How Much Does Japanese Knotweed Removal Cost?

Japanese Knotweed | 26th September 2022

If you have searched online for the title of this blog, then you have searched for one of the most frequently asked questions about invasive weeds in the UK, ‘How much does Japanese knotweed removal cost?’

Why is this such a hot topic?

If you have discovered Japanese knotweed on your property and have done a little research, you may already know that it is the only plant that must be declared on the TA6 form when selling your property. This makes Japanese knotweed the number one invasive weed that affects house sales and values. Finding the plant on your land is a chilling prospect for any homeowner, particularly one locking to sell.

What is worse is that many mortgage lenders will outright refuse to authorise a mortgage if Japanese Knotweed is present. So, of course, upon the discovery, the first thing you might want to know is: how much does it cost to remove Japanese knotweed? To answer this, we need to consider some of the factors involved.

How will the Japanese knotweed be dealt with?

Every Japanese knotweed removal is a different story, so ‘how’ is an important factor in pricing. There are two commonly used methods for Removing Japanese Knotweed in residential properties, herbicide treatment and excavation/removal.

Herbicide treatment

Herbicides are sprayed onto the leaves of the plants to control and manage them. However, if a more controlled treatment is required (due to proximity of other plants, habitations, neighbouring gardens etc) herbicide can be injected directly into the stems.

This form of management is typically long term and applications will need to be repeated several times a year for 3 to 5 years.

Whilst herbicides are available to the homeowner, these are not usually very strong. It is therefore vital to work with a PCA (Property Care Association) registered professional who will have access to professional grade herbicides that will be much more effective. Importantly, they will also have the appropriate training and provide the documentation to support their work.

Japanese knotweed up right beside a house

Japanese knotweed up right beside a house

Prices for herbicide treatment plans can range from £1000-£6000. Ultimately the cost of Japanese knotweed herbicide treatment will be determined by whether you need a knotweed management plan and an insurance-backed guarantee. These guarantees last five or ten years and are typically needed when buying or selling property.

If you don’t have any long-term desire to sell your property, then a pay-as-you-go treatment programme may be the answer. In this scenario, a single Japanese knotweed treatment may cost as little as £120+VAT. Taking this approach, typically one or two treatments are undertaken each growing season.

Excavation and Removal

The excavation and removal of Japanese knotweed is the most reliable form of Japanese knotweed eradication, but it can be expensive. One of the reasons it costs more than herbicide treatment is that all the waste is classed as ‘controlled waste’, which can only be removed to licenced waste facilities. Everyone involved in the process has a duty of care to comply with Japanese knotweed removal legislation. This situation means disposal costs are high because of landfill charges, landfill tax and haulage costs.

A professional invasive weed contractor can make a big difference as they can ensure that the right amount of waste is designated as knotweed contaminated. Not too much (which would be expensive) and not too little (which would need to be rectified). A professional contractor should dig out the visibly impacted area and extend the dig to around 2 or 3 metres, taking out all material to the full rooting depth of Japanese Knotweed.

Removing knotweed to the required depth

Removing knotweed to the required depth

Prices for Excavation and removal of Japanese knotweed are highly variable and depend upon individual site conditions and size.

For a domestic sites, the cost of Japanese knotweed removal is typically ranges from £7000 to £15000+VAT.

For a larger project, the cost will be approximately £5000 for every 10m2 area of impacted land. In addition, there would be a minimum of £5-10k of preliminary costs involved in site setup, reporting, surveying, welfare and health and safety.

When Knotweed eradication is a requirement

If knotweed eradication is required, then knotweed excavation really is the best solution. It can be quick enabling the land to be reclaimed and used again. Controlling Japanese knotweed with herbicide is not really eradication as the knotweed rhizome (root) remains present in the ground, and may will be viable many years after herbicide treatment has ended.

Who to use?

A quick search of Google for ‘Japanese Knotweed near me’ will bring up lots of service providers but beware of opting for the best-looking website or cheapest price listings.

Here are some important things to consider when selecting a Japanese Knotweed Company:

  • Is the company PCA registered? PCA registration is one way of assuring you that the contractors have the correct training and experience to deal with your Japanese Knotweed problems. However, not all PCA members have experience and knowledge of knotweed excavation.
  • Does the company offer an eradication guarantee, and if so, how long is it for?
  • Is the guarantee insurance backed? This is often referred to as an insurance-backed guarantee (IBG) and is a vital assurance that if the knotweed were to reappear. It means that you are covered against any costs that may be incurred for further work.
  • Does the company have the appropriate public liability and professional indemnity insurance in place?
  • Excavating knotweed can be dangerous risk assessments are needed, and safe working systems need to be in place.
  • One way of telling if a company is competent in knotweed excavation is to see if they are CHAS or SafeContractor approved. Equally, their key staff should be health and safety (H&S) trained, usually having SMSTS of SSSTS training and accreditation.

Lastly, if you have decided upon herbicide treatment as your method, ensure that whoever you decide to use is PCA accredited, trained, NPTC qualified for herbicide application, is fully insured, has been approved under CHAS or SafeContractor, and has H&S aware personnel.

There is a lot to consider

As you can see there is much to consider when looking at the cost of Japanese knotweed removal, and sadly there is no definitive answer to the question. A well-qualified experienced contractor will be able to walk you through the process and make a solid management plan that will see the end of your Japanese knotweed problems. Beware of companies that offer simple solutions and over-the-phone quotes based on the information you have provided.

Concerned that you have Japanese knotweed?

Find out more about our Japanese knotweed surveys.


japanese knotweed survey

Every site is different, and management plans should always be based on a physical site visit and Japanese Knotweed Survey carried out by a qualified PCA registered professional. A visit to site will allow the surveyor to properly examine the extent of the problem on-site, as identification of Japanese knotweed in winter, in particular, can be more challenging. It will also provide the opportunity to assess the extend of Japanese knotweed at neighbouring properties and create a plan that prevents knotweed from spreading back into the garden. Make sure that works are guaranteed and, most importantly, that the guarantee is backed with bona fide insurance. Most importantly remember, the cost of removing Japanese knotweed is always related to the size of the site. So, the sooner you deal with it the cheaper it will be.

About PBA solutions

PBA Solutions is a PCA registered company that has providing Japanese knotweed and invasive weed remediation for over 20 years. From herbicide treatment of small areas to large-scale commercial excavation and removal, PBA has the knowledge and experience required to deal with your Japanese Knotweed problems. PBA were PCA contractor of the year in 2019, have since achieved ISO9001 accreditation, and provide £2m professional indemnity insurance to cover advice given.

Do you need help or advice about selecting the best Japanese knotweed treatment program? Call 0203 174 2187 or 01202 816134 to talk to one of our consultants.



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