What To Do If You Have Japanese Knotweed

by Mike Clough | 10th March 2020

Discovering Japanese knotweed can be the stuff of nightmares, but if you act quickly it need not be the headache that you first anticipated. Correct identification, effective treatment, and monitoring can all ensure that your knotweed problem is dealt with permanently.

So what should you do if you suspect that you have Japanese knotweed present on your land? Our guide to your next steps should ensure that you get your knotweed problem handled effectively. 


Confirm the presence of Japanese knotweed

For avoidance of doubt, Japanese knotweed identification is best left to trained eye. There are many plants that look like knotweed and have similar characteristics. Some of the plants commonly mistaken for Japanese knotweed include Bindweed, Russian vine, Bamboo, Broadleaf dock and Ground elder.

You can submit some photos to us of the plants you suspect are knotweed and we’ll usually be able to confirm or otherwise the presence of the invasive plant. We can then follow up with you on a course of action to deal with the knotweed infestation. It is important if you have Japanese knotweed on your property, that you start treatment as soon as possible to prevent further spread and potential long-term structural damage. 

large Japanese Knotweed plant in a garden

Do I have to treat knotweed on my land?

You do not have to treat Japanese knotweed if you find it on your property. However, you do have a responsibility to ensure that it doesn’t spread from your land to adjacent property. This also includes responsibilities for the proper disposal of any Japanese knotweed material removed from your land. That is why it is highly advisable to employ the services of a professional Japanese knotweed removal company to tackle your problem. 

Local authorities have the power to issue a Community Protection Notice requiring you to treat Japanese knotweed if it can be shown that you are causing an impact on “local amenity” through your failure to treat or manage the plant.


So do I have to tell anyone if I have knotweed on my land?

Although Japanese knotweed is classed as a controlled plant under the Wildlife and Countryside Act 1981, it is not illegal to have Japanese knotweed on your property, nor do you have a legal duty to notify anyone that you have Japanese knotweed on your land.

You are however required to declare the presence of knotweed on your property when as a seller completing a TA6 Property Information form which gives a potential buyer detailed information about the property being sold. Giving false information could lead to you being sued in future by the buyer.


Can I treat Japanese knotweed myself?

DIY attempts at removing knotweed are not recommended. While it is possible to buy regular herbicides that could potentially be used to tackle knotweed, these are usually of a lesser strength than those available to knotweed removal specialists so will have limited effectiveness.

Tackling knotweed requires regular treatment, sometimes over the course of 3 to 5 years, and this can only be done with any certainty by a knotweed removal company. Because of the nature of knotweed, which can grow from the tiniest of root fragments, you have to be certain that every last trace of the plant has been removed.

Attempts at removing knotweed by hacking and digging have the real potential for causing the knotweed infestation to be spread even further. This is why we always recommend getting the experts in to help with a knotweed infestation.

japanese knotweed removal

What is the best way to remove Japanese knotweed?

The simple answer is to contact a knotweed removal company and seek their advice. The most cost-effective method is through the use of glyphosate-based herbicides, which over time will kill the troublesome weed.

Treatment will usually involve chemicals being sprayed on the foliage of the weed, but it can also be injected into the stem, which can be an especially useful method when being used in ecologically sensitive areas. Repeat spraying to the foliage (or stem injection) will usually be carried out during the growing season and is best performed in later summer/early autumn, at a time when the plant is in full leaf and flowering. 

While it is important to act when you first spot knotweed, it can sometimes take many years to completely rid a property of the plant. Japanese knotweed treatment should be viewed as a long-term project, and utilising the skills of experts will increase your chances of a successful and permanent resolution of your problem.

Other methods, such as using excavation to dig up the roots is a more speedy option, but is considerably more expensive than chemical treatment and not always a viable option on a domestic property. The additional cost usually comes from any removed materials often having to be disposed of in a controlled way either onsite or offsite at properly licensed facilities.

The choice of treatment often depends on the severity of the knotweed presence, as well as other environmental factors and your personal circumstances. In cases where more immediate removal is required, often on commercial or development sites, then Japanese knotweed excavation may be the preferred option. For most domestic premises though, chemical control will usually prove the most cost-effective option.


How do I choose a Japanese knotweed removal company? 

Choosing the right Japanese knotweed removal firm is vital to ensure your problem is dealt with effectively and is unlikely to return. Try and choose a company based on recommendation so you can be confident they have done a good job for others previously.

Take a look at how long they have been in operation so you can be sure they have many years of knotweed experience. A long established company will give you confidence that any warranties of their work will be valid for the length of the guarantee and there is less chance of them folding in that time.  

Check if the company you are considering is a member of a trade body that represents the knotweed industry. INNSA (Invasive Non Native Specialists Association) and the PCA (Property Care Association) are trade bodies within the industry and ensure members work to high standards and hold the relevant accreditations.

A number of the well-established Japanese knotweed removal companies are actively involved in research into the best ways to eradicate or control the plant. They engage with research projects, often with top experts, to find more effective and innovative solutions to knotweed control and this is often a good sign of their professionalism.


What do I do if Japanese knotweed comes back? 

If you fail to have effective Japanese knotweed control in the first place then it is possible and quite likely that it will return at some point. The plant has been known to lie dormant for up to 20 years before again springing back into action. This is why we don’t recommend DIY attempts at removing Japanese knotweed.

Some people make the mistake when they first find Japanese knotweed on their land of hacking at the plant without properly considering what is going on underground. By cutting down the plant may only succeed in dispersing it across your property as well as spreading it to neighbouring properties, especially if any plant material has not been properly disposed of.

If knotweed returns after you have had an eradication programme completed by a professional company, get in touch with them to see what kind of guarantee there is for the work they have previously carried out. 

Japanese Knotweed growing through concrete

Can I get insurance against Japanese knotweed returning? 

You’ll have total confidence when it comes to Japanese knotweed removal if the work comes with an insurance backed guarantee. In some instances any guarantee might just be under the company’s Professional Indemnity or Public Liability insurance, which could become meaningless if a company ceased trading. 

This is why you need an insurance-backed guarantee for any work carried out which would cover you for the cost of any additional work should the knotweed return to your previously treated site. Only well established Japanese knotweed removal companies would be able to offer this kind of guarantee. 


What can I do if a neighbour has Japanese knotweed that is affecting my property?

If a neighbour has knotweed on their property that starts to encroach upon your property, you could take action against them. They do not have to act until the point that the knotweed starts to impact on neighbours and causes ‘private nuisance’. They could be liable to pay damages for loss of enjoyment, property damage and costs of removal. 


Japanese knotweed removal is a job for the specialist. There are many knotweed removal companies claiming to be experts, but it can be difficult to find the right one to tackle your knotweed problem. Correct identification and timely knotweed treatment will ensure that you deal with the issue before it truly gets out of hand. By hiring a company like us with a quality insurance backed guarantee for our work, you can be confident that your knotweed problem is eradicated permanently.