Considering they are native to Baja, I'd be very surprised if they needed chilling.

I've linked a British website that says they do chill them if the seed was stored.

Here is a link that might be useful: Asclepias eriocarpa - Benth.

the seed comes from the Mendicino area of California which is cooler than Napa but I decide to plant afew seeds and see what happens. If they don't sprout under growing lights than I will put them in refrigerator for a few weeks.

Penny

Stick a few in a moist paper towel, roll it up, and put it somewhere warm for a few days. If a seed is going to germinate, it will do it in 24 to 72 hours with this method from my experience.