Frost will kill the green foliage, that is when you cut the foliage back & dig to bring inside if you want to save them for the following year. I assume the point is to let the canna grow as long as possible save energy for the winter storage.

I'm in zone 5b-6a and on campus we have Canna that come up year to year fine after over-wintering in the ground. It's location is near a building facing south.

Vera

My canna's stay in the ground year round and I am in zone 7. Last year I cut the stalks back though and may leave them 'til the frost kills them. Right now they are still blooming.

I'm also in Zone 5b/6a and recently acquired what I believe to be Cleopatra Cannas. We haven't had a hard freeze yet and they are still blooming. I am considering leaving half of them in the ground to see if they survive the winter.

If you are going to leave them in the ground in Zone 7 and lower (colder) use lots of mulch to insultate and rake it back in the spring.

Do you recommend any canna's in the 4-5' range of pink hue that would do well in Dallas TX? How do you keep them blooming all summer? I've only seen some bloom once & then done for the season.

Thanks,
debalu