Hi, encouraged by @SamClaus, here is a topic to discuss gardening.

We bought an house with a big garden 5 years ago - old detached house on 1000m2. After a good 3 years ago we discovered the infamous Japanese Knotweed. Since it was in our fullgrown hedge, there was only the option to consequently pull the knotweed out. On 1 of the 3 places, it has not returned this year (yet - touch wood).


Anyhow … this topic is for questions regarding gardening - feel free to post your questions & suggestions. I’ll drop a question every now and then - I have no ‘green finges’, really need advice for my gardening endeavour!

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Oh dear, that is really, really bad news, if it is Japanese knotweed.

Do your neighbours have it? If nor, and they get it by it spreading from your property, you might be liable for their costs. The other way round: if your neighbours had it already and not you, and has spread to your property, you may be able to claim against them.

As someone else observed in the other thread, I believe it is a notifiable pest in UK meaning you are legally obliged to inform the responsible authority (Possibly the local authority). Your neighbours likewise if they had become aware they had it). You have to notify of its presence if selling a property.

The first thing needed is confirmation that is what it is. This tool may help:

I Looking at that reference myself, it might not be as the stems in that reference are red, yours aren’t. I suggest researching range of sources.

If confirmed it would then be highly advisable to seek expert help: it is incredibly hard to eradicate, and if not done effectively it can spread (underground), travel to your neighbours if not already - and cause structural damage to buildings. It may be worth seeing whether it is covered by your home insurance.


It’s easy to be intimidated by Japanese Knotweed, but as long as you have access to it from all sides, you can, like any invasive plant, eliminate it easily enough as long as you are persistent. People seem to think that a single application of weedkiller should do it, but although it can help, it’s always going to take several attempts. Likewise, vigilant removal of any visible foliage will kill any plant sooner or later.


Thats the approach I use. On one spot it has not appeared again this year, on one spot it is definitely present, but I check it every night and remove it thoroughly. I think it is weaker than last year and it has not spread further.

I think it is caused by the local government. They maintain the roadsides and further down the road there is a significant presence of the knotweed. The hillbillies doing the work on their mowers don’t seem to care and spread it everywhere. I have informed the local government a few times and asked for their policies, but no response.

The good thing is that is seems to be a good weed to brew beer from. Maybe I do that and publish in the local newspaper. That will work for sure :slight_smile:


This link gives a lot more, and authoritative, info including more definitive info re UK legislation.

Again, from the one picture you’ve posted it might not be JK because there is no visible red on the stems.

On other gardening matters, one thing we try to do is grow enough vegetables for our own needs. Over the summer months - and normally achieve it apart from buying other things for greater variety. Unfortunately where we live is a cool, damp and windy place, so we can’t so readily grow what some others can, and the season is shorter than some.

At present more pak choi than we can keep up with (lovely vegetable), a dependable staple (as are runner beans). Last year was an odd bumper one for cucumbers - from just two plants we had several weeks eating cucumber several times - as a main, cooked veg (it’s amazing how versatile it can be if you have a glut, the year before kast had an unbelievable bumper crop of tomatoes (greenhouse) - and honey!

It becomes quite a time consuming operation from spring through to autumn keeping on top of the garden - vegetable patch and a moderately large lawn, plus flower beds etc: the weeds always win!

Rather than just pulling the knotweed out - which will have little or no effect on root spread (the bit that causes all the damage) - I’d paint any leaves you find with a systemic weedkiller. This will weaken the plant and may eventually kill it, but it’s a process that takes years to achieve.

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There you go, IB.

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Removing foliage will kill any plant sooner or later, even Japanese Knotweed. As long as the affected area is accessible, this would be my method of choice in your own garden where you are in a position to keep a close eye on it. Without leaves to photosynthesise, no plant can survive.
Weedkillers are a last resort in my books. They are very nasty chemicals, despite what their manufacturers would have you believe. Unless there is a large amount of foliage, instead of spraying, I would cut the stems, dispose of them, and inject the hollow cut ends with a syringe. This can be more effective than spraying, and it’s easier to avoid contaminating other plants, although there is still the concern of harmful residues left in the soil.


This is the approach I have taken in our garden. Previous owners had planted Ivy and Russian Vine so even strong plants like Buddleja and Fatsia Japonica were being overwhelmed. Fortunately I was able to yank out all the Russian Vine, and eliminated any Ivy by just pulling it out. I did not want to nuke it with weedkiller so have gone for the no photosynthesis =death route.

But if the knotweed still has a stem with leaves that can’t be reached it will keep the plant alive no matter how much foliage you remove elsewhere. Pulling leaves from knotweed is a bit like throwing pebbles at a gorilla - you might get lucky, but probably not :grimacing:
Being an organic grower (I’m not a gardener!) I’m with you on chemical use, but sometimes you have to throw everything you can at something and this is one of those times.

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Wild garlic identified…

The things I have read recommend a multiplex approach because it is so difficult to eradicate, and specialist intervention if extensive. One of the most effective approaches is supposed to be covering the entire affected area with tarpaulins, and periodically crushing growth as it happens underneath - and that may have to be in place for several years. Unfortunately that is not always practicable, although in a garden you could put planters on top, presumably then being vigilant lest the weed breaks through into the planter.

I’ve been able to remove both Knotweed and Himalayan Balsam in the past without resorting to weedkiller, but in some circumstances I would probably give in and use chemicals. What works for me is Ammonium Sulphamate, which used to be sold as RootOut, and was a highly effective weedkiller that could be shown to break down into harmless, or even beneficial chemicals in the soil. Although still available, it is no longer licansed as a herbicide, unlike the ubiquitous Glyphosate which has been overused for far too long.

Mulching with a plastic sheet can be effective. Obviously it looks awful, and will be impractical in some situations. I’ve seen Himslayan Balsam break through heavy plastic sheeting in the past, which is perhaps not surprising given that it can force its way through Tarmac roads and masonry. Still, it has its place in your arsenal.

It’s like cancer - catch it early and the chances are it can be eradicated without resorting to drastic measures, but let it get established and you’re in a world of trouble. There’s a building site for multiple houses a few miles from me and it’s been fenced off for the past 5 years while it undergoes knotweed removal. Word is it may be another 5 years before it can safely be built on and yet none of the knotweed can be seen anywhere above ground.

Obviously I have only the two photos you’ve posted to go on whereas you have it in the flesh, but from those two pics it still doesn’t look like the Japanese Knotweed I’ve seen, nor the pictures I’ve seen online: From the limited angle of the pics you’ve posted I can’t really tell if the bases of the leaves are flat (straight), nor can I see for certain if the tips are symmetrical, nor a clear ziz-zag of the stem, while the red appears different. I am not saying it isn’t JK, but it I suggest it may bear more detailed scrutiny if you haven’t already.

I’ve now found the resource I was looking for yesterday:

(No) worries, IB, it is JK. I know how it looks when it is small, or full grown. Google Amersfoort and Japanse Duizendknoop and you know how I know that it really is JK.

Any tips for controlling this particular weed? Think its horsetail or mares tail. Its taking over our borders and even grows through our gravel drive (which has a hardcore base).

Another tricky devil … keep pulling it up - if you have the stamina and perseverance.
I’m not a believer in herbicides but I might be tempted …