To sow outdoors, direct seed in late fall or early winter for emergence the following spring. Plant seeds .5 cm deep and firm soil. To sow indoors, cold moist stratify seed before sowing. To do this, scatter seed between sheets of damp paper towel, place in a zip lock bag and store in the fridge for 30-60 days. Take out of the fridge and sow seed in a warm location. The young butterfly milkweed seedlings develop a tap root (like a carrot) and resent transplanting so transplant to the final location.