Avocado trees make lovely house plants or patio plants, adding greenery year-round. Avocado trees have 6 inch oblong leaves that grow off a straight stem. Branches won't appear until the tree is at least 3 feet tall. Avocados are tropical plants so they need to be protected from freezing or near freezing temperatures. If that sounds like your climate you need to bring your avocado trees inside for the winter.
Peel the avocado and make a salad or guacamole with the flesh of the fruit. Remove the seed in one piece. An easy way to do this is to cut the avocado in half around the seed but not cutting the seed in half. Use a spoon to scoop out the seed. The seed may have a brown papery covering. That's perfectly normal and doesn't need to be removed. Wash any remaining fruit off the seed and dry for a couple of days. Any remaining fruit will rot and may cause the seed to mold or rot as well.
Prepare the pot or container. Place one or two coffee filters over the drainage holes in the pot. Don't use a pot that doesn't have holes. Place 2 inches of gravel in the bottom of the pot. Fill about two-thirds full with potting soil.
Put the seed in the pot pointy end up. Some seeds are rather roundish rather than pointed on one end. If you can't figure out which end is pointy, don't worry about it. The seed will figure it out. It will just take longer to sprout. Cover the seed with a good 2 inches of soil. Water thoroughly. You can plant up to five seeds in one pot.
Place the pot in a sunny window. During the winter months, windows facing south or west receive the most sun. Water when the soil dries out. Test this by sticking your finger in the soil. If it's dry, it needs to be watered. If the soil is damp, don't water.
Fertilize with water soluble plant food at half-strength every month after the seeds have sprouted, which takes from four to six weeks. Turn the plant every week so it doesn't lean toward the light and become crooked. Keep away from cold drafts and heating vents. Be patient, the seeds can take awhile to sprout. If you think they're dead, gently dig down and take a peek. You'll probably be surprised to see a shoot peeking back at you.