I think they're OK from zones 8-11.
Just put it into a large pot and place a tomato cage
over it. When the winter come in, move the whole thing inside until the warmer weather comes in.

Rick

Here is a link that might be useful: More info here

I seriously doubt it can survive the winter in your zone. My hardy varieties that have been coming back for quite a while don't look like they made it through last winter which was unseasonably cold and I'm in zone 7a. Grow it in a container and if space is an issue you can allow it to go dormant over the winter in a cold (but above freezing) area like a basement or possibly a garage. Cut way back on watering if it's dormant. You can keep it going inside under grow lights as well but I'd cut it back to a reasonable size before trying to get it inside. I keep several tropical passies protected over the winter under HID lights. Some will continue blooming but the colors aren't nearly as vibrant as when they are outside.

I live in SWPA zone 6a. I keep mine in a 2 gal. container with a tomato cage and put it in my basement in the winter and bring it back out in the late spring. It does fine this way. I do the same with my gilberti. I planted incarnata in the ground last year and it came back, YEAH!!!
Roxanne

Thanks for all the info. I am going to repot to a larger pot and get the tomato cage. I'm opting to bring it in for the winter just to be safe.

Barb

I used to live in southern NY, zone 6b I think. I planted a P. caerulea outside and mulched over it before the cold weather set in. The next spring I waited for it to come up again...and waited, and waited, and waited

I've been told me that it will survive along the coast in CT, which might be closer to zone 7.