Avocado tree – Persea americana – Tips for my garden



The avocado tree belongs to the Lauraceae family, to the Persea genus and to the Gratissima or American species. It is a tree of considerable development, reaching 15-20 m in height, with superficial and dilated roots and a compact and persistent crown. The leaves are alternate, ovate-lanceolate or elliptical, light green in the upper part, more tending towards the greyish in the lower part; in many cultivars the leaves drop at the time of flowering, while in others the loss is more gradual and continues throughout the spring. The flowers are small, yellowish and grouped in clusters located at the top of the branches; Although hermaphroditic, self-fertilization hardly occurs, in fact, at the first moment of the blossoming of the flowers, only the female part is receptive, while the pollen is released in a second time. Each plant has many flowers, but only 1% of them complete the assembly. Flowering is scalar and can last for months, pollination is entomophilous, carried out by bees and other pollinating insects. The fruits are large, pear-shaped or globose, with yellowish green, dark green, dark blue or brown skin and yellowish or greenish flesh, buttery and with a characteristic smell; the seed is unique and varies in shape and size. buttery and with a characteristic smell; the seed is unique and varies in shape and size. buttery and with a characteristic smell; the seed is unique and varies in shape and size.

Climate and relief

Avocado has different climate adaptability, it can be grown in tropical, subtropical and warm temperate climates, West Indian varieties are more heat demanding, while Mexican ones have greater cold hardiness, some even up to at eight degrees. below. .the zero. The optimum temperatures for development and fruiting are 24-26°C during the day and 20°C at night. If they exceed 35°C and fall below 17°C, there may be problems with fertilization and fruit set. Hot winds make flowering very difficult, so it is not recommended to plant in areas affected by these phenomena. The avocado tree prefers subacid, cool, deep, fertile and well-drained soils, while it avoids heavy, suffocated soils with impermeable and calcareous subsoil, as they cause ferric chlorosis phenomena. It is a species native to Central America, but it is also cultivated in Hawaii, India, Madagascar, Polynesia, northern Australia, Madeira and the Canary Islands. In the Mediterranean basin, it is present in Israel, Algeria, southern Spain and to a limited extent in southern France, Liguria and south-central Italy.


Avocado cultivars are distinguished into different breeds according to different traits.

The Mexican breed has leaves that smell of anise, a small fruit with very thin and smooth skin, which ripens in late summer and fall. The main varieties are Zutano, Mexicola and Topa Topa.

The West Indian breed is characterized by a large fruit, with a moderately thick, leathery skin and a ripening period corresponding to summer and early autumn.

The Guatemalan breed has purple rather than green shoots, has an intermediate-sized fruit, with a thick, woody, rough epidermis, which ripens at the end of winter and continues until spring. The most important cultivars are Haas, Pinkerton and Reed.

Hybrids between Mexican and Guatemalan breeds are also prevalent, including Fuerte, Bacon, and Rincon. The varieties are also distinguished from each other according to the behavior of the flowers, in the first case (group A) the flowers open in the morning behaving like females and in the afternoon they close, while in the group B flowers open next day emit pollen then close at noon; to favor the fertilization of a plant, there must be both cultivars. The main varieties belonging to group A are Haas, Mexicola, Topa Topa, Pinkerton, Reed and Rincon; to group B belong Zutano, Bacon and Fuerte.

Propagation and rootstocks

The avocado tree is propagated by seeds, the plants of which are characterized by heterogeneity and slow fruiting, and vegetatively, by cuttings, which emit roots without problems only if taken from seedlings, and grafting, carried out in nursery one year after age. seedlings obtained from seeds which, once grafted, are planted the following year.

The most used rootstocks in California are the Mexican Topa Topa and the Duke 7, which are characterized by good frost tolerance, moderate lime and poor salinity. Antillean rootstocks such as Maoz and Nahlat, used in Israel, fear frost, have great resistance to saline waters (especially chlorine), tolerate limestone and, in addition, reduce the size of plants.

The rootstocks of the Guatemalan breed tolerate frost and salinity on average, but are afraid of the presence of limestone.

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