Helpful Tips

Stay vigilant over Knotweed threat

Sally Walmsley
Written by Sally Walmsley

With the nightmare tale of a family unable to sell their home due to Japanese Knotweed hitting the headlines this week, we are reminding members to be vigilant.

According to reports a family in the Midlands are unable to sell their property due to an extensive outbreak in a neighbour’s garden – with potential buyers warned by surveyors and shunned by mortgage lenders over fears the roots of the giant weed could interfere with the foundations of the home.

As landlords it is vital that you know how to spot knotweed – and that you get rid of it as soon as you do. Also to keep an eye on neighbours’ gardens as the bamboo-like weed, which can have roots of up to 3 metres can spread extremely easily. Catching it early can help minimise the costs and means that you will be in a position to sell your rental property if and when you want to.

When checking whether a plant is knotweed look for:

  • fleshy red tinged shoots when it first breaks through the ground
  • large, heart or spade-shaped green leaves
  • leaves arranged in a zig-zag pattern along the stem
  • a hollow stem, like bamboo
  • dense clumps that can be several metres deep
  • clusters of cream flowers towards the end of July that attract bees

For help identifying Japanese Knotweed, you can view the below video from Youtube:

About the author

Sally Walmsley

Sally Walmsley

Sally Walmsley is the Magazine and Digital Editor for the NRLA. With 20 years’ experience writing for regional and national newspapers and magazines she is responsible for editing our members' magazine 'Property', producing our articles for our news site, the weekly and monthly bulletins and editorial content for our media partners.


  • Knotweed is also very difficult to kill off, but not impossible. You can buy from Wilko’s super strength glyphosate (360 g/l). Spray some leaves with this and on other stems cut them close to ground level, get something like a chopstick and push it down. When you meet some resistance, push it a little further and this opens a valve in the stem. Pull out the chopstick and pour glyphosate into the stem. It will take the poison down into the root stock. Spray leaves in spring as they come up and do a mixture of some leaves and stem in early autumn as it takes nutrients back down. It will take 3 years to make a significant killing. Never take cuttings off site. Burn them. Wear gloves when handling chemicals.

  • Mortgage companies typically look for accredited contractors to manage knotweed with works supported by a 10 year insurance backed guarantee. The Property Care Association has a search engine so you can find an accredited JK surveyor to advise you on the impact to your property.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.