What are the conditions for starting Milkweed seedlings?
All may not be lost. It's best to start milkweed seedlings after a killing frost. I'd keep the seeds in the pots and sink the pots into the ground and put a marker in the pots so you will be able to see any growth from the pots in the spring. In a way, it might be better that the seeds haven't come up as the young seedlings would be suseptible to frost. I'd also save some seeds and wait until a killing frost to do the same thing. If you wait to sow the seeds after a killing frost, the seeds will be ready to grow early in the spring. And seeds often germinate better in cool soil, which may be why the seeds that you planted haven't germinated. You don't need to sow the seeds deeply, just a surface planting, covered with soil. Good luck.