The Current

Destructive Japanese Knotweed sprouting in Canada. Brace yourself.

It started as a innocent looking, green sprout... but turned nasty. Japanese Knotweed, an invasive species has clogged up the British Isles, causing property prices to tumble, and fraying neighbourhood nerves. Find out where it's sprouting in Canada and what to do if you spot the menacing leaves.
The Japanese Knotweed plant can expand to acre-wide that re-grow from the roots each year. This photo shows knotweed in bloom. (U.S. Fish and Wildlife Service Northeast Region)

"This is the terrorist of the weed world."

The plant is called Japanese Knotweed... and as the name suggests, it originates in Japan.

But it's become one of Britain's most pernicious invasive species, and it's putting down roots in Canada. If the Canadian experience mimics anything like what's happened in Britain, then Japanese Knotweed is liable to grow so ferociously that it will actually pull down property values, and pit neighbour against neighbour.

Knotweed is so pernicious it can grow through concrete. (
What occurs is the person trying to sell the property has no knotweed on their property but it's growing from an adjoining property into theirs. They can't sell their property and may approach the neighbour to help pay for it to be eradicated. In the UK it's a criminal offence if you try and remove it yourself.- Mark Haywood with Britian's National Association of Estate Agents

For some background on just what this plant is all about -- and why it can be so dangerous, we were joined by 
Guy Barter. He is the Chief Horticultural Advisor with Britain's Royal Horticultural at Wisley Gardens in Surrey.       

Japanese Knotweed damage through brick wall. (

The Japanese Knotweed isn't just Britain's problem. It has arrived here in Canada. Just ask Joe Cindrich, of Langley B.C. He noticed a patch of unusual weeds growing out of control in his neighbour's yard. And though he didn't recognize the plants themselves, he knew they weren't something he wanted growing on his property. That's when he took action.

​For a sense of where else in the country Knotweed has sprouted up and how serious the situation is, we were joined  by Gail Wallin. She's executive director of the Invasive Species Council of BC, and co-chair of the Canadian Council on Invasive Species. She was in our Vancouver studio. 

You can send us your knotweed stories. 

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This segment was produced by Calgary Network Producer Michael O'Halloran and Winnipeg Network Producer Suzanne Dufresne.     


The plant that's eating B.C. - Macleans

Japanese Knotweed (Fallopia japonica) - Ontario's Invasive Species Awareness Program

The top 10 unwanted garden plants - Canadian Gardening