| You can plant as many as you can find or afford! There's a huge, breathtaking garden of them at a city park in East Dallas. The designers built rounded berms to cushion the recreation buildings & ballfields from the noise of a busy street, & planted cannas "wall to wall" on those berms, shorter ones toward the street & playing fields, taller ones in the middle. Cannas need protection from strong winds, which will catch those big leaves like sails & whip them to shreds, & they do better if they aren't crowded right together competing for nutrients (don't know how fast they'll spread in Ontario, but you'll have to dig them out & separate them as they multiply.) Even here in Texas, they love full sun, so I'd probably look for a southern exposure, maybe even a warm brick or stone wall for extra heat. I have some coral canna indica Indian shot close to a big coral honeysuckle;
it's beautiful, & supposedly both plants are attractive to hummingbirds (I never can see hummers, but my neighbor assures me they're there!) Best luck, & enjoy! | 
