The Itoh Paeonia peony is named after the man who is credited with having crossed the herbaceous peony with the tree peony. Itoh peonies are sometimes referred to as "inter-sectional hybrid peonies." Itoh peonies resemble the tree peony but die back each autumn. They can grow to 36 inches tall and are hardy in the USDA Zones 3 to 8. Plant an Itoh peony in full sun and provide it with well drained, fertile soil.
Prepare the planting area by turning over the soil to a depth of 12 to 16 inches. Remove all twigs, rocks and weeds from the area.
Dig a hole that is 12 to 16 deep and about 16 to 24 inches in diameter. From the soil you just removed from the hole, mix two parts compost, and one part peat moss together into the soil. Scoop in the mixture of soil into the previously dug hole until it's about half-full.
Place the bare root peony into the hole and spread out the roots onto the soil. Make sure the crown of the plant (according to the National Gardening Association, the crown is where the stem and roots of a plant meet) is sitting about 3 to 4 inches below the level of the surrounding garden soil. Remove, or add, soil if necessary until the peony is sitting at the correct level.
Scoop in soil around the roots of the Itoh peony carefully, tamping it down gently as you go. Pour 1 to 2 gallons of water into the hole, but let it drain away before proceeding. Scoop in more soil to fill the hole full and tamp it down gently all around the planted area.
To keep moisture in, weeds downs and keep the root system protected during periods of cold, spread a 2 to 3 inch layer of wood chips or straw (or similar material) for mulch around the planted area. Water the Itoh peony thoroughly.