Wow, I'm jealous! I started a bunch of cannas from seed in April and they have magnificent foliage now, but no blooms. Are they supposed to bloom in the first year? I was planning on lifting the tubers and storing them over the winter, thinking that's the only way to get blooms from my seedlings.
I did get some to bloom first year when i did them last year, not all will however.. It really depends on weather, water, sunlight ect... This one is the first to bloom this year but like i said its only 18" so I'm sure thats why its bloomed already.. I had banana cannas last year that did bloom from seed first year, yet my one from a root never did.. The seed ones were only 4 feet high, but the root one was almost 8 feet.. Didn't keep any from seed last year cause i think they all were virused, the leaves would burn on most and they had the streaky look to them so better safe then sorry.. Plus i had enough roots from my good one anyways..
For sure as longs theres no signs of virus come fall i will be lifting them and keeping them till next spring.. Seeds started that year have enough of a root clump to keep.. In fact the ones i had last year from seed, were bigger then some of the roots i had purchased from stores..