Hammocked Banana

To me it looks more like cold damaging the leaves than too much sun. Was the leaf touching the glass? When u transplanted did the roots look nice and white or more brownish? Yes im in zone 5, this winter is probably more like zone 4 lows though. I have several varieties of bananas, all edibles and most ornamentals stay in pots all year and some are ground planted in spring and dug back up in fall. I have several basjoo mats that stay outside all winter, although this winter will be a real good test with many nights hitting -30 C. I think your basjoos are your best bet at overwintering outdoors there. Most people would wait one more year to plant them outside, but im all for just getting them outside as they grow so much faster in the ground and in one year you can get them to a decent size. So since u have several, I would recommend maybe planting 2 outside this year if u have a protective corner near your house, and that way u will have 2 still safely in pots incase the other 2 dont make it. Also a ground planted nanner should give u some pups to pot up, as added security.