An avocado tree (Persea americana), hardy in U.S. Department of Agriculture plant hardiness zones 9 through 12, can be grown from a seed taken from a grocery store avocado and may produce fruit eventually. After putting in five to 13 years or more of watering, fertilizing and pruning, even if the tree blooms and produces fruits, the avocadoes are likely to be different than the original fruit or, in a worst case scenario, inedible. Most avocados grown for your kitchen are hybrid cultivars, so any tree grown from the seed will be genetically different than the original tree that produced the fruit.
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The new tree will, however, be a good base for grafting branches from an existing avocado tree that's producing reliable fruit. Once you've grown your seedling to a height of about 3 feet, it's time to graft an avocado tree branch onto it to produce avocado fruit in a process called topworking. Begin grafting in the spring when bark slips easily from the inner wood of the tree.
Step 1: Sterilize Your Tools
Dip the blades of your cutting tools in rubbing alcohol or a household cleanser, like Lysol or Pine-Sol, and allow them to air-dry. Also put on safety goggles and gloves before preparing to graft an avocado tree onto a sturdy rootstock.
Step 2: Select a Budwood Cutting
Select budwood from a healthy, productive avocado tree to graft onto the homegrown tree. The best buds are located near the ends of branches that are 1/4 to 1 inch in diameter.
Step 3: Take Healthy Cuttings
Cut 6-inch lengths of healthy branch tips that each contain several buds, using a sterilized sharp knife or pruners. Take six to eight cuttings, also known as bud sticks, wrap them in damp paper towels, and lay them in a bowl of ice to keep them cold and moist.
Step 4: Cut Into the Rootstock
Make a T-shaped cut on a branch of 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 pry the bark away from where the two cuts meet.
Step 5: Remove a Bud
Examine the bud sticks you 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. The bud should also have bark and the green layer, or cambium, found just under the bark, attached to it.
Step 6: Insert the Bud
Bring the selected bud back to the rootstock. Slide the long end of the budwood into the long part of the T-shaped cut, matching the bud to the horizontal cut in the T. Make sure that the cambium of the bud and rootstock are touching. This ensures a successful graft.
Step 7: Secure the Graft
Wrap the budded graft with a rubber band or grafting tape, 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 8: Remove the Rubber Bands
Remove the rubber bands when the bud unions have healed and buds begin to open, which should be within three to four weeks. As these new branches grow and mature, avocado fruit will be produced on them.
Cat McCabe has been a freelance writer, editor, director and actor since the early 1980s. Her work has been featured in commercials, regional magazines and business publications throughout North America. She holds a Bachelor of Fine Arts in theater from New York University and is currently a contributing writer for a national quarterly.