People who actually live in Zone7 may have better ideas than I do, but I'd think if you plant it near the base of a building, like your house, garage, etc., then it could spread roots underneath the building. Of course, it'll also spread roots in every other direction - p. incarnata always does - so you'll end up with volunteers all around the original plant, but at least having some roots under a building would keep some of them alive for sure.
It got down to the upper 30's here last night, and it's supposed to go down to the mid-30's tonight - I don't remember it getting this cold this early in a long time. If the weather is colder than usual where you are, then that building for your passi roots would be extra important.
Sherry

First off, try and get one native to your area. Incarnata from southern states aren't as cold-hardy as those native to more northerly climes. Secondly, plant it in a well-drained area. Persistently wet roots can kill the plant any time of year, but they seem more vulnerable during the winter.

Incarnata is generally a very hardy plant that will suffer lots of abuse once established. You shouldn't have too much trouble once it's started.

In zone 7, you will not have to do anything once it is established. In fact, I doubt you will ever be able to get rid of it once it gets going. It grows here like a weed. Are you starting with a potted plant or seeds? I would strongly suggest you don't plant one now, but wait until spring. They really need to get established in order to over-winter well.

Thanks for answering! I was not planning on planting until next year (I wanted to figure everything out first). I had planned on using potted, is there any reason not to? Also, I was not going to plant them by a building, but by concrete; will that work well enough to insulate them? Lastly, are there any tips or anything else I should know about Incarnata before planting?

Genlisea, I have one other suggestion for you. Unless you have a local nursery that you really like to support, you might consider trading other folks here at GW for your plant rather than spending $$. You'll probably save money by just paying for postage, and deal with people who are more knowledgeable about passis than most retail nursery people.

For example, I've got three different types of incarnata growing in my yard, but two would probably be a very bad choice for you since they're more cold-sensitive. I have one that might work for your situation, but you'd be even better off talking with kiwinut, since his Tennessee native passis can likely tolerate far more cold weather than you'll ever have in your zone.

I had one more question; how much area would it spread on a six foot fence?

How long is the fence?

Genlisea, I have my passion flowers on a 5 foot high chain link fence and they were spread out over 50 to 60 feet last summer and loaded with flowers. My plants are out in the open and I have never had a problem with them freezing. Good luck!