If you want to start milkweed from seed, the easiest way is to mimic Mother Nature and sow your seeds in place in fall after the first killing frost (typically in November).
This allows the seeds to go through a period of cold stratification over winter and then germinate in spring.
But if you live in a warm zone without frost, or if you want to start milkweed seeds in spring, you can cold-stratify the seeds in the refrigerator.
Simply put the milkweed seeds in a damp paper towel or paper coffee filter, place it in a resealable zip-top bag, and refrigerate in an out-of-the-way spot for about 30 days before planting out.
Once the seeds have been cold-stratified, you can sow them directly outside or start the seeds indoors for transplanting later. Milkweed seeds may take up to two weeks to germinate, so be patient!