That is a question that would vary by the province. Let me rephrase that slightly. Across Canada, landlords on first renting could impose a ban on cultivating and/or smoking. However, enforcing that ban would be relatively easy in the Atlantic provinces and in the west from Manitoba west.
In Quebec and Ontario, it would be difficult to enforce because in Ontario, where I have the most familiarity with the law, it is very clear law that a landlord cannot.... The way a landlord enforces a termination of the lease is by giving a notice and then bringing eviction proceedings. You don't necessarily want the tenant to go. You want them to stop doing what they shouldn't be doing, and the way you do it is with a notice of termination. It is not possible in Ontario to give a notice of termination for merely breaking the term of a lease. Merely to prove the smoking when it's banned in the lease, the growing when it's banned in the lease, will not get a landlord what they want. The tenant can basically flip them the bird.
To enforce the term in the lease, the landlord needs to demonstrate a substantial interference with the reasonable enjoyment of other tenants, or with the lawful rights and interests of the landlord. The first one is easier to do, although it's not easy to do. It requires bringing other tenants as witnesses to the landlord and tenant board to give their evidence about how they have been impacted.
You can understand people don't want to do that because they are living right next to this person, they are going to see them in the hallway, the person may crank their TV at night as the least of what they might do in retribution, and they are just uncomfortable doing it. They don't want to do it.
Ninety per cent or 95% of the steps landlords take to address tenant behaviour is, in fact, to protect other tenants in the building. In Ontario, thanks to Ontario's landlord and tenant law, it would be much easier to enforce against an illegal act than to enforce a lease term.