Buying or Selling Know Your Japanese Knotweed

Japanese Knotweed can wreak havoc with your chances of either selling or buying a home. This plant has become the scourge of home owners throughout Britain. It can drastically reduce the price if you are selling, and make it difficult to get a mortgage if you are buying. It’s a problem that can be overcome if treated and successfully eradicated, but Japanese Knotweed is not to be taken lightly!

It spreads easily and quickly and the plant doesn’t even need to be in your garden to be a problem. It’s sometimes enough for the price to drop or for lenders not to lend if it’s in next door’s garden or any waste land backing on to the property. It’s often found growing wildly on untended railway banks, sidings and disused properties and it keeps growing year on year.


The Victorians found it so beautiful on their trips to The East that they wanted it brought back so they could continue to enjoy its beauty here. By the mid-1880s, it had become very well established before anyone realised what a disastrous decision that had been. It’s not only a menace in itself, but it also starts to strangle other plants in the garden if left to its own devices.


The first thing to do is to inspect your garden and surrounding areas. Spring is the best time, because the plant lies dormant throughout the winter and starts to come to life in the spring. By summer it will be too late because by then it could have reached a height of over 2m (7ft), as it can grow at the rate of 30cm (one foot) a week. If in doubt, take photos and get advice!

In spring you can recognise it by its lime-green bamboo-like stems speckled with purple and red. The sprouts have a reddish tinge before becoming lime-green, which later produce clusters of white or cream flowers.

If you’re selling, it’s unlikely that you won’t have noticed it, but you might have thought, as the Victorians did, that it’s a pretty plant and not something that could change your life quite drastically. That might sound a bit dramatic, but the consequences of having Japanese Knotweed on your property is a serious matter.

The roots can penetrate as deeply as 3m (10ft) and they also grow outwards. Significant damage can be done to the foundations, the drainage systems and walls of any nearby buildings.


This might be a good time to mention that concealing the fact that it’s present on your property is illegal and punishable by an ASBO or a fine, which could be thousands of pounds.

Failing to control Japanese Knotweed, or trying to conceal it, is false economy. If left to grow, you will quickly have a dense infestation, and by the time it is detected it could be near the house. In one extreme case, the home owners had to pay £18,000 for excavation, treatment and the removal of 60 tonnes (59 Imperial tons) of contaminated soil. So you can see, the financial and legal implications are something to think about.

When buying or selling, check for Japanese Knotweed on or near the property, although your surveyor will include any findings in the RICS (Royal Institution of Chartered Surveyors) survey report.

Start treatment as soon as possible, and be sure to get the documentation from an approved Japanese Knotweed professional, as this will prove that the remedial work has been done by an eradication specialist. It is transferable when buying or selling a property and will be vital if you need a mortgage.

Get a survey done now so that any Japanese Knotweed can be found, treated and eradicated leaving you with your dream home. Call for advice on 07973 302088.

Tags: Japanese Knotweed, buying, selling, mortgage, spring, home owners, survey, surveyor, Property Care Association, Royal Institution of Chartered Surveyors