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What is knotweed and how can I get rid of it?

Knotweed is a major problem in King County. This non-native, noxious weed chokes out native vegetation, increases erosion, degrades water quality and hurts habitat for fish and wildlife. It can also damage roads, pipes and building foundations.

This workshop teaches participants:

  • How invasive knotweed grows and spreads
  • How, when and where to control knotweed
  • What is being done to fight knotweed on rivers in King County
  • How to use and borrow a stem injector for use on your own land
  • What opportunities for habitat restoration may be available for your own land


All sessions are from 6:30 p.m. to 8:30 p.m. and share the same agenda

Class participants can borrow our knotweed stem injectors for their own knotweed projects!

The workshops are free and open to the public, but have limited capacity, so sign up early!

How to sign up: Register online

Can't take a class, but want to borrow a stem injector? No problem. Watch our videos and take a quiz to qualify instead.

For more information contact us by email or phone at 206-477-9333.

worker injecting invasive knotweed - click for more information on knotweed

Related information

Related agencies

Program offices are located at 201 S. Jackson St., Suite 600, Seattle, WA 98104. To contact staff, see the Noxious Weed Control Program Directory, send an email, or call 206-477-WEED (206-477-9333).