I have had a few canna over the years in different colours. I settled for two smaller flowering plants a few years ago and they never disappoint me. I have each in its own pot and when it has finished flowering and the leaves begin to turn brown in Autumn I shift them down to a cool place in the cellar and forget about them until the following Spring. As soon as the weather improves, is not so cold, I put them back on the porch and some time in Summer they produce the first flower stalks.
This year they were a little late, and up to now only one of them is flowering. The other has produced many large leaves, so I am hoping that it will also eventually blossom.