This is my first year with cannas, and I staked my tall ones, but not until they got buds..just because I was a lil nervous about them tipping when the flowers popped..one is leaning, I am not sure if the stake is holding it up or what, but I'm not moving it, lol.
If you have cannas in shade, they will not flower. They need full sun. Are your 2-3 footers dwarfs or are they supposed to be tall? They may be that small because of the shade or because they are meant to be that small.
Don't know if I helped, but good luck!
Daniella

I have never had any tip, but I grow a lot of them, (30-40 plants) in one large bed. I place shorter varieties around the border.