DIY Knotweed control could have legal consequences
By Ross Cheeseright

DIY Knotweed control could have legal consequences

Vital information for homeowners that could save them £1000s

DIY is a popular practice for many ‘money saving’ enthusiasts, but there are times when it simply isn’t the best option, and finding you have an invasive species sharing your habitat is one of these. Doing a bit of Google research (as we all do with when venturing on a new DIY journey) may have you believing this ‘dreaded plant’ can be killed with diesel, vinegar or simply running it over with a lawn mower, but after reading this article, homeowners on the hunt for a quick fix to their garden infestation will be thinking again!

Discovering the legal implications of failing to put the right control measures in place or ignoring the problem could cost one family thousands of pounds in court fines and even imprisonment, but let’s start by busting some of the DIY myths about controlling or killing Japanese knotweed.


Contrary to popular belief, diesel does not kill Japanese knotweed. Whilst it may look like it is doing damage by distorting the top growth, the rhizomes in the soil will not be affected. This means, after a certain period, new top growth will appear and grow just as prominent as before.

Even if you cut the stems and pour diesel into the top, the underground rhizome system will still regrow. In addition to this the surrounding soils will be polluted with risk of diesel, which is toxic to humans and animals, soaking into the groundwater. Most importantly this or any use of diesel other than its intended purpose is completely unethical and, in many situations, illegal.

Bleach is another chemical that is ineffective and causes other additional problems to the environment. Cutting stems and pouring bleach down them will damage the top growth, but the rhizomes will not be affected. If bleach seeps into a pond or watercourse, it’s highly toxic to aquatic life, and if it seeps into soils it can damage surrounding plants, causing more harm than good.

Whilst burning Japanese knotweed may remove the top growth, it won’t have any effect on rhizome growth. The top growth will die back, and the plant may appear to be dead, but the rhizome will be unaffected and will ultimately produce new above-ground stem growth.

So, burning knotweed will inevitably just leave a black patch of land on your property, which will eventually return to Japanese knotweed growth.
Neither vinegar or salt will help eradicate Japanese knotweed, and both are best used on your fish & chips.


Moving, strimming, or flailing Japanese knotweed is likely to significantly increase the risk of knotweed spreading across your property and onto neighbouring land (see ‘encroachment’ below). As well causing a further knotweed problem, it’s also an offence to plant, disperse or allow dispersal, or cause the spread of Japanese knotweed and other non-native invasive plant species listed under the Wildlife and Countryside Act 1980.


In short, Japanese knotweed cannot be killed and can only be controlled via herbicide treatment or removed via excavation by a professional knotweed company. The underground rhizome is how the plant spreads, so any disturbance to these root systems will generate new growth.


The Government website has guidance called “Prevent Japanese knotweed from spreading”. It states: “You must dispose of Japanese knotweed waste off-site by transferring it to a disposal facility that’s permitted, e.g. a landfill site that has the right environmental permit.”

“You must prevent Japanese knotweed on your land from spreading into the wild and causing a nuisance. You could be fined up to £5,000 or be sent to prison for up to 2 years if you allow contaminated soil or plant material from any waste you transfer to spread into the wild.”

This means if you cut back knotweed or dig it up and take it to your local waste and recycling centre that does not have the right environmental permit, you could be fined up to £2,000 or be sent to prison.

The Government website continues to state: “You must not: dispose of Japanese knotweed with other surplus soil sell soil contaminated with Japanese knotweed as topsoil. You can only reuse knotweed-contaminated soils after treatment, on the site where they were produced.”


Any homeowner who has attempted to either cover up the fact that they suspect or have identified a knotweed infestation with a DIY solution will fail. There are massive legal and financial consequences to this and there is a reported lack of awareness of the legal responsibility of homeowners to prevent knotweed from spreading, with only 36% knowing they could be sued and just 18% aware they could face prosecution.

As a rule of thumb: If you own or manage a property or land affected by Japanese knotweed, you are responsible for its control. Failure to do so could lead to unwanted disputes, substantial fines, or even imprisonment.

If Japanese knotweed is allowed to spread beyond the property boundary this is deemed as encroachment. This means if a property has knotweed growing on their land, they should make every effort to control the knotweed and prevent this invasive weed from spreading onto a neighbouring property.

Actionable private nuisance claims can be served against anyone found responsible for having allowed or caused encroachment to take place, and this includes if just the underground rhizome of the plant has been found to have spread from one property to another – so it may not even be visible yet.


Anyone wishing to pursue a neighbour, individual or organisation responsible for the adjoining land must be given the opportunity to deal with the nuisance (knotweed). In these circumstances the neighbour should be given a chance to effectively treat the knotweed not only on their land but also on the neighbouring property in order to solve the problem and ideally the remedial action they choose should include a suitable guarantee. Should the neighbour not comply with this request (or notice), a claim for “nuisance for encroachment” can be pursued through legal channels.


The government has reformed the Anti-social Behaviour, Crime and Policing Act 2014 so that community protection notices can be used against individuals who are acting unreasonably and who persistently or continually act in a way that has a detrimental effect on the quality of life of those in the locality. Under the Act a Community Protection Notice (CPN) can be used to require someone to control or prevent the growth of Japanese knotweed or other plants that are capable of causing serious problems to communities.

The test is that the conduct of the individual or body is having a detrimental effect of a persistent or continuing nature on the quality of life of those in the locality and that the conduct is unreasonable. Under section 57 of the Act, “conduct” includes “a failure to act”. A CPN could therefore be used to require someone to control or prevent the growth of Japanese knotweed or other plants that are capable of causing serious problems to communities.

This means if an individual, or organisation is not controlling Japanese knotweed or other invasive plant and could be reasonably expected to do so, the CPN could be used after a mandatory written warning (the notice) has been served beforehand to get them to stop the anti-social behaviour. Breach of any requirement of a community protection notice, without reasonable excuse, would be a criminal offence, subject to a fixed penalty notice. On summary conviction, an individual would be liable to a fine not exceeding £2,500. An organisation, such as a company, is liable to a fine not exceeding £20,000.

In short, DIY is non-effective, Japanese knotweed cannot be killed, and ignoring the issue may result in legal offences, possible fines or even imprisonment. The only sure way to control knotweed is to hire a professional company who will plan a treatment programme or completely eradicate knotweed from site.