Hi Steve,

Canna don't grow from, or form bulbs, nor are they lilies :) Their underground storage systems are rhizomes - which look very much like root ginger, to which they are closely related. As such they start to create small rhizomes more-or-less as soon as they have germinated.

As for the time to flowering, it all depends how you are growing them. Canna indica is capable of growing to flowering size in it's second year after germination, but only under optimum conditions. Once they have broken dormancy and are in active growth (i.e. once the weather has warmed up) they can take as much food, water and heat as you can give them, and their rate of growth will respond accordingly.

From what you've said I would guess that you have kept your seedlings semi-active through the winter & they're indoors, presumably. In which case they will come back into growth as a response to increasing daylight in Spring & that's when you can start feeding, watering and repotting to bulk them up as quickly as possible.

Some dwarf varieties can bloom within 15 months, if kept growing coninuously, but most kinds take at least two years, even in tropical countries. Ilex is right: they love water, warmth, and high nitrogen and potash food.