The peony tree (Paeonia suffruticosa) is not actually a tree but a small growing, deciduous shrub that is indigenous to regions in northwestern China. It can grow to between 3 and 6 feet tall and produces large, 10- to 12-inch wide flowers in early spring that come in pink, purple white, red and yellow colors. Plant peony trees in good draining soil and make sure they are provided plenty of room to grow.
Dig a 2 foot wide by 2 foot deep planting hole in the middle of the planting site. Do this for each of the peony trees you are going to plant. Keep the planting holes 8 to 10 feet apart.
Amend the soil in the planting site according to the type of soil. If it is sticky and heavy, mix into the soil approximately 1/2 to 1 cubic feet of aged manure, or perlite. Mix in sphagnum moss or dehydrated plant-based compost if the soil is light and sandy.
Apply a high-phosphorus fertilizer, such as 0-4-0, and incorporate it into the soil in the planting sites, as suggested by Sunset Plant Finder. The use of a phosphorus fertilizer will encourage plentiful blooms, as well as strong root growth. Read the label and follow the spread rate as suggested by the manufacturer. Do this 3 to 4 days before planting the peony trees.
Cut along the sides of the peony growing container, beginning at a drain hole, moving up to the rim of the container, using a pair of all-purpose snips. Do this at every drain hole until you can peel the plastic back and remove the peony tree from its growing container.
Spray water around the root ball to remove about 1 inch of soil from the root system. This will encourage the formation of new root growth.
Place the peony tree into its planting hole. Look for the graft line which is usually indicated by a slight bulge, or gray line, at the base of where the stem meets the root system. The peony tree should be planted with the graft line 6 to 8 inches below the level of the topsoil. Remove the peony tree from its planting hole and scoop in, or remove, soil until you are sure it is sitting at the correct height.
Scoop in a few shovelfuls of soil to secure the peony tree in the planting hole. Fill the planting hole full with water. Scoop in soil once the water has settled away until the hole is approximately two-thirds full. Pour 2 to 3 gallons of water into the hole and fill the remainder of the hole full with soil as soon as the water has dissipated.