14 Fascinating facts about olive trees

“The olive tree is much more than merely a tree with a gnarled trunk; it is the emblematic embodiment of the values of peace, wisdom and hope – values that we wish to celebrate today, on this World Day.”

—  Audrey Azoulay, Director-General of UNESCO on the occasion of International World Olive Tree Day

In honour of the olive tree here are some fascinating facts

1. Olive trees can get very old. The average age of an olive tree is 300-600 years. But the oldest certified olive tree is more than 2000 years old. It can be found in the small town of Ano Vouveson on the island of Crete in Greece and it still bears fruit. The tree is visited by more than 20,000 people every year. Its trunk has a perimeter of 12,5 meters, and a diameter of 4,7 meters. The oldest trees on our olive grove are estimated to be around 1000 years old.
2. The olive tree ranges in height from 3 to 12 metres and has numerous branches full of silvery-green feather-like leaves.  
3. It takes about fifteen years before an olive tree is mature and you can start harvesting fruit. After 4 to 6 years an olive tree will begin to take on a mature shape. An olive tree does not change much after that and only becomes a larger version of its present condition.
4. Olive trees need regular pruning because the olive fruit requires strong sunlight at every stage from fruit set to oil production. Olive flowers that are in deep shade will not set in large numbers. Those that are will not produce good levels of oil. Pruning is therefore needed to reduce the density of the foliage and allow sunlight to penetrate into every part of the olive tree.
5. Olive trees are extremely resilient. They survive long droughts, and even when a wildfire has burnt large parts of the tree, the tree is very likely to recover. 
6. The olive tree is widely known for its strong tendency for alternate bearing (biennial bearing), which severely affects the fruit yield from year to year. A large production in year 1 removes most of the various carbohydrates, organic nitrogen components and other essential nutrients, making the available stock insufficient to produce a new crop in year 2.
7. A mature olive tree will produce on average 20 to 40 kilograms of olives per year. Since it takes about roughly 100 kilograms of olives to make 15 liters of oil, a mature tree is capable of producing about three to six liters of oil per year. 
8. There are 139 olive varieties (cultivars) which are grown in 23 different countries (as estimated by the International Olive Council (IOC)). Each olive cultivar has its own unique chemical and taste characteristics.
9. The olive branch is a sign of peace. This symbol was used in history to declare armistice by giving it to enemies. It appears on the national flags of seven nations, four US states and the flag of the United Nations. A small gold replica of an olive branch was left on the Moon’s surface by Astronaut Neil A. Armstrong, an Apollo 11 crew member. The gesture represented a wish for peace for all mankind.
10. Olive oil was already used in ancient times. In 2014, scientists discovered 8,000 year old olive oil in Ein Zippori, a town near Nazareth. The first eyeshadow was created by mixing olive oil and ground charcoal. It was used in ancient Greece. 
11. Olive trees are protected by the Law. In Ancient Greece, a person could be fined for digging up too many olive trees, even on their own land. In France, parts of Italy and parts of Spain it is illegal to sell old olive trees. That is necessary, because many old olive trees die during transport. 
12. The olive tree needs a long, hot summer and a cool, not frigid, winter – a Mediterranean climate is best. Warm, arid conditions help keep natural pests away.  Olive trees are hardy and can live in other climates than the Mediterranean climate. What an olive tree needs is a long and hot summer and a cool (not cold) winter. That’s why you see this tree in many parts of Asia, America, Europe and Australia.
13. Olive tree waste provides renewable energy. When burned it produces 2.5 times the heat of burning wood, and the smoke is harmless. Its ash is used for fertilizing gardens.
14. The olive tree provides for life. It feeds us with a tasty fruit and a healthy oil, its oil cures our skin and hair, its oil provides light, in winter its wood produces heat, and in summer its branches provide shade.