You can plant them now- they will be more cold hardy in the ground versus a container. Will be approx. 2' tall and wide. You said the right requiurements: dry and sun. They don't like being in pots as a general rule. This holds true for most dry species. I would try and mass them if possible. Think about adding native grasses and cactus to the mix.
Hope this helps. I know of a terrific nursery specializing in S.E. natives.

Here is a link that might be useful: Nearly Native Nursery

Thanks for your comments. I have now planted them, so we shall see. I do have two Conradinas that have been in pots for a few years. I am almost afraid to put them in the ground as they have done quite well so far. I imagine, if the others do ok where I have planted them, that I will move the other two over there. Thanks also for the link although I know about his nursery. We were negotiating some trillium this summer, but with the heat and no rain, we have postponed my request/order until this coming spring. My next project is to gather together all of the potted plants that did not get planted this spring so that they can more or less protect each other...and let the leaves cover them. I have done this in the past and usually have good luck with their returning the next spring.