I've got an avocado pit currently sitting in water. It's already been there a couple of days and the skin is starting to split.
Growing steps courtesy of avocado.org
1. Wash the seed. Using three toothpicks, suspend it broad end down over a water-filled glass to cover about an inch of the seed.
2. Put it in a warm place out of direct sunlight and replenish water as needed. You should see roots and stem sprout in about two to six weeks.
3. When the stem is six to seven inches long, cut it back to about three inches.
4. When the roots are thick and the stem has leafed out again, plant it in a rich humus soil in a 10-1/2" diameter pot, leaving the seed half exposed.
5. Give it frequent, light waterings with an occasional deep soak. Generally, the soil should be moist but not saturated. Yellowing leaves are a sign of over-watering; let the plant dry out for a few days.
6. The more sunlight, the better.
7. If leaves turn brown and fry at the tips, too much salt has accumulated in the soil. Let water run freely into the pot and drain for several minutes.
8. When the stem is 12 inches high, cut it back to 6 inches to encourage the growth of new shoots.
9. Don't expect your house plant to bear fruit. Although this does occur occasionally, it usually requires grafting. A plant grown from seed will take anywhere from five to 13 years to flower and bear fruit. Fruit on trees grown from seeds are seldom good to eat.
Other Growing Methods
Another method of how to grow avocado plants is leave the pit in the sunlight until is begins to split and then potting it in soil partly exposed like an amaryllis bulb or sweet potato vine. Use a four or five-inch pot to start your plant and set it in a nutrient rich potting soil that has good drainage. After your plant is about a foot tall, pinch it back to half. Pinching it back produces a rounder and fuller plant. Once your plant has filled its pot with roots, it’s time to move it to its permanent home.
Method #2
Push pit into a mix of sand and potting soil (pointy side up) with the top half above soil surface. Keep the soil moist. Leave it in a sunny spot. Pinch new growth and care for as mentioned above.
Method #3
Wrap an avocado pit in moist paper towel and place in a ziploc baggy, seal. Place bag in a warm, sunny spot or somewhere warm (ideas: top of fridge, your computer monitor, television, under sink). Once it starts sprouting and the roots are about 2″ long, proceed as noted above.
My own notes
I've done this before with not very good success. I had a good shoot, but the pit developed mold. I've found that it's very important with this water method to make sure the water line doesn't reach the toothpicks. Wet toothpicks seem prone to developing mold.
From what I've read there also seems to be different opinions on the changing the water or not. I'm gonna be changing it every couple of days.
