I have read many messages about passion flowers. None of them have any information I can use. I need to know how to winterize my perennial passion flower that is planted in the ground. I live in Northeast Wisconsin. Do I cover them with burlap so they can breath or do I cover them with a pot to protect from the cold? Do I put a loam based mixer over the top or can I stuff leaves over the top of them? I can't seem to find a straight answer. Any ideas out there?