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.
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Sandy Burrell
Northern Tropics Greenhouse
1501 East Fuson Road
Muncie, IN 47302
www.northerntropics.com
specializing in bananas, heirloom tomatoes and water gardening plants~
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