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Posted by cahnrs.webteam | April 16, 2014


What is knotweed? Knotweed is the 800 pound elephant of northwest weeds. Knotweeds are perennial plants native to Asia. The plants were brought here as ornamentals in gardens.

This plant or group of plants, including: Japanese knotweed, Giant knotweed, Himalayan knotweed, Bohemian knotweed, a.k.a. Reynoutria, or Fallopia japonica, are all behaving badly away from their natural enemies. Insects and diseases that normally keep a native plant in check are not present to slow the spread of knotweeds.

  • Knotweed can sprout from a piece of stalk as small as a dime.
  • Knotweed can push through inches of asphalt.
  • Knotweed spreads by water.
  • Knotweed spreads by mowers and equipment.
  • Knotweed is extremely difficult to control without herbicides.
  • Knotweed dominates streambanks and river edges

How to Control This Aggressive Invader:

Knotweed-Control-Video – King County