Selling a house with knotweed

How to get rid of knotweed

Japanese knotweed can cause all sorts of problems to the structure of a property. It can take up to four seasons to get rid of knotweed with a normal store-bought weed killer, however a licensed professional may have access to a stronger weed killer that can reduce this period by half. For home-gardeners, a good weed killer to use is one that is glyphosate based such as Roundup Tree Stump and Root Killer. Knotweed treated with a killer of this kind will often regrow in the form of a 50-90cm small leafy bush the following spring – it is essential that the regrowth is treated. 

Removing Knotweed –

Step 1 – cut the weeds as close to the ground as possible. 

Step 2  – apply weed killer as soon as the canes have been cut. 

Step 3 – 7 days after applying the weedkiller, then pull the weeds. 

Step 4 – mow the plants down weekly. 

Step 5 – reapply the weedkiller twice a year, once in late spring/early summer and again in early autumn. 

You need to ensure that the weed is being disposed of in the correct way – you must arrange for a registered carrier to transport the knotweed to a registered landfill site as the weeds cannot just be disposed of in normal bins in bin bags. Do an internet search to find the rules regarding knotweed disposal in your area. 

If you are looking to sell your property it is important to note that a home gardener will not have an insurance backed guarantee without using a professional company to control the knotweed. This is also important if your neighbour is threatening litigation from the spread of knotweed from your property. 

How to sell a house with knotweed

A property with a knotweed problem will not be able to obtain a mortgage. Selling a house with Japanese knotweed can be a nearly impossible process, as the plant is so destructive to the structure of a house and can take up to 5 years to properly treat – even then there’s no guarantee that it won’t come back. Only a cash house buyer is in a position to enable you to sell a house that’s affected because it will require years of constant treatment before the property is mortgage-able again and can be sold normally on the open market. Having no choice but to sell to a cash buyer will usually result in selling at a reduced price. This could be anywhere between 10% and 20% lower than market value.


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Bobby Turner

Market research, writer & property specilaist for Zoom Property Buyer. Over 10 years in property sector. Previously at WhatHouse?