The large seed inside an avocado can be used to graft avocado trees. The small seedling you will use to graft is known as a scion. You can either create scions from avocado seeds or cut them directly from avocado trees. Grafting avocado trees from seeds is most successful during the spring months, and yields trees that produce avocado.
Place four to eight toothpicks in the avocado seed. Fill a small dish with warm water. Hang the avocado seed in the center of the dish, using the toothpicks as support. Place in a partially-sunny location. Repeat with each avocado seed.
Empty the water dishes weekly. Allow the avocados to sprout roots and grow seedlings.
Transfer the seedlings to potting soil when they are approximately 1 foot tall. Allow the seedlings to continue growing until it is a minimum of 2 feet tall.
Select your strongest seedling to use for your grafting base. This seedling should be the largest and sturdiest one of the seedlings grown from the avocado seed. Cut all the leaves and growth off of this seedling, leaving you with a bare, strong center stem.
Cut one of the other seedlings at the base with a knife. Make a 45-degree angle-cut at the base of the seedling stem. Cut a small incision in the grafting base branch (from step 4). Insert the scion into the branch joining the two areas that were cut.
Wrap grafting tape around the two plants to join them. Repeat steps 5 and 6 with up to four scions on one base.
Water regularly and keep the plant in an indirect light location. Allow the scion to join to the main plant for 3 weeks. Remove the tape.