Canada's Condominium Magazine
Cigarettes “put out” in flower pots caused 60 fires in Montreal this year. In Edmonton, Vancouver and Toronto, where they began tracking, similar numbers were found:
- Edmonton: 54 this year; 63 last year, and 88 the year before.
- Vancouver: 90 in 2015, and by 2017, 120
- Toronto: 51 in 2017, year-to-date 2018 is 25
- Montreal: 60
To put the damage in context, in Edmonton alone, costs last year hit $19 million in property losses, plus the expense of putting up home-owners in hotels.
The Toronto Fire Services division chief of fire investigations, Larry Cocco, pointed to people throwing still lit cigarettes off balconies. This rude habit of throwing on the street can backfire when wind carries the still smouldering cagarette onto another balcony. He pointed out: “a lot of people have cushioned chairs on their balconies for comfort.” These are highly combustable, made of petroleum foams.
One of the problems is that smoking is generally not allowed indoors. Condo owners probably dispose of cigarette buts safely when they go out, but guests are likely butting out in the only place available: flower pots on the balcony, or over the rail. Fire departments caution it’s one of the top causes of fires. In the case of a condo, it will not be one owner who suffers losses — it can be dozens of home-owners.
“Perhaps residents don’t smoke, but they have guests. And the guests, to be courteous, they go out and smoke. But because there are no regular smokers there, there is no appropriate receptacle,” said Carole Henke of the Calgary Fire Department. 
The soil in pots is combustible
There are reasons smoking is prohibited in most condos, mainly health and fire-safety related. Even where it’s not against the law, most condo bylaws include a prohibition. A lot of condo owners don’t realize that the same rule applies to the balcony. Deryn Rizzi, deputy fire chief with VaghanFire and Rescue said:
“What they don’t realize is they are taking an ignition source and putting it into a soil that’s full of combustible materials.”
Potting soil often has vermiculite and styrofoam for drainage, and oxidizing fertilizers — a potent, combustible mix. Depending on the type of soil mix, the fire can ignite immediately, or smoulder and ignite slowly.
In other words, the best option for smokers is the elevator to the ground floor and outside to a proper ashtray.
With Marijuana about to become legal in Canada, most condo boards have rushed to ban smoking marijuana in the condo and on the balcony, these are the same type of rules that govern regular smoking. Fire Departments are wary of the impact, since even people who do not smoke regular cigarettes, might socially or medically smoke Marijuana. Again, unsafe ashtrays, such as the “wind” and the dry flower pot can be deadly.
 CBC: Flower pots and cigarettes don’t mix, fire officials warn.