Musa basjoo is a banana species able to tolerate most central Maryland winters when grown in the ground (and yes, all top growth will die back once it freezes), though any hardy plant spending the winter above-ground in a pot runs the risk of root damage from exposure to temperature fluctuations, freezing, and drying out to a greater degree than roots in the ground would. If you don't have a spot in the ground to plant the banana permanently, then consider "heeling it in," which entails essentially planting the whole thing (pot still on) so it can spend the winter surrounded by insulating soil but still easy to pull up and put back on display in the spring/summer. If heeled-in, it will still need occasional monitoring for watering needs during mild spells in winter; if cold doesn't damage a plant outright, getting too dry during winter can.

Keeping the pot as-is but wrapping it with an insulating material won't help very much, as it doesn't add enough mass to the pot to markedly slow its chilling or warming-up as the temperature fluctuates. Piling mounds of soil, mulch, or perhaps solid bales of straw snugly around the pot might suffice (a sort of above-ground "heeling-in" technique, by giving the pot a mound to be effectively planted into), but we have not tested this with Musa basjoo.

If you put it into the greenhouse, the temperature should probably be allowed to get fairly cool, just above freezing, as the best way to give it a chilled dormancy period while not having the soil freeze/thaw often (if at all). Of course, here too, the plant will need periodic watering checks so it doesn't get too dry for very long.

Miri