Mary, I know for sure that Orion does not self sow. I am not sure about Espresso though because that is a new one for me. I also really like Havana Blues but this one sprawls and blooms from July to fall which does not coincide with blooming peony season. I am sorry but I don't know much about clematis hardiness. You maybe right that some clematis are not be hardy for your zone. The one that I have, Little Duckling is hardy to zone 4. Looks like most Proven Winners clematis are hardy to zone 4. They are 5-6ft tall but if you wrap around a support structure, it can be maintained at 3-4ft.
