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Getting rid of Japanese knotweed

In CategoryTim Whitcombe
ByGardenAdvice Tim Whitcombe

Japanese knotweed: two words no gardener ever wants to hear — especially when it’s connected with their own glorious patch of green. You only have to open a newspaper or turn on the TV to see another case of a garden and property being overcome by this fast-growing pest that can be incredibly difficult to eradicate.


Before we get to how to best get rid of this imported scourge, a bit of history. How did this exotic Japanese knotweed end up in the UK in the first place? To answer that, we have to lay the blame firmly at the feet of a German man — and a botanist at that. Philipp Franz Balthasar von Siebold thought Japanese knotweed was a pretty little plant and would go down well among plant-lovers in the UK. So, in the 1840s, he brought it here. Indeed, the public lapped it up — members of elite high society and botanical gardens, at least.


The love affair with this dainty-leaved, tear-shaped plant was fleeting, however, and soon people grew tired of it and threw it away. This marked the beginning of Japanese knotweed’s seemingly unstoppable spread right around the UK, with invasions particularly concentrated in the southeast of England and parts of Wales. We’ve been trying to get rid of it ever since.


Japanese Knotweed: DIY or the Pros?


Now that we know how this giant and growing mess came about in our country, it’s time to look at ways of properly treating it, so that it doesn’t grow back. The big question, one that every gardener affected with this dastardly problem wants to ask, is: can you deal with Japanese knotweed yourself, or is it a job for the experts?


Part of the answer lies in how extensive the weed’s growth is in a garden or elsewhere on a property. Simply slashing back the branches and hoping for the best is not going to work, however, as like most tenacious weeds (think nettles and thistles), it will quickly shoot back up and start growing all over again. Bear in mind that this is one rapid grower. During its peak growing season in the summer, it can expand by up to 20cm in a day. That’s a lot of plant to deal with.


It’s safe to say that most gardeners find it an entirely frustrating experience when trying to eradicate Japanese knotweed themselves. The plant’s extensive root system can be just too entrenched and complicated to exterminate, which is where the problem really lies. Even if you dig up the roots, some parts of it will surely remain in the ground and soon start sending up new shoots.


A Task for the Experts


Japanese knotweed removal is best left to those who know what they’re doing. Experienced Japanese knotweed eradication firms will use herbicide treatments or dig-out methods to ensure nothing is left. The best ones will provide an insurance-backed guarantee that it won’t come back — and, if it does, there will be no further cost for additional extermination work.


Many gardeners will naturally be worried about the Japanese knotweed removal cost and it’s certainly a valid one. But consider that, if left untreated, Japanese knotweed can cause significant damage and loss in value to a property, as the root network becomes ever more extensive. Also, there are legal ramifications if it spreads onto a neighbouring property or land.


It’s not illegal to have Japanese knotweed on your own property, but you’ll almost certainly encounter difficulties if you want to sell it. A new survey shows that most people would walk away from a property they were considering buying if they knew there was Japanese knotweed growing somewhere on it. Not only that, but mortgage providers will not approve a mortgage unless the problem is professionally dealt with and there’s a solid guarantee in place.

With Japanese knotweed in your garden, it’s best to leave it to those with experience and keep your hands clean. Call in the pros. Here is a link to some of the latest information on dealing with Japanese knotweed click here