The Olive tree thrives in areas with Mediterranean climate, where mild winters are followed by sunny springs and hot summers. The areas where olive trees are cultivated for commercial use must have an average annual temperature of 60-68 °F (15-20 °C). The absolute maximum temperature can reach 104 °F (40 °C) without causing damage, but the minimum should not fall below 20 °F (-7 °C). Lower temperatures than this can cause serious damage to the trees. Of course, the temperature of 20 °F is only indicative, because the resistance of the tree in cold depends on other factors as well, such as how quickly the temperature drops, the length of the frost, the presence of strong cold winds, humidity, germination and health of the tree variety, weather conditions before frost etc. In general, we can say that the olive tree cannot not be cultivated commercially in areas where the temperature often drops below 20 °F (-7 °C). However, a certain amount of cold is necessary for the fruit set. This is the reason why olive trees cannot be grown in tropical climates.
Being an evergreen tree, the olive is sensitive to hard freezing temperatures. Buds and fruiting shoots are usually damaged by temperatures below -5ºC. Large branches and whole trees can be killed if temperatures fall below -10ºC
Some olive varieties, such as those grown in Egypt, Tunisia or Israel, bloom and fruit with very little winter chilling, whilst other varieties require more chilling for a normal flower differentiation.
The olive tree is a perennial, evergreen tree that can live and produce olives for more than a century. In some rare cases, olive trees have been reported to live and produce sprouts at an age of 1800 years old. The tree reaches a height 15-65 ft. (5-20 meters). As it happens with most trees, the height of the tree is affected by the vividness of the subject or of the variety, the soil and climate conditions, and finally the cultivation methods used. The trunk is cylindrical, smooth on young trees and bumpy in older, because lumps of varying size appear as the time goes by.
The root system of the olive trees develops vertically until the third to fourth year of its life. Later on, the original root system is replaced by another flocculent root system, produced mainly by spheroblasts or conger, formed in the olive tree neck, just below the soil surface. The root system development method is mainly determined by the nature of the soil. In some cases, it is reported that olive trees developed roots, which had reached 40 ft. (12 meters) in width and 20 ft. (6 meters) in depth.
Olive trees are cultivated globally in an area covering more than 15 million hectares. The number of cultivated olive trees reaches and maybe exceeds the stunning number of 1 billion. About 80% of these trees are located in the Mediterranean region. Countries such as Spain, Italy, Greece, Tunisia and others traditionally export olive oil, which is the cornerstone of the agricultural economic development and sustainability of some of those countries. However, other countries such as USA, Australia, Japan, China etc. have during the last two decades realized the huge economic and strategic importance of olive trees. Thus, they have given financial motives to olive growers, in an effort to become autonomous in olive products.
The olive tree plays a very important role, because not only does it utilize land that is unsuitable for other crops, but also helps to protect the soil from erosion. The main products produced by olive tree are olive oil and table olives. The pomace of olives is also important for industrial use. Some other by-products that may have economic importance are the leaves, wood, core etc. Finally, olive trees are often grown in pots indoors or outdoors as ornamental.
The genus Olea includes 30 different species, which are cultivated in five continents. The most important of these are: Olea europea. L., subspecies euromediterranea, Olea europea. L., subspecies cuspidate Vall, Cif, Olea europea. L., subspecies laperrini Batt and Trab, Olea chrysophylla Lamk, Olea hochstetteri, Olea somaliensis, Olea subtrinervata
Olives are one of the most extensively cultivated fruit crops in the world. In 2011, about 9.6 million hectares were planted with olive trees, which is more than twice the amount of land devoted to apples, bananas, or mangoes. Only coconut trees and oil palms command more space. Cultivation area tripled from 2,600,000 to 7,950,000 hectares (6,400,000 to 19,600,000 acres) between 1960 and 1998 and reached a 10-million-ha peak in 2008. The 10 largest producing countries, according to the Food and Agriculture Organization, are all located in the Mediterranean region and produce 95% of the world's olives