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Gardening Answers Knowledgebase

Plant Answer Line Question

Keywords: Polygonum, Noxious weeds

I'm having difficulty removing knotweed from my garden. Can you give me advice on how to eradicate it?


I'm sorry to hear you are struggling with knotweed. Manual methods include cutting, mowing, pulling, digging, or covering. Dig surface roots in loose soil. Check frequently for new shoots and dig them up as soon as you notice them. Cut stems close to the ground every two weeks throughout the growing season. After cutting completely, you could instead decide to cover the area of the knotweed patch and the immediate area around it with black plastic or other impermeable material. This is a long-term process, and it may take several years to eradicate the Polygonum. Here are some helpful links on knotweed:

Invasive Knotweeds from the King County Noxious Weed Control Program

Knotweed Biology and Control from the King County Noxious Weed Control Program

Controlling Knotweed in the Pacific Northwest (a large file!)

Japanese Knotweed from the PCA Alien Plant Working Group

Date 2017-04-15
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August 01 2017 12:36:01