One week left in the shade with a bit of water whould be just fine.

I've left them uncovered to cook in the back of my truck for a couple weeks and they made it. The canna rhyzome is a bit like a potato. It's not gonna die easily.

Good luck!

update: I still have these cannas in the 2 big 20+ gallon tubs, many things have come up since my trip and I just have not had time to get to them.

they are growing and flowers are starting to appear. Should I just wait now to move them? I am in the process of re-doing a new bed around my deck and I'd like to put some of them there but it's not ready yet.