The avocado's deep green, glossy foliage and edible fruit makes the tree popular among gardeners, according to Texas A&M University. It can be grown anywhere as a houseplant and outdoors in areas that are frost-free. Instead of buying an avocado sapling in a nursery--an often expensive endeavor--start your own avocado plant by sprouting a seed collected from a ripe avocado fruit.
Cut open a ripe avocado with a knife, being careful not to slice into the seed in the middle of the fruit. Ripe avocados vary widely in size depending on their variety but typically have a dark green to purple hue and feel soft to the touch.
Remove the seed from the middle of the fruit. Rinse it under cold running water to get rid of any clinging pieces of avocado flesh.
Insert four toothpicks into the avocado seed. Arrange the toothpicks halfway up the seed's side in a horizontal line around its circumference. Space each toothpick apart by an equal distance. The end result will look like a cross with the avocado seed in the center of it.
Suspend the avocado seed on top of a water glass so that the toothpicks are holding it up in the center of the rim of the glass. The pointed or narrow end of the seed should face up, and the wide end should rest in the glass.
Fill the glass with water until the bottom 1/4 of the seed is submerged, according to Iowa State University.
Replenish the water as needed to keep the bottom 1/4 of the seed in the water. The seed will germinate within four to six weeks, according to Purdue University.
Transplant the sprouted seed into a gallon-sized pot once the seed's roots are about 2 inches long. Fill the pot with one part peat, one part perlite, and one part standard potting soil and bury the seed so its sprouted top is level with the surface of the soil.
Move the pot into a sunny location. Water the pot so that the dirt at its bottom is moist, then hold off on watering until the top inch of soil feels dry to the touch. Fertilize the avocado seedling once a month; the University of Iowa suggests using any fertilizer labeled for use on houseplants.