Do you know if it's a caerulea? If so it's a hardy variety but I don't know about hardy enough for zone 5. I'd sink the pot and dig it up in the fall. You can let it go dormant in a cold but above freezing room. I say above freezing because it's in a container. They can withstand below freezing temps inground where the roots are more insulated. You can also keep it growing inside but you'll need a grow light and keep an eye out for bugs. I always have problems with mites, scale and mealy bugs on my plants that need winter protection whether they are inside or in the greenhouse.

My friend had a cutting or passionflower given to them and was planted Z5 next to a white panelled wall and grew to 5 ft high and five wide and was covered with many many blooms. Dug up and overwintered in greenhouse and many cuttings made which all started this last winter. Now many of us are growing passionflowers in zone 5.