I used to live in central Ohio, zone 5b. My soil was yellow potter's clay. When it was wet, you could literally twist it into a rope and it wouldn't break. When it was dry it was as hard as cement with cracks over an inch wide and 8+ inches deep. It was moderately alkaline and would eat compost and spit out more clay. In the early 90's I bought a bare root twig of a tree peony that was no more than 10" long, root included. It was sitting on the shelf in a small box at Sears Hardware. I thought it was mighty expensive - I think I paid $7 or $8 for it. LOL Twenty years later it was 5 feet tall, over 5 feet wide and had over 120 blooms in spring. Each bloom was 8-10" in diameter.
I never gave it any fertilizer other than homemade compost. I gardened organically but never had any problems with disease or insects so that was easy. The dreaded Japanese beetles never bothered it but of course it was done blooming before they showed up. Each fall I mulched all my beds with a couple of inches of shredded leaves after the ground froze. I never gave the tree peony any additional protection. It was located in a bed at the NE corner of the house so it got sun until early afternoon. I only pruned to remove the tips of branches that died over the winter, to remove crossing branches and to shape it.
Your tree peony looks like it has some sort of nutritional deficiency, possibly a lack of iron. It is definitely too close to the house. Even though tree peonies are supposed to be difficult to transplant, I think yours is small enough to handle it and it is definitely not in a good site now. I would recommend moving it this fall. If you wait until spring it will have to contend with hot weather while still trying to get established. In fall, the soil remains warm for a long time so the roots can continue to get established even after the top has gone dormant. Choose a site where it will get morning to early afternoon sun. Make sure it is not getting the hot afternoon sun. Make sure it is not competing with tree roots and that it is getting adequate air circulation. Two hours of sun is not enough and if it is afternoon sun it will be harmful. Mostly dappled shade or shade will probably reduce your bloom count. Be sure to dig a large hole and amend the soil well with organic matter. When you dig the peony up, try to dig as large a root ball as you can. The less you disturb the roots, the better. Water it well, and make sure the soil stays moist until the winter rains take over. Do not mulch until the ground has frozen - you don't want to encourage the local rodentials to move in and snack on tender roots during the winter.
Tree peonies are absolute show stoppers when they are healthy and blooming and they are beautiful shrubs even when not in bloom.
Mine was Hana Kisoi. It was more of a shell pink than it appears in my pictures. I recently googled it and found it is considered somewhat rare and I can buy a 3 year old root for $100. Sigh. I'm pretty sure my old one wouldn't have survived the move to Western Washington.
