Last winter I thought I dug up all my Canna's, then today I went out to turn over and amend the flower bed, to my surprise I dug up two very healthy canna rhizomes each with a couple of growing points. I also want to note that my beds are covered with plastic sheeting and Red Cedar Mulch to keep the weeds down, this probably contributed to them surviving the cold. I think I will leave some out next year, instead of digging so much in fall.