I have an orange colored canna that was pretty new when planted outside. It thrived quickly. I brought it in for winter (indiana) and figured it would never make it. It is still thriving and growing quite tall (3-4 ft. now). The problem is that the leaves are so large and the stalk is so thin that it keeps breaking the stalk. When I cut it off, the whole stalk dies. Is there a proper way to prune these before breaking occurs? SHOULD I be pruning on a regular basis maybe to fatten the stalk? I have many new sprouts in the 20" (probably 20" deep too) pot, but hate to lose the tall ones.