The better solution would see the feds to scrap the silly 4-plant limit per household and replace it with a block of continuous floorspace representing maximum 1% of floorspace, with 'floorspace' calculated on the area of any single floor of a house or condo, to a maximum of 10 sq meters in any household.   

A 700ftsq condo would allow for 7sq ft, enough to accommodating a single plant or two.  This wouldn't be outrageous even in a condo.  A 1000 or 2000sq ft home would allow for the maximum 100 sq ft (a 10 x 10 room), and this too wouldn't be outrageous inside a large single family dwelling.

Nuisance matters, like smells, etc, are easy to handle if a resident strives to be sensitive to other tenants.  If not, offending tenants surely fall under existing condo by-laws or city ordinances.  Nobody has the right to bother adjacent tenants, whether it's excessive noise, garbage, or odours.