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How can Japanese Knotweed affect your property?

Updated: Feb 22, 2023


Japanese Knotweed

Japanese Knotweed has been the subject of much debate within the media. As with most things, there are several opinions on the subject. However, one sure thing is that the plant has had a lot of negative publicity.



Types of Knotweed in the UK


Japanese knotweed is the most common of 4 invasive knotweed plant species in the UK. These are:

  • Japanese knotweed

  • Dwarf Japanese knotweed

  • Giant knotweed

  • Bohemian (hybrid) knotweed

Japanese Knotweed, also known as JKW, is from Asia, where environmental factors keep it under control. Unfortunately, the English weather does not have the same effect...

Identifying JKW


During the summer months, Japanese Knotweed has a heart or spade-shaped leaf. Towards the end of the summer, white/cream-coloured flowers bloom in clusters. During the colder months, a tell-tail sign is the zig zag-shaped stem. Despite this, it can be challenging to identify it from native plants, and the roots can spread significant distances underground. JKW can overgrow and has been known to cause damage to brickwork and tarmac, and other materials. Therefore, it presents a risk to buildings.


What happens if JKW is found on your property?


If JKW is found at your property, it can cause financial costs and inconvenience and give rise to legal responsibilities. The government state that you must stop Japanese knotweed on your land from spreading off your property. Furthermore, soil or plant material contaminated with non-native and invasive plants like Japanese knotweed can cause ecological damage and may be classified as controlled waste. You do not legally have to remove Japanese knotweed from your land unless it’s causing a nuisance to others, but you can be prosecuted for causing it to spread into the wild.


If JKW weed is found on your property, it could lead to problems when attempting to sell, as the plant has a very negative reputation. For anyone looking to purchase a property, if JKW is present on the proposed property, it can affect your ability to obtain a mortgage if a specialist's plan on how it will be removed has not been received. Most lenders will ask that specialists remove the JKW and that a 5-year herbicide treatment plan is put in place with monitoring and a 10-year insurance-backed guarantee to cover the works that have been completed.


What should you do?


Should you be concerned about JKW, we recommend contacting a specialist who can advise on whether an area requires treatment. Equally, we recommend that if you are concerned about the risk of JKW on the site, you arrange for a separate specialist to attend the property to ensure it is not present.


Upon receipt of your specialist's report confirming that Japanese Knotweed is not present on your land, you should then be able to obtain indemnity insurance; this will provide you with cover against the plant's future growth on your land.

You can supervise the management and disposal of knotweed yourself, or you can hire a specialist to do it for you. Look for a contractor with the following accreditations and registrations:


Amenity Forum Membership


Many of these companies belong to one of these trade bodies:

Invasive Non-Native Specialists Association (INNSA)

Property Care Association (PCA)


On our inspection of the property, we do not search for Japanese Knotweed, as you can hopefully appreciate that we are not specialists in this field. It can be difficult to distinguish from the plants around it, especially in winter. We strongly recommend to all clients to obtain a specialist's report, upon receipt of which you should then be able to get indemnity cover to insure against any future instances.

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