‘These can be very, very large plants:’ the risks of growing cannabis at home

When marijuana prohibition ends on Wednesday, it will also become legal to grow cannabis at home – and that has some realty groups sounding the alarm about the relatively unknown risks of cultivating the plant.

The damage can get extensive, even impact property values, and critics say it is far different than taking care of other common house plants.

“You’re not contemplating four house plants sitting on the kitchen table – these can be very, very significant and large plants,” said Keith Lancastle, Appraisal Institute of Canada CEO.

Ontario will allow homeowners to grow up to four plants per residence, and there are no limits on their size. If properly taken care of, they can grow to be taller than a house.

Lancastle warns the humid conditions needed to cultivate the plants can cause water damage, mold, fungus and structural issues.

“You could have a very, very significant impact on the value of the property. Mold is a very insidious and dangerous substance. The cost of the remediation of mold can be very, very high,” he said.

There’s also the problem of the lingering odor, because it’s not just the smoke that smells.

“There’s a very distinct odor from the plant itself,” said Lancastle.

And the stigma associated with pot could make it harder to sell the home. But when CityNews caught up with a few real estate sales representatives at an open house Sunday afternoon, they told us they don’t foresee much of a problem.

“The only thing we have to be careful about as realtors is that the house itself has not been a grow op,” said Sylvia Santarelli, RE/MAX sales representative. “That’s different, that we’ve had problems with in the past, but not with legalization and the couple of plants.”

The Ontario Real Estate Association says already, first-time buyers are extremely particular before purchasing a property, and the cultivation of cannabis could create a nightmare scenario.

“I deal with a lot of first time buyers in the small community I’m in,” said Steve Kotan, Chair of OREA’s Ontario Realtor Party Committee.

“They’re concerned about everything when they walk into a house. They’re concerned about the yard size, they’re concerned about the windows, they’re concerned about the electrical and everything. You walk into a home and it has four cannabis plants growing at unlimited sizes, I’m sure they’re going to have concerns.”

OREA has a five-point plan with extensive recommendations, including mandatory training for home inspectors to spot the signs of a former grow-op, and for the government to provide clear guidelines about disclosure requirements.

They’re most meaningful recommendation is that the government restrict the number of plants for apartments and condos smaller than 1,000 square feet. They suggest just one plant for a unit that size – as four can cause significant damage magnified by the small space.