Mindy, read about my experience with Florida seiboldii and its relative Viennetta in this thread... It might give you an idea.
Note that Buyorsell tried to grow them in zone 8.

I have seen various different claims for zones on this one. Most of the claims were for zone 7 or above, sometimes zone 5, but this is a first for zone 4. Actually I think zone 4 is an error. I have this in a pot in zone 5, first year overwintered it in the house, I was so scared it would die. Now I keep it in the garage and it has overwintered great. This is year 3 and it bloomed like crazy this year. I gave it bloom booster and fish emulsion fertilizer.

The one I bought this spring has died too before I could even plant it. We had some late frosts. I have had terrible luck with both Florida seiboldii and Cassis (another one of the Floridas like Vienetta and Peppermint). Two mail ordered Cassis were DOA and one mail ordered Florida seiboldii was too. Two locally purchased seiboldii died.

Spoke to the curator of the Rogerson Clematis Collection and she said they need extra good drainage that it is our rain that kills them in winter not cold but they are called hot house Clematis in England so that should be a clue to their hardiness. They had issues with mail orders too, posted recently on their Facebook page when they posted a picture of their Cassis.

888, as my mother would say, in all facetiousness, "888, you are a goddamm JEWEL!!" And how very helpful that you spoke with the head of the collection(where is that, btw? website?)and referenced the england point.(btw, i'm thinking that england and portland have alot in common, and it seems like difficulty growing this clem. is a manifestation of that climactic sisterhood.)?
from you i have learned:
-no matter anything else, give it wicked good drainage
-don't be surprised if it dies
-feel lucky if it lasts long enough to be an annual.

sunny, dare i be excited that mine might actually live if treated like yours? do tell us your location (and add it to your i.d.!!) so i can relate to your hopeful info.

personal experience and professional references: to me, these combine to make the very most helpful info here on GW,
so i am really thankful for you two posting.

depending on sunny's response, i'm thinking to sink its 1 gal. plastic pot (it appears to be just a 1-2 yr baby though it has 10 blooms on it.)into a large glazed pot of soil, and bring that onto the screen porch, heavy mulched, for the winter. another GW poster on another thread- said that they had better luck growing on baby clems in their pots and then planting them in the ground after a yr or so.

best,
mindy
www.cottonarboretum.com/

Gosh, I am wishing I didn't buy FS this year. I had no idea it was so fussy.

I live in midwest. I have it in filtered sun in a sheltered area in a deep pot. I keep it moist but probably don't water more than once or twice a week. I have wondered what would happen if I plant it in the ground but have been afraid to try.