Peonies live for decades. In the garden bed they require very little care once planted. Container-grown peonies require more maintenance but they also provide you with the freedom to move the plants and change your landscape design each year. Tree peonies have smaller roots which makes them more suitable for containers than herbaceous peonies, but both can thrive with the proper care.
Peonies have large root systems so small containers and pots will not work well. For single plants, a 5-gallon or larger container is usually sufficient. Half barrel planters provide an attractive and suitable large peony container. If you must move the peonies throughout the year, consider placing the container on a small wheeled cart. Large containers are otherwise heavy and difficult to move without disturbing the plants.
In garden beds peonies thrive in moist but well-drained soils. The plants require the same thing in a container so choose pots with predrilled drainage holes in the bottom and use a quality potting soil that is rich in organic matter. Containers dry out more quickly than garden beds, so check the moisture in the soil daily. Water when the top inch begins to feel dry. When watering, provide enough so that the excess drips from the bottom of the container. This ensures that the soil in the root zone receives enough moisture.
Container-grown peonies need regular fertilization. Soluble plant foods work well, since the excess is washed out of the soil at each irrigation. A balanced liquid fertilizer applied every four to six weeks when the plants are actively growing provides enough nutrition for the plants. Follow label application rates and avoid applying more fertilizer than that recommended on the package.
Peonies require a period of cold in order to break dormancy and flower each year. Unfortunately, the soil in containers freezes solid in colder climates, which kills the peony tubers. Bringing the containers inside prevents the cold treatment from occurring and the peonies won’t bloom. One way to provide the proper cold but prevent freezing is to move the peonies to an area that is sheltered from freezing but is unheated. Enclosed porches, sheds and unheated garages work well.