Japanese knotweed

Today we were working in a garden rescuing it from what is one of the worst weeds known: Japanese knotweed ( Fallopia japonica, syn. Polygonum cuspidatum if you want to google it).This poor client has been a victim of a neighbour?s neglect. The people behind her have a huge stand of this awful stuff. It has snuck into my client?s garden. It was hacked out but I have no illusions that once we?ve bumped up her soil, it will come back again.This stuff is unbelievable. People call it by many names including bamboo. Well it?s not. It is a noxious weed which spreads underground by a rapid tough root system.? It produces a humungous amount of seed, which spreads it even faster.I had a neighbour behind me with this stuff and had to threaten them with dire consequences if they didn?t get it out of their parking area.? I was this miserable because once it hits my place it will put paid to all the glorious plants I have here and that I choose to have. No one wants someone else?s weeds.Here?s how to get rid of this stuff with its nice puffy fluffy white plumes and bamboo-like stems.? Remember it is a noxious weed, illegal in many parts of the country.Instructions for removal:Cut back all plants flat to the ground, scraping up every seed possible. Put the seeds into a bag.? Don?t put the seeds into the green bin or the compost. Put it in the garbage garbage in a sealed bag.?Cover the infected area with thick black plastic held down by bricks. This should be left in place until well after the soil warms up in spring.? If it starts to grow again (and it will), it has to be cut back to the ground.? Cover it with plastic, and start the? whole process once more.So it doesn?t look quite so bad, spread a 4-inch layer of dampened newspapers over the plastic and then cover it with compost or soil.? Once the root system has been defeated you can use the composted newspapers to start a new bed.This stuff is really bad.? I?ve seen such dense jungles of the plant, a backhoe was need to remove the roots.? So don?t let it get ahead of you. If you spot this plant, get rid of it immediately.If you notice a neighbour with it, make them remove it or you?ll be paying for their selfishness for the rest of your life. It can ruin a garden.

  • Hazel Smith

    January 26, 2009 at 1:57 pm

    Thanks Marjorie,

    I live on Wright Street, just down the road from Chris and Sherrilee, so you can appreciate how narrow my garden is.

    I initially put in a knotweed for privacy. I took it from my mother’s in Parry Sound where she has enough space for it not to be so bothersome.

    Although I had a great experience with it and the monarch butterflies one year {I had over 100 butterflies at a time on the plant in early September} it really chews up my grass. Luckily it hasn’t gone under the fence yet.

    We dug up one root system and it doesn’t seem to matter. It’s deeper than we can imagine and runners still come up.

    I’ll try smothering it with black plastic.


  • Marjorie Harris

    January 26, 2009 at 3:44 pm

    They do attract butterflies but there are better plants: eupatoriums for instance. Once the snow has gone cover the knotweed with plastic, old carpeting from the garbage anything that will keep it for starting. It will take weeks but worth the effort. Then once it warms up remove everything but the plastic and fry it to death.

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