• This topic has 22 replies, 20 voices, and was last updated 2 years ago by JoeG.
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  • Horticulturists…have I got a japenese knotweed / neighbour problem?
  • Premier Icon tomd
    Full Member

    I was starting to clear up the abandoned corner of the garden and noticed an odd plant had sprung up next door and was coming through the fence. The main plant is about 2m high, red flecked reed like stems that zig zag. To me, it looks like knotweed but is there anything else that I could be mixing it up with? At the moment it’s a fairly isolated clump as far from the houses as can be.

    It’s growing from the neighbours side. He doesn’t have clue and suggested he’ll just chop it down (again) if it’s a problem when I spoke to him a few days ago. I told him not to, look it up and we’ll chat again in a week. To be fair, he’s not had the house that long and isn’t really a gardener.

    I gather it’s a bit difficult to get rid of properly. Has anyone had experience with it coming through from a neighbour? I understand it’s very much not allowed to let it spread to other people’s land. It’s already on my land and is going onto another neighbours as well (it’s a corner between 4 gardens).

    At the moment I’m thinking of giving him a month (with a few friendly nudges) to start doing something sensible about it before getting into the formal route. I’m not that inclined to faff about it with due to potential impact on mortgages and stuff like that.


    Premier Icon daddydave
    Full Member


    Looking at this website it does look like it is knotweed, they offer an identification from a picture but will no doubt then offer the eradication service as well.

    good luck

    Premier Icon Nomad
    Free Member

    Yes that is knotweed.

    Been treating some for 4 years now that has been coming in from the land behind my garden.

    Using a glyphosate weed killer but its nasty stuff.

    Premier Icon twicewithchips
    Free Member


    rhs: https://www.rhs.org.uk/advice/profile?pid=218

    I wouldn’t wait a month to start spraying your side.

    Premier Icon Nobeerinthefridge
    Free Member

    Nightmare Tom. As above, don’t wait, report it and seek advice.

    Premier Icon Mattbike
    Full Member

    Yes that’s knotweed. Legally your neighbour must not let it spread on to your property. Check out the environment agency web pages or natural resources Wales.

    You can treat it with glyphosate. As mentioned above

    Premier Icon yetidave
    Free Member

    Looks like JK.  The way I understand the law is that it is not allowed to be spread through action (digging it up and disposing of the waste, cutting it with a strimmer and/or disposing of live growth inappropriately etc.  But there is nothing in the law which prevents inaction.  (by doing nothing he is doing nothing wrong.)  Get spraying it, have a word with them.  Injection works really well if done at the right time of year (just before it starts dying back in the late summer.)  (this law thing may be a Scottish thing)

    Premier Icon cloudnine
    Full Member

    Looks like knotweed.. he can get into shit if it spreads onto your land..

    Handy link


    Premier Icon thepurist
    Full Member

    Maybe one to discuss over at the GardenLaw forum


    They know more about boundaries and neighbour problems than we do about riding bikes Audis, coffee machines and artisan trousers

    Premier Icon legend
    Free Member

    Some councils have a programme for getting rid of it, might be worth a call or two (because the first one will just be trying to find the right person)

    Premier Icon neilwheel
    Free Member

    Considering it’s prime growing season, waiting a month will be like shooting yourself in the foot.

    Premier Icon one_happy_hippy
    Free Member

    It’s a criminal offence to actively plant it / spread its growth as it’s a red list invasive species.

    It can cause serious foundation issues.

    It is also a nightmare to kill and even more of a nightmare to dispose of any cuttings as they have to be buried, preferable in a liner, a min of 5m down.

    If it’s not already in your garden (which the roots may well be) get a root barrier down asap and burn any soil you suspect of containing roots from the plant.

    I know if a few JK disposal companies if you want to PM me I can send you their details depending where in the country you are.

    Premier Icon one_happy_hippy
    Free Member

    Also this is one of the time the quote “nuke it from orbit, it’s the only way to be sure” is probably true.

    Premier Icon NZCol
    Free Member

    Had it on another site, waiting can be useful as when the stem is a bit thicker you can inject it and that definitely works a bit better long term. Does need managed though for sure.

    Premier Icon Houns
    Full Member

    I’m currently dealing with a single plant of JK at a relatives. What I’ve done is cut the stems at about 15cm above ground (and burnt the stuff I’ve cut off) and poured in the nastiest, strongest weed killer I could buy from a farm suppliers down the stem (they are like tubes) I’ve also totally covered the plant so it can’t get any light.

    I’ve been doing this for last 7 months and yet it’s still putting out new shoots, sadly I think it’s time to get professionals in (OHH I could do with those suggestions please)

    Premier Icon lovewookie
    Full Member

    If you’re up glasgow way, the company I work for treat invasive weeds, PM me.

    Premier Icon munrobiker
    Free Member

    Houns- we use Eco Control at work and they’re pretty good. They work nationwide.

    Eco Control Solutions

    Premier Icon miketually
    Full Member

    Our Surveyor’s report said we had that in the garden. Ten years later, I still haven’t seen any.

    Premier Icon imp999
    Free Member


    I did what you are doing. The weeds got smaller(Bonzai’d?) each year. Took about 3 yrs to kill.

    Premier Icon perchypanther
    Free Member

    I had one plant growing up between our garden and our neighbours.

    A bottle of Roundup Ultra concentrate applied , undiluted , to each leaf with a paintbrush and leaving it for a couple of weeks before cutting it back were , seemingly, enough to kill it.

    That was 6 or 7 years ago and no sign of regrowth

    Premier Icon djglover
    Free Member

    I treated some with glyphosate in a previous house.  it took 4 years to extinguish.  I treated shoots in my neighbours garden (without asking) and in the alley behind the property.

    Premier Icon tomd
    Full Member

    Thanks for all the input. It sounds like I need to get cracking on this stuff. I’ve checked with Trump and he wasn’t up for nuking the North East from orbit this week so that’s off the  table.

    Premier Icon JoeG
    Full Member

    Most effective time to treat is late summer:


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