This is a variation on existing posts, with similar values. However, I would make a note that most of the barrels of this type are used to store toxic chemicals (if not to humans, then your bananas), so be certain they are thoroughly and carefully washed out. Secondly, without some sort of mulch to protect the soft tissues of the banana from freezing, this is not much more than building a different refrigerator for the bananas. Without mulch to surround the p-stem, this would only be effective in areas without significant freezing temperature days. My two-bits....
