There are three popular types. Herbaceous peonies (figure B) die back to the ground in the winter and are the type most folks are familiar with. The herbaceous peonies bloom early to mid summer in most places. The second type of peony is the tree peony, which is a woody-stemmed shrub that loses its leaves in the fall. You can expect blooms from these beauties in the spring (figure C).
Finally, intersectional peonies are a cross between tree and herbaceous peonies (figure D). For years hybridizers were unsuccessful at crossing the two until a Japanese nurseryman finally got it right. The results opened up a plethora of peonies for folks who thought they couldn't grow them.
"I'm a great fan of them because they're more disease-resistant and more rigorous," says Rogers. However, there is one caveat to growing peonies. They require a period of dormancy so the plant can store energy to grow and bloom the following year. In this case, dormancy means cold temperatures. Peonies typically do poorly in places like Georgia, southern California and Florida. A peony has to have about 400 hours of cold--not freezing--temperatures, about 40 degrees. Containers and north-side plantings are common tricks for warmer locales. But ensure three months of dormancy for productive plants next year.
After 10 or so years of growth, you may notice smaller flowers and crowded stems. This usually means it's time to make more peony plants. "The right time to divide peonies is in the fall," says Rogers. "By that time they've finished their year's growth and have started to go dormant."