Don’t get yourself in knots: understanding Japanese Knotweed

Introduced to the UK in the early 19th century, Japanese Knotweed is a perennial plant which is native to Japan, Northern China and Taiwan. Perhaps most importantly, Japanese Knotweed is notorious for spreading rapidly throughout underground rhizomes, causing ecological damage and nuisance to gardens.

Several years of treatment are sometimes required to rid a garden of well-established plants. According to the Environment Agency, Knotweed can grow in most soil conditions found in the UK, but for the most part in ‘man-made habitats’ such as:

• roadsides
• waste grounds
• railway embankments and cuttings.

Whether you are a buyer or a seller, it is vital to be able to recognise Japanese Knotweed within your garden as there may be negative implications on the property. The existence of Japanese Knotweed causes structural damage to homes, and it can also affect the value of the property being sold.

If you are a buyer and Knotweed has been flagged by your surveyor, it is important to note that this may cause issues with your lender as they often do not offer mortgages on properties with an ongoing Knotweed issue.

Going forward, you should have a ‘Japanese Knotweed management plan’ in place which outlines the severity of the infestation and what is to be done in the future to eradicate it via treatment and removal by professionals. The RICS 2022 Report can be used by surveyors to monitor the developments in official Knotweed guidance. For instance, the distance that Knotweed must be from your property has been reduced from 7m to 3m.

For those who have experience with Knotweed, you may attempt to remedy the situation yourself. The Environment Agency recommends spraying the stems of the plant with chemicals to prevent any further spreading; however, you must use approved herbicides. You can find these on the Pesticides Register of Great Britain and Northern Ireland.

Provided you are successful in removing the Knotweed, you can then bury it, although you must notify the Environment Agency at least one month beforehand.

Here are four general rules to aid you along in tackling the tricky issue of Knotweed:

1. You must stop Knotweed from growing beyond your property. While it is not a legal requirement to tackle Knotweed on your land, you can be prosecuted if you allow it to spread into the wild.
2. It is not advised to remove Knotweed yourself unless you are an expert in the relevant field. There will be specialists available that will be able to provide the services to assist you and provide a guarantee for those works.
3. The distinguishing feature of Japanese Knotweed are its leaves, which are shovel shaped with a point at the tip and staggered on the stem. Look out for this if you are concerned you may have a Knotweed problem.
4. Act fast. As previously mentioned, Knotweed is a fast-growing perennial. To avoid the plant seeping into other adjoining property and incurring any legal action, it is essential that the Knotweed is removed in a timely manner.