It would be
helpful to know where or the zone where you live and/or how long until your normal
frost date.

Under good
growing conditions, canna seedlings often bloom within 75 to 90 days of
emergence and have developed a small but increasing rhizome system. Individual
plant genetics plays a major role in seedling performance as well as the cold
weather survival rate.

Generally
speaking, seedlings with only 70 days of growth would have a much lower
survival rate than the same seedling having 100 days of growth. Plants grown
full season or 120 plus days would certainly have the best survival rate along
with multiplication of rhizomes for the next season.

Kent

I live in zone 7b near Chesapeake Bay. Any advice on how to store the young lilies? I am hoping that they will get about 90 days before the frost arrives. I have them in individual pots right now and was planning to simply put the pot in the basement or perhaps enclosed porch area which stays cold, but should be above freezing for the winter and see if anything re-grows. I am worried that if they have not formed a substantial rhizome, then it might be bad to empty out the dirt and cure them as I would with a mature plant.

any suggestions?

Decapitate the potted cannas and store the pots in sealed plastic garbage bags at about 40-45 deg. F. in the dark. It is unnecessary to dry the soil.

Does anyone know the likelihood of surviving winters in zone 7 in the ground? I read conflicting things. It seems like it is a question of luck - do you have a strong plant and is the winter on the mild side. Is that right?