my first year growing banana plants here in toronto canada.. i tried storing the plants dormant for the winter in the basement (2010)
unfortunately due to the basement flooding it did not turn out well
also i think the temperature was too high
ideally you dig them up in the fall and knock most of the dirt off the roots
let it dry out a bit and then keep it in a 10C dark dry place for the duration of winter
this year i tried the dormant storing thing again and i am fairly optimistic
i made a box out of foam and put a thermostat and a 5 gallon bucket with a fishtank heater in there
this is in an unheated garage.. here is a pic
if it works i will attempt to do this in zone 2
but with an earth insulated structure
i might use the cables they sell for keeping eaves from icing instead of the fishtank heater buried in some gravel/stone
i plan to have 4 solar panels arranged in a diamond shape on a post well above the ground
two steeply angled pointing up and two steeply angled pointing down
if the two pointing up are caked in snow hopefully the two pointing down will get the reflected light off the snow
the batteries and inverter will be in their own compartment within the shelter
if it is insulated with lots of earth it should not need to run often
might need a quarter full bucket with silica gel crystals to absorb excess moisture
i will still keep some baby banana plants inside my living space by a window just in case it fails