Japanese Knotweed

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  • Japanese Knotweed
  • Markie

    There is no painless way of removing it. If you get it on your property it will become your responsibility. Stay away. IMO.


    The above thread covers it!


    Are there any relatively painless (to me) ways of removing the stuff?

    No. It’s a big bloody nightmare and the root systems have been known to cause rapid and significant damage to building foundations; hence:

    Is the surveyor right about mortgage companies not lending if Japanese Knotweed is flagged in the home report?

    Try a web search.

    As said: stay away.


    think asbestos crossed with nuclear waste..total pita to sort out..


    Don’t buy, i run a grounds maintenance business and have a pesticide license, i wouldn’t go anywhere near it.

    If you do need to sort it inject the stems with this:



    Wow, thanks for the replies. I think I’ll stay far away from it. One thing to own a property and discover it, another to walk into a deal knowing about it.

    Thanks for the other thread link.

    Premier Icon Shackleton

    Not a lot you can do to kill it in the short term. It is resistant to most herbicides that you will have access to, will regenerate from tiny fragments and stays in the soil seed bank for years.

    If you do decide to go with it and want advice on how to get rid of it feel free to contact me. But personally I’d run.

    Premier Icon stumpyjon

    It can be controlled with liberal usage of weed killer over time, if you can clear the whole infestation. If it’s coming in from else where you’re knackered. trouble is it grows so fast, a foot a week at peak, it’ll suck the ground dry which is what causes subsidence issues (same thing works for trees, people assume it’s the roots themselves causing the problems, it’s not it’s the rapid dehydration on the ground).

    The railway people should sort it (I used to be involved with weed control on the railways in the dim and distant past) but you could wait a while before it gets sorted. Really depends how much you like the house and whether your mortage company will lend.


    Quite common on river banks and train sidings, I know at least two people have it growing in their gardens and seem to think its a normal garden plant!

    A friend at work has just found out the funny weed from her neighbours garden that is breaking up her patio is the same stuff!

    Neighbour could not care less, council now getting involved, but sounds like a nightmare!

    I would carry on looking somewhere else tbh


    As all above, really don’t touch the property. Lots of stories of people getting it in the garden, then it effectively destroying their houses structural integrity and even growing through, into the house. Property value then becomes practically zero hence why mortgage companies won’t lend.
    It’s an arse to lose the survey costs, but a lot worse to lose the house value!

    Premier Icon BoardinBob

    Out of curiosity, whereabouts in Scotland?

    (panics as he lives next to a railway track with property for sale in my street!)

    Premier Icon NewRetroTom

    This is my mate’s company – based in Scotland. Give them a shout and they’ll be able to give you an idea how much it will cost to sort out.Japanese Knotweed Agency


    Anyone know anything about this stuff? I am going to view a house soon but Japanese Knotweed has been flagged in the home report (Scotland). The surveyor has advised:

    “The property has been constructed adjacent to a railway track. There appears to be a growth of Japanese
    Knotweed in the adjacent plot. A number of lending institutions will be unwilling to provide mortgage funding on a
    property with Japanese Knotweed in the vicinity of the mortgage security.”

    The bit that worries me is that the Knotweed may be originating from a plot of land that I would not have control over.

    Is the surveyor right about mortgage companies not lending if Japanese Knotweed is flagged in the home report?

    Are there any relatively painless (to me) ways of removing the stuff?

    Premier Icon cb

    There is even a programme of introducing a bug into the UK to deal with it.

    Is the plot that is referred to owned by Network Rail?


    Bad stuff, almost impossible to get rid off completely and if is more than capable of pushing its way through bricks and mortar and can in extreme cases weaken your property foundations. STAY WELL CLEAR


    its a lovely thing, so clever and manipulative, you will have a job killing it, its roots go down for a long way it turns corners, and knots itself round stuff, worked in a garden with it, dug alot of it out one week a few weeks latter it was back, worse.

    Its just such a pity a good use cant be found for it.

    As for the house avoid buying it at all costs.

    Premier Icon speaker2animals

    I went to Quarry Bank Mill on Saturday and all over the gardens are notices apologising for areas being closed while being developed. The big problem being Japanese and another type of Knotweed. A lot of the signs said that digging out is ineffective and the only way forward is repeated spraying with an approved herbicide.


    I have it encroaching on my property. I have been treating it with glyphosate for the past two growing seasons. It is growing in waste land across the lane from my garden. Lots of spraying has been very effective. Just two shoots so far this year, already dosed. I just climb the fence, spray the stuff and revisit regularly. Railtrack might not be so understanding though. Good luck.

    jonah tonto

    the stuff can grow from a cutting, in de-oxygenated water, excluding all light! no hope of fighting that.


    On NWR owned property i.e. within the boundary fence the official line is not to touch it unless it encroaches on the infrastructure.

    Walk away as they won’t be doing anything about it soon.

    Premier Icon muddy@rseguy

    Nuke the site from orbit.
    It’s the only way to be sure…. 😉


    Countzero that wouldn’t kill it as the root system has been known to go down at least 6 feet.

    Got a company dealing with knotweed in the garden of a house we/re trying to sell. It’s costing us 5 grand. A bloody nightmare!!!!!

    People throw their hands up in horror at the mention of JK just like they do with asbestos.

    Its a perfectly manageable plant if you understand its lifecycle and have the time. Theres no cheap quick fix.

    Digging out will take alot of effort and be costly, but will be quick. You’d need very good validation procedures on the face of the excavation to ensure that you’ve captured it all.

    Cutting can manage it too, but only by hand, since strimming will throw small parts of the plant away from the worked area and it will re-establish itself over a wider area.

    Sprayed twice a year in its growing season, with the correct commercial herbicide, properly applied will see it gone in a single growing season, but domestically, you won’t be able to get anything of that power. There are any number of techniques for commercial herbicide treatment, including injection and cutting then filling the stumps.

    Domestically available, reasonable strength glyphosate mixes, used twice/three times through the growing season will usually see it gone in two too three years, but you may need to be vigilant for 4 or five years.

    How well you apply your herbicide and and the correct times is the key.

    The key is to exhaust the rhizomes energy supply, or to get enough herbicide into the rhizome for direct toxic action.

    You may be able to keep it off your land, but your difficulty will be getting it eradicated from the rail land, and this may be a loosing battle.

    Personally, I’d avoid, but I don’t know the specifics.


    My wife showed me a link yesterday about a house that is being destroyed due to Japanese knotweed.

    There’s a few if you do a quick search…houses dropping in value from £300,000 to £50,000 etc.

    You shouldn’t even be considering this house as an option, although saying that, if you buy it I’m sure the current owners will feel incredible relief that they’ve got rid of it. So you’ll be making them feel good.


    The stuff Flip linked to is £318 a pop, jeez that must be agent orange, do you need licences to buy that stuff as you could do serious harm to a water course with that kit.

    Good luck to the OP, it sounds horrendous stuff.


    It was me that started that first thread.

    Yes some mortgage companies won’t lend (abbey for one). We had to get the vendor to signup for treatment (prepaid at about £5k over 4 years – 3 sprays first year, 3 checks + spray if required per year over the next 3). Halifax does lend if correct treatment plan is in place. The treatment is also killing the good plants in the same area as well.

    The soil is now ‘contaminated’ and needs a special licence to get rid of. Once the treatment is complete then the soil is ok again.

    We’ve now got the house and after a year it doesn’t seem to have come back yet (reminds me – I must go and check)

    pm me if you need more info and I can also give you names/companies that sorted/sorting ours out.


    Fairly sure we’ve got a small amount creeping into the bottom of our garden. Very worried now, until today I had no idea what an issue it is. 🙁


    I think it is a civil offence to let it leave your property – if that’s any help


    cheers, i’ve just been reading up on it. the problem is that the garden adjacent is owned by the other leaseholder with whom we jointly own the freehold of the house/whole plot so it’s arguable we’ll have to treat it together. i’ll have to get down the garden tonight and work out exactly where it all is. there are a few gardens down there that all border each other so sounds like it could be something of a nightmare if it’s in a load of them… 🙁


    I didn’t know about it until my better half fell in love with a house that had it in the garden.

    Don’t try and dig it up – it will make the problem 1000 times worse, carefully cut the stems off and let the cut off stems dry out, pour round up down the centre of the stem that’s still in the ground.

    Premier Icon yoshimi

    AVOID AVOID AVOID AVOID AVOID!!!!!!!!!!!!!!!!!!!!!!


    As people have said pouring very very strong weedkiller into the stem of the thick ones is the best bet. My neighbour has this and it was brought up on my house inspection 2 1/2 years ago. No problems with halifax giving me a mortage. I guess because its not in my garden. Some of it has of course encroached but i have a cheeky fence panel that opens so i can check on the otehr guys garden (its huge and weirdly shaped so he’ll never seeme, oh and hes about 120 years old.)

    I’ve found that if you want to kill the smaller stems off when they first start growing a little bit of white spirit will kill it in about 4 hours. I have no idea how effective it is below the surface but I seem to be winning the war slowly…

    JK is a serious thing. So much so it is a criminal offence to handle it incorrectly or NOT treat it if its on your property. The damage it does is insane and yes it really does grow a foot in a week as per the above post. In fact in last years hot rain showers i’m sure some of my neighborus grew more than that. probably 18 inches plus shoots from the side and big big leaves. Crazystuff.

    edit: as you cant control whats on the railway embankment i wouldnt even bother going near the property.

    Hi everyone,

    I realise that I am late to the discussion but I thought I’d throw in my thoughts as it might help some people out down the line.

    I run a Japanese knotweed eradication company and I have an extensive knowledge of treatment of the plant. I would not be put off a property because Japanese knotweed happens to be within the vicinity. Over the past 6 years of working in this industry, I have encountered very few cases where Japanese knotweed has caused structural damage. A quick google search on the weed will take you to loads of websites packed full of scaremongering as well as media reports of huge costs or devaluation of property. Most of it is total nonsense.

    Japanese knotweed can spread quickly and it can be difficult to eradicate if you do not know what you are doing and these factors perpetuate the myth that it’s invincible (I’ve actually had engineers telling me that it is impossible to kill…).

    It is not an offence to have Japanese knotweed on your land. In fact, there’s nothing to stop you planting it within your own property boundary. Legal issues may arise if it starts to spread from your property on to neighbouring land. Also, there are laws to discourage people from spreading it in the wild or disposing of it incorrectly.

    Should you encounter Japanese knotweed, I urge you to get in touch before attempting to treat it yourself. I am happy to advise people on the best treatment method for their site. If treated incorrectly then it may make it more difficult to eradicate which will put up the cost of professional assistance, should you require it down the line. Few mortgage lenders will be happy to find that the Japanese knotweed is not being treated professionally. Incorrect treatment may be against the law. I read a suggestion that Tordon 22k is used to stem inject. Stem injection of Tordon is illegal- very few products are licensed for injection.

    My friend Tom has already posted a link to my site so I won’t post it again for fear of spamming this forum. Check out our identification pages and video as well as the blog for further information on the subject.

    Before I go, perhaps a more worrying weed for cyclists is Giant hogweed (Heracleum mantegazzianum). If you don’t know about it then you need to find out. Accidentally brushing past it could lead to severe chemical burns. More info can be found on my site (japaneseknotweed dot com).



    And what are your thoughts on the HT vs FS argument?


    Is this house in Perth by any chance.

    If so, there are many more scary things a lurking.



    Thanks for your input, experience and sense. Can you comment on biological control? Is it authorised yet?

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