Planting Canna Lilies?

I have Canna lilies in pots and since transplanting them the leaves have gone limp and fallen over. Will they come back? What can I do to help them?

The pots are in a south facing yard with bright sun throughout a good portion of the day. The overnight temperature has not dropped below 7C since they were planted. I have Canna lilies in this location every year and this is the first time this has happened.

Please help.

Thanks.

Hardiness Zone: 3b

By Kal from Alberta