Nightmare Weeds

If a plant can colonise the flanks of a volcano it sure is going to love growing in an average back garden or near a gentle stream. For a plant to shove its root into just-cooled magma then, let's face it, a clay soil or tarmac drive is going to be a cinch. A plant that creates such havoc and terror surely deserves its own tracking-app. Japanese knotweed is that plant.

Now I’m lucky in that the worse weed I have to endure is bindweed. Or maybe the ground elder that pops up in a border and one corner of the lawn. Or actually it could be the ever-present bittercress - but that’s my fault because it flowers and sets seeds before I get to it, reinforcing the ‘one year seed = seven years weed’ gardening saying. Japanese knotweed is at the moment miles away. Actually, five miles away. But how do I know? Do I scour the local vicinity looking for it? No. I now take an almost sadistic line of checking the reported sightings and recording of the weed on a new website. But it is fundamentally flawed.

Let’s work it all through. You spot Japanese knotweed at the end of your garden. You log onto a site, record its appearance and up pops the red dot showing your sighting. Great stuff, but consider this. Does everyone really want to record this invasive weed as being close to their homes. I would suggest not as it can cause lending banks to have heart palpitations and stop lending. Buyers turn their heels and run at the thought of inheriting it in a garden. The only people who benefit from the appearance of it are the Japanese knotweed eradicators. I bet they watch the red dots appearing like acne on a teenager’s nose with unabated glee.

So, what do you do if you find old JK in the garden?

Firstly, stay calm. OK, it can grow 15cm a day in summer and romp under your lounge floor spitting up under your telly or alarming the dog snoozing in its bed - but calm you must stay. You must, however, sort it. I hate to say it but digging it out is not really practical or effective. Some gardeners have told me that vinegar works on it. Really? Keep that for your chips. Others say that total weed killer is the best but think twice about throwing around chemicals in the garden. It might not even work. This stuff is well hard. Call a professional in. It is expensive but so is the remedy - removing metres of soil, injecting the weed stems with industrial strength glyphosate and generally crunching around in a biohazard suit (I imagine they crunch - my cheap overalls for decorating certainly do).

And then maybe get your details on the PlantTracker website (all Environmental and Heritage Agency information stuff) to warn others. There’s a good citizen. But just because you are the only red dot in your surrounding neighbourhood doesn't mean you are the only garden with that particular weed. There may be others who are shyer in admitting they have that weed. They may be the ones trying to sell a house at the moment. The only way is to be vigilant.

Japanese knotweed

  • Those lovely Victorians did so much for us, but they did introduce the weed into the countryside to stabilise railway banks
  • JK is a monster. It can penetrate concrete and takeover gardens