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A knotty problem

Japanese knotweed has been a scourge for decades, but some gardeners embrace the invasive weed

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Dartmouth gardener Debbie Richard is in an ongoing battle with invasive Japanese knotweed. Photo by David MacDonald

Dartmouth gardener Debbie Richard is in an ongoing battle with invasive Japanese knotweed. Photo by David MacDonald

Looks can be deceiving. Just ask Debbie Richard, an avid gardener from Dartmouth. She endlessly battles with innocuous-looking plants determined to overrun her back yard.

She points to a patch of gout weed elbowing up against some rose and daphnia bushes. The pest has grown steadily for the past couple of years. “You can’t even put mulch down because [the gout weed] grows under it and grows right through,” she says. “They’re terrible creatures.”

But that’s nothing compared to the Japanese knotweed lining the back of her yard and those of her neighbours along James Street. Scores of tall, bamboo-like shoots with heart-shaped leaves pop up each and every year, growing as tall as three to four metres.

“You can almost see them growing,” Richard says. “It grows really fast.”

Japanese knotweed has been a scourge in Halifax for decades. Settlers introduced it to Nova Scotia in the 1800s for “ornamental, erosion control, and screening purposes,” according to HRM archives. Noble intentions aside, it’s a nuisance today.

“Nothing else will grow,” says Peter Duinker, a professor at Dalhousie University and a member of the HRM Urban Forest Management Steering Committee. He explains that once knotweed becomes established, it “almost 100 per cent” decimates the surrounding vegetation.

Clusters of knotweed dot the landscape all over the Halifax. Keen eyes will notice a patch near the entrance to the navy yard on Upper Water Street. There’s also a large patch on McNab’s Island.

HRM has tried to fight the invader, especially in areas such as Point Pleasant Park. City staff placed black tarps over some patches in hopes of depriving the knotweed of sunlight. Workers have had little success.

“It is a very deeply rooted species that can reproduce from root fragments,” says Duinker. “Unless you want to nuke it with chemicals, you have to excavate a metre of soil and even then you may not get it done.”

And some people are accepting that it’s probably here to stay. “I think it looks really, really pretty,” says Dartmouth gardener Susanne MacLeod. “I love mine, I think it’s beautiful.”

She finds it makes for an excellent natural fence around her property.

“I actually dug a little bit up and planted it on another corner of the yard,” she said. “The flip side of the coin is that you have crazy gardeners like myself who love it, who can manipulate and work with it. It makes a nice accent to your garden.”

Most property owners aren’t so zen about it, though. “If I was looking at a property and it was surrounded by Japanese knotweed, I’d be thinking, first, would I even want the property,” Duinker says. “Secondly, I’d want to knock some value off before I buy it because I’d have to pay $10,000 for an excavator to get rid of it.”

Japanese knotweed is such a problem in the U.K. that some banks have refused to approve mortgage applications after discovering the weed on the homeowner’s property. Lenders have even refused mortgages if the weed was found on neighbouring yards.

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