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Chemical Treatment

Chemical Treatment - treatment period - 24-48 months

Special herbicides can be used during two to four growing seasons and is generally the most cost effective way to control Japanese knotweed..

Depending on the size of plants, season and prevailing weather, chemical treatments can involve:

  • stem injection

  • cut stem treatment

  • spraying


This solution should only be undertaken by fully qualified and experienced personnel; this is often the cheapest treatment option. For quicker solutions Japanese Knotweed Killers can provide alternative methods of control and management.


Herbicide treatment periods can also be reduced by using a number of methods that can challenge the proliferation of rhizomes.

Beware of contractors who claim that knotweed can be eradicated using herbicides within a single growing season.


Various sources of guidance and advice from professional bodies and regulators, warn of spurious claims to quickly eradicate knotweed.

There are no products or commercially available chemicals that will, eradicate mature knotweed growth in a single season. 


It should be noted that according to recent studies, full knotweed eradication by use of chemical treatment may not actually be possible. Read this recent report for further details (BBC Report).

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