The cool climate of Michigan can make gardening a challenge, however, peonies thrive in cooler climates. Peonies are heavily-scented perennials and can survive quite well in a Michigan garden.
Many cultivated peonies are derived from a wild species of peony, Paeonia lactiflora, native to Siberia. There are also other species of wild peony that grow throughout Europe and Asia that have been cultivated for the garden. Peonies have been grown for medicinal purposes and in ornamental gardens. In North America, they are often considered an "old fashioned" garden plant. A single plant can produce flowers for 50 to 100 years.
Michigan's Growing Season
Michigan winters are long and harsh, and the planting of peonies and other flowers must be arranged around the frost free dates. Lower Michigan is usually frost free from mid May to mid October, and the Upper Peninsula may only be frost free from early June to late September. Siberian peonies will grow well in all parts of Michigan, and warmer climate peonies can be grown in the southern parts of lower Michigan. Some varieties of tree peonies, which are taller and bushier than regular garden peonies may need protection in the winter in Michigan. Wrap burlap around the above-ground parts and spread straw or leaves around the base.
When to Plant
Since peonies flower in the early spring, it's best to plant them in the late fall. This allows the peonies to establish a strong root system in the last few warm weeks of autumn, and then be able rest during the winter. It's best to plant peonies two to four weeks before the first predicted frost, although you can plant them all through the fall so long as the ground is workable. Peonies planted in the spring may put out too much top growth too quickly without having strong roots underground to support them. Spring-planted peonies are more susceptible to disease and may take several years to recover and produce flowers.
Peonies like lots of sun and may not flower in locations with too much shade. Make sure your peonies get at least a half day of direct sunlight, with indirect sunlight the rest of the day. Since peonies compete with neighboring trees and shrubs for sun, water and nutrients in the soil, it's best to plant them where they'll have plenty of room to themselves.
Water, Soil and other Necessities
Peonies don't like having wet feet, and need to be planted in well-drained soil. They generally don't need fertilizer, and over fertilized plants may not blossom well. A handful of compost or aged manure added to the bottom of the planting hole is usually all they need. Cover your peonies with a layer of straw to protect them during their first winter, but once they are established they won't need winter protection.