Seeds must be ripe to be viable...so, I seriously doubt they are ripe enough in your zone..I will provide an awesome website that Brian Collingwood create just for people like you that are interested in growing clematis from seed..He is just fabulous and so knowledgeable...Hope this helps...Jeanne

Here is a link that might be useful: Brians site for growing clematis from seed

The new plants wouldn't come true from the seed. Plus, it is far easier to air layer one of the vines.

http://www.ces.ncsu.edu/depts/hort/hil/hil-8701.html