After a stratification period of 3-6 weeks, the seeds can be planted in warm (70˚F), moist soil. Without stratification, the percentage of seeds that germinate is usually low. Seeds from the tropical milkweed, Asclepias curassavica (and other tropical milkweed species) do not require this treatment. "Shocking" seeds that have been refrigerated by soaking them in warm water for 24 hours also seems to improve germination rates.
#tropicalmilkweed from @Katalin 💕