Japanese Knotweed – Please Keep Out!Providing solutions for 25 years.

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Japanese Knotweed is known as one of the World’s worst invasive species, and it can seriously damage buildings and construction sites if left undetected. It is originally from Japan (obviously) and came to Britain in the late 1840’s by a Dutch doctor called Phillipe von Siebold who started to sell Japanese Knotweed to botanical gardens and to high society figures as in those days it was classed as being ‘ornamental’. Then, by 1869, it became available for public sale because farmers started to use it as feed for their animals. A few years passed until people started realizing that ACTUALLY Japanese Knotweed was a bad thing because it had started to grow in the wild. The 1930’s came and the rise of Japanese Knotweed was starting to reduce house prices, with East Cornwall’s dropping by £100.

In 1981, the Wildlife and Country Act made it an offence to introduce Japanese Knotweed into wild spaces & fast forward a few years, in 2011 Aphids were released in Swansea to try and combat the plant, with no luck. Removing the plant altogether would have a hefty price tag, £1.5 billion to be exact. We understand that the plant cannot be dug out of the ground, as it’s so difficult to eliminate all of the roots effectively. If less than a grass of its roots is missed in the process, it will rapidly regrow. You can spray, or inject, herbicides into its stem, but this takes six months, so you’ll have to be patient and rich, too – this can cost £1,500 for just a small patch of the weed.

The reason why everyone hates it so much is because it has really a wide-ranging root system, which can extend up to 3m in depth and 7m in all directions. These can pose a serious threat to construction works and have devastating consequences to building foundations and drains.

Yes it does grow quickly, at a rate of more than a yard per week. The damage caused by its roots and stems costs the economy around £166 million every year in weed control and property devaluation.

If you are found to be failing to stop the spread of the plant, you can be issued with an Antisocial Behaviour Order – yes, an ASBO. Under these orders, you could be fined up to £2,500.


Thank-you to the Telegraph for this wonderful information.