Prune peonies during the fall by using clippers to cut back dead stems, just above a healthy bud, all the way to the ground. Pick off or clip stems that have disease or insects when there is a problem at any time during the year. Additionally, remove peony branches that have sustained damage from the winter weather in the spring.
Typically, peonies do not need a lot of pruning, but doing so helps the shrub keep its shape and promotes growth, as well as the desired look. In addition to pruning at the times listed above, look for two branches that are crossing each other and rubbing together. When this occurs, remove the branch that’s in the worse shape. In doing so, insects and diseases are prevented from finding an entry point to infest the plant.
Control the size of the flowers by removing specific buds. For example, if larger buds are desired, use small clippers to remove the buds at the tip of the stem on the side of the branches. The peony produces one large peony at the top of the stem when pruned in this manner. Leave the buds on the sides of the stems if smaller flowers are more desirable.