Maybe its not a canna.. or some weird mutated type.. I planted my canna in late july, and well its just about to explode open with a bright orange flower and its outside in the ground too! Im waiting a few more days for it to bloom and still no frost or one expected for at least a week. Not only that but I plucked it from my friends mother canna and It didnt even have roots or a corm when I planted it!
Something must be wrong with that one of yours..

Pat

Is it receiving full sun & lots of water?

Hi Gwyn, there could be several reasons why your canna is not producing flowers related to when the rhizome was planted, lighting, watering, type of soil, etc. But it sounds like you are doing a lot of good things for the canna otherwise it wouldn't grow to 3-4 feet tall. I would guess that canna either the canna is growing in too much shade or it is more of a foliage type canna that is reluctant about producing flowers.

Thanks everyone for your suggestions, it is in the sun so may be I did not water enough, and something may be wrong with the spot as a rose of sharon right there did not grow much ( started from seed last year) however dahlias, gladioli and butterfly bush near there bloomed like crazy and flourished.
Will try again next year before I give up.

Lots of people cut off the flowers because they detract from the beautiful leaves. I wouldn't worry about it.

Thanks everyone.
I dug them up last weekend and am going to wrap in news paper and put in basement till after Christmas. And then pot indoors to see if this will make them flower.