I am no expert with bananas, as the people here are. But I am very good with plants in general. When I have a plant that does this, I use a clay pot to place it in. Size of clay pot determined by the plant of course. Then I dig a hole in the earth where the plant will be happiest, and to the size of the pot. Sinking it into the ground, (The plant inside clay pot) and filling in around, so the plant 'thinks' it is in mother earth, if I may be poetic about this; seems to make my plants happier. You are in colder climate than the plant likes, so I understand reason for potting. But this really does help my plants that are even more tropical than my own zone to perk up and thrive.
In fall, it may be a challenge to remove the pot, but I do it when necessary. And at this time of year, perfect to attempt this. I also always use the plant hormone 'superthrive' when transplanting any plant, and when making cuttings or seedlings. That stuff is truly awesome!
No matter what you end up doing, I just thought I'd let you know what works for me, and I wish you the best of luck with the banana.
Gino
PS. I saw the home addittion you added in another post. Really great work!