FAQ

What does Japanese knotweed look like?

Fully grown Japanese knotweed has bamboo-like stems, shovel‑shaped leaves, and grows rapidly in spring and summer. In winter, it dies back, leaving brittle brown stems, which can make identification harder.

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How can I tell if I have Japanese knotweed?

Misidentification is common. Plants such as bindweed and Russian vine are often confused with knotweed. A professional survey is the only reliable way to confirm it.

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Can you Get Rid of Japanese Knotweed?

Whilst the internet provides a plethora of solutions for getting rid of Japanese knotweed, there are only two methods of dealing with knotweed; herbicide treatment or excavation. Find out more about the methods to get rid of Japanese knotweed.

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Is Japanese knotweed dangerous?

Japanese knotweed is not dangerous to people or pets, but it is classed as an invasive plant due to its aggressive growth and ability to spread.

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Can Japanese knotweed damage buildings or drains?

It does not usually cause structural damage on its own, but it can exploit existing weaknesses in hard surfaces, drainage and boundaries if left unmanaged.

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How far can Japanese knotweed spread?

Japanese knotweed will continue to spread if not controlled or removed. It can grow up to 7 metres in distance per year.

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Can Japanese knotweed grow under foundations?

Yes. It can grow under fixed structures and underground infrastructure and has been known to enter properties through cracks in foundations.

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How Does Japanese Knotweed Spread/Propagate?

Japanese knotweed spreads as a result of the plants’ stems, or rhizomes (underground roots) being moved and spread around. Only the female form of the plant is present in the UK and therefore it cannot pollinate and produce any viable seed, other than hybridising with other similar knotweed species. Trials have shown as little as 0.7 grams of rhizome material, which is smaller than your little fingernail can propagate into a new plant within 10 days.

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Is Japanese Knotweed Notifiable/Reportable?

No you are not obliged to report Japanese knotweed on your premises to the authorities. Find out more about Japanese knotweed law.

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Do I need to tell my neighbour?

If there is a risk of spread across boundaries, early communication and professional management is strongly advised.

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Is Japanese Knotweed Poisonous, Can it Cause Burns?

No, Japanese knotweed is not poisonous and does not cause burns. Some people get the name confused with Giant hogweed, which can cause burns or Common ragwort, which is poisonous. Both of these are also non-native invasive weeds.

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Can I buy Japanese Knotweed?

No, it’s illegal to sell Japanese knotweed under the Wildlife & Countryside Act 1981. Additionally, under the same Act, it’s illegal to cause Japanese knotweed to grow in the wild or to allow Japanese knotweed to “escape” from your property into the wild. You can be fined up to £5,000 or sent to prison for up to two years if you flout these laws.

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Does Japanese Knotweed have Seeds?

Yes, Japanese knotweed has seeds. However, as we only have the female form of the plant in the UK, it cannot pollinate and produce any viable seed, other than hybridising with other similar knotweed species.

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Is Japanese Knotweed Edible?

Yes, Japanese knotweed shoots are edible but we do not recommend harvesting them due to their invasive nature and the risk of spreading which can lead to criminal prosecution. Note that it is illegal to transport Japanese knotweed without a Waste Carrier Licence.

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Can I Burn Japanese Knotweed?

You can but you must do this with extreme care. When the knotweed material has been excavated, cut the stems and leaves and leave it to dry before burning it, ideally without contact with the soil. The knotweed material must be burnt on site and not be burnt anywhere else as you could potentially carry a fine and in extreme cases, a custodial sentence. Bear in mind though, in its native area, Japanese knotweed grows on volcanic ash and around hot fumaroles. Check the local bylaws with regards to burning/bonfires.

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Do I need to declare Japanese knotweed when selling a house?

Yes. Sellers must disclose known Japanese knotweed during the property transaction process.

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Can I get a Mortgage on my Property when it has Japanese Knotweed?

This very much depends on the mortgage lender. Always check with them first. For most mortgage lenders they are happy to lend as long as there is a professional company in place to control the knotweed infestation. Make sure you instruct a reputable contractor like Japanese Knotweed Ltd who are Property Care Association accredited and can document all work being done. Find out more about Japanese knotweed and mortgages: READ MORE

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Are the Herbicides used to Treat Japanese Knotweed Harmful to my Children or Pets?

No. The herbicides we use are completely safe for your children and pets. The herbicide we use is safe when wet, but for precaution, we advise that pets and children are kept out of the treated area for approximately 1-2 hours following application until the herbicide has dried.

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Do Goats Eat Japanese Knotweed?

Yes, there are many reports of horses, cows and goats eating Japanese knotweed. Whilst goats can be used to control Japanese knotweed, they will not kill or eradicate an infestation of Japanese knotweed.

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Can I put Japanese Knotweed in my Garden Bin?

No, this would be illegal. Japanese knotweed is classed as “controlled waste” and needs to be cut down carefully and either burnt on-site or taken away to a licensed landfill site or incineration facility.

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Can I Cut or Mow Japanese Knotweed?

Yes but you must keep the knotweed waste on-site or dispose of it at a licensed landfill. Clean the mower before mowing other parts of the garden.

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Can I add Japanese Knotweed to Compost?

No, as this would likely lead to knotweed taking root growing in your compost heap.

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Can Japanese Knotweed Spread from its Leaves?

No it can’t. Whilst the leaves drop off in the autumn/winter, they should not cause concern regarding the plant’s spread.

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Can Japanese knotweed be Killed?

Japanese knotweed can be killed through excavation and various eradication methods. These often involve digging up the knotweed and removing it from the contaminated ground to a special landfill. In order to do this effectively the root-system needs to be fully mapped out so that all the contaminated ground is removed, if even a little bit of the roots are left, then Japanese knotweed can re-emerge. There are a lot of myths on the internet telling people how to kill Japanese knotweed. These range from mowing to using petrol! Japanese knotweed can’t be killed through DIY methods and it requires specialist skills, equipment and herbicides to control it.

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What happens when knotweed is on open land?

Amenity spaces are impacted by knotweed outbreaks and can be severely reduced, affecting open or green spaces, facilities and parks: READ MORE

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What are the issues for Issues for construction projects?

Construction projects must be put on immediate hold if knotweed is suspected on land under development: READ MORE

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What damage can knotweed cause?

Knotweed can cause significant damage to structures such as concrete, brick and tarmac by taking advantage of any weak areas or cracks and growing through them often forcing the structure to break or fall down: READ MORE

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What are the Legal implications of knotweed?

There are several legal implications of not declaring knotweed is on your property or land, allowing it to spread onto other property and not disposing of knotweed in a compliant manner: READ MORE

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What does knotweed removal cost?

Knotweed removal services should always be carried out by a qualified contractor. The survey should be free unless no knotweed is found, and costs for treatment or removal are quoted for by project. FIND OUT MORE

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What is the cost of Japanese knotweed treatment?

Costs vary depending on the size of the infestation, access and treatment method. Long‑term treatment plans are often more cost‑effective than excavation. A treatment plan for small infestations can typically range between £1,800 and £2,500. Costs for excavation projects start from £4,000. All costs depend on a site survey to determine what’s required.

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Can Japanese knotweed be fully eradicated?

Yes. With professional management, Japanese knotweed can be controlled and eradicated. The key is early identification and the right treatment strategy.

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Is treatment cheaper than removal?

In many cases, yes, a herbicide treatment with monitoring is the most common and lender‑accepted approach.

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What does knotweed look like now?

Knotweed changes through the seasons, from early shoots that appear like asparagus to tall stems that form dense thickets of green foliage and small white flowers in summer. In autumn the leaves turn golden/orange, falling off in winter to leave brittle brown stems. READ MORE

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Can I remove knotweed myself?

Knotweed is governed by legislation, meaning there are strict and legal guidelines that must be followed when removing knotweed. Always get a licensed contractor to get rid of knotweed for you. READ MORE

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How can I schedule a Japanese knotweed inspection?

A knotweed inspection is called a ‘survey’ which allows the contractor to provide a survey report and knotweed treatment or removal quotation. This can be booked here: Book a knotweed inspection

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Why do I need a licensed knotweed contractor?

There are many reasons to use a knotweed contractor – they will be qualified and licensed and hold all industry standard accreditations required to provide knotweed removal services. A licensed contractor will not only correctly identify knotweed, but remove it in a safe and compliant way. Attempting to remove knotweed yourself is never recommended. FIND OUT MORE

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How long does Japanese knotweed treatment take?

Treatment typically takes 2–5 years, with regular monitoring. While this may sound long, it allows normal use and sale of the property when supported by the correct documentation.

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Is knotweed near me?

Yes – it could be. With 5% of UK property currently having knotweed, it could be on your land or garden. FIND OUT MORE

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Is my property affected by neighbouring knotweed?

Knotweed within 3m of the property boundary is classed as a risk – If knotweed is within 3m of the boundary you should seek, as advised by the RICS, a survey and guidance from Japanese Knotweed Ltd.

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What should I do if I think I have Japanese knotweed?

1. Avoid cutting or disturbing the plant
2. Do not attempt DIY removal or disposal
3. Arrange a professional survey
4. Put a management plan in place if required

Early action reduces cost, risk and stress.

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KNOTWEED GUIDELINES

Whether you encounter knotweed on a major building project or as part of a maintenance scheme, please ensure you follow these basic guidelines:

Do

• Contact Japanese Knotweed Ltd so we can manage, control and remove the problem for you.
• Fence the Japanese knotweed off if there is an imminent risk of disturbance. Fencing should be erected 5-7 metres away from the visible growth to prevent disturbance of the plants’ underground rhizome. It should be clearly signed.
• Draw up a Knotweed Management Plan – especially if a number of contractors are to be involved on the site and adhere to it throughout your project.
• Commence treatment/removal of Japanese knotweed as soon as possible after discovering its presence.
• Adhere to recommendations in the PCA Code of Practice for managing knotweed, when controlling or removing Japanese knotweed.

Don’t

• Where possible allow works to commence on a development site without first drawing up a Knotweed Management Plan (KMP).
• Allow contractors to undertake site work until the site has been properly surveyed for the presence of knotweed.
• Allow knotweed material to leave your site intentionally or unintentionally in a manner that will contravene the Environmental Protection Act and the Environmental Protection (Duty of Care) Regulations.
• Allow Japanese knotweed to spread into adjacent properties, as this could contravene legislation and private nuisance laws leaving you vulnerable to third party litigation from your neighbour(s).
• Flail or strim knotweed, as this will cause the Japanese knotweed to spread.
• Store materials on top of Japanese knotweed areas, or the materials themselves could become contaminated with knotweed.
• Chip Japanese knotweed material, as mechanical chippers do not kill the plant and could result in new Japanese knotweed growth wherever the chipped material is spread.
• Add Japanese knotweed to compost, as this can lead to knotweed growing in your compost heap.
• Burn Japanese knotweed as a sole means of treatment as large rhizome and crowns can survive burning.