I bought some amsonia plants a few years ago. They come back every year and they are beatiful. This year I noticed that they had set seed. Can I grow them from seed? If so, how?
Sure! This article will help you to do so, with some patience:
https://www.gardeningknowhow.com/ornamental/flowers/amsonia/how-to-plant-amsonia-seeds.htm
I plan on transplanting about October 15th.
Fall is a good time to transplant shrubs, especially spring-blooming plants. You are in hardiness zone 4, so I'd recommend transplanting as soon as possible, so it has time to settle in before the frosts start.
https://www.gardeningknowhow.com/ornamental/shrubs/shgen/best-times-for-transplanting.htm
https://www.gardeningknowhow.com/ornamental/flowers/amsonia/moving-amsonia-plants.htm