Allan Rogers, a well-known peony grower, in his book Peonies, published by Timber Press in 1995, states that "Peonies are among the least demanding of all perennials. Successful peony growing requires little more than good drainage and a climate with weather cold enough to satisfy dormancy requirements—with a bit of fertile soil thrown into the mix for good measure."
Peonies should be watered well when new growth emerges in the spring. Subsequently their needs for water are moderate. Continuing care consists of weeding, and protecting them from fungus diseases such as botrytis and Cladosporium blights. Application of a copper-based fungicide, like Bordeaux mixture when new growth emerges, and again if signs of blight appear is usually effective. Some heavy-flowered peonies may benefit from staking.
Peonies flourish in hardiness zones 3 through 7. They grow from tubers, underground food storage roots which put out their feeder roots in the fall before the ground freezes, and continue to develop after the leaves die back. This is considered the best time of the year to divide old clumps or plant new tubers.