The avocado (Persea americana) is a fast-growing, dense, evergreen tree that can reach up to 80 feet tall. It has alternate, glossy, elliptic, dark-green leaves that shed in early spring. The West Indian varieties are scentless, while the Guatemalan and Mexican types smell like anise. Small, yellow-green flowers appear in January to March before the first seasonal growth. Fruits vary from big, smooth, round, glossy green fruits (West Indian) to medium, pear-shaped, pebbled green to blackish-green fruits (Guatemalan) or small with paper-thin skins that are glossy green to black (Mexican).
Young avocado trees prefer shady locations due to their lack of barks that offer sun protection. Planting avocados under the shade of mature or parent trees on the north side of the house can offer enough sun protection until they mature and break through the canopies of the bigger trees. Whitewashing the trunk or branches will prevent sunburn in locations that experience hot summers. Ensure that the plant receives enough sunlight in the winter if planted in cooler locations. Roots can be invasive, so choose a location with ample space to grow. A windbreak will protect young trees planted in windy locations. Once established, avocado trees will need sun to produce flowers and fruits.
Avocados prefer fast-draining, organic soil. Dig a hole up to three times as wide as the container, but no deeper than the root ball. Loosening hard soil improves water absorption. Mix soil with 50 percent sand and 50 percent compost. Planting in mounds by creating berms 4 inches high improves drainage, offers freeze protection and prevents root rot.
Avocado trees do not tolerate wet soggy soil, but prefer regular deep watering, especially during warmer months. Allowing water to drain completely before the next watering helps prevent root rot. Use drip irrigation to provide slow and deep watering to allow water to penetrate so the roots can reach it. Avocados are sensitive to salt water; therefore, keep this in mind if your water has high salt concentration. Mild salt concentration will cause the tips of avocado leaves to burn.
After the first year, fertilize with a balanced fertilizer four times a year. Feeding with nitrogenous fertilizer in late winter and early summer will benefit older trees. Spray leaves with fertilizers containing traces of iron to prevent yellowing due to iron deficiency.
Add stakes to container and dwarf avocado trees. Staking is not necessary when planting in orchards; fencing with plastic mesh for the first three years should be enough to protect the young plants.
Trimming the skirts of young columnar cultivars will form a rounded tree, and it also prevents trapping of water. Branches exposed to the sun are highly susceptible to sunburn and can kill avocado trees; therefore, there is no need to prune them. It is better to whitewash the branches instead.
Avoid harvesting off-season fruits with the main crops. Leave them on the tree to mature. Guatemalan varieties usually take up to 18 months to fruit after they bloom, while Mexican varieties only take up to eight months. Avoid harvesting purple cultivars until they turn fully purple.
Pests and Diseases
Six-spotted mites can cause avocado leaves to shed. Spray with insecticide for prevention.