When tree peonies are grafted, the nurse root and the tree peony scion are merged together as one.
; as you can see, the tree peony is only the small upper part of the plant the large root system is the herbaceous rootstock. If not planted deep enough, the herbaceous peony can take over the plant preventing the tree peony from developing its own root system (not good). The best thing you can do is let the plant grow and it will become obvious if the new growth is herbaceous or tree peony growth. They look very different. If the new growth is tree peony in origin, you are good to go. If however it is herbaceous growth, wait until the tree peony goes dormant in the fall, dig it up and remove the nurse root. Again, it will be obvious what is herbaceous, the new growth will be attached to it. I had to do this to two of my tree peonies last year. Not only are they alive and well, I planted the nurse root that I cut off and got a beautiful herbaceous plant to grow as well. Good luck and be patient. Go to www.peonies.org/grafting/ and it might help you understand the grafting process and what happens afterward.