When You Have an Outbreak

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Japanese knotweed flowers

Credit: Bradley Kriekhaus, USDA Forest Service

You can get rid of Japanese knotweed on your land--and clear space for native plants. Here are some options for getting rid of this nasty shrub.

• Pull or dig. Young plants can often be pulled out by hand. It may be possible to dig out larger plants, too. Try to get out all the roots, because they can resprout. Bag all the plant material and throw it away.
• Spray herbicide. If you have a lot of Japanese knotweed, you can kill it by spraying the leaves with glyphosate or triclopyr.
• Apply herbicide to stems. If there are other plants around the Japanese knotweed that you don't want to spray, you can cut the plants two inches above the ground and apply glyphosate to the stem. You may need to spray the plants again later if they resprout.
• Check for spread. Since Japanese knotweed spreads through rhizomes, you should also check the ground up to 20 feet away from the original patch to see if it's reaching farther.

A local extension agent or forester can help you work out how to control Japanese knotweed on your land.

It's easier to take care of Japanese knotweed before it's in 10-foot-tall thickets. Learn how to prevent this.