What is the average temp in that garage over winter? Many people do exactly what you suggest to overwinter their bananas in colder zones. The corms will have no problem with cool and dry, but not cold . There are cold hardier bananas you might want to add to your collection next year--basjoos, Chinese yellow, Himalayan, Mekong Giant.

The garage is not insulated, but above it are bedrooms and beside it is the living room. The rear wall of the garage is actually below grade, so there may be some ambient warmth there (?). There is exposed plumbing in the ceiling of the garage and we have never had any freezing issues. If I had to guess, I would say that it is somewhere between 5-10 degree Celsius, or I guess like 40-50 degrees Fahrenheit. Is that too cold?

Thanks for the hardier suggestions - I'll definitely try that next year, but this is my first year growing bananas at all, and I would have to find a source. I bought these guys at a local garden centre, and I really like the look.