New tree peony plants should be planted 5 feet apart on center, and approximately 2.5 feet from any edge.
Start by digging a hole at least 2 feet deep and 1 foot wide. This will seem like a huge hole, but it is necessary for root growth and drainage. Your tree peony prefers to be planted and left in one location for generations, so it is worth taking the time to do it right. Amend your soil, as mentioned below.
Tree peonies should be planted deeply.