How a Garden Menace Could Tie Your House Sale in Knots

Paul Hajek | 20 May 2017

Gardens sell houses.

No doubt about it.

It’s why most people put their houses on the market in the Spring and the Autumn. Allow the garden to look its best.

How much more appealing is a chameleon-like display of Japanese Acers to enhance your chances of selling your home? What about big structural Hydrangeas, also from Japan, make a pleasing back drop to your pride and joy.

But, there is one non-native species you really don’t want to be within miles of (literally): Fallopia Japonica.

You may have heard of the aforementioned Fallopia under a different name –Japanese Knotweed.

And if your garden ( or an unkempt neighbour’s garden) has the beastly weed your chances of a quick sale could be considerably diminished.

Welcome to Chapter 20 of our Series, your Conveyancing Questions Answered All in One PlaceJapanese Knotweed

Get Knotted

So what is Japanese Knotweed?

It’s over here, pretty much everywhere and it’s and here to stay. It first arrived in Britain in 1850 as an innocent shrub, but now you can find it in most areas (in fact, the Orkney Islands are the only area in the UK free from Japanese Knotweed). It has tall, dense stems, a heart shaped leaf, with a pointed end and is typically a lush green colour.

A record was set at the London Olympics in 2012 which you may not have heard about – it cost more than £70 million to clear the blight.

A cunning little so and so as well.

In the winter, it hibernates into its shriveled, bamboo-like stems with no sign of leafage.

But, in the summer it really comes alive – it can grow a staggering 4 inches every day, and the stems shoot to over 2.1m (7ft).

And don’t think that concrete and tarmac can win the day. They can’t.

Knotweed can even grow through the floorboards and into your home.

Japanese Knotweed costs an estimated £166 million a year to clear and control, and would take a conservative £1.25 billion to eradicate.

Rapacious Blighter

But how is it so ferocious? It spreads mainly when we move soil around to build roads and develop Brownfield sites, and just 0.7g of its rhizome (creeping underground stem) can generate a new infestation. Its rhizomes suck up the limited nutrients available, particularly in Japan, where it even survives in volcanic fumeroles. Here’s an astonishing timelapse of Japanese Knotweed, and the rate in which it grows.

We’ve already posted about its impact in the Conveyancing process as part of this series Your Conveyancing Questions Answered – All in One Place here as Japanese Knotweed is included in the Property Information Form, the form all sellers complete when selling their homes.

When you sell your property you’ll be asked if your property is affected by Japanese Knotweed, and whether there is a management plan in place (note: “management” – Japanese Knotweed is not eradicated overnight – it can take up to five years).  

The Knotty Problem

The presence of Japanese Knotweed may result in a sheer drop in the value of your home.

Some cases have reported a 50% decrease in their house value – just because there’s a presence of Japanese Knotweed.

For Robin Waistall, 70, the value of his property dropped from £130,000 to £70,000, once a surveyor found out Japanese Knotweed was present.

Others struggle to sell at all.

Treatment is costly.

Aside from chemical control, trials have undergone which introduces psyllids into a handful of selected Japanese Knotweed areas. They suck on the sap of the leaves, thus reducing its growth and keeping it under control.

Looking forward, the situation is only likely to get worse. Hybrids have already formed, and the fear is we will eventually end up with unimaginable amounts.

Whatsmore as a homeowner if you fail to control Japanese Knotweed you could face criminal prosecution and a fine of up to £2,500.

If there is evidence of it, or there is a history of it in the area, a specialist survey will be required. Lenders will demand a professional eradication plan and will most likely not lend until the homeowner promises to sort the problem out. 

What You Should Do

If you are buying – be on the alert for the weed. Not just in the garden but in the neighbourhood as well. Buying a house next door to a house which has succumbed to the Knotweed will put off future buyers of your house.

If you are selling you have it think ahead. You may need to reconsider (and it will take years) until it has been eradicated to avoid disappointment.

Culinary Disposal

We cannot recommend the following as we have not (no pun intended) tried this ourselves.

We came across a few recipes such as Japanese Knotweed on Oatcakes and Knotweed Fool.

You can also see some creative takes of Japanese Knotweed on Instagram, here and here.


A few years ago, Japanese Knotweed was little heard of.

Now you need to distinguish your Knautias from your Knotweed to avoid an extremely knotty problem, and a potential Conveyancing Nightmare.

Your Conveyancing Questions Answered – All In One Place




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