In North Dakota, the best time to plant peony roots is between September 1 and October 15. You can also plant in early spring using roots you have stored in dry peat moss or sand. The gardener who plants peonies will have a beautiful display of flowers each spring. Peonies also have dark glossy green foliage that remains attractive from early spring until a killing frost. To form a simple perennial border for all season color, plant peonies with spring-flowering bulbs, iris, day lilies, chrysanthemums and hardy asters.
Peonies are also good background plants for low annual flowers.
Plant peonies in well drained soil where they will get at least a half day of full sun. However, full sun, all day is preferable. Allow at least two feet between dwarf varieties and four feet between standard flowering varieties. Do not plant the roots too deeply. This is one of the most common causes for failure to bloom.