Procure avocado seeds from ripe avocados.
image by Brybs: sxc.hu
Finding an avocado seed is as simple as visiting your local grocery store. The seeds, or pits, of store-bought avocados are perfect for planting. Choose a large, healthy avocado from which to save the seed. Growing avocados in only water is a common project for school-age children, but to grow an indoor plant and successfully keep it alive for a long period of time is best done in soil. Avocados are attractive trees that do well as houseplants and in containers.
Fill a 4- to 5-inch plant pot with porous potting soil. Choose a pot with plenty of drainage and a bottom drip tray.
Plant the avocado seed in the center of the pot with the pointed end just showing above the soil surface.
Keep the soil moist but not soggy. Place in a well-lit window and keep the room temperature between 60 and 70 degrees F.
Pinch back the stems once they reach 12 inches tall to encourage fuller foliage. Pinch off each stem with your fingers to approximately 6 to 8 inches in length.
Fertilize the plant with houseplant food every 3 weeks in summer and every 6 weeks in winter. Keep the soil moist at all times.