Japanese Knotweed: A Menace To The Environment?

When asked about the foreign invaders that are threatening our environment, it’s surprising that most don’t think of Japanese Knotweed.

The invasive plant has been steadily growing in numbers since its introduction in the Victorian era and can now be found all across the UK, including in Cheshire.

Where did it come from?

Japanese knotweed was first introduced to the UK during the Victorian era by horticulturists eager to share their new discovery with their countrymen. The plant had been discovered growing in a vast array of climes throughout Japan and had been praised for its ability to seemingly thrive wherever it was put to ground. In its native land Japanese knotweed grows seasonally and reproduces through seed dispersion from creamy white flowers, it has a similar appearance to bamboo and these adventurous horticulturists saw an opportunity to use the plant as a structural aid back in England where new buildings, railway lines and canals were in need of reinforcing.

Upon their return to England, Japanese knotweed was distributed throughout the country to reinforce the sides of canal banks and to keep other plants from venturing into railway lines. The plant performed its job admirably, however by the time those same horticulturists realised that it was doing its jobĀ too well, it was too late.

Why is it so bad for the environment?

In its native land, Japanese knotweed is not a threat to the environment, however it is not combated by the same natural enemies here in the UK. Whilst other plants and insects keep Knotweed in check in Japan, in the UK it has proved too much of a match for our flora and fauna.

Due to the dense patches that it grows in, Japanese knotweed hogs sunlight and blocks valuable rays that would otherwise make their way to low-lying plants. In addition to this, the plant waste that it produces actively discourages other plants from growing. It are these properties that, in conjunction with its regenerative rhizomes, allow it to dominate outdoor spaces within a few months.

Are there any legal implications to having Japanese knotweed?

To reflect the serious impact that Japanese knotweed has on the environment, the government has classified it (and any soil containing fragments of the plant) as ‘controlled waste’ which must be properly disposed of. Those who attempt to distribute, plant or dump any soil or materials containing Japanese knotweed will be in violation of the Environmental Protection Act 1990 and the Wildlife and Countryside Act 1981. In addition to these laws, a precedent has also been set to protect homeowners whose neighbours are allowing knotweed to grow onto their property. Negligent cultivation of Japanese knotweed is now under the remit of the Anti-social Behaviour Crime and Policing Act 2014, and can lead to hefty fines or jail time.

What can we do about it?

There a number of things that you can do should you see a Japanese knotweed infestation. If you discover knotweed that is not on your land then it’s a good idea to let the owner of the land know, so that they can do something about it themselves. You can also log the sighting over at Planttracker.org.uk to let the government know about it. If you’ve discovered the knotweed on your own land then you should take action to eradicate it by contacting an accredited removal expert. If the plant has grown onto your land from a neighbouring property then you should inform them of this, if they refuse to act then it may be time to call a legal expert.