Some peonies like “Zhao Fen” (Paeonia suffruticosa “Zhao Fen” or “Zhao’s Pink”) can grow to a height of 3 to 6 feet (0. 9 to 1. 8 m) and width of 2 to 4 feet (0. 6 to 1. 2 m). Two smaller, more suitable options are “Zhu Sha Pan” (Paeonia “Zhu Sha Pan” or “Cinnabar Red”), which grows to a height and width of 2 to 2 ½ feet, and fern leaf peony (Paeonia tenuifolia), which grows to only 1 to 2 feet (0. 3 to 0. 6 m) tall and 9 to 16 inches (22. 9 to 40. 6 cm) wide.
Larger varieties will require an even larger pot. The container must also have several drain holes in the bottom. Gardeners should also note that these plants respond badly to being transplanted and should start out their lives in large containers. Therefore, a 5 gallon (18. 9 L) size pot is ideal for peonies.
When the potting mix is at the right depth, mix water into it until it is thoroughly moistened.
In the spring, adding some slow-release low nitrogen fertilizer to the peonies is also recommended. This will help keep them healthy and encourage blooms but will not burn the plants as other types of fertilizer might.
Gardeners should err on the side of caution in such cases because peonies that are buried too deep will not bloom. Specimens that are producing lush foliage but no flowers may have to be dug up and reburied to appropriate depths before they begin to produce blossoms.
If the peony is to be grown indoors, put it in front of a south- or west-facing window where it will get plenty of direct sunlight.
Set up the fixture so that the bulbs are about 6 inches (15. 2 cm) above the peony and leave it on for 12 to 14 hours each day. The light should be plugged into a timer that turns it on in the morning around sunrise and turns it off at the end of the day.
It is important to use houseplant fertilizer as opposed to fertilizer for garden-grown peonies since it is being grown in a container. A water-soluble fertilizer is best. Always give it the fertilizer after a regular watering. Stop giving fertilizing around mid-summer.
If the peony is being grown indoors, slowly reduce the number of hours of supplemental light it receives to coincide with the shorter days of autumn. If the peony is outdoors, leave it out until after a few hard frosts.
Set the pot in an unheated garage or cool area in the basement. Bring it back out in the spring when the weather warms. Put it outdoors in a sunny spot or in front of the window and water it generously.
