Japanese knotweed

How to identify Japanese knotweed near your home

Guest post by Nic Seal, Founder and MD of Environet UK

Awareness of Japanese knotweed has grown in recent years. Research by Environet suggests that around a third of us might consider walking away from our dream home if we discovered it was affected by this invasive weed.

But it doesn’t have to be a deal breaker. With the right help, knotweed can be treated with guarantees that will satisfy most mortgage lenders, meaning sales can then proceed successfully.

What is Japanese knotweed?

Hailing from the volcanic slopes of Nagasaki, Japan, knotweed arrived in the UK in 1850 in a collection of samples sent to Kew Gardens and, rather favoured by the Victorians as an ornamental plant, has since become established here.

Now number one on the Environment Agency’s list of the UK’s most invasive plant species, Japanese knotweed spreads through its powerful underground root system, pushing up through asphalt, cracks in concrete, drains and even the cavity walls of our homes in search of light and water.

What does Japanese knotweed look like?

Red or purple asparagus-like spears emerge from the ground in early spring and as they grow, bright green heart or shield-shaped leaves unfurl in a zig zag stem pattern.

Japanese knotweed red shoot

As the plant reaches full height of up to three metres in summer, the canes harden and become bamboo-like with distinctive purple-flecks.

Knotweed flowers in late summer, when clusters of pretty creamy-white flowers emerge.

In autumn the leaves turn yellow and eventually fall to the ground as knotweed enters its winter hibernation period. The stems by now are brittle and dead-looking but beneath the ground, the plant is very much alive and waiting to re-emerge next spring.

Japanese knotweed

What should I do if I discover knotweed on my property?

If you discover knotweed on your land and you decide to leave it, you’re not breaking the law and it’s not a notifiable weed either, so you don’t need to report it to the authorities.

However, you do have a legal obligation to prevent knotweed from spreading to neighbouring properties and failure to do so could result in legal action under ‘Private Nuisance’ legislation – or even an ASBO!

Can I buy or sell a property with knotweed?

Honesty is the best policy when it comes to Japanese knotweed.

Sellers are obliged to answer truthfully to a direct question relating to Japanese knotweed on the TA6 Property Information form, completed as part of the conveyancing process – and failure to do so could lead to a very unpleasant and expensive misrepresentation claim further down the line.

If you’re not sure whether knotweed is present, you could commission a detection dog survey to find out.

Environet’s team of sniffer dogs will scour the garden and indicate by freezing if knotweed is present, even if it’s hidden beneath the ground. If a property is affected by knotweed, the buyer should insist that a treatment plan is put in place immediately and a guarantee for the work secured in order for the sale to proceed.

Japanese knotweed

Will knotweed affect my property’s value?

The simple answer is yes, knotweed can knock up to 10% off the average house price, but don’t panic. If the problem is professionally remediated with an insurance-backed guarantee, the property’s value normally returns to close to the ‘non-affected’ value.

How can Japanese knotweed be treated?

There are several methods of dealing with knotweed, the least expensive being herbicide treatment over two to three years. Increasingly, homeowners are opting to have the knotweed physically dug out of the ground, with all viable rhizome roots sifted and removed from the infected soil.

This can be carried out within a few days, at any time of year – and it’s an instant fix. An insurance backed guarantee can then be secured, meaning there will be no difficulties obtaining a mortgage and the property can be bought and sold.

There’s no doubt Japanese knotweed can cause serious damage to buildings and negatively impact their value. But with the right treatments and guarantees in place, there’s no reason why it needs to be a deal breaker.

For help and advice on dealing with Japanese knotweed, please contact environetuk.com.

Japanese knotweed

READ MORE: Getting a mortgage on a property with Japanese knotweed

Please note: Rightmove is not authorised to give financial advice; the information and opinions provided in these articles are not intended to be financial advice and should not be relied upon when making financial decisions. Please seek advice from a specialist mortgage provider.


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