Avocado trees are tropical, evergreen trees that can grow quite large--up to 80 feet tall--although they are usually pruned to remain much smaller. The trees feature dark green, leathery leaves at maturity. Some varieties of avocado lose those leaves in the spring when flowering occurs. Native to the tropical climates of the Americas, most notably Mexico, these somewhat fragile trees are highly prized for their delicious, nutritious and commercially valuable fruit.
Avocado trees require full sunlight and warm temperatures in order to survive. The trees need at least six hours of sunlight per day and, ideally, eight to 12 hours. Young trees can be scorched by hot afternoon sun. Avocado trees in the first three years of life should be protected with some shade from the late day sun. This can be done by building a temporary shade structure, coating the trunk with a protective layer of white latex paint, or planting or placing the tree (if grown in a container) in a location that receives dappled afternoon shade.
Persea americana is a tropical plant and should only be grown outdoors in tropical or subtropical parts of America, or U.S. Department of Agriculture hardiness zones 10 and 11. The trees are very cold sensitive and will not survive in temperatures that dip below freezing for prolonged periods of time, although some varieties can withstand brief cold temperatures, such as Meya and Brookslate.
Avocado trees prefer well-draining soil. They will tolerate a wide variety of soils as long as the ground is not consistently wet and boggy. Such conditions will quickly lead to root rot. The tree should not be planted anywhere that flooding occurs, or in a depression where standing water will collect.
Avocado trees need frequent watering--but only during the summer--for the first three years of life. Give the tree a deep, slow watering twice a week during the growing period. Use a drip or soaking hose for best results. These hoses release water very slowly over the period of a couple of hours, giving the water a chance to soak into the soil and reach the tree's deep roots. There is no need to water during the rainy winter season. Once the tree is established, it only needs to be watered during long, hot periods.
The method for fertilizing your tree will vary depending on where you live and what type of soil you have. Do not fertilize the tree during its first year of life. In general, an application of a general fertilizer formulated for citrus trees will benefit any trees over 1 year old. Wet the soil before applying the fertilizer, and give the tree a dose in early spring, early summer, late summer and fall.