Spring is here and everyone’s greenery is starting to, well, green. Unfortunately for some, their green stuff may include the dreaded Japanese knotweed – Fallopia japonica. This pestilent plant is dormant over winter, but come April it suddenly springs (sorry) into action, strangling other plants and possibly even hampering your chances of a mortgage.
Yes, really. This plant can grow a foot a week and mortgage lenders really don’t like it because its invasive and incredibly tenacious roots can damage foundations, drainage systems and walls.
What to do if you find knotweed in your garden
First of all, you should take photos and send them to a weed control company. If it’s not knotweed, you can stand down. If it is, then you need to get a professional in for a survey to see how bad the invasion is and whether or not you can deal with it yourself or if more drastic action is needed.
Japanese knotweed has a lime-green bamboo-looking stem, heart-shaped leaves and large, trumpet-like white to cream flowers in the summer. The plant was introduced from Japan as an ornamental in 1825, but its habit of sending out underground shoots hasn’t endeared it to its new home. While you can grow it if you want, you can’t allow it to have any detrimental effects on your neighbours’ gardens or let it grow wild.
Mortgage lenders call in the reaperman
Most mortgage providers blanch if they see Japanese knotweed on a survey and will demand a strict eradication programme before they even think about offering a mortgage. Many also demand expert removal with a guarantee that the plant won’t return for at least ten years. Some will agree to a mortgage but with the proviso that money (usually £3,000 or so) is set aside in a separate account for the eradication programme.
I can’t afford several thousand pounds!
Spring is a good time to look for knotweed, but June and July are the best months to treat it because this is when the plant is at its greediest and will absorb more of the weedkilling compounds. If you’re treating it yourself, a glyphosate-based solution is best; the stronger the better.
You should cut out every tendril and smaller stem that you find until you hit the main stem. Leave around eight-to-ten inches of this hollow stem above ground and fill it with your weedkiller. You may have to repeat this the following year, or at the very least give your buyers enough weedkiller to do it themselves.