The more I read from different sources the more I think that preparation for permanent peony spots should be extremely extensive. Next time I plant peony I would aim for at least 24 inches deep and 30 inches wide soil amendment hole. Something smaller will only provide for 3-5 years of development needs. Looking at peonies sitting in the same space for over 10 years and with well developed green mass and you realize that only stems are occupying 20-24 inches of space. Adding 15 inches for roots from each side and it makes it 70-80 inches in diameter...
