There are about 25 species of canna all native to South America. Canna are loosely related to gingers and bananas. Like bananas and gingers they do not have true stems but stems made up of leaves.
Cannas love heat, hate frosts. I find some years they will die back, some they won’t, but they do come back when the warm weather arrives.
Cannas love sun. Yet I have these growing in a mostly shady area. They escaped under the fence from the neighbor’s garden. On her side of the fence they receive full sun, on my side mostly shade.
Cannas do well on the edges of bog gardens. They prefer soil to be moist rather than dry. That said they’ve done quite well through a recent drought.
Like ginger, the flower stalk is done when blooms finish, cut it to the ground if you want, or leave it for the foliage.
Bud rot: Flower buds appear but rot before opening. This is a bacterial problem. It can be caused by watering at night or if we just get too much rain. Try to keep plants drier.
Corn earworms and Canna leaf roller both can be treated with insecticides. BT might be a good first try if you wish to avoid toxic chemicals.
Note: Survived, thrived and bloomed during the great drought and heat of summer 2011