Here is a link to the detailed milkweed germination guides developed by the University of Texas at Austin.
Hundredfold Notes: we raised many milkweeds for nursery stock with a quick and easy method. That is throwing the seeds on the ground without even burying them.
The trick is, you have to do it at the right time: fall or early spring. Otherwise, you may have to follow the instructions.
The featured image shows a swamp milkweed growing from seed from our Toronto garden.