Jane, pot up small clematis in one gallons sized pots and use regular potting mix you would use for any container. Let them grow out until this fall at the earliest (unless you get some very vigorous clematis that might fill the container with roots by fall). I don't know if fall or spring planting is better for people in the colder zones since I live in zone 7a in NC. Some people in the colder zones think spring is a better time to plant their clematis directly in the garden and others think fall is better. I fall into the latter group since our springs turn from cool to hot in a hearbeat. Our falls are cooler, wetter, and the cooler soil temps allow the roots to continue to grow well into December.

Either way, I would give the plants as much sun as possible when they are potted up. Depending on where they are coming from, you might want to gradually acclimate them to the full sun environment. A great way to protect pots of clematis, whether in the summer or winter, is to bury the pots in the ground in well draining soil. The soil with act as an insulator and protect the plants from drying out as much in the summer than if they were sitting on top of the soil and will protect them from freezing in the winter.

Thanks for the idea of planting them in the garden in their pots. I don't know what to do with them this winter though as it can get to zero here in CT. The little potted ones I got at Lowes should have a decent root system started, but the bare roots I have coming might take longer to establish roots. Since I don't have a garage I guess I will just plant them, cover them well and cross my fingers.

If the plants will survive in your zone after normal planting, then planting them in their pots in the ground should allow them to survive over the winter as well.