What is Japanese Knotweed?

Within Britain today, Japanese Knotweed is the most invasive plant known but as the name suggests it actually originated in Japan where it is able to thrive. It got into Britain in the early 19th Century as an ornamental plant which could be used to feed cattle.

It was introduced by a Victorian Horti­cul­tu­ralist and way back then they were not in a position to foresee what the future held for Japanese Knotweed and the sheer impact it as going to have.

Japanese Knotweed actually grows at around 10cm per day in any soil type and it can form dense clumps of foliage which can reach around 3m in height. It thrives on disturbance to the ground and spreads both naturally and by humans. The smallest of fragments can create new Japanese Knotweed plants but it isn’t the 3m high foliage that is causing problems!

The problems come underground where they create root networks extending 3m in depth and around 7m in all directions. Imagine just for a second this in your back garden extending to 7m. Would this disrupt your house foundations?

In actual fact Japanese Knotweed causes a massive threat to structures; it damages their foundations, drains and other underground services leaving a path of destruction behind.

How to identify Japanese Knotweed?

The plant itself can be easily identified by its large oval-shaped leaves and bamboo style stems. In Spring time the Japanese Knotweed will start to send new shoots from underground to the surface; these are a red/ purple colour and have leaves which are rolled back as you can see in the photo on the right

At the beginning of Summer the plant has distinctive branching ; it is hollow and bamboo like stems which are often covered in purple speckles and this is when they reach around 2-3 meters in height. When we head into the later parts of summer the plant will begin to flower; you will be able to clearly see small, cream/white coloured flowers appearing on the plant. Here seeds are produced but at this time they rarely survive.

In the Winter time you can easily see the leaves die back in order to reveal stems which are orange/brown coloured and are strong routed as usually they will have been in position for several years. The leaves and stem may decompose during Winter leaving behind a pile of plant matter but the Japanese Knotweed is not dead!

Why is Japanese Knotweed such a problem?

Within the UK there is no way of controlling the Japanese Knotweed plant naturally. This contrasts to Japan where it originated from because they have a combination of fungus and insects which control the plant and keep it at pay. There are no natural enemies in the UK for Japanese Knotweed and in the process of survival of the fittest it wins every time! It can outcompete all of our native species winning light, water and vital nutrients.

You may have never seen a Japanese Knotweed plant; maybe you have but you just didn’t realise, whichever you are one thing cannot be overlooked. The damage caused by Japanese Knotweed to commercial and domestic structures is uncountable.

The plant is not classed as “controlled waste” under the Environmental Protection Act 1990 and thus it has to be disposed of at licensed landfill sites. In addition to this Act it is also listed under Schedule 9 of the Wildlife and Countryside Act 1981 which makes it a criminal offence to cause or allow the plant to spread within the wild.

What is the Laws concerning Japanese Knotweed?

As this is such an aggressive and rapid growing plant causing serious damage to commercial and domestic structures there are a number of laws which have been applied in relation to Japanese Knotweed.

The five most common legal issues which surround Japanese Knotweed are outlined below:

  • If you allow Japanese Knotweed to spread from your property onto that of your neighbours or those around you then you will be liable for court costs and any damages caused. 
  •  If you aid the cause of spread of Japanese Knotweed then you are committing a criminal offence under Section 14(2) of the Wildlife and Countryside Act 1981 (WCA 1981)
  • If you are going to be disposing of Japanese Knotweed material then under the Environmental Protection Act (EPA) 1990, Duty of Care Regulations 1991 it must be disposed of as controlled waste.
  • It is not illegal to have it on your land providing you control it and it doesn’t cause any harm to others.
  • It is not a weed which you have to notify the relevant authorities about as many often wrongly believe.  

What will happen if I break the laws in regards to Japanese Knotweed?

Committing an offence and breaking the law in regards to Japanese Knotweed could see you face a fine of £5000 and/or 6 months imprisonment and some have even been faced with 2 years imprisonment and/or an unlimited fine.

What can I do to control Japanese Knotweed?

There are a number of ways in which you can control Japanese Knotweed however one of the most effective is through powerful herbicides such which can be found at Twistfix. Our Knotweed Control Treatment comes with everything you need to eradicate the Japanese Knotweed plant.

Japanese Knotweed Video

We have for our customers a short video covering some of the items in this article as well as some additional information. This was shown on the BBC One Show and you can see just how easily it spreads but then just how hard it is to remove.

For more information then please contact Twistfix on 0845 1236007 or email

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