The peony flower's vibrant colors have been enjoyed for centuries, and it's one of the easiest ornamental plants to grow in North America, according to Kansas State University. Though peonies are traditionally raised in the ground, homeowners with limited garden space or who want to bring peonies onto a balcony or into a home can grow the flowers in containers.
The bigger the container, the better, recommends Martin Page in "The Gardener's Peony." Start with a container that's at least 2 to 3 gallons in volume, and monitor the flower plant's roots. The peony needs transplanting if roots begin appearing at the surface of the potting soil that borders the edge of the pot. Keep in mind that peonies live for over a hundred years and will continue growing during this time, according to the University of Illinois.
Peonies require well-drained, rich soil for optimum foliage development and blossom production, according to North Dakota State University. Start with a standard potting soil labeled for use with flowers. Combine two parts potting soil with one part aged compost--compost adds organic material, which boosts moisture retention, and micronutrients to feed the peony's roots--and one part vermiculite or perlite. Vermiculite or perlite ensure proper drainage.
Peonies are relatively heavy feeders and need fertilization once a year to ensure proper growth, according to North Dakota State University. The university recommends mixing a couple inches of well-rotted manure, available from most garden stores or nurseries, into the surface of the potting soil. In the spring, add 2 tablespoons of liquid 5-10-5 fertilizer to one of the plant's regular watering sessions. If you prefer granular fertilizer, the University of Vermont suggests using a 10-10-10 or 5-10-5 dry fertilizer, applied according to its labeled guidelines since potency varies by product.
Peonies naturally enter dormancy at the end of August, according to Kansas State University. If you live in a warm climate, a cool season must be simulated or the peonies will not emerge from dormancy. Place the entire plant in the refrigerator until February or March. Ideally, the plant's temperature should be brought as close to freezing as possible without actually freezing.