Olive trees are admired across the world for their beauty and are found especially in sunny regions such as the Mediterranean and North Africa. Olive trees are also known for their aesthetics and functional uses. In Malta, the olive trees (siġar taż-żebbuġ) are very popular across the country, especially in older gardens and homes. Given the right conditions and location, growing and caring for an olive tree is an interesting and achievable challenge.
In the following article, we will discuss how to grow & care for olive trees, along with questions such as:
- Where do olive trees grow best?
- Do olive trees need a lot of sun?
- How often should you water an olive tree?
- Can you shape an olive tree?
- Can an olive tree live over 2,000 years?
Growing Olive Trees
The olive tree is usually associated with warm and sunny locations and indeed requires exposure to the sun for optimal growing conditions. Areas of high heat and sunshine are ideal, and the olive tree is therefore grown well outside in gardens and fields throughout Mediterranean countries such as Malta, Spain, Italy and Greece.
Olive trees grow silver looking leaves and often go well with many other plants in your garden. Whilst beautiful to look at visually, the olive tree is also grown for its fruit, the olive, which can be pressed for oil or else cured to be consumed during cooking.
How to plant olive trees
If your olive tree was grown in a greenhouse, make sure it spends some time outside in a sheltered place so it can adapt to the outside temperature. Keep it outside for a few hours a day for around two weeks, after which the olive tree is ready for you to plant outside in a permanent location.
Plant olive trees around 5 to 6 metres apart, to ensure that all trees can get enough air, oxygen and sunlight as they grow larger.
Water your new olive tree consistently in the first few weeks, until it establishes itself in its new location. Watering will also help roots become stronger and ensure the tree is more independent in the long run.
Olive trees need a sunny place, one that gets around 8 hours of sun daily. The soil needs to be ideally very fertile and well-draining. The last point is very important, as poor drainage can lead to severe or permanent damage to your olive tree.
Olive trees prefer a Mediterranean climate, with 97 % of cultivation concentrated in the Mediterranean basin. Therefore, if you live in a different environment, do your best to re-create dry, hot, sunny conditions. These conditions will help your olive tree grow stronger.
Olive harvest is affected by the level of sunshine, and with enough water, more sun will produce higher yields. Avoid locations where temperatures drop below zero degrees Celsius, in which case you need to protect the tree by wrapping it in a protective blanket, especially in the tree’s first years.
Intense watering is required in the first weeks after planting. However, you still need to water regularly and lightly over the first few years, as the tree will be dependent on you for water in very hot conditions.
In drought conditions, increase the level of watering. Eventually, as the trees’ roots grow deeper, they will need less water. Soil that is deeper and away from the surface tends to maintain water better. Furthermore, soil situated on a rocky surface, sometimes metres below the surface, can support an olive tree’s water requirements for many years, without human intervention or rain. For this reason, once established, you don’t need to provide supplemental watering unless the climate is very dry with no rain at all. In Malta, for example, it is not uncommon for the country to pass from many hot months without any rain. This, along with the strong and direct sun, usually requires gardeners and farmers to provide additional water to their plants and trees.
The olive tree comes in two different categories. The first is self-pollinating, which means that you can cultivate just one tree and still have olives to harvest. Other olive tree varieties need another tree to pollinate them.
Self-pollinating olive trees include Koroneiki, Fantoio, Arbequina and Coratina. Olive trees that require pollinators include Sevillano, Manzallino and Mission.
In Malta, there are a larger number of cultivars, including the ‘Bidni’ cultivar, Il-Maltija – the Maltese Olive; Il-Bajda – the white olive, Il-Ħelwa ta’ Sqallija – the sweet Sicilian olive, and L-Imrajja ta’ Marsala – the Marsala olive.
Pruning the olive tree is very important for shape and aesthetics, but more importantly to allow enough oxygen and sunlight around the tree. Improved airflow and new growth will help produce more flowers and fruit.
When it is time to shape the tree, a recommendation is to make a few, correct cuts instead of many small ones. For this reason, you may want to consult a professional when heavy pruning or shaping the tree. If you go for it yourself, you can use a tree lopper and a pruning saw to make these cuts. Pruning allows you to remove the tree’s central branches and let sunlight pass through the tree. Open pruning also improves the surface area of the tree that produces olives.
Pests or diseases
Olive trees are tough and generally do not suffer from many problems related to pests. If infested by scale, treat the tree with neem oil. The olive fruit fly is another issue, although traps and lures exist to combat this problem.
Unfortunately, many olive trees are sometimes forgotten, in the sense that their fruit is not harvested for consumption. When harvested, olives are usually picked, pressed into oil, bottled and then sold for consumption in Mediterranean dishes or as part of wider cuisine.
The wild olive (Oleaster) and the cultivated olive (Sativa) have different varieties based on taste, size, and other characteristics.
In many Mediterranean countries, for example in Malta, September is olive picking and pressing month. The traditional way of picking olives is by hand, a method essentially used for thousands of years by people living in the Mediterranean.
In autumn, the olives are ready for picking, harvested and pressed into oil. One way of doing this is to open a large net around the base of the tree, and then use rakes to drop the olives onto the net. A mature tree can easily produce hundreds of kilos of olives in one year.
Once the olives are in the net, the next stage is to sort out the olives from the leaves and the stems that are dropped to the net during raking. To retain freshness and the highest possible quality, olives are ideally pressed into olive oil the same day they are picked from the tree. This timeliness will in turn keep the olive oil acidity low and the quality of the oil high.
In other Mediterranean countries, such as certain zones in Greece, the olives amass large amounts of oil in September and October and are picked around November time. It is essential to finish the harvest before there are too many olives lost on the ground through the natural process, as olives that have fallen to the ground have higher acidity and lower oil quality. Earlier picked olives are usually known to produce less oil but of a higher quality.
Olive trees prefer soil that has good drainage and is rocky. If potting the olive tree in a container, you might wish to include some small to medium-sized rocks at the bottom of the pot or container, underneath the soil. It is also important to use a container that is larger than the root ball, to allow the olive tree plant to grow.
By having rocks at the bottom of the pot, you ensure that any excess water not required by the olive tree can drain out of the holes at the bottom of the container. Be careful not to block the draining holes with the rocks themselves, however.
In summary, olive trees can tolerate either acid or alkaline conditions, but good drainage is extremely important.
Olive trees need a warm climate, either the Mediterranean or similar, resulting in a long, hot summer and a cool, not frigid, winter. A mature tree can survive temperatures that are below zero degrees Celsius for a short time, but longer periods of freezing weather can create permanent, often deadly damage to the tree. Whilst some olive tree varieties can live outside of the typical Mediterranean zone, these tend not to produce large crop levels, making them not viable from an economic point of view.
Olive trees propagation can happen in a few different ways. Cuttings and seeds are probably the simplest ways of growing new trees, and both techniques can provide a ready to plant tree in around one year.
Olive trees that have been propagated through cuttings tend to develop quicker. They will also grow similarly to the parent, original tree from where the cutting was taken. The similarity will be based on size, growth patterns and the making of olives.
The olive was indigenous to Asia and stretched from Iran, Syria and Palestine to the rest of the Mediterranean around 6,000 years ago. Historians believe that the olive tree is one of the oldest grown trees worldwide, some stating it was cultivated before written languages were invented.
The Minoan kingdom grew olive trees on Crete around 3,000 BC, whilst the Phoenicians transported the olive tree to the Mediterranean parts of Southern Europe and North Africa. Signs of olives have also been discovered in Egypt from 2,000 years BC.
However, the two cultures that are most closely associated with olives and olive trees in the Mediterranean are the Roman and Greek cultures.
Olive trees are known to live for thousands of years, with the oldest known olive tree alive being around 4,000 and 5,000 years old, known as the al Badawi olive tree in Bethlehem. However, the production of olive oil might find its way back to 8,000 years ago.
When compared to the above, the olive trees on the Mount of Olives in Jerusalem are said to be over 2000 years old, and therefore considered as relative newcomers. Over thousands of years, people have created different varieties of the olive tree, to the extent, it is now difficult to determine which varieties come before others. Gene mapping techniques are nowadays being used to better map the olive family tree. In the past hundreds of years, the olive tree has been moved across the world, from America and Japan to New Zealand and Australia.
Olive trees have also been present in Malta for thousands of years. Olive remains were discovered during excavations at Skorba Temples (4500–4100 BC), whilst the ‘Bidni’ olive trees in Bidnija are 2,000 years old. These olive trees are extraordinarily still producing olive fruit to this day, which can be used for food consumption or to produce olive oil.
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