Where does it grow?

What is the distribution in Washington State?

• There are two known field locations in Washington. All sites appear to have been originally cultivated as an ornamental species.
• The site in Pend Oreille County, was discovered in 1981. This site is an abandoned homestead.
• If you think you may have seen this weed, please contact your county weed coordinator or us at noxiousweeds@agr.wa.gov.
   
• Distribution map not available at this time.

How do I control it?

General control methods: Bighead knapweed is a tap-rooted perennial, pulling is impractical for large infestations, but small plants may be dug. Bighead knapweed can re-sprout if root is left intact.

Herbicide: The rates for various chemical control options are found in the annually updated Pacific Northwest Weed Control Handbook, or contact your county weed coordinator.

Mechanical: Repeated mowing will diminish seed production and will eventually deplete root reserves.

Biological: None known.

For more information

• For more information, download our Written Findings.

• View Garden Wise (Eastern Washington Guide) for better noninvasive plant recommendations for your yard or garden.

Bighead knapweed infestation.