I'd cut back the dead growth just leaving a few inches of stem then wait and see what happens. I've had a number of passifloras, even tender tropical varieties, send out new growth after the same thing. Keep them warm and make sure that you don't over water. I wouldn't worry about hardening them off with regard to temp, just sunlight. I slowly acclimate my plants that have been wintered over under grow lights to natural sunlight, even then I often get some scorched foliage but that's just cosmetic. It will drop as the hardy new foliage grows in. Good luck.

I live in zone 10. I have a red Passion flower vine that's taking over my flower bed if you like I can send you a lot if cutting. Email me if you want me to send you some .

Hi Pinkflower,thank you so much for the offer of Passionflower cuttings,however I might have to rethink as to whether they are worth it in my Zone.They sure are beautifull though.I believe one of my plants is showing some signs of life,so fingers crossed t makes it.