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What Damage Can Japanese Knotweed Do?

When it comes to our gardens and the many beautiful plants and shrubs that we now enjoy in plentiful supply, it’s the Victorians we have to thank for a lot of the greenery we see on display. 

Plant hunters bravely struck out for parts unknown, risking long-haul travel on uncomfortable boats, shipwreck, pirates and disease, all so we could see the likes of rhododendrons and camellias for ourselves.

While these botanists did bring us some really beautiful plants and flowers (and it’s certainly true that the great British garden as we know it today simply wouldn’t exist without them), they also brought with them Japanese knotweed, which is a very different story altogether.

Originally from Japan (but also native to Korea and China), this particular plant is kept well under control in its native environment by various predators, including insects and fungi, but in the UK, the landscape is far more welcoming and this has allowed it to thrive and flourish.

This doesn’t sound problematic in itself, but Japanese knotweed is incredibly invasive and can cause serious damage to houses and other properties, leading to significant structural damage and potential issues with the foundations, as well as potentially leading to subsidence. 

The root system is able to grow through paving and tarmac – and it can have a big impact on the value of your home.

In the summer months, it can grow up to 10cm a day and even if you deal with the plants that are visible on the surface, you still have to take into account the rhizomes below ground. Unless you deal with these as well, the plants could reappear in the future and cause even more damage.

It is a legal requirement to stop Japanese knotweed from spreading off your property if you do have it on your land and it’s causing a nuisance. Note that you can be prosecuted if you let it spread into the wild, as it can cause ecological damage.

One effective way to get rid of the plant is to use an approved herbicide. It typically takes at least three years to treat the plant and you’ll have to respray, since rhizomes can lie dormant in the soil for a long time.


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