Can japanese knotweed be contained??

simcoe_ponder(z 5 On)January 29, 2004

I have recently found out that one of my favourite plants is japanese knotweed. It is still a small patch and does a great job as a screen. I had intended in moving it in the Spring . If i planted it in a bucket would this be enough to curtail it?

Thanks for any insight -M

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jancarkner(Ottawa CAN)

Don't keep it; it's not worth it. I moved some to our new property in 2001, and realized my mistake within a year, and am now trying to eradicate it. Even though it doesn't spread as rapidly in our area, it is still an exotic invasive. I agree that it is wonderful at screening, but it grows from the ground to 5' in a matter of weeks, and when you think about it, that's pretty scary!

    Bookmark   January 30, 2004 at 8:27PM
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mary_rockland(USDA4 Ottawa)

In my area some people use it as a fence. On my clay like soil it's not invasive. We've had it about 7 years and it works well as a screen between neighbours (far away from any garden). I know many people in my area who use it the same way and we all just mow over anything that creeps beyond where we'd like it and into the lawn.

Look around your neighbourhood in the spring and ask any locals their experience with it. Planting in a bucket is a good idea - but you probably want to be sure that the bottom is cut out so that it can drink well.

I suppose I should mention that I do not live on a small city lot (but not a farm either) and neither do my other friends with the same plant. Good luck.

    Bookmark   February 3, 2004 at 4:55PM
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Mary_Rockland is right. How knotweed behaves depends on the location. I've seen pictures of knotweed in Britain where it has completely covered ravines. Terrible stuff if you live in the wrong place. Some states in the U.S. have it on their noxious weeds list which makes it illegal to grow. Perhaps there is such a list for Ontario.


    Bookmark   February 6, 2004 at 3:48PM
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Woody_Canada(~USz5 - Canada)

There is a noxious weeds list for Ontario - see link below...

It's a pretty short list. It's mainly things that are a problem for farmers.

Here is a link that might be useful: Ontario noxious weeds

    Bookmark   February 6, 2004 at 4:30PM
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I have some on my property when I bought the house six years ago. I kept it there to act as a fence/screen. Last summer, I attempted to eradicate it due to the fact that I have money in the budget for a new fence this coming summer. It stayed put with the only control on its spread being the lawn mower trimming the off shoots. Last summer, I started out by trimming it back every second day. I made the mistake of going on vacation for five days. When I came back it was four feet high and sent suckers throughout my back yard and into my vegetable garden. In August, I rented a mini excavator and pulled up the woody roots after breaking two shovel handles and straining my back. I also experimented with spraying the young, tender shoots with household bleach at full strength. This weakend them at first, but they seemed to come back with renewed vigour. As soon as they come up this spring, I will continue to cut the new shoots off at the ground as well as hit them with full strength super concentrated Round-Up (50% active ingredient) I don`t care about the surrounding grass, I can always re-seed, but I HAVE to get rid of this stuff once and for all! I`ve come to realize that this may be a battle that will take several seasons, but I intend to win at any cost! DO NOT plant this for any reason. It is not worth it!

    Bookmark   February 10, 2004 at 11:23AM
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leftwood(z4a MN)

Japanese knotweed is on Minnesota's knoxious weed list. Grown in the sun it is unstoppable. Grown in the shade, it is usually manageable with vigilance.

    Bookmark   February 10, 2004 at 7:17PM
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I planted 4 one gal containers of it on a steep bank at the back of our property about 6yrs. ago and only 2 have survived and they are pathetic looking - weak and spindly and smaller than when I got them. The woman I got them from is still doing the round up and shovel-prune and can barely control it in her yard let alone get rid of it completely. She thought I was nuts when I asked her for some. In fact I had to keep promising her I wouldn't blame her "when" it took off. I have grown it before in similar conditions (sandy,rocky bank) and it was a little fuller but never spread much. So it does depend on where its planted - big time. When its bad - its real bad !!!

    Bookmark   February 11, 2004 at 11:47PM
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karyin(z5b Canada)

We have Japanese knotweed in our backyard from the previous owners of our house. We have been trying for the past 2 1/2 years to get rid of it. When we first moved in, it had spread into our lawn and under our cedar hedge. It has also spread over into the neighbours' backyard who don't mind it. Every spring, I pull out the sprouts and continue to do so every 2 to 3 weeks until the fall. I have read that Roundup and other herbicides do not work on knotweed, that you physically have to pull out the roots. The problem is they can go down to 6 feet under! So I will continue to pull at them - the encouraging thing is that every year it seems to come back weaker and weaker.

    Bookmark   February 21, 2004 at 8:26PM
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Pulling this plant once established will only make it spread more in the long run. For more than very small clumps, the only solution for this plant is use of herbicides. Roundup will work, although foliar sprays will take repeat applications. Cut stem treatments will work well. Injections of stems is the latest technology being used in the NW. This link explains more.

Here is a link that might be useful: Knotweed control

    Bookmark   February 22, 2004 at 4:07PM
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I second that digging the roots is not advisable for knotweed.

It can reproduce from a remnant of a rhizome less than 1 cm. And if you pull the roots, you're leaving behind a whole pile of pieces of rhizome - each one that can become a plant.

Of course, in urban BC knotweed is invasive species #1. In fact it can even outcompete himalayan blackberry! I am horrified whenever I see it in a garden - but i know the colder places don't suffer from it's destruction as much (at leastnot as quickly).

The organic treatment being experimented at test sites here, is a combination of 2 spring cuts when the plant is a foot high, and then a late fall cut when the plant is at full height. Then a heavy mulch for the winter. I have to admit, the test sites are not all that promising. Better not to plant it anywhere, IMO.

    Bookmark   February 29, 2004 at 2:36AM
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what does knotweed look like?

    Bookmark   September 21, 2004 at 12:59PM
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jbann23(6 RI)

I've been fighting a wide stand of well established knotweed for three years now. Kept is down by cutting weekly. No good. Last year I sprayed the leaves in the fall with Roundup and nothing much seemed to happen. This spring I've discovered that 95% of the weed is dead. The roots rotted in the ground and only a small bit survived where I couldn't reach with the spray. This fall a final application of Roundup and the whole patch will be gone - FINALLY.

    Bookmark   May 11, 2007 at 10:09AM
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Japanese Knotweed really very scary. Japanese Knotweed removal is something which is essential if you have recognised or think you may have an issue with the type of weed. Similar to bamboo in looks, Japanese Knotweed is not at all similar and can cause serious issues if it is not removed early on. so, It should not be contained.. Thanks..

Here is a link that might be useful: Knotweed Eradication

    Bookmark   July 19, 2012 at 3:09AM
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I can't believe people suggesting containment is possible!
It also spreads by seed! It may not land in other parts of YOUR garden but it will be in the hillsides, farms and gardens of those who don't know better.
Please dig it out, irradicate it- and replant something that isn't detrimental to the environment- there is plenty to choose from.

    Bookmark   August 4, 2012 at 12:49PM
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Knotweed control treatment in a 3-pack kit for the eradication of Japanese knotweed, hogweed and other invasive plants. Powerful herbicides for use by professionals only. Japanese Knotweed is a hardy and invasive bamboo-like plant that can cause costly problems on construction sites and in residential gardens.

Effective knotweed control requires high strength herbicidal spray treatments and excavation of the extensive root system. Due to the hardy nature of Japanese knotweed, hogweed and other invasive plants, it can often take several rounds of herbicidal treatment to fully control and erradicate the knotweeds outbreak.

Roundup Pro-Biactive herbicide concentrate contains Glyphosate and is sold for qualified professional use only. Users must wear suitable clothing (coveralls), rubber boots and suitable protective gloves (not provided).

Dilute at the rate of 1 part herbicide to 40 parts of water for treatment of most prenial weeds and 1 to 40 for treatment of hardy invasive plants like Japanese Knotweed and 1:20 for Ivy

Here is a link that might be useful: A PRODUCT

    Bookmark   June 17, 2014 at 10:05AM
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