Japanese Knotweed.jpg

What is Japanese Knotweed and What Can You Do About It?

Phi Spencer

By Phil Spencer

Did you know that a plant could wipe significant value off your property? Even if it’s not actually on your land? Japanese knotweed is that plant.

In fact, in 2017, a couple sued the individual they bought their home from, 15 years prior, because she had failed to disclose knowledge of Japanese knotweed near the property and the extent of the problem.

But, what is Japanese knotweed and what can you do about it? We take a close look at this plant and why it’s such a nuisance.

What is Japanese knotweed?

Japanese knotweed is an incredibly resilient plant, introduced into the UK by the Victorians who thought it would look good in their gardens.

With its red shoots and heart shaped green leaves adorning any herbaceous border in the spring and summer, it’s easy to see why this plant was once considered attractive. Japanese knotweed grows up to 20 cm a day, before appearing to die in the winter.

However, the Victorians quickly turned against their new favourite plant when they realised quite how destructive it was. But, by then it was too late, the damage was done.

What does Japanese knotweed do?

Above ground, Japanese knotweed looks pretty and innocent. However, looks can be deceiving! Below ground is another matter altogether.

Whilst Japanese knotweed isn’t poisonous, it’s extremely harmful.

Its roots, which can extend down to 7ft render, are virtually impossible to remove yourself, without the use of extreme chemicals.

If left unchecked, these roots can exploit the weakness in any building, causing significant structural damage to walls, drains, floors and any hard surfaces.

This means that this plant not only affects the health of your garden, but your entire property also!

Japanese knotweed house damage

As recent reports have indicated, the presence of this destructive non-native weed, can knock thousands of pounds off the value of your property, in some cases, up to 10%.

Property Wire reported a case where a family, who had a mortgage agreement in principle, had their offer rescinded when the survey revealed Japanese knotweed, not on the property they were trying to buy, but in the vicinity of it.

How do you get rid of Japanese knotweed?

Wondering how to get rid of Japanese knotweed? There are some methods you can try.

If you already have Japanese knotweed growing on or near your property, there’s a few courses of action you can take, either chemical or non-chemical.  

Unfortunately, Japanese knotweed eradication is expensive and can take up to three years to have any effect.

Here’s what to do if you find Japanese knotweed:

  • Spray the plant with approved chemicals (herbicides) - glyphosate-based weed killer.
  • Dig it out and burn it. This involves digging down to the roots and disposing of the plant appropriately - you can’t dispose of it with normal household waste as that can cause it to spread and never put it in green waste bins without killing it first.

Also, it is worth noting that Japanese knotweed is not typically covered under most general insurance policies. If you find it growing in or near your property, and have it removed, you will most likely have to take out a special knotweed indemnity policy to prevent potential future attacks of the plant and to mitigate against all damage it can do.

These special indemnity policies provide cover for cost of treatment, any damage caused by the plant, third party legal fees (should the plant have spread onto neighbouring properties), and the resultant devaluation of any property found with Japanese knotweed growing in or near the grounds.

If you have any doubt about Japanese Knotweed, speak to the Environmental Agency, or contact specialist removal companies.

Research is absolutely key! Want to learn more about your area? With a Move iQ property report, you can find out everything you need to know about a specific area, from local schools to neighbourhood demographics. Get your full report here!

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