Cannas are lush tropical plants, grown as perennials in garden zones 8-11. In northern garden zones like ours (zone 6A) cannas are treated as annuals. Four years ago, Beautification Committee members Bob Stuller and Mike Wright planted some left-over canna rhizomes along the back wall, just to see how the plant would do in the Hillside Garden. Much to their surprise, the cannas have survived the last three winters, each summer looking better and better. The wall which the cannas are planted against, receives full sun all day and must provide the warmth the plants need to keep them from freezing in the winter. The committee also mulches all the gardens. Perhaps these two factors have created a micro climate fit for tropical plants.
You can grow cannas in large pots or in the ground. Select a site that is full sun and has moist soil. Tall varieties should be sheltered from the wind. Plant the canna rhizomes around the time you plant your tomato plants and plant them four or five inches deep.
In the fall, after frost has turned the leaves brown, cut the plant down, leaving about six inches of the stalk. Dig up and divide the rhizomes and store in a cool basement. If the cannas are in pots, just bring the whole pot into the basement and if the cannas are not too crowded, you can just set the pot outside in the middle of May, water well, and in a few weeks the cannas will have new shoots.
Posted by Ann Samul