Cannas hardy to zone 6

Anyone know of a cultivar hardy to zone 6? I dont want to have to cater a microenvironment for them on my family farm since I will have them out in the open. I am in zone 7a and if they are hardy to zone 6 they'll survive here fine without help. Anyone know? I was told they have an excellent tuber for eating.

I don't know of a variety that is hardy to Zone 6.  Most of the information that I have seen says that the canna are dug up then replant in the spring.

Since you are Zone 7a, have you tried growing them all year without digging?

Here are some threads that might be of interest to you or others:

https://permies.com/t/51284/kitchen/Edible-Canna-Canna-Edulis

https://permies.com/t/158732/perennial-vegetables/Achira-canna-edulis