The dogs or the bananas?
I'm sure others will chime in here but I believe that the plants are too small to leave out, even with mulch, but I could be wrong.
I had a plant that a squirrel decimated and was on its way back with several pups and I potted it up and brought it in for the winter. I was advised to do this by a grower and told that next year, the plant will be better established to mulch for winter. It's been doing quite well in the past couple of weeks.
Am already looking forward to May 2009.