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Polygonum cuspidatum, Japanese Knotweed

posted Jun 21, 2015, 1:36 PM by Bernadette Vangool   [ updated Jun 21, 2015, 4:06 PM ]
In a recent article Maclean's magazine features Japanese knotweed, The plant that's eating B.C. by Ken MacQueen. Japanese knotweed is extremely invasive in all Canadian provinces except so far in Manitoba and Saskatchewan. It is possible however, that with climate change this particular plant might become a problem for us as well, so I would like to alert the Saskatchewan gardener about this possible pest. The only way to eradicate this intruder is to treat it chemically (Roundup) repeatedly till it disappears. The four species found in B.C. are Japanese knotweed, Polygonum cuspidatum or Fallopia japonica; Bohemian knotweed, Fallopia x bohemica; Giant knotweed, Fallopia sachalenensis; and Himalayan knotweed, Polygonum polystachyum. All are considered invasive.

Some of you have contacted me to find out if we sold this particular plant at one of our plant sales in conjunction with our Plant Exchange a few years ago. I have looked back to our plant sales to 2012 and have not found it on the list. In 2012 we did sell Giant Fleece Flower or Polygonum polymorpha, now also known as Persicaria polymorpha. This perennial is extremely drought tolerant, forms strong upright clumps with flowers that resemble giant white astilbes, and is well behaved and non-invasive.

If you are not sure if you have the Japanese knotweed in your garden go to www.invadingspecies.com/invaders/plants-terrestrial/japanese-knotweed this web page has some good pictures of the invasive species in different stages of growth.
or http://bcinvasives.ca and search for knotweed to see a photo gallery of the different species.