I did not have luck last year with clems...I read that sometimes they can take over a year to germinate...right now I have some in wet coffee filters in the fridge that have been there since November and nothing germinating yet...you could try googling 'clematis germination table' and look up the varieties you have...I think there is much variation in germ times. Good luck and happy winter sowing, its a blast!

Hi Lisa:
I also have received Clematis seeds in some of my trades, but I looked up growing them from seed as found out that they take a year or more to germinate, and need lots of care to survive to the blooming stage. It was not recommended for impatient gardeners like me, so I have abandoned the idea of growing them from seed, and am prepared to try growing from a cutting or shelling out the money for a plant from the garden centre.
Northerner.

Clematis Tangutica (same as Radar Love) will sprout the first year. It is one of the only reliable Clematis to do so. I winter sowed it 3 years ago and the second year it started taking off. Last year it went up 8 feet unto the deck and started taking it over. :) I'll have to cut it back this spring and start training it as it comes up. It needs discipline!

I also have another at the bottom of a birch tree where it gets full sun all day and the soil is rather dry. That one is still chugging along and starting to climb the small birch tree.

Thanks everyone. I'm thinking I might just stick to the Radar Love since I am more likely to actually get results from that... I'm not one for delayed gratification. Part of the problem as well is that I don't really have a safe area where I can sow the others and just leave them be for two seasons waiting for them to germinate.

Thanks again!
Lisa