I can't say I can answer your question, but I can tell you what my new ones have done this year.

I got some from a friend this year. Mine are red with the purple leaves... We dug them up and transplanted them in June. They seemed to be doing nothing and then started growing like crazy in Mid july... new shoots coming up from the ground. Then this week we had one of the 3 throw up a long stalk and finally pump out blooms. Still nothing from the other 2 though. They are growing well though and getting big. So maybe your blooms are still to come?

Just wanted to let you know another of my 3 shot up a flowering stalk this weekend. The original sent out another flowering stalk, so yours might still have a flower yet to come.

My Canna are weeks later to flower than last year, and about 2 feet shorter than they were at this time last year. We had a very late frost that put mine behind in the growing season, I'm guessing. I have several varieties (Red and Yellow King Humbert, Robert Kemp, Wyoming, Madame Butterfly and Bengal Tiger). All are way behind this year. :-(
Candy