If Japanese knotweed has established itself, removing it can be a difficult job that can take years to complete and expose you to expensive consequences from different pieces of Japanese knotweed legislation unless you employ contractors who are skilled in Japanese knotweed removal.

So, how much does Japanese knotweed cost to remove is one of the obvious questions when you realise the task may be too big or complex for you to undertake? Seeking professional help is your best start.

If removal efforts are not backed up by sufficient assurances, Japanese knotweed can cause significant blight to land, resulting in significant decreases in property values (typically between 5% and 20%). As a result, if you don’t hire suitably trained experts to complete the job, you’re actually taking a big risk.

To minimise such threats, you can hire a Japanese Knotweed removal company to ensure complete and assured eradication and, more importantly, to prevent legal action from prospective occupiers and potentially affected neighbours.

Is Japanese knotweed expensive to get rid of?

The cost of treatment plans and eradication pricing varies depending on the size of the affected area and the land’s intended usage. A simple herbicide software will solve the problem in the vast majority of cases. If the affected land needs to be excavated in the future (for example, to expand it), an excavation solution would almost certainly be required.

This may include anything from complete excavation and disposal of the arisings to partial excavation and the application of suitable root barrier membranes. The table below provides a rough estimate of costs.

If you think you may be affected by Japanese knotweed, please contact a professional to give you an idea of how much it will cost to resolve the issue. Check out the proposed costs below to give you an idea of what it could cost.

Size of infestationSmall (<50m2)Medium (50m2-100m2)Large (100m2-500m2)Very large (500m2-1,000m2)
Herbicide treatment£2,000- £3,000£3,000-£5,000£4,000-£6,500£5,000-£10,000
Reduced dig and root barriers£2,000-£5000£5,000-£10,000£15,000-£40,000>£40,000
Pick and sort / screening£2,000-£5,000£5,000-£10,000£15,000-£40,000>£40,000
Onsite relocation and herbicide (treatment bund / lay down area)£5,000-£10,000£8,000-£15,000£12,500-£20,000£18,000-£30,000
Burial on site£5,000-£15,000£12,500-£20,000£18,500-£35,000£30,000-£75,000
Full excavation and disposal (dig and dump)£5,000-£20,000£15,000-£40,000£35,000-£120,000£100,000-£200,000

Factors affecting the cost of extracting Japanese knotweed

To evaluate the cost of extracting Japanese knotweed and the best approach, a PCA-trained surveyor will consider a variety of factors.

The scale of the affected area and the level of development are arguably the most significant factors. The roots of the weed can grow up to three metres deep into the earth, making it incredibly difficult to eradicate completely.

Furthermore, if even the tiniest piece of the plant is left in the soil, it will quickly regrow.

A surveyor will also look at the following items:

  • The environment.
  • Watercourses in the region.
  • Issues with access.
  • Whether or not the property is adjacent to Network Rail property.
  • Its separation from a livable room.
  • If it’s encroaching on or from a neighbour’s land.

Following the survey, a specialist will normally recommend a management strategy that outlines the most effective ways to contain or handle the infestation. For their work, certain professionals will have a 10-year warranty and an insurance-backed guarantee.

Japanese knotweed Removal Methods and their cost
Japanese knotweed Removal Methods and their cost examined – how much does Japanese knotweed cost to remove?

What is the procedure for getting rid of Japanese knotweed?

There are a variety of processes that can be used to remove Japanese knotweed, and each will have an impact on the cost.

However, particularly in domestic settings, there are only two that are widely used. There are the following:

Treatment with herbicides

Herbicide therapy, rather than eradication, is a long-term remedy for handling and maintaining Japanese knotweed. To deal with only a few square feet, you’re looking at a starting cost of about £950.

There are a variety of pesticides that can be used to control Japanese knotweed, but we suggest working with a specialist who will have access to stronger herbicides. Herbicides are typically sprayed on the plant’s leaves (although herbicide stem injections are a choice if you don’t want to damage your neighbours’ plants).

The treatment will normally need to be repeated two to three times a year. The knotweed will usually stop growing after three to five years, at which stage you will be able to stop treating it. To ensure that you’re dealing with the issue efficiently, work with a trained PCA Surveyor who will provide you with a five-year plan and an insurance-backed guarantee.

Excavation and removal are both needed

Excavating Japanese knotweed, also known as a dig-out or dig-and-dump, is a method of eradicating the plant rather than merely managing it, as is the case with herbicide application.

In this scenario, a specialist would dig down to about two metres and then transport the waste to a landfill. The waste is hauled away as “managed waste” and disposed of in landfills that are completely licenced to handle Japanese knotweed.

This method of Japanese knotweed removal is very successful, but it is more costly than herbicide treatment. Prices start at about £4,000 and vary depending on the severity of the issue.

Other ways to get rid of Japanese knotweed

There are a few other methods for removing Japanese knotweed, but they’re uncommon and wouldn’t normally be considered if you’re trying to get rid of Japanese knotweed from your garden. There are the following:

Screening and sifting

Sifting and screening is the process of digging up knotweed-infested soil and screening it (both mechanically and manually) for any signs of the weed. The waste is then disposed of, while the non-infested soil can be reused elsewhere on a construction site.

While soil screening can be a long-term and cost-effective method of removing Japanese knotweed, it is not a one-time treatment. Since a small amount of knotweed can slip through the net, it should always be used in conjunction with other removal methods.

Root barriers and excavation

Professionals are able to minimise contamination levels by excavation before using root barriers to prevent the knotweed infestation from spreading in this process of Japanese knotweed removal (for example into neighbouring gardens). This decreases the amount of waste that must be transported to a landfill off-site.

How much does Japanese knotweed cost to remove when it consumes so much of your garden?
How much does Japanese knotweed cost to remove when it consumes so much of your garden?

Excavation and relocation on-site

Japanese knotweed can be excavated and relocated to a lower-risk position on-site, where it can be held under control with herbicide treatment for the long term. This is a more environmentally friendly and cost-effective alternative to dumping waste in landfills (especially as Land Remediation Tax Relief can be claimed).

This approach is more suited to larger locations, such as staggered designs, and isn’t used very much in domestic environments.

Burial on-site

After excavating the knotweed, it is encapsulated in a cell and buried on-site in a deep burial pit. The top of the cell must be at least two metres below ground level in order for humans or burrowing animals to unintentionally disturb it in the future.

This option may be a lot less expensive than dumping waste in a landfill. It does, however, necessitate sufficient space for a wide pit, so it is often ideally suited to areas that have been proposed for public open space.

Buying or selling a property with Japanese knotweed - what to look out for can save you from a costly mistake later on
Buying or selling a property with Japanese knotweed – what to look out for can save you from a costly mistake later on


How much time would it take to get rid of Japanese knotweed?

How much time would it take to get rid of Japanese knotweed?
This will be determined by the size of the affected area as well as the seriousness of the issue.

How long does the herbicide for Japanese knotweed take to work?

If the herbicide is added to the plant’s leaves, it generally becomes rainfast in 10 minutes. It does, however, necessitate three to five years of care. It could take even longer if the plant is well-developed.

After you’ve cut down Japanese knotweed, what do you do with it?

Any Japanese knotweed that has become loose should be stored in plastic rubble sacks for analysis. These sacks must be disposed of at a landfill that specialises in this type of waste.
Japanese knotweed is collected for free by several councils in the United Kingdom. We recommend contacting your local government to see if this is something they provide in your region

I’m not sure how to get rid of Japanese knotweed on my own.

If you just have a small amount of Japanese knotweed, you may be able to treat it yourself with a herbicide. For controlling Japanese knotweed, glyphosate-based products are the most effective, with a standard 5l bottle of glyphosate-based herbicide costing about £30-£50.
However, if you have no previous experience, we suggest that you leave it to the experts. There are safety concerns, and the job must be completed in order to eliminate the infestation.

Is Japanese knotweed a weed that needs to be reported?

Despite the fact that Japanese knotweed is a garden pest, there is no legal obligation to monitor, eliminate, or even report it.
Planting or causing Japanese knotweed to grow in the wild is, however, illegal. You could face fines of up to £5,000 as well as a two-year jail term if you do so. Furthermore, allowing Japanese knotweed to spread to private lands, such as your neighbour’s garden, can result in legal action against you.

Is it possible that a Japanese knotweed infestation would prevent me from obtaining a mortgage?

This will depend on the mortgage lender, but many will refuse a loan outright if a survey reveals that the property contains Japanese knotweed.

Want to know more about how much Japanese knotweed cost to remove?

Knotweed Removal aims to provide the most up-to-date information, help and advice for YOU to make informed decisions. If you are unsure or uncertain about how to proceed, please reach out to us and we will gladly come back and advise you as best we can.

Governmental advice can be found here and the UK law covering the removal of Japanese Knotweed as stated under the Wildlife and Countryside Act 1981 can be found here.

The best means to contact us is via our email – hello@knotweedremoval.tips

Do not forget we have a library of blogs covering many areas relevant to Japanese Knotweed, our free downloadable How-to Guides and Product Reviews on the latest methods being employed to eradicate or remove Japanese Knotweed.

Knotweed Removal, UK

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