Grafting includes joining two or more different trees together so they bond and grow as a single tree. This method of asexual propagation is usually done to form a new breed altogether, or to help weak cultivars root well. Ornamental trees are grown specifically for aesthetics rather than fruit, nuts or wood. The part that forms the stem and branches is known as the scion, whereas the bottom part that forms the root system is called the rootstock or simply stock.
Practice a few cuts on a branch of the tree you are grafting to the rootstock to master the technique that requires speed and precision. Cut a ¼-inch-wide branch. The thickest part of this branch forms the rootstock. Make a 1-inch sharp cut through the center, without splitting the limb.
Separate the scion from the rest of the branch on which you are practicing with a straight cut. Position the knife at the top of the cut and remove a thin layer of bark to cut the scion into a wedge. Make sure the cut is straight and sharp, as jagged edges impede the proper union and the graft can be a failure. Repeat the cut on the other side of the scion to form a wedge with a blunt tip.
Practice on a few branches until you learn to form a perfectly shaped scion within minutes. The layer of cells beneath the bark, called the cambium layer, should be exposed only briefly to prevent it from drying out.
Select a healthy rootstock that is the different variety of the same tree from which you will select the scion. Make sure the rootstock is up to 1 inch in diameter.
Remove the top of the tree you want to use as the rootstock and remove any foliage. Make a sharp vertical cut in it, and prepare one to two scions, depending on the thickness of the rootstock. Make sure the scion has three buds.
Separate the cut you made in the rootstock with a wedge or knife. This cut is known as a cleft, and the graft is a cleft graft. Slide one scion into the cut if it has the same diameter as the rootstock, and two if the rootstock is larger in diameter. In such a case, insert each scion at the outer edge of the cleft so the barks of both the rootstock and scion are in line with each other.
Wrap polyethylene tape around the graft to secure it and assist both the pieces to grow as one. A callus will form around the graft in 4 to 6 weeks; it will split on its own.