Olives are a very popular part of a Mediterranean diet. First cultivated around 7,000 years ago in Mediterranean regions, it has been a long-standing part of diets. As well as being important taste-wise, they are a rich source of oils, minerals and vitamins A, E, K and B. When turned into olive oil, it’s naturally cholesterol, sodium, and carbohydrate-free. Here’s a guide on how to grow olives and how to produce olive oil from olive trees…
Take a look back…
If we go back to the beginning, fossilised leaves of Olea were found in the volcanic Greek island of Santorini. Olea relates to the botanical name for olive ‘olea europaea’ meaning ‘European olive’. Across the world, olive branches hold the symbolism of peace and victory – for this reason Cyprus, Eritrea and the United Nations have olive branches on the flags.
In each year, there is global consumption of approximately 2.5 million tons of olive oil. And just one litre of olive oil takes 6-7kg of olives.
In terms of nutrition, olives have a lot to offer. In fact, eating olives can improve the appearance of wrinkles due to the oleic acid in them which makes the skin healthy and soft. Then, when made into olive oil it’s loaded with antioxidants that are biologically active and may reduce the risk of chronic diseases.
Extra-virgin olive oil can reduce inflammation which can cause cancer, heart disease, type 2 diabetes, Alzheimer’s, arthritis, and obesity.
Uses of olives
Bear in mind that olives shouldn’t be eaten straight from the tree after harvesting because they have an extremely bitter taste. So, the olives need to go through a process with brine to become edible.
Taste-wise olives are very salty, adding a recognisable taste to salads and pizzas, or to make tapenades. Interestingly, only 10% of harvested olives are used to eat as table olives, with 90% of them used to make olive oil.
There are even cosmetic uses of olive oil, with it being used as a hair treatment from ancient Egyptian period. This can still be done now by warming between 2 tablespoons and 4 tablespoons of olive oil in the microwave and applying it to the ends of the hair. Leave it to sit for 10-20 minutes before washing it out with shampoo.
Another cosmetic use for the soil is as a lip scrub by mixing sugar with a teaspoon of the oil.
Growing olives in the garden
These evergreen trees with silvery foliage are beautiful, even without the fruits. As a Mediterranean plant, to grow these in the UK requires a bit more care in terms of stable temperatures and growth conditions.
In terms of care, olives have very slow growth rates, and don’t require much pruning. Although when young, pinching the young plants can encourage a good branching shape.
The trees can either be grown in containers or the ground. Containers are ideal because they can be easily moved indoors for winter protection. On the other hand, if planting in the ground, do this in spring. Choose a sheltered spot with well-drained soil, a space where there is room for support until they are established.
These trees are drought tolerant, but feeding and watering well is necessary if you want to produce fruit. But don’t expect harvests right away because this can take between 3-5 years. It’s well worth the wait.
Can you grow them from seed?
It’s a long process, but yes, olives can be grown from seed. Although it’s important to bear in mind that the plant will be a wild variety, not identical to the parent cultivar.
Give the seedlings a good start by sowing them in spring and keeping them in a propagator. Sow in a peat-free compost that’s half sand, half seed compost to ensure it’s well drained. Keep the top two inches of the compost damp, watering as it dries out until the seeds germinate.
The time for harvesting olives tends to be in autumn, but it can be as early as August through until November. Harvesting will depend on a few factors including the ripeness level you want, as well as the region and variety you are growing.
Olives start out as green, then become a rosy colour which signifies that they are ripe. Then, finally they’ll turn black which is very ripe. Once harvested, they’ll need to go through a process to make them edible before they make it to your dinner table.
- For green olives, they will need soaking in salted water for a few days. This will remove bitterness so they can be eaten.
- For black olives, the curing process means you’ll have to leave them in salt, or the brine, for several weeks. Even after this process, store them in olive oil or brine to keep them stored well.
About the oil
There are so many oils on offer in supermarkets like coconut oil, avocado oil, sesame oil, vegetable oil, and corn oil. Even with olive oil there are many types, so what’s the difference?
Well, compare to sunflower oil, olive oil has higher amounts of vitamin K, fatty acids and minerals. In addition, the polyunsaturated fats in sunflower oil can make it go bad easier than olive oil.
Then, compared to vegetable oil, olive oil is high in antioxidants and is not as processed.
It’s widely thought that olive oil is best to cook with, especially extra virgin which is the least processed form. It also has a relatively lower smoke point compared to many other oils, which means it’s best suited for cooking on low and medium heat.
Making olive oil
As you’ll see in my behind-the-scenes video, I use a long-handled vibrating tong to harvest olives from the trees. This is used on all the trees, catching the olives in the netting that has been laid on the floor. Then, when they’re all gathered together, they’re taken to the processing plant where they’re separated from any foliage that has fallen and cleaned.
The olives are transferred into one large crate so they’re easier to handle and feed into the machinery. After being weighed, the olives are tipped into the hopper which collects everything and feeds it through to the escalators which splits the large amount into more manageable quantities.
The leaves and branches are separated from the olives, to be discarded. The olives are cleaned, and then an extra step of suction is used to remove any foliage or bugs that were missed.
A drill separator draws the olives together, to then be deposited into the section where they are crushed.
The two stone wheels then crush the olives to make a paste. This paste is sent onto the mats, which are then stacked and taken to the hydraulic presses, so all of the goodness and juice comes out. This oil is all collected at the base of the presses. Then, a mixture of oil and water is taken into a drum, which uses centrifugal force to separate the water and oil.
At the end of the process, the dry husks of the olives are left over. These are recycled and used to create fertiliser, so nothing gets wasted.
Now you know all about olives, how to grow them, and how olives are harvested and made into olive oil. You can grow your own olive tree here in the UK to appreciate the foliage as well as the fruits when they appear.
David Domoney is a Chartered Horticulturalist, Broadcaster, and Author. David has worked with a number of the UK’s leading garden retailers as a plant buyer and strategic consultant. With more than 30 years experience, in horticulture, David is as passionate about plants now as he was when he bought his first plant at a village fete.
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