

Ecological Threat:

  • Especially threatens dry prairie, oak and pine barrens, dunes and sandy ridges.
  • Spotted knapweed is poisonous to other plants (phytotoxic).
  • Spreads rapidly in artificial corridors, gravel pits, agricultural field margins and overgrazed pastures.
  • A native of Europe and Asia it has become a serious problem in pastures and rangeland of the western states.
  • Spotted knapweed is a MDA Prohibited noxious weed (Control List) in Minnesota.

Control Methods:


  • Early detection and pulling
  • Mowing as needed so plants cannot go to seed
  • Prescribed burning, only very hot burns are effective which may also damage native plants


  • Apply selective herbicide clopyralid during bud growth in early June for best results (48 oz per 100 gal water). Use caution in quality natural areas herbicide affects native plants of the sunflower and pea family as well.


Native Substitutes:


Additional Resources