There is a great debate on the optimum harvest time for olives. It depends greatly on weather conditions, olive tree variety and cultivation methods, and it also differs depending on whether olive trees are grown for table olives or for olive oil. Picking the right time is a matter of accumulated experience and gives the olive grower a competitive advantage in yield, sensory characteristics, colour, taste and aroma.
When olives are harvested
Generally, high temperatures during the autumn result in early ripening and vice versa. In Greece the harvest starts in mid-September for green table olives and early harvest oils and can run into March, as the experience of growers across Greece shows, with a clear trend in recent years towards ever earlier harvesting.
Each of the Greek olive varieties has its own window. Green Chalkidikis olives are picked from late September, Koroneiki from late September for early harvest oil, with the main harvest from mid-October and a peak in November, while Manaki is harvested from November to February.
There are many maturity indexes that can set the harvest date, such as skin colour, micro oil extractions and fruit detachment force. The weather often changes plans, and after rain the harvest waits for trees and fruit to dry, for reasons that concern yield, olive knot and oil quality.
How many olives a tree produces
The average production of a mature olive tree ranges between 22 and 90 kg (50 to 200 lb) of olives, depending on the cultivar, tree age, irrigation, planting density and the season, since olive trees bear alternately. There are of course striking exceptions, with reports of individual centuries-old trees producing several hundred kilograms of olives, but trees have to be more than 30 to 40 years old to achieve yields well above average.
As a rule of thumb, the production of non-irrigated olive trees is related to their age, so a 100-year-old tree can often produce more than it did at 60. Irrigated trees, on the contrary, reach their most productive period at 50 to 65 years of age.
How many kilograms of olives make a kilogram of oil
On average, 3 to 7 kg of olives yield 1 kg of olive oil. The range follows fruit oil content, which in Greek cultivars runs from 14% in Chalkidikis to 30% in Agouromanakolia, with Koroneiki at 27%, and also depends on ripeness, irrigation and the season.
With early harvesting the ratio rises considerably. A grower in Itea who picks Amfissis olives green for high-quality oil reports needing 12 to 13 kg of fruit for 1 kg of oil. After rain, too, fruit gives less oil per kilogram, because it takes on water without gaining oil, while the wet paste makes extraction at the mill harder.
How olives are harvested
Olives can be harvested by hand or with modern machines. In countries like Morocco and Greece most olive groves lie on sloping fields with various other obstacles, so fully mechanical harvesting is very difficult. Most growers in these countries use hand rakes or electric harvesters that shake the branches and drop the olives onto nets, and on larger holdings trunk shakers mounted on tractors. Choosing between olive harvesting tools and machines starts from the intended use of the fruit, tree height and the size of the grove.
Hand picking is slow and costly, and today is used mainly for table olives, where the fruit must not be bruised.
Fully mechanical harvesting requires over-the-row harvesters for super-high-density hedgerow plantings (SHD). These consist of a tall tunnel, a moving cab, a full-height catching system and plates onto which the olives fall. The machine passes over the tree, and inside the tunnel the branches are shaken so that the olives drop onto the plates. This method, used mainly in California, Australia and parts of Spain, works only on fields without slopes or obstacles, where trees are kept low and planted to set patterns so that the machine can pass between them.
From the tree to the mill
Olives are delivered to the mill immediately after harvest, normally the same day, because if stored they face multiple risks that affect their quality. They are carried in perforated crates, because sacks, whose use is one of the most common harvest mistakes, restrict airflow, heat the fruit and crush it, and when milling cannot happen straight away the fruit is kept in a shaded, cool, well-ventilated place.
Freshly harvested olives are best milled the same day, before they heat up and start to ferment.
After the harvest
The end of the harvest is not the end of the year for the grove. Copper on harvesting wounds where olive knot is present, removing fruit left on the trees, pruning in dry weather and fertilising by analysis are the tasks that decide next season's crop.
In Greece, from the 2027/28 season, holders of olive groves will also have to file a mandatory olive harvest declaration after delivering their fruit, based on the data in the olive registry, which is worth updating now.
You can see olive oil prices and exporters on the Wikifarmer marketplace, and you can enrich this article by leaving a comment or photo of your olive trees' harvest methods, techniques and yields.
The olive tree growing series
- Olive tree information and uses
- Growing olive trees
- Are olive farms profitable?
- Olive tree alternate bearing
- Olive tree propagation and pollination
- Olive tree climate and temperature requirements
- Olive tree soil requirements
- Planting olive trees
- Olive tree fertilizer requirements
- Olive tree water requirements
- Olive tree pruning
- Harvesting olives
- Olive tree diseases and pests
- Q&As on olive trees
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Sources
- Agricultural University of Athens, Roussos, P. Classification of olive cultivars by fruit size. Laboratory notes (in Greek).
