Here is one of the best threads for overwintering Bananas in general. There area some bananas that are less tollerant to cold and must be brought inside the house or in a greenhouse for the winter. Use the search button above and type in "Overwintering". This should give you a weeks worth of reading on the subject..
For me most of mine get dug up and placed under the porch, with my Siam Ruby and Zebrina coming inside the house. Hope this helps.
Time to put the bananas to sleep for the Winter