I'm not expert, but if that is a hybrid Sarracenia it should be hardy in your zone. I've wintered Sarracenia outdoors here in Iowa (z4) and know a guy who grows them outdoors year round in St. Louis. In my experience it is not the cold, but the drying wind that kills them. If it were mine, I would sink the pots into the ground in a protected location (next to the east side of your house?). Then when it starts staying near freezing, pile a good foot of mulch over them.