I can't take all the credit for this method. Someone suggested it to me a long time ago on gardenweb.
But I perfected putting a tarp over the top and leaving a circle around the plant and filling it in with dry fluffy leaves. It seems to make a difference in zone 5 anyway, if you keep the bags of leaves dry, and the banana dry underneath it.
Northern Tropics Greenhouse
1501 East Fuson Road
Muncie, IN 47302
specializing in bananas, heirloom tomatoes and water gardening plants~
check out our new online store at our website!