Answer: Fig varieties vary in their cold hardiness, but zone 7 is a challenge for the toughest fig. Wrapping trees will probably not provide enough protection from the cold.
One option that has worked for some is to construct a cover that could be heated inside. A wooden frame is built around the fig bush, filled with leaves and covered with tarp or something else to keep the wind out. Some source of a little heat is place inside the bush before covering it up (need not be much heat...one or two of the coated wires used to keep pipes from freezing might be enough). The bush needs to be pruned prior to the "winterizing process" to keep the project managable. If you don't want to worry about electrical cables, you can keep the tree well pruned, and bury it in a trench for the winter. This involves digging under one side of the tree to loosen roots, which should allow you to bend the tree into the prepared trench. Cover the tree with boards, plastic sheeting and soil, leaves, or other insulating material. Another option is to move the tree up against a south-facing wall and train it in espalier fashion. It'll be easier to insulate this way.
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