Although it is possible to grow fruits such as plums from the pit, many fruits on the market today grow from hybrid trees that were created to improve the cold tolerance and disease resistance of a tree. As a result, a tree planted from a seed or pit of a hybrid such as pipestone or superior may produce a tree that will not grow similar fruit. One way to propagate hybrid plum trees is by grafting cuttings onto plum tree root stock.
Select a branch (scion) from a plum tree that is less than five years old. Younger branches graft better than older branches. If your tree is older, select a branch from the tree’s youngest growth. You should take scions in fall when the tree goes dormant.
Sharpen your pruning shears before cutting the scion to prevent bruising. Clean the shears with a solution of 1 part bleach and 9 parts water to prevent the spread of diseases.
Position your pruning shears at a point 6 to 12 inches from the tip of the branch. Make a horizontal cut across the branch.
Store scions in a plastic gallon freezer bag with slightly-damp peat moss. Place the bag in a refrigerator that stays a contestant temperature of 40 degrees Fahrenheit.
Wait until spring when the root stock plant begins to produce buds before grafting.
Select a point on the tree to graft the scion. Scions should be grafted to a tree on a smooth surface that is free of knots and located within 4 feet of the root zone.
Measure your scion to determine which graft you will use. A whip graft is advised for scions that are less than ½ inch in diameter. A cleft graft is for scions that are 1 inch or thicker in diameter. A side graft is preferred for scions that are between ½ and 1 inch in diameter.
Cut the end of your scion in a 45-degree slash down 1 ½ inches of the scion with a sharp grafting knife. Create a tongue in the scion by making a vertical cut starting halfway down the slash and extending through the branch until it is level with the end of the first cut. Make a mirroring cut in a branch of the root stock. Press the scion into the root stock so that the two cuts align and the bark layers of both parts touch. Wrap the joining point in grafting tape. Remove the tape once the two pieces heal together.
Cut the trunk or a large branch away from the root stock for a cleft graft. Open a vertical cut into the stump or branch stub between the tree’s bark and the trunk of the tree with a grafting chisel and mallet. Take care not to split the bark in the process. Cut the scion into a blunt point with one side thicker than the other. Insert the scion into the split in the rootstock. Cover the point where the root stock and scion join with asphalt water emulsion compound.
Select a smooth understock branch and make an incision into the branch not more than 1 foot away from the trunk. The incision should extend at a 45-degree angle almost into the core of the tree. Cut the scion’s end into a blunt point with one side thicker than the other. Insert the scion into the split in the branch, making sure the bark of the two pieces touch. Cover the cut in asphalt water emulsion compound.