Japanese knotweed is described by the Environment Agency as “indisputably the UK’s most aggressive, destructive and invasive plant”.

Due to the powerful root and rhizome system, which extends deep into the ground, knotweed is notoriously difficult to treat or remove without professional help – and failure to do so could result in your property being damaged and devalued.

For those looking to develop on knotweed affected land, there could also be implications for construction programmes and costs.

Commercial solutions Does Japanese Knotweed Damage Property?

Identification of Japanese Knotweed

Accurate identification is key. You’ll find a useful video and photos here to help you identify knotweed through the various seasons - send a photo to our FREE identification service and we’ll confirm if it’s knotweed.

The devil is in the detail. It’s imperative to know what type of knotweed it is, the maturity, extent and condition of the underground rhizome and root system - and the ground conditions in which it is growing. That is why a site survey is often required. Knowledge is key; armed with this information a suitable Japanese Knotweed Management Plan can be devised that has the highest chance of success.

Identify Japanese knotweed

The RICS guidance for Japanese knotweed on Residential Properties has Changed.

Find out what it really means for you.

Understand the RICS Changes

Can I Treat or Get Rid of Japanese Knotweed Myself?

If you’re tempted to treat it yourself, consider these points:

  • Most people attempting a DIY solution will fail, making subsequent professional treatment more complicated and expensive
  • Using chemicals purchased from a garden centre or DIY store will rarely be strong enough to kill the underground root system, and will often result in dormancy which means that even if the plant appears to be dead above-ground, the underground rhizome remains very much alive ready to regrow at any moment
  • Killing Japanese knotweed with bleach, does not work!
  • Damage to other prized plants may be caused by poor herbicide application
  • DIY treatment won’t provide you with much of a legal defence If it spreads into your neighbours’ land
  • Digging out the rhizome system is difficult; it’s best left to professionals
  • You won’t get the all-important insurance-backed guarantee which could make it very difficult to sell your property in the future and adversely affect its value.

How Much Japanese Knotweed have you Got?

In order to determine the knotweed infected area in sq m on a subject property measure/approximate the length and breadth of the visible Japanese knotweed at ground level. Multiply the length x breadth to give you the total visible in sq m. As knotweed rhizome spreads laterally underground the actual area of infestation is greater than is visible above ground. A buffer zone is therefore added in each direction to the visible length and breadth of 1m in normal circumstances, 2m or more in exceptional cases.

For example, a stand of visible knotweed measuring 2m x 1m with a buffer of 1m in each direction would be 4m x 3m, to give a total 12 sq m. It is not necessary to add the buffer if the buffer falls outside of the property boundary. So for example if the above was in the corner of the garden, the area would be 3m x 2m , to give a total on the subject property of 6 sq m.

If there are 2 strands of Japanese knotweed within 2m of each other, it is likely that these are interconnected underground and should be classed as 1 stand when measuring the length and breadth.

How do you Eradicate Japanese Knotweed?

As you might expect, Japanese knotweed eradication is actually a specialised service. Yes, you can try to do it yourself but don’t be surprised if the weed appears again pretty quickly after you think you’ve got rid of it. It can be backbreaking work to try and dig up all the roots and, depending on the ground, is often all but impossible without using some form of expert treatment.

Over the last 20 or so years, our team at Environet has developed a range of different tools for Japanese knotweed eradication. That includes our cutting edge Eco-Innovative Xtract™ which is an excavation and screening tool that is used to identify and remove the rhizomes of the plant in commercial properties.

If you don’t want to use herbicides, this process is a great choice. The good news is that it’s cheaper than many of the traditional approaches, diverts a lot of waste from landfill and works well for business locations including industrial estates.

Residential areas often need highly specialist approaches when it comes to Japanese knotweed eradication, mainly because buildings and gardens are smaller and closer together. At Environet, we use a couple of different trademarked approaches including DARTTM and Resi-Dig-OutTM (a kind of scaled down version of our more commercial Eco-Innovative XtractTM).

Our treatments for Japanese knotweed eradication have been developed over many years, using the latest technology and our own experience. Of course, our specialists need to take a closer look at your property and the extent of the infestation before they decide which approach is best. The aim is to make sure all rhizomes are treated or removed, leaving your property and surrounding areas clear.

Knotweed Distribution

Research indicates that approximately 5% of homes in the UK are affected by Japanese knotweed. Search Exposed the Knotweed Heatmap by postcode to see if your property is in a high-risk area.

Go to the Heatmap

Does Knotweed Affect Property Value?

The simple answer is Yes. You’re legally obliged to disclose whether the property is “affected” when selling and mortgage lenders will impose conditions which could prompt a buyer to renegotiate or even walk away. But don’t panic, a professionally prepared and actioned Japanese Knotweed Management Plan normally returns the value close to the “non-affected” value. Check out this online calculator to get an idea of how your property’s value might be impacted.

Go to the Calculator

Knotweed Dormancy - There’s More to it than Meets the Eye

Rhizomes can remain dormant in the ground for many years. Unfortunately, the absence of above ground growth does not mean no viable rhizomes are present. Where the human eye can’t spot knotweed, the canine nose can. This is where Knotweed Detection Dogs can assist, sniffing out rhizomes hidden underground – great for buyers and sellers where there is uncertainty as to whether a property is affected or not.

Go to the Detection Dogs

The Japanese Knotweed Management Plan

The all-important document that should identify:

  • The extent, maturity and location of knotweed on the property
  • Whether any physical damage has, or is likely to be caused
  • If encroachment to or from the property is likely
  • The recommended method for its control or removal and associated costs
  • Details of the guarantee

Is the Guarantee Important?

Absolutely, yes. Mortgage lenders will want to see an insurance-backed guarantee for up to 10 years from a reputable specialist (e.g. Accredited members of either PCA or INNSA). This has implications for those who attempt DIY methods.

We provide insurance-backed guarantees for up to 10 years, backed by an “AA-“ rated insurer, meaning that if there’s regrowth post-treatment – you’re covered.

How can Environet Help me?

Here’s what you can expect:

  • Identify Japanese knotweed - Just send us a photo of the suspected infestation. Japanese knotweed is pretty distinctive, and our experts will quickly be able to identify the plant, free of charge, and tell you if there’s a problem. If it’s knotweed, you’ll need a survey and a Management Plan prepared.
  • Treatment and removal - Once we have received the go ahead, we’ll schedule the work. We follow industry best practice, giving you the reassurance that your Japanese knotweed problem will be dealt with discreetly, courteously and professionally. We will leave your garden neat and tidy, ready for replanting.
  • Insurance-backed guarantee - we will provide you with our market-leading insurance-backed guarantee (IBG) for up to 10 years, underwritten by an “AA-“ rated insurer. Our IBGs are accepted by all main banks and building societies.

Excellent service. We needed to eradicate some knotweed quickly to avoid delays in our development project and Environet really came up trumps.They were infinitely more helpful and professional than other specialists we had spoken to and we would recommend them highly.

Why Should I Deal With Japanese Knotweed?

It’s perfectly legal to have Japanese knotweed on your property, so this is a worthy question. Here are the main reasons why a property owner should get knotweed tackled that is growing on their land.

  1. Protect your Assets. Knotweed will make it more difficult to sell an affected property, on average knocking 10% of its value. 50% of would-be buyers will walkaway from a property known to be infested with knotweed. Sellers will need to disclose the knotweed presence – if they don’t, they risk an expensive misrepresentation claim in the courts.
  2. A Growing Problem. Knotweed is programmed to grow, its underground rhizome system extending year on year, infecting more ground. It’s a problem that simply won’t go away on its own, so the sooner it’s tackled the better.
  3. Nuisance Neighbours. Knotweed does not respect property boundaries, and those who allow it to spread diminish the value of their neighbour’s property; neighbour disputes, civil claims in private nuisance, and lots of work for lawyers.
  4. Damage. Knotweed can and does cause damage to property. Perhaps not as bad as some tabloids might make you believe, but don’t under-estimate the damage the plant can cause.
  5. DIY Disasters. Knotweed and building or landscaping projects don't mix! If you want to add that conservatory, summer house or home office pod to the garden, you won't be able to unless you tackle the Japanese knotweed first. Otherwise you risk an unwelcome visitor down the track. 
  6. The Heavy Hand of the Law. And for those that are still not convinced, be aware that an injunction or Community Protection Notice, otherwise known as an ASBO, can enforce them to act to remove knotweed from their property.

Did you Know?

  • We have a track record of over 20 years of successful knotweed removal from homes and development sites across the UK
  • We might be able to help you recover costs if you are the victim of non-disclosure, encroachment or professional negligence
  • We provide a full consultancy service for projects large and small, so you’ll benefit from our knowledge gained from experience and our research programme
  • We’re 100% employee-owned, meaning all our staff go the extra mile
  • We offer the only “AA-” rated insurance-backed guarantee on the market
  • We’re recognised as the best in the business by our trade body, the Property Care Association (PCA) who named us their ‘Contractor of the Year 2020’
  • Over 99% of our customers describe their experience with us as “Excellent” or “Great” on TrustPilot

Having said all that, we recognise we’re only as good as our last job, so we never rest on our laurels (or other invasive plants for that matter).

We offer professional Japanese knotweed solutions for all circumstances and budgets, so please be assured that with Environet, you’re in safe hands.

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