To sprout an avocado seed, remove the large seed from the center of the fruit and wash it in water. The broad end of the seed is considered to be the bottom and thee pointed end is the top. Insert several toothpicks into the sides of the seed. They should be placed about halfway up the pit. Then suspend the seed in a glass of water. The bottom one fourth of the seed should rest in water. Place the seed out of direct sunlight and top up the water as needed.
The seed should sprout within a few weeks. During this time, periodically add water to maintain the initial water level. If it doesn't sprout within two to three months, discard the original avocado and begin another. The roots are usually the first to emerge from the seed. The stem appears later. Pot the seedling when the root system has become well developed; the roots should be at least two to three inches long.
Remove the toothpicks and plant into a six to eight inch pot using a commercial potting mix. Position the seed in the center of the pot. The top of the seed should be level with the soil surface. After potting, water thoroughly, then place the plant in a brightly lit location. Keep the soil moist, but not wet. Fertilize once or twice a month during the spring and summer with a houseplant fertilizer.
Avocado plants grow rapidly. They often have to be discarded after two or three years because they've become too large for indoors. The avocado is actually a tree. It will never produce fruit indoors as it may take 20 or more years to bear fruit.