What is Japanese knotweed?

Japanese knotweed is a highly invasive plant, imported into the UK in the 1840s from Asia as an ornamental plant by Victorian horticulturists. Mature knotweed has an extensive underground root/rhizome system which extends several metres in each direction and deep into the ground, by as much as 2m. The rhizome is highly regenerative, meaning that even a small piece has the ability to grow into a new plant.

It continues to spread onto land and gardens in cities, towns, villages and the countryside throughout the UK. It is now thought to affect at least 500,000 homes. Take a look at our heatmap to see the regions that are affected most.

It causes damage to buildings, its spread creates legal disputes between neighbours, and it affects property value due to restrictions on mortgage availability. It is included in the Law Society’s Pre-Contract Enquiry form (TA6), meaning that those sellers who do not disclose that the property is affected by knotweed run the risk of an expensive misrepresentation claim from their buyer.

To find out more about the origins of the plant, read our page on Japanese knotweed history, or get yourself to a copy of MD Nic Seal's book Unearthing the Truth.

Not surprisingly the Environment Agency describe it as being Indisputably the UK's most aggressive, destructive and invasive plant. However, we have plenty of experience helping clients as we specialise in Japanese knotweed and have been in business since 1996. Most knotweed problems can be resolved with expert help, despite all the scare stories in the press and on the internet. We offer insurance backed guarantees underwritten at Lloyd's for up to 10 years, to provide our clients with added peace of mind. These are accepted by the majority of banks and building societies as suitable security to enable them to lend.

We have developed a range of solutions to deal with Japanese knotweed. We assess each site carefully, taking into consideration our client's circumstances and site constraints, and engineer tailored solutions on a case by case basis.

You can read more about our different solutions below; or jump straight to our commercial and residential solutions pages.

Japanese Knotweed Management Plans

Required if buying or selling a property
Detailed management plan
Site specific issues
Determine extent of knotweed
Highlight potential encroachment issues

Further Info



Environet's Eco-Innovative Xtract™ method involves the excavation and screening of soil to separate and remove knotweed rhizome. It can be carried out in a matter of days, involves zero waste to landfill and uses no herbicides.



This method has been developed for residential properties from our patented Xtract™ method, and involves physical excavation and removal of knotweed rhizome from the ground.



The revolutionary new DART™ method from Environet is the most effective treatment programme available and comes with the added benefit of being less intrusive during the summer when you want to use your garden.


Site Supervision

A cost effective solution for clients who want to provide their own plant, machinery and labour - we supervise.


Stockpile and Treat

Stockpile and treat (the Bund method) involves soil excavation and relocation on site, followed by herbicide treatments.


Herbicide Treatments

Herbicide treatment is an effective Japanese knotweed control method, with repeated chemical applications. It's a relatively inexpensive method but it does take at least 2 growing seasons, possibly longer.


Dig and Dump

Knotweed infested soil is excavated under expert supervision and is consigned to landfill in accordance with EPA 1990 requirements.


Root Barriers

A containment method using root barriers to prevent the spread of Japanese knotweed across boundaries.


Stem Injection

A stem injector is used to inject herbicide into the lower part of each mature knotweed stem.