Olive trees, Olea europaea, are native to many areas that surround the Mediterranean Sea including parts of Europe and the near East. All these regions have a warm summer climate with very little summer rain. In winter, the temperature never drops below 15°F (-9.4°C).
In the U.S. the true olive belt includes the whole of lower California and much of the rest of the State of California. Other areas in the United States where olive trees thrive include parts of Arizona, Texas, Louisiana, Mississippi, Alabama, Florida, Georgia, South Carolina, and smaller portions of southwestern Utah and Nevada.
Where do olive trees grow naturally?
Olive trees are native to the Mediterranean as well as parts of Asia and Africa. In these Mediterranean climates, olive trees grow just about anywhere, from barren hilltops to fertile valleys.
But even though olive trees will grow and produce fruit in soil that hasn’t been cultivated, its olive production rate will increase dramatically if it is planted in deep, friable, well-cultivated soil. It will grow to between 20 and 52 feet tall.
Ancient Olive Trees
There are more than 260 varieties of the olive tree with about 25% unique varieties named according to their geographic origin. Many of these are now grown by farmers and home gardeners.
According to a scientific paper by C. Pérez and J. Aranceta, published in Encyclopedia of Food and Health in 2016, the original wild olive tree grown in the Mediterranean region was called acebuche (Olea sylvestris). Over time, it was crossed with other types and upgraded, eventually evolving into the Olea europaea we know so well today.
In its natural habitat, the olive tree is known to grow for at least 500 years, and olive farmers produce top-quality oil from them called ancient tree oil.
In the south of Catalonia, there are about 4,400 trees that are aged between 700 and 1,000 years. The olive oil produced from them is certified.
In another scientific paper, written by S.G. Kailis and published in Encyclopedia of Applied Plant Sciences in 2017, the olive is described as one of the world’s first domesticated trees. It is believed to have been domesticated more than 8,000 years ago from the thorny wild olive (Olea europaea ssp. Europaea var. sylvestris) probably in Persia or the Phoenician Levant.
Olives Grown for Their Oil
Today, the most widely cultivated Spanish varieties grown for their oil are:
- Picual, which is the world’s largest variety
- Arbequina, which produces high-quality, fruity olive oil
- Cornicabra, mainly grown in Toledo in Spain
- Empeltre, one of Spain’s oldest varieties
- Farga, which is valued for its oil, particularly that produced from ancient trees and grown in Castellón, Valencia, Tarragona, and Teruel
In Greece, Koroneiki, and Kalamata are the best-known varieties. Two stand-out varieties grown in Italy are Ascoli from Ascola, and Leccino.
Two major varieties grown in France are Nice and Picholine. And in Israel, you’ll find the biblical variety, Barnea.
Another paper published in Encyclopedia of Food and Health in 2016, by F.N. Arroyo-López and A. Garrido-Fernández, discusses the origins and production of table olives.
Production was largely a craft process until the mid-20th century when sophisticated fermentation and storage systems were introduced and pitting and stuffing were automated.
Today, the greatest table olive producers are in the Mediterranean region, with Spain, Turkey, Egypt, Syria, Algeria, Greece, and Morocco producing the most. Other important olive-producing countries are Argentina, Peru, and the United States.
Some popular table olive varieties are Mission, Kalamata, Manzanilla, and Barouni (for Queen olives).
Where is the best place to plant olive trees?
In the United States, many farmers in California grow olives on dry hillsides where other crops won’t grow. The soil is naturally fertile and the climate is dry, which is ideal for an olive grove.
USDA plant hardiness zones 10-11 are the best areas to plant and grow olives. Some cultivars are cold-hardy and will grow in zones 8-9.
How to Choose the Best Spot to Grow Olive Trees
When you decide to grow an olive tree in your home garden you need to choose the best possible spot. There are several factors to take into account including soil conditions, sun, temperature, and water.
Olive trees need soil with good drainage. They will grow in poor quality soils and aren’t demanding in terms of fertilizer.
That said, it’s a good idea to add organic matter to the soil when you plant your olive tree. Compost or peat moss will help the roots establish themselves and grow.
Nitrogen fertilizer will help the growth of leaves and will encourage trees to produce fruit. But be careful because too much nitrogen can promote the growth of shoots at the expense of fruit production.
The ideal pH for soil is between 5.5 and 6.5.
Olive trees like the heat. If the temperature drops below 15°F (-9.4°C) it is likely to kill the tree. Anything below 28°F (-4.4°C) will damage the fruit.
If there are freezing temperatures for more than a couple of days, they will likely kill the trees or severely damage them. If there is frost when the flowers bloom during mid-fall, frost damage will wreak havoc with your olive crop because your trees won’t bear fruit.
One popular olive variety, the Mission olive, does withstand colder climate zones. Developed by Spanish missionaries in California during the late 18th century, it is the only American cultivar that is listed by the International Olive Council in its world catalog of different olive varieties. It is widely grown for table olives in the U.S. and South Africa.
Olive trees grow best in full sun. They like as much sunlight as possible to remain healthy.
Even though olive trees thrive in areas that experience hot, dry summers, you need to water them regularly so that the trees grow and fruit production is encouraged. Be sure to water weekly when it is dry.
Drip irrigation is very effective because they only water the roots. But then, you will need to water your olive trees for about an hour every day during the dry summer months.
Just be aware that too much water can make trees susceptible to root-rot diseases. It can also cause flowers to drop before they form olive fruit.
Tips to Grow Olive Trees
Here are a few varied tips to help you grow olive trees at home.
Tip 1: When to Plant
Even though olives grow best in hot, dry summers, it’s best to avoid planting them in summer when it is very hot. Rather plant them in spring or the fall.
Tip 2: Cross Pollination
Many varieties of olive need to cross-pollinate to set fruit. So, don’t only plant one olive tree. Plant compatible cultivars that will cross-pollinate each other.
For example, according to the University of Florida’s Gardening Solutions team, farmers often plant Koroneiki and Arbonsona to support the pollination of Arbequina, even though it is a self-pollinator. The Mission olive is also a self-pollinator.
Tip 3: How to Test for Good Soil Drainage
If you’re not sure if your soil offers good drainage, here is a quick test you can do. Dig a test hole and fill it with water.
If it drains out of the hole at a rate of 1-4 inches (2.5-10.2 cm) per hour, your drainage is good. If it isn’t draining well enough, amend it by adding gravel.
Tip 4: Don’t Prune for the First 4 Years
Let your olive trees grow without pruning for the first 4 years. Thereafter, trim your mature tree every year so that light can get to all parts of the tree. This will also encourage it to bear fruit.
Pruning will also control the shape of your olive trees and increase airflow through the trees, which will minimize any risk of fungal diseases.
Tip 5: Pests and Diseases
Happily, olive trees are relatively pest- and disease-free. The most common problems are scale, caterpillars, and grasshoppers. Not much in the scale of things!
If you keep an eye out for pests and diseases you shouldn’t have any major problems.
Are olive trees easy to grow?
Given the right conditions, olive trees are very easy to grow. If you plant them in a nice sunny spot in well-drained soil, once they are established they will practically grow themselves with minimal care from you.
Your olive trees should start producing fruit in about three years. But don’t be surprised if it only fruits every second year. Typically, olives will produce lots of fruit one year and then very little the next.
Olives will grow in any area with a Mediterranean-type climate. They need lots of sunshine and aren’t fussy about the soil they grow in.
They do best in areas that get little or no rain in summer, although they will still need some irrigation.