Japanese Knotweed

(Question)

I am a new gardener and I have an unusual plant growing in my vegetable garden. I thought it may be kohlrabi, but it is not growing with any consistency in rows. My garden is in full sun in Essex Ontario. The plant has unusual ring like parts growing up a thick stem. I would appreciate if you could identify it for me. Thank you in advance.

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(Answer)

This is not a kohlrabi, but rather the invasive Japanese Knotweed, Polygonum cuspidatum, or Fallopia japonica which is named for the ring-like nodes on its stem.  It is an aggressive semi-woody perennial introduced to Canada in the 1800’s as an ornamental plant.  From your photo, your examples appear to be quite small, and you could likely be able to remove them simply by pulling them up, being as careful as possible to remove the entire root: Japanese knotweed spreads vigorously by a very strong system of underground rhizomes.

Here is useful information in this previous Toronto Master Gardeners post: https://www.torontomastergardeners.ca/askagardener/japanese-knotweed-control/  Also, the Ontario Invading Species Awareness Program’s website has photos that will be helpful in identifying your plant and understanding it:  https://www.invadingspecies.com/invaders/plants-terrestrial/japanese-knotweed/.