Tree peonies are relatively slow to establish. That depends on what type of soil you used last year. Pick up a handful and squeeze it. If it springs back, go ahead and use it again. Having good soil in containers makes a tremendous difference.
Soil needs to hold air, water and nutrients as well as support the root systems of the plants.
If you have any doubts, start with a fresh mix. Lots of gardeners are having great luck with both fox urine to repel rabbits and coyote urine to repel deer. There had been some concerns about heavy metal concentrations in Milorganite, but it meets all the regulations on metals and the product is tested daily to make sure it stays that way. Many golf courses and parks have turned to Milorganite as a safe, effective alternative to synthetic fertilizers. Actually, the soil is now warm enough and we should have them available this weekend.