How cold hardy is Passiflora Incarnata? I have seen it labeled as zone 6, but how accurate is that? Any passiflora even more cold tolerant?

I really want to try it but I live in Canada (Southern Ontario, Niagara region), and from what I can tell officially my location is listed at zone 6. So it seems like it should be able to grow and survive the winter. So, i' wondering if its worth trying because I don't want to care for it and get excited about something if it just dies in the winter.

How far North and how cold do you know it can tolerate? It's fairly mild here with some really cold nights sometimes, but zone-wise it's suppose to do fine, right?

If so, then how come I have never seen anyone grow it here? Is there some kind of problem with it that i'm not aware?