Here is my neighbor Helen's canna. She started out a couple years ago with just a few tubers. And they have increased almost tenfold each year. She plants them in her hellstrip between sidewalk and street and this is what they do for her. They are currently about eight feet tall with profuse flowering - even now in late September. These photo were taken late yesterday afternoon.
I told her I am going to do EXACTLY what she does next year with my own - put them out the same day, water them the same amount, and bring 'em in at the same time in the fall she does. She stores the tubers overwinter in peat moss. It's not fair that hers look like this and mine looks like it does (in the photo to the right) - where the Persian Shield is larger than the canna!
Helen's an excellent gardener, her garden is on Garden Walk Buffalo each year. Her front yard garden is something the neighborhood appreciates all year round.