I've been direct seeding my own bulbs for years and years, I dig them every fall and sell 2/3 of them in the spring to a greenhouse and then plant the last third for that's years crop.^^^^
Do you plant the Canna tubers (bulbs?) directly, or start them in pots? We usually get them going inside to give them a head start. One year I saved seed and started those the following spring; I'd read that they don't come true to the parent and can produce unique plants.
That may be true but mine looked just like the plants I started vegetatively.