Plant Common Name
Common Olive, Cultivated Olive, European Olive
The olive tree is a native of the chaparral regions of the Mediterranean where the oil from its fruits have fueled the diets of many great, early civilizations. Unlike most other fruit trees, olives are very long-lived and produce better with age, so ancient groves across countries such as Greece, Italy, Israel and Turkey. Trees as old as 1800 years still produce bumper crops of olives. Contemporary groves also exist worldwide, where the climate permits. In the North America, California is the center for olive production.
Olive trees develop low branches that support a dense cover of small, lance-shaped, gray-green leaves with whitish undersides. These remain evergreen all season. As the trees age, the grey trunks become quite gnarled and attractive. Olives are slow growing and usually take between five and eight years before they are fruitful. Mature specimens produce clusters of small, fragrant, white flowers in the spring. The flowers give way to the familiar olive fruits. Some cultivars are self-fruitful, others set more fruit with cross pollination and a few ornamental selections are sterile and fruitless. Those grown for their fruits are typically harvested in late fall or winter.
Provide olive trees with plenty of sun and very well-drained soil with average to poor fertility and a neutral to alkaline pH. The best time to plant new trees is in spring. They are quite drought tolerant, but newly planted trees become better established if regularly fed and irrigated in the first two to three years after planting. Protect the trunks from damage because nicks and gouges may induce unwanted shoots, or suckers. Hardiness varies from cultivar to cultivar, so keep this in mind when choosing a tree for your landscape. Common pests include the olive fruit fly and black scale. Fruit-bearing trees grown as ornamentals can be sheared after flowering to prevent fruit formation, but this is time consuming and can spoil their natural beauty. Fruitless varieties make better specimen trees.
There are many olive cultivars that differ in fruit size, flavor, color and/or oil quality. The immature fruits may be harvested green or allowed to mature to shades of brown, purplish black or deep green. Immature and mature olives differ in flavor and texture. Olive flavor is complex and rated according to its fruity, bitter, pungent, green or sweet flavors. Some better known cultivars include the Spanish ‘Sevillano’, which is prized for its mild, green, fruity, pungent flavor; the spicy sweet Italian, ‘Leccino’ and the Greek favorite, ‘Koroneiki’, which has fruits with a bitter, pungent flavor.
Commercially grown olives are harvested by machine, but home grown olives are best harvested by setting nets or tarps beneath the trees and picking, shaking or raking them down onto the nets before gathering them up. Olives can be fermented, cured with lye, pickled in brine or pressed for oil. Olive oil is pressed, or centrifuged from the fruits. Culinary olive oil has a quality rating based on purity, flavor and acid levels. The most superior in flavor and low acidity (under 0.8%) is extra-virgin olive oil, followed by virgin olive oil, which has good flavor but slightly higher acidity (under 2%), then pure olive oil and olive oil, which are stronger in flavor and mixes between virgin and refined production olive oil, which is a high acid oil requiring refinement for consumption. Lampante oil is a non-culinary olive oils used for oil-burning lamps.
Olive trees make beautiful specimens for dry, chaparral landscapes across the globe and are some of the most commercially valuable of all fruit-bearing woody plants.