How to sprout an avocado seed and grow the plant

Sprouting of an avocado seed
The avocado (Persea americana) is a tree native to South Central Mexico, classified as a member of the flowering plant family Lauraceae. Avocado (also alligator pear) also refers to the tree's fruit, which is botanically a large berry containing a single seed.
Avocados are commercially valuable and are cultivated in tropical and Mediterranean climates throughout the world. They have a green-skinned, fleshy body that may be pear-shaped, egg-shaped, or spherical. Avocado trees are partially self-pollinating and are often propagated through grafting to maintain a predictable quality and quantity of the fruit.
Avocados can be propagated by seed, taking roughly four to six years to bear fruit, although in some cases seedlings can take 10 years to come into bearing. The offspring is unlikely to be identical to the parent cultivar in fruit quality. Prime quality varieties are therefore propagated by grafting to rootstocks that are propagated by seed (seedling rootstocks) or by layering (clonal rootstocks). After about an year of growing in a greenhouse, the young rootstocks are ready to be grafted. Terminal and lateral grafting is normally used.
Store avocados at room temperature, keeping in mind that they can take 4 to 5 days to ripen. To speed up the ripening process, put them in a paper bag along with an apple or banana. When the outside skins are black or dark purple and yield to gentle pressure, they’re ready to eat or refrigerate. Wash them before cutting so dirt and bacteria aren’t transferred from the knife onto the pulp. While guacamole is arguably the most popular way to eat avocado, you can also puree and toss with pasta, substitute for butter or oil in your favorite baked good recipes, or spread or slice onto sandwiches.
Indoors, an avocado tree is usually grown from the seed of an avocado fruit. This is often done by removing the seed from a ripe, unrefrigerated avocado fruit. The seed is then stabbed with three or four toothpicks, about one-third of the way up from the flat end. The seed is then placed in a jar or vase containing warmish water.
It should split in four to six weeks and yield roots and a sprout. If there is no change by this time, the avocado seed may be discarded. Once the stem has grown a few inches, it is placed in a pot with soil. It should be watered every few days. Avocados have been known to grow large, so owners must be ready to re-pot the plant several times.
Notice that the avocado fruit used in this video is dark, overripe, not good to eat, but good to give us the seed.
Sometimes, we peel the seed for a faster sprouting.
Avocado trees like the soil pH around 6-6.5. If you have a heavy clay soil, elevate the tree in a mound for better drainage. Make the mound 1-2 feet high and 3-5 feet around. Add some sand in the mixture.
The sooner the roots get out into the bulk soil, the better the tree will grow.
Fertilize your young avocado trees with 1/2 -1 pound of actual Nitrogen per tree per year. The other important nutrient for avocado trees is Zinc and Potassium. Ordinary home fertilizer for houseplants normally should work.
Plant your tree from March through June. If you plant during the summer, there is always the risk of sun damage, because the avocado trees can't take up water very well when is young. Plant in a non-lawn area, and away from sidewalks. And if you can, plant your tree in a spot protected from wind and frost. Remember, full sun is best.
Dig a hole as deep as the current root ball and just as wide as the width plus a little extra so you can get your hands into the hole to plant it. The avocado is a shallow-rooted tree with most of the feeder roots in the top 6" of soil, so give it good aeration. Its root system is very sensitive and great care should be taken not to disturb the root system when transplanting. If the tree is root-bound, however, loosen up the soil around the edges and clip the roots that are going in circles.
Typically trees need to be watered 2-3 times a week. As the roots reach out into the bulk soil, more water can be applied and frequency of watering diminishes to about 1 time per week by the end of a year. When watering the tree, soak the soil well, then, allow it to dry out somewhat before watering again. Seedlings will require quite a bit less water, of course. Check the soil before watering again.