Certified GKH Gardening Expert
This depends on the type of hibiscus plant you have. A tropical hibiscus plant will not survive winter outdoors and must be brought inside. Only the hardy types can survive winters outside. In your zone, it would need little additional protection in the pot, unless harsh weather is expected.
You can choose to sink the entire pot into the ground to help insulate the roots and then mulch over top of that. Or you can leave move it to a sheltered location and insulate the pot by wrapping in bubble wrap or something similar.