Starting an avocado plant from seed is a novelty project for the home gardener to produce a viable fruit tree. The avocado seed (pit) produces fruit, given proper growing conditions, in four or five years. Purdue University states the avocado tree may reach a height of 30 feet.
Clean the avocado pit thoroughly to remove any leftover residue from the fruit. Decaying residue contaminates the growing medium, exposing the avocado pit to disease. Do not remove the brown skin of the pit.
Locate the bottom end of the avocado pit. The bottom will appear more rounded than the top. It is important to make sure the seed is in the right position for rooting.
Insert four toothpicks at uniformly equal positions around the middle of the avocado seed about 1/4 inch deep. Fill a glass jar with water and suspend the avocado pit on the rim of the jar so the bottom half of the pit is submerged in the water.
Set the glass jar with the suspended avocado seed in a bright location. Maintain the water level so the seed does not dry out. Change the water every two to three days to keep bacteria from building up and killing the seed.
Watch for the avocado seed to split at the bottom and send out a taproot. The top splits next, sending out a shoot which resembles a curled up leaf. Continue to maintain the water level and water changes, taking care to disturb the root as little as possible.
Transplant the avocado plant into a growing container filled with a quality potting soil by making a hole in the middle of the soil and placing the plant there--leaving the top half of the pit exposed. Water the plant thoroughly and sit the new plant in a bright location. Continue watering as needed.