Does any one know how to get rid of Japanese Knot Weed?

  2 answers
  • Mogie Mogie on May 23, 2018

    • Do not strim, cut, flail or chip the plants as tiny fragment can regenerate new plants and make the infestation harder to control.
    • Do not attempt to dig out Japanese Knotweed, this can actually encourage the plant into growing faster, therefore colonizing an area more aggressively.
    • Do not move or dump soil which may contain plant material as this may also add to its spread.
    • Do not attempt to pull the plant out of the ground, as this can expose part of the infectious crowns, stimulating growth.
    • Do not use unlicensed herbicides close to any watercourses, plants or wildlife.
    • Do not compost any part of the plant as due to the resilient nature of knotweed it could survive and grow on when the compost is ready for use.
    • Do not dispose of Japanese Knotweed in garden waste allotments as this just transport the plant to new locations..

    Do not spread any soil that has been contaminated with Japanese Knotweed rhizome as new plants will sprout.


    The most common method for how to kill Japanese knotweed is using glyphosate based herbicide, such as Round-up. You will need to use undiluted or at least a high concentration Round-up on this weed. Remember that this is a tough plant and one application of herbicide will not kill Japanese knotweed, it will only weaken it. The idea is to spray it repeatedly until the plant uses up all of its energy reserves while trying to regrow repeatedly.


    You can also try calling your local city hall or extension service. Due to the highly invasive nature of this plant, some areas will provide free spraying of Japanese knotweed.


    Another control method for Japanese knotweed is mowing. Chopping down the plants every few weeks will start to eat away at the plant’s energy reserves as well. Another way to get rid of Japanese knotweed is to dig it out. You will want to dig out as much of the roots and rhizomes as possible. Japanese knotweed can and will regrow from any rhizomes left in the ground.


    No matter how well you dig up the roots, there is a good chance you will miss some of the rhizomes, so you will need to watch for it to start regrowing and dig it out again.


    The most effect Japanese knotweed control is to combine methods. For example, mowing and then spraying weed killer will make your efforts at killing Japanese knotweed twice as effective.