Tree peonies are not actually trees, but 4-foot tall shrubs with flowers the size of dinner plates that bloom in late April and early May. Native to mountain regions, tree peonies grow well in partial shade and slightly basic soil. These unique shrubs occur when you graft a woody peony onto an herbaceous garden peony. Knowledge of what to use for grafting and how to perform the graft will help you produce an attractive addition to your landscape.
Take a scion from an existing tree peony in early August. This is the piece that makes up the top of the graft. Cut straight through the branch, including two or three buds.
Choose a rootstock (the bottom section of the graft) from an existing herbaceous peony that is about the same diameter as the scion. Herbaceous peonies have stems that die back in the winter, while tree peonies do not. Measure about 8 inches of root and cut clean through.
Soak the root and scion in a solution of 1 part bleach and 10 parts water. Rinse them clean with water. Sanitize all tools and surfaces you use as well.
Cut the bottom of the scion at a 30-degree angle. This is the beginning of the wedge cut. Flip the scion over, with the cut facing down. Make a mirror cut on the other side, ensuring it has the same surface area as the first one.
Slit a sliver of wood from both the top and bottom of the rootstock. This will remove any bleach that penetrated the root. Cut a cleft on the top of the rootstock to match the wedge cut you made on the scion. Try to make it the exact same size as the scion cut.
Fit the scion into the rootstock and wrap the graft with rubber tape. This will create a waterproof seal for the new graft.
Place the grafted tree peony in a plastic bag with paper towel that is just moist. Leave the graft in a warm place, such as on top of the refrigerator, for one month to six weeks, allowing it to heal.