Unless you have a LOT of patience, I wouldn't recommend growing them from seed. It can often take 1 or 2 years for the seeds to germinate and then about 5 more years to get blooms. You would be better off just buying the plant.
Absolutely gorgeous. I love it. I hope it wasn't damaged in the hail storm. I have peonies but no tree peonies because of money issues. So far I have 3 plants that have put out buds and one plant that has disappeared. The others are still growing but not flowering yet. I'm always excited about the peonies.