Thanks for the responses.
I'm not sure about the microclimate comments. Winters up here are cold, wet and gray. There isn't much sunshine to really warm anything up anywhere. The only real microclimate would be shelter from the wind.
So far the p-stems of these bananas are still firm and green.
I used to dig and store in the garage but after hearing about LPN and others leaving their plants outdoors I thought I would give it a try. Now I'm second guessing my decision.
Cage and mulching are options but I have about 8 large basjoos and some have a lot of pups. Seems like a ton of work and possibly some $$$. Digging might be easier at this point.
Oddly I have two small basjoos in pots that were outside through the same storms and cold. They had more shelter from the wind so the leaves were still okay. I recently moved them into the greenhouse and they now look terrible. Leaves have turned all yellow and died. I considered digging some of the smaller basjoos and potting them for storage in the greenhouse but now I don't know if that is a good idea either.
I might just mulch around the base of each plant and let the p-stems die and hope they re-sprout next year. Will I get good height/size out the plants?
I guess I have enough for a fun experiment if I get really enthusiastic.
