Tree peony_ Graft or seed ???

O.K. I'm getting conflicting information.Can you truly start tree peony from seed? I was at a freinds house this weekend and he has 6 tree peony.There was a yellow one he didn't like so he dug it up and COMPOSTED it(I died ,wish I had known he was going to do that)Any how,He did't get the whole root out and the leaves from the root stock it was grafted on keep popping up.When I asked him if he has ever started any from seed he said no,they have to be grafted. Grafted on what??A regular peony root stock?Are they not hardy if they are not grafted? Can a normal person take a piece of tree peony and graft on to a rootstock?If you grow one from seed does it then have to be grafted on to something?Or is it then a viable healthy gunna bloom some year plant?

Don't know anything about grafting, but Plants of Distinction have had seed for Chinese Tree Peonies in their catalogue so they can be grown from seed. They also sell plants, and they're really expensive, so it's a toss up whether you want to pay money for a flowering one or wait for years to get flowers from seed.

Checked in the RHS Encyclopaedia: Sow seed in containers outdoors in autumn - may take 2-3 years to germinate. Take semi-ripe cuttings of tree peonies in summer or graft in winter.

I should visit your friend again with a pair of scissors and a plastic bag.

I know they can be started from seed,but I guess what I'm asking -is the seedling hardy or does the seedling need to be grafted to a hardy rootstock to be a hardy plant.Why graft if they can be started from seed? Is it to make more plants quickly or some other reason?I know they don't bloom for 3- 5 years if started from seed- is that why they graft?