Persea americana
Family: Lauraceae

Thought to be from the West Indies and Central America, the avocado can now be found in warm Climates throughout the world, even in places with occasional light frosts. This evergreen tree comes in erect-growing types, which reach up to 12 m (40 ft), as well as spreading types. It has shiny dark green leaves and very small spring flowers. Its round or pear-shaped fruits have a hard green or purple skin with creamish green pulpy flesh which is very nutritious. It is a high energy food, low in carbohydrate and high in vitamins and minerals. Avocado is used in salads and soups, and also as an accompaniment to seafood, chicken, pasta, and many other foods. Grafted trees start bearing lightly in three to five years, but the fruits will not ripen unless taken from the tree. Seedling trees can take much longer to produce.

Varieties

Where avocados are grown outdoors as a crop, availability of cultivars will vary according to area. Cultivars are generally classified as belonging to a particular area such as West Indian, Guatemalan or Mexican. Better crops can be achieved through cross-pollination, but avocados are self-fertile and capable of cropping alone. Cultivars like 'Hass', 'Duke' and 'Puerte' are the most popular, with 'Puerte' accounting for about 50 per cent of all varieties planted. Small-growing trees like 'Wurtz' and 'Rincon' may be better for the home garden. They grow to about 4 m (13 ft).

Cultivation

In frost-prone Climates, grow in pots in a cool greenhouse as a foliage plant only. In areas where avocados are grown for their fruits, cuttings can be taken from good-bearing trees and grafted onto the seedling rootstock of suitable trees, especially those with resistance to the fungal root rot, phytophthora. Otherwise, plants can be bought from a nursery. Planting times are not crucial, except that the small plants should be given time to establish before the hot weather sets in. They should be planted about 5 m (16 ft) apart in a reasonably fertile soil, with good surface and subsurface drainage, as these plants cannot tolerate 'wet feet'. Poor drainage contributes to phytophthora. These trees respond well to NPK fertilizers and to calcium and magnesium from dolomite. This treatment will create a suitable, slightly acid pH of 6.5-7. A generous amount of organic matter from animal manure or mulch, for example, helps to reduce the risk of phytophthora by keeping up the activity of soil micro-organisms.

Climate

Zone 10 and above.