A cousin of the more common herbaceous peony, tree peonies need little pruning. They are native to China, and have become popular in the West in recent years. Tree peonies are drought-tolerant plants and grow best in partial sun (four to six hours of sun per day or dappled shade all day). Tree peonies come in a wide range of colors, from white and pink to dark red. Yellow tree peonies are rare and expensive, and make an unusual garden addition.
Inspect your tree peony annually in the early spring, once frost danger has passed. Look for signs of damaged or dead branches. Damaged branches will have physical deformities or wounds, while dead branches feel light to the touch.
Prepare a sanitizing solution of bleach water in a ratio of one part bleach to 10 parts water. Dip pruning shears in this solution, then cut away a dead or damaged branch. Dip the pruners in the sanitizing solution in between every cut, and prune away all dead and damaged wood at the base.
Sanitize your pruning shears before putting them away, to avoid spreading bacteria to healthy plants. While this needs to be done annually, more detailed pruning is purely cosmetic in nature and can wait several years.
Cut away extra growth in the interior of the tree peony. Choose six to 10 dominant branches, then prune back all other branches. This allows your tree peony to put more energy into flowering (and produce more flowers). This type of pruning also improves air circulation, which keeps your peony healthy.
Trim back low-growing branches to expose the shape of the trunk, if you prefer. Having exposed wood at the trunk is the traditional Chinese way to shape a tree peony.