Avocado (Persea americana) is an evergreen tree native to Central America, so most varieties are sensitive to cold and frost. It belongs to the same flowering plant family Lauraceae, along with cinnamon, camphor and bay laurel.
The trees grow up to 20 m tall, having alternately arranged leaves of 12-25 cm long. The flowers are inconspicuous, greenish-yellow, 5-10 mm wide. Trees are partially self-pollinating. The fruits have a green-skinned, fleshy body and may be pear-shaped, egg-shaped, or spherical. They and are 7-20 cm long and weigh between 100-1000 grams. The fruit has a large central seed, 5-6.4 cm long.
The avocado is a climacteric fruit, like bananas, which means it matures on the tree but ripens off the tree. Avocados must be mature before picking in order to ripen properly. Once picked, avocados ripen in one to two weeks at room temperature. Avocados that fall off the tree ripen on the ground. Generally, fruits are picked once they reach maturity.
All avocado trees need to be protected from heavy frosts and strong winds. The subtropical species needs a climate without frost and with little wind because high winds reduce the humidity, dehydrate the flowers and affect pollination. When even a mild frost occurs, premature fruit drop may happen.
Avocados prefer to be planted in sunny locations that are protected from wind. They will need a well drained soil, ideally more than 1 m deep, and will not thrive in heavy clay soils for long. If you do have heavy clay soils consider planting your avocado tree in a raised bed. The raised bed should be at least half a meter above the existing level of the soil. It is also very important not to plant avocado trees too deeply. Plant them at least 3-5 cm above the existing soil level and then create a small mound around the base with a mixture of compost and well drained soil. Avocado trees are susceptible to root rot so you should avoid planting a new avocado tree in a place where an old tree had died, as the soil may be contaminated.
As most avocado trees can reach a height of more than 7 m tall when fully grown, selecting the proper place to plant your avocado tree is important for successful growing. Avocados should only be minimally pruned in order to shape and control size and this should be done after fruiting. Frequent pinching of young trees is a good method to shape the tree, rather than heavy pruning.
Do not overwater your avocado trees. Over watering trees in the ground in certain soils is often the main factor in causing root rot. Avocados prefer infrequent deep root watering. It is best to allow trees to dry out watering again. Avocados growing in containers need consistent frequent watering.
Avocado trees should be fed on a regular basis. Fertilize using well balanced citrus food. Avocado trees that have been well feed year-round are better able to deal with cold temperatures in the winter. Apply a 8-10 cm layer of mulch to avocado trees each year to help retain soil moisture and improve soil quality. Apply mulch in spring and fall under the canopy of the tree, keep it away from the trunk of the tree.
You can grow your avocados indoor if your climate doesn’t allow you to grow it in the garden. Usually, avocados are grown from pits indoors. Remove the pit from a ripe, unrefrigerated avocado. Stab it with three or four tooth picks, about one third of the way up and then place it in a jar or vase with tepid water. The pit should split in 4-6 weeks and roots and a sprout should appear. Once the stem has grown a few cm, place it in a pot with soil. Water it every few days. As avocados grow quickly you must be ready to repot the plant several times.
The species is only partially able to self-pollinate. This limitation makes the species difficult to breed so most cultivars are propagated via grafting.
Avocados can also be propagated by seeds but it will take about 4-6 years to bear fruit. The offspring is unlikely to be identical to the parent cultivar in fruit quality so prime quality varieties are therefore propagated by grafting to rootstocks. After about a year of growing in the greenhouse, the young rootstocks are ready to be grafted. The best time to plant avocado trees is in spring or in autumn. Prepare the ground two months before planting by adding compost and well-rotted manure to avoid the delicate roots being burned.
Harvest the fruits when their skin will begin to dull. A good indicator to know that your fruits are ready is when the first fruits start to fall to the ground. It will be fully ripe two weeks later. You can harvest the other fruits progressively, as you need them.