If you are referring to bearded irises, then I would say the cannas need more water than that type of iris. So you would not want to plant the two near each other. I keep my cannas, grown in large ceramic containers, watered almost every day.
They are also not real cold hardy. I lost cannas when it got down to the low 20s F.
Cannas are not true lilies but can be very rewarding in both the flowers and foliage that they produce. The way I look at it, I get a "tropical" look without living in a tropical climate!
