I want to grow milkweed for butterfly.
Growing Milkweed in Flower Pots Can It Be Done and When to Start in NY
Certified GKH Gardening Expert
Yes, this can be done relatively easily! You can sow them indoors at anytime in a bright south facing window, but I always recommend horticultural lighting for complete control of the lighting they receive.
If you want to put them into containers, you may. They will do best with one plant per container, and they will survive happily in a two gallon pot.
You can put these outside after the threat of frost is gone. This article will help you with further care of these plants, which will also pertain to container gardening in this case: https://www.gardeningknowhow.com/ornamental/flowers/milkweed/growing-milkweed.htm