How to Treat Japanese Knotweed with Herbicide (And When Not To)

Looking to get rid of Japanese Knotweed? One of the most common and affordable methods is herbicide treatment—but it’s not always simple.

Why Herbicide?

Chemical treatment is often used to stop the spread of knotweed. It usually takes multiple applications over a few years to control it properly. The severity of the infestation will affect how long it takes.

Who Should Apply It?
This isn’t a DIY job. Herbicides must be applied by a qualified contractor with an NPTC Certificate of Competence—ideally someone who’s also a PCA-approved specialist. They’ll choose the right product based on how much knotweed is present, nearby plants or trees, and whether water or wildlife are nearby.

When It’s Not the Right Choice
If you’re planning to disturb the ground—maybe to plant, build, or install a hot tub—herbicide might not be effective. Digging can actually trigger regrowth. In those cases, excavation may be a better option.

Summary
Herbicide treatment is a cost-effective way to manage Japanese Knotweed—but only when done by professionals. If you're unsure whether it’s the right approach, speak to a specialist before taking action.