Grafting is the process of combing two plants to form a hardier hybrid. Grafting old trees with young limbs is top working. Farmers top work citrus, apple and nut trees to extend the tree's overall productive life in an orchard.
Select a piece of bud wood from a young citrus tree. The bud wood should be roughly eight inches long with at least one leaf petiole.
Saw off two to three limbs from the adult citrus tree. Do not remove more than 1/3 of its foliage.
Cut an upside down "T", four inches in length, into the bark at the base of the removed limb with the grafting knife. Form a point at the end of the bud wood by removing some of the wood from both sides of the bud wood. Do not make this cut larger than 3 inches.
Slide the bud wood into the bark of the "T" until all of the exposed bud wood is tucked inside.
Wrap the bud wood in grafting tape to hold it in place. For the best outcome, use wax-based grafting tape, as it will stretch with the limb and fall off naturally.
Apply two layers of grafting wax with a paintbrush over the entire grafting site. Grafting wax protects the area from insects and disease.