Avocado trees grown from a grocery store avocado seed will produce a tree, but its fruit may be different or even inedible. The tree will, however, be a good base for grafting branches from an existing, productive avocado that's producing reliable fruit. Once you've grown your seedling to a height of about 3 feet, it's time to start grafting fruit-bearing branches onto it in a process called topworking. Begin grafting in the spring when bark slips easily from the inner wood of the tree.
Step 1
Select budwood from a healthy, productive avocado tree. The best buds are located near the ends of branches that are 1/4 to 1 inch in diameter.
Step 2
Cut 6-inch lengths of healthy branch tips that each contain several buds with a sharp knife. Take six to eight cuttings, wrap them in damp paper towels and lay them in a bowl of ice to keep them cold and moist.
Step 3
Make a T-shaped cut on a branch from the rootstock tree, about 12 inches from the trunk. The long part of the T should be about 1 inch long. Make a shorter, crossing cut that goes 1/3 of the way through the branch. Twist the knife slightly to slip the bark away from where the two cuts meet.
Step 4
Go back to the bud sticks you cut and placed in the bowl. Choose a healthy bud, and cut it from the stick beginning 1/2 inch below the bud and ending 3/4 inch beyond it.
Step 5
Bring the bud back to the rootstock. Slide the long end of the bud wood into the long part of the T-shaped cut, matching the bud to the horizontal cut in the T.
Step 6
Wrap the budded graft with a rubber band, securing it above and below, but not actually on the bud. Repeat Steps 3 to 5 in different areas of the tree until you've used buds from all the bud sticks.
Step 7
Remove the rubber bands when the bud unions have healed and buds begin to open, which should be within three to four weeks.