How Can You Prevent Japanese Knotweed From Spreading?

Industrial Japanese Knotweed removal root barrier membrane and burying

Identification of Japanese Knotweed

If you are unsure what Japanese Knotweed is then Information about it and how you can identify it can be found here.

Japanese Knotweed with flowers in summer
Flowering Japanese Knotweed in Summer.

Preventing the Spread of Japanese Knotweed

It may not be illegal to have Japanese Knotweed growing on your property, however you do have a duty to make sure it does not spread beyond the perimeter of your property. If you allow it to spread then you could be prosecuted or given a community protection notice for causing a nuisance.

Japanese Knotweed is extremely resilient, it was first discovered growing on the sides of volcanoes in Japan, a harsh environment, where the plant faces animals, fungi, diseases, mountainside climates along with regular ash deposits from volcanoes. However, in the UK none of these factors affect the plant meaning it grows virtually unaffected. This is why it is classed as an invasive species in the UK.

Sometimes prevention is the best cure for Japanese Knotweed and as it is infamously very difficult to remove without years of treatment or expensive professional techniques. Due to the plants rhizome system (roots) can lie dormant for years and disruption of the soil around It can trigger regrowth of the plant. The plant does not reproduce using seeds, instead it reproduces via dispersal of rhizome pieces, stems, or rhizome crown fragments.

It usually takes 3 years of treatment using herbicides to place the rhizomes into a dormant state, meaning that you must keep your eye on the area where the plant was and also be sure not to disturb it when gardening or doing projects, because potentially you could re-awake the dormant rhizome.

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Part of a Japanese Knotweed Rhizome crown with shoots.

Is It Compostable?

Unfortunately composting is not a viable solution for Japanese Knotweed, as soil or plant material that has been contaminated with non-native invasive plants, such as Japanese Knotweed has the potential to cause ecological damage and should be classed as controlled waste. As it is classed as a controlled waste it means you can’t just get rid of it as you would just normal garden waste. In the case of Japanese Knotweed, it is very persistent, and a tiny fragment of rhizome could cause a regrowth, meaning it can survive the regular composting process and then would infect areas where that compost is used.

Spraying or Injecting With Herbicides

Spraying with chemicals is probably the most common method of treatment against Japanese Knotweed, although it does take numerous rounds of treatment to get rid of it fully and depending on the size of the infestation can take up to 3 years to place the underground rhizome system into dormancy.

If you decide to use herbicides as a method of treatment you need to make sure anyone spraying or injecting holds a certificate of competence for herbicide use or is working under direct supervision of a certificate holder. Carry out a Control of Substances Hazardous to Health assessment, get permission from Natural England if the area is protected, for example sites of special scientific interest and get permission from the Environment Agency if the plants are near water.

You may need any of the following to dispose of certain chemicals:

  1. A Waste exemption
  2. Trade effluent consent
  3. An environmental permit
Fallopia japonica wilting April 2017 D
Japanese Knotweed wilting after a round of treatment with Glyphosate based herbicide.

Burying It

You need to check with the environment agency before burying Japanese Knotweed waste on your land, to see if this is allowed. Normally you will not be able to bury waste on any land unless it is a landfill site with a suitable permit.

However, you can bury Japanese Knotweed on land if it has grown on that site, meaning you dig it up and bury it in the same location rather than transporting it. You can bury it in this way as long as you do not bury it with any other waste and it needs to be buried at a depth of 5 meters.

If it is not possible to bury the plant at a depth of 5 meters, then cover the plant remains with a material that contains the plant and doesn’t allow it to grow through it (known as a root barrier membrane layer or geotextile membrane) and then bury them at a depth of at least 2 metres. However, you may need to let the environment agency a week before you intend to bury the plant waste.

Japanese Knotweed root barrier membrane installation on a large commercial site.
Installation of a root barrier membrane and burying of Japanese Knotweed on a commercial site.

Burning It

If you are doing this on your own land by yourself without professional help and you want to burn the waste privately as an individual you do not need a permit, however you should check with your local council to see if burning is allowed. If you are a business that wants to burn Japanese Knotweed you must tell:

  • The Environment Agency at least a week before you burn it
  • The environmental health officer at your local council

The Japanese Knotweed crown and rhizome could possibly survive the burning process, so it is best to maybe bury the remains or dispose of it off-site, again if you’re a business or a farmer you’ll need an environmental permit or a registered waste exemption.  

How to dispose of Japanese Knotweed

If you allow contaminated soil or plant material from any waste you transfer to spread into the wild, then you could be sent to prison for up to 2 years or be fined up to £5,000. In this case you can hire a specialist to do it for you or you can do it yourself. If you use a specialist to get rid of Japanese Knotweed make sure they operate within the conditions in ‘treatment and disposal of invasive non-native plants: RPS 178’ and has the relevant environmental permit.

You do not necessarily have to hire a specialist contractor to treat Japanese Knotweed, as you maybe able to give it a go yourself. However check the companies that specialise in the treatment are part of either of these two trade bodies:

INNSA or Property Care Association.

Knotweed showcasing it’s resilience as it grows through the cracks in the concrete.

Taking Japanese Knotweed Off-Site

You MUST use a registered waste carrier and a landfill site with the correct permit to dispose of the waste. If you’ve been employed to transfer goods you must follow the law if any of the waste contains Japanese Knotweed. You must NOT dispose of Japanese Knotweed with other surplus soil or sell soil contaminated with Japanese Knotweed as topsoil.

If you have leftover contaminated soils after treatment, then you can only use them on the site where the Japanese Knotweed had grown. When transporting the waste, you must cover and enclose it so no waste can escape, you need to tell the waste site that you’re transferring Japanese Knotweed waste, and to check they have a permit to accept waste that contains invasive plants. You may need to let them know up to a week in advance as they may need to prepare.

After you have transferred the Japanese Knotweed waste to a disposal site, you must brush vehicles down vigorously or jet-wash them to clear any leftover debris as well as inspecting your vehicle to check there is no trapped pieces of plant material or rhizome.

How can JKWClaims Help you?

If you think that you have seen Japanese Knotweed and you’re unsure get in touch and we can help you identify whether you have an infestation. If it turns out you have an infestation and it has grown onto your property from a neighbouring property then you could be eligible for compensation as well as having the removal service paid for. If you have just bought a home and it was missed by a surveyor and it was missed by the previous owners on a TA6 form then you could also be eligible. If you’d like any more information or to discuss further you can get in touch, and start your No Win No Fee claim.

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