Spring and fall are both good times to buy and plant peonies in Minnesota. When you choose plants, consider the flower type and color you want. Peonies have a beautiful display of flowers every spring, and glossy dark green foliage that stays attractive from early spring until a killing frost.
Peonies prefer full sun all day, but will bloom as long as they receive four or five hours of direct sun daily. Plant them in well-drained soil and allow at least two feet between dwarf varieties and four feet between standard varieties.
When you plant, cover the peony roots so the pink buds or "eyes" are pointing up. Make sure to plant the top of the roots only one and one-half to two inches beneath the soil line. A common error is to plant them too deep, which means they won't bloom.
Most peonies will flower for years with little care if you plant them in a sunny area in rich, well-drained soil. For a simple border with all season color, they may be planted with spring flowering bulbs and with iris, day lilies, chrysanthemums, and hardy asters. Peonies are a versatile perennial. They make good background plants for low annual flowers.
You can divide peonies in early spring or late summer. Dig up the entire clump, then split it into halves or quarters with a sharp knife or shovel. The smaller the division, the longer it will take them to bloom again.
Do not cut down peony foliage until it is damaged by frost. Once the soil freezes, simply rake some leaves over the plants, then remove the mulch in spring.