The next time you make guacamole, don't throw away the avocado seed. They root easily and under the right conditions will grow into a houseplant up to 6 feet high with large, oval, dark green leaves. Avocados are tropical plants that normally grow from 20 to 30 feet high. Keep your avocado plant inside during cold winters. Unlike other fruits, avocados do not ripen on the tree, but must be picked to get ripe.
Remove the avocado seed by carefully cutting the avocado in half. Don't cut the seed itself. Use a spoon to scoop the seed from the green flesh. Wash the seed under running water to remove any clinging avocado fruit. Let the seed dry a few days.
Brush off the brown papery skin from the seed. A few bits and pieces left won't hurt the germination process. The seed has a rounded end and a slightly pointed end.
Place the seed in fresh potting soil with the pointed end up under an inch of soil. Keep moist in a sunny window. The seed will sprout after a few weeks.
Start the seed in water if you prefer. Push three toothpicks in the seed so the toothpicks will hold the seed in a glass of water. Fill the glass until water covers the bottom half of the seed. As soon as the root breaks through the bottom of the seed and a stem with two leaves grows from the top, transplant in soil.
Let the soil dry out slightly between waterings, but don't stress the plant until it wilts because it may not recover. How often you water depends on temperature and humidity levels in the house or outside if the weather is warm. If the top inch of potting soil feels dry, it's time to water the plant.
Fertilize once a month with water-soluble plant food diluted to half strength. For example, if the directions say put 2 tsps. in a quart of water, only use 1 tsp.