Japanese Knotweed

How to protect your property from Japanese knotweed

What is Japanese knotweed?

Japanese knotweed (Fallopia japonica), as its name may suggest, is a plant species that originates from Eastern Asia. It’s thought to have been introduced to the UK in the 1840s, to be used both as an ornamental garden plant and a cattle feed. At first, farmers and horticulturalists were enamoured with the weed, with influential gardeners including William Robinson encouraging its use through their writings. But come the turn of the 20th century, perceptions of the species were changing, and its rapid and unruly growth saw it fall out of favour. Unfortunately, this realisation came a little too late. By the early 1900s, Japanese knotweed had ‘escaped’ its managed gardens and plantations and was now growing in the wild right across the UK.

What does Japanese knotweed look like?

Japanese knotweed is a ‘perennial’ plant, meaning it lives for several years, growing and blooming through spring and summer before dying off back come autumn and winter.

It begins its (visible) life cycle as a small shoot, red and green in colour and similar to asparagus in appearance. As the shoot grows taller through spring, it becomes greener, with only red speckles remaining. Growing into a bamboo-like stem as much as three metres tall, this will then sprout an abundance of shield or elongated heart shaped leaves, initially red but turning to a bright green. At maturity, these leaves will be roughly hand-sized, while the stem will be noticeably hollow and easy to snap.

Around September each year, Japanese knotweed will sprout small white flowers all over, sometimes covering the plant almost entirely. It’ll then begin to drop its flowers and leaves around November time, reducing to a browning and brittle stem that will eventually collapse. Once spring comes back around, the plant will re-emerge from its roots in the very same spot as before.

Why is Japanese knotweed a problem?

Like any plant or tree which isn’t well maintained, Japanese knotweed is notoriously eager to branch out into neighbouring properties which can cause issues when it comes to conveyancing.

Growing as much as six centimetres a day at its peak, and with the ability to break through cracks and hard surfaces, this beautiful but brawny plant has the strength to penetrate property foundations, roads or walls.

Japanese knotweed is unique in the sense that it has almost no natural predators in the UK, leaving the pruning down to homeowners as opposed to nature. As a result, it’s estimated that Japanese knotweed damage, management and removal is thought to cost the UK as much as £166 million each year and to help reduce this number, it’s now against the law to introduce this weed in the wild.

What is the law around Japanese knotweed?

The Environment Agency declared that it is not an offence to have existing Japanese knotweed growing on your land.

However, ‘private nuisance’ laws may be broken should your Japanese knotweed spread onto neighbouring land or property, so be sure to keep a watchful eye on the growth of your plant.

How can Japanese Knotweed affect a property purchase or sale?

If you are selling a property:

It’s a legal requirement to declare if Japanese knotweed is present on a property. Sellers can declare this as part of the conveyancing process in the Seller’s Property Information Form – also known as the TA6.

If you aren’t aware of any Japanese knotweed on the property, the conveyancing survey for the buyer’s should pick this up, as many surveyors will check for the plant as part of their fee.

Should it be found on the property you wish to sell, a management plan for its removal may be required before being permitted to continue with the sale.

If you are buying a property:

Once Japanese knotweed is found on a property you wish to purchase, your mortgage provider will typically ask for a plan of action for its removal as part of your mortgage agreement.

Your conveyancing surveyor should be able to advise on what action is required and how to negotiate if it will become your responsibility, or if it must be dealt with prior to an agreed sale.

As a buyer, the best way to protect yourself is to have a survey conducted before you complete on your purchase. For more information, have a read of our guide to house surveys.

How do I remove Japanese Knotweed?

It is not advisable to remove Japanese knotweed yourself and getting rid of the plant is not easy.

Japanese knotweed is a robust species, and it’s widely recommended to hire a licensed expert for any Japanese knotweed removal. For a thorough removal, this may require two or three treatments, but a professional will advise on when this is the case.

Ensuring your new home or current home is free of potentially dangerous plants is just one of many steps involved in the home buying and selling journey. For more advice on conveyancing, surveying and getting a mortgage, speak to us at Post Office and find out about the house buying process.