most cannas are tender perennials in colder zones, im in zone 6 n have to dig m up in fall to store overwinter, i folded em in newspaper, stuck em up in the coubard,then have to start them early indoors in spring to blooms,
i left mine out to long last year n lost em. they didnt die back as soon as they use to,
if they still have good groth on em you could pot em up n stick in your cellar n wait till they die back. then cut the dead off n store em.
there are some that are hardy for my zone, i didnt know that till njoynit gave me one, she said its hardy n should withstand my cold zone, so im leavin it in the ground.