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Sep 10, 2012 09:02 AM

Japanese Knotweed in Toronto

Hi All,

I've just identified the "fake bamboo" in our garden as Japanese Knotweed. It's growing at the base of a massive oak tree and along a path where the drains are.

In the UK where I'm from it's a huge problem, and there are very strict regulations about disposing of it when you cut it down in case you inadvertantely spread it even more, and I think it might even be a criminal offense to cause it to grow in a new location. A few Google searches suggest it's not regarded as as much of a problem here in Toronto and that there isn't a special way to dispose of it. Does anyone know anything more about this?

I'm going to have a go at removing it, even though my landlord likes it (I think he likes having a house with solid foundations more!). Any tips for what I know is a nearly impossible job? I've read that spraying the leaves with Roundup in early autumn, then cutting down and injecting the roots and covering the ground with plastic might work.

I need to read up on using pesticides in Toronto near the lake, too.


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  1. Before we knew what it was, my husband transplanted a clump of Japanese knotweed to our property where, of course, it flourished. Eventually we built an addition to our house and so removed the knotweed - or most of it, anyway. I am still - almost 10 years later - finding sprouts of it that creep up beside the foundation of the addition in the area where it used to grow. I pull them out the minute they show up but I absolutely can't believe how unkillable they are. We haven't used herbicide - which, by the way, you can't use in Toronto for "cosmetic" reasons. So unless it is actually clogging a vital drain or breaking through the foundation you'll just have to keep digging it out forever.

    The shoots are edible, by the way, like asparagus. So you may want to try that approach.

    1. Wow, what a problem plant. I'd never heard of it and thankfully have not had to battle it my gardens. When I saw your post, I too googled it, and found this article quite informative:

      Reading the article indicates that eradicating it is a long-term on-going project. Good luck!

      1. Here in the US we were lucky not to have bamboo on our property until the town mowers probably deposited some pieces when the mowed the roadsides. Since it was just small branches of it we did not wait until autumn but used the strongest brush killer. It is sprayed on the leaves and has to be re-applied every time you see new growth or after a rain. It hasn't gotten to be a problem but we start in the spring as soon as we see signs of it. The brush killer doesn't seem to bother the grass or day lilies that are also growing in the area.

        We did see a neighbor did some out with a backhoe and they seem to have gotten rid of it. They had a clump of it but not as bad as some areas along NH roads where there is huge bushes of it. Right now, it actually looks pretty with lacy white flowers.

        1. Thanks all. Jannie that article was particularly dramatic! I shall try chopping it to keep it somewhat under control so it doesn't mess up the rest of my planting but luckily it's my landlord's responsibility! However there are some pretty tasty-sounding recipes out there (apple and knotweed pie!) so I know what to do with the cuttings :)

          2 Replies
          1. re: gembellina

            Just to be clear - it's only really edible when it first comes up in the spring. After that it becomes woody and hollow like bamboo. Report back when you've tried it! I never did. Still have a small patch of it out by the chicken coop so I suppose it's not too late for me.

            1. re: Nyleve

              Ha I'm sure I won't have managed to destroy it by springtime so I'll save that treat for next year :)

          2. If you want to say sayonara to your Japanese knotweed plants, you can try the following method. It is important that the knotweed NOT be very close to any plants that you value. Boil 3 quarts of water and pour it over the plant while the water is still very hot. Be generous, repeat as necessary.

            Mission complete.

            2 Replies
            1. re: Cheese Boy

              Ok that sounds like it's worth a try, and if it kills off some of the other weeds, so much the better!

              1. re: gembellina

                Try here FIRST ... 'along a path where the drains are'.

                It will kill (cook) the other weeds also. This hot water method works better than any product on the market ... and it's rather inexpensive too. Be VERY careful and mindful of the boiling hot water when you're carrying it.