New house has Japanese knotweed

[Ann3216]

Bought the house in November. Gardener showed me a growth and told me it’s Japanese knotweed. He’s come before and not seen it so must be new growth. Any experience or advice very much appreciated. I’ve been watching some horror stories on YouTube about the savage it can do,

It should have red stems as it says on google

I had jk in my old house. Paid specialist removers about 750 to get rid and provide a guarantee. They came a couple of times a year for two years to spray and check and was no sign when I sold with the guarantee. Caused no problem other than the pretty hefty fee to sort.

Your vendor should have declared it. How far from the building? It can’t just sprout up as it is not dispersed with seeds. I would go and tell neighbour also, you will need to tackle together. I would also contact the solicitor who dealt with the purchase

What kind of compensation did you get if you spent 1000s on the legal action?

It's really not a big deal. We had some in our last house. We left it alone for a few years, then got a specialist company in to deal with it, which came with an insurance policy. We deliberately used a local company to us but one that usually dealt with huge contacts of the stuff. When I say local, I mean 2 streets over local - it meant we paid them very little as they'd do as a first thing in the morning/ last thing before heading back to the depot job. Worked well. Easily dealt with and cost about £400 including the insurance back up.

What is on the other side of the fence. If your knotweed spreads, you are liable. But also if a neighbouring house has a garden full of it and been negligent - they are liable. I agree with many posters. Don’t chop or hack at it. Glyphosate it. Repeatedly. For years.

My DS had JK in his garden. He gets a specialist to treat it. It’s a long term programme, they come a few times a year and treat it as necessary. It’s all documented for when he comes to sell the house eventually.

There’s a road on the other side of the fence. Like a private road. I haven’t noticed any when I’ve walked but haven’t walked for a few weeks there. I’ll go and check it out in the morning

This was an interesting recent read - a new plant can spread from a sliver of rhizome (the root part) that is as big as a fingernail clipping.

That's why people say not to dig/cut it - if pieces fall off then you'd actually be starting new plants with each fragment.

Sorry if this seems like a horror thing, just to be aware!
https://www.theguardian.com/environment/2023/may/16/the-war-on-japanese-knotweed

In your shoes I'd be contacting the solicitors who acted for you with the purchase to get their advice on next steps in terms of whether the sellers knew or are liable to compensate you.

Then get a specialist to glyphosphate the bejeezus out of it - as many times as needed over however many years - and document everything so that you have evidence of treatment for your future buyers.

Wish you all good luck.

Don't spray it yet!! Timing of the spraying is crucial for eradication.
Let it put on as much growth as possible and hopefully flower. Spray around end of August when it will have plenty of foliage to take as much weedkiller as possible down to the root.
I bought a house with a professional treatment program in place and that's what they did. They used Glyphosate but I don't think you can buy that anymore so I'm not sure how successful your treatment will be but certainly worth a try for this season. If it grows again in April next year you could do the same again, it often takes more than 1 season to get rid of it or you may decide to get a professional in.
Don't try and dig it up or disturb the soil in that area or you can set it off again.
We were given a guarantee at the end of the treatment. One of the conditions was that we didn't disturb the soil.
As it is near the fence you should inform your neighbour. It may have come from them

I’ve just seen this advertised from Amazon:

DONT put it in your bin - if your caught your in the poo!
Like upto £5000 fine / 2 years in prison poo.

I’ve been reading horror stories online I’m so worried. Should I tell my neighbours?

An ex of mine had it and yep he used round up over and again seemed to knock it on the head but it took about three years (that's essentially all most professional services are doing unless they excavate and bury). I heard a program on the radio about gardeners not touching it as it can carry on tools and boots etc so don't faff with it too much and I agree let it get bigger before poisoning it and definitely tell the neighbours. No point you tackling it and them having a lovely bush of it on the other side of the fence.

I can well understand you being frightened by what you read online but a lot of that is old stuff when it got exaggerated out of all proportion.
It is not a triffid. Just needs careful management.
Your weedkiller looks OK. Don't use it yet though and don't be tempted to make it up stronger than the directions as that actually makes it less affective.

Yes that’s Japanese knotweed. Classic zig zag stems and heart shaped leaves.

Ask your gardener if he treats it (I’d assume no) if not call in a specialist. It’s very treatable but requires someone who know what they are doing.

Id also call your solicitor as the previous owners should have declared it. That is not new growth - that has bee. That has been there for several seasons. It doesn’t spread that fast.

If it’s not glyphosate don’t bother.

Does this work on bamboo also. That's just as horrific and invasive

Don't spray it yet !! It's not the right time od year it'll kill it this year but it'll grow back. You need to wait.

You need this stuff. Not cheap but very good. We had the same and discovered JK hidden behind 2 sheds. We bought in March so it didn't appear til a few weeks later.

Do NOT dig, you'll spread it. We treated it really aggressively year 1, when it regrew/got new shoots we sprayed it when shoots got to about 1 and a half foot and leaves were open, same year 2, about 3 or 4 sprayings, we didn't let it grow big enough to flower to take hold again. We are now on year 3 and I've only had 3 or 4 shoots which ive sprayed once the leaves have unfurled at less than a foot high, but the neighbour isn't treating it particularly well on his side (though he does let me lean over and spray).

Oh and to add, I've got enough from that 5l tub for next year aswell cos you dilute it, so although it's expensive to start, that will be 4 years worth of treatment. If I get any next year, very little this year. And I sprayed whenever shoots appeared through the summer, rather than wait for a specific time frame.

I'd use SBK hardwood killer, then cover it with a plastic bag to keep the rain off.

Not heard of SBK. Where can I get from?

Amazon or Ebay. I like the brushwood killer because it kills right down to the roots while being environmentally friendly - its a plant hormone, so its not soil persistent, and they can't develop an immunity to it.

I'm pretty sure OP isnt going to eat it so no worries about it ending up in poo.