In a Greek Koroneiki grove, the trees flower in May, set fruit in June, build oil from August to October, and are harvested from late October to December. Early-harvest, high-phenolic oil comes from green fruit picked in late October and November. The main harvest of riper fruit follows in November and December. Pruning and soil care fill the winter and early spring before the cycle starts again.
The Koroneiki year at a glance
Dates shift with region, altitude and weather, so read this as a typical year in a lowland Greek grove rather than a fixed schedule.
| Month | In the grove | What it means for the oil |
|---|---|---|
| January | The last of the main harvest is picked in later groves. Pruning starts on trees already harvested. | Late-season oil from ripe fruit is milder, with less bitterness and pepper. |
| February | Pruning continues. Growers clear dead wood and open the canopy to light and air. | Good pruning shapes next year's fruiting wood and helps the tree ripen its fruit evenly. |
| March | Pruning finishes. New shoots appear and flower buds begin to form. Soil is fed and cover crops are managed. | The tree's potential crop for the year starts to take shape. |
| April | Flower clusters develop. Spring rain refills the soil. | Water stored now supports flowering and early fruit growth. |
| May | The trees flower. Olive flowers are pollinated mainly by wind. | Heat, strong wind or rain during flowering can reduce the crop. Flowering largely sets the size of the harvest. |
| June | Fruit sets. Many small fruits drop naturally, leaving the olives the tree can carry. | The number of olives for the season is now mostly fixed. |
| July | The pit hardens. Summer heat arrives and irrigated groves are watered. | Water management now affects fruit size and the balance of the oil. Severe stress can cut yield. |
| August | Oil begins to build inside the fruit. Growers watch for the olive fruit fly. | The fruit is green and rich in phenolic compounds, but it holds little oil yet. |
| September | The fruit swells and oil accumulates. The first autumn rains may arrive. | Oil content rises week by week. Growers start sampling fruit to judge timing. |
| October | Fruit reaches full size while still green. Early harvest begins in late October in many groves. | Early-harvest oil is made now: low yield, intense green flavour, high polyphenols. |
| November | Early harvest continues as fruit begins to change colour. The main harvest starts in many areas. | Green fruit early in the month gives high-phenolic oil. Later picking gives more oil with a softer taste. |
| December | The main harvest of purple to black fruit continues. Pruning begins in finished groves. | Ripe fruit yields the most oil per kilo, with milder flavour and lower polyphenols. |
Koroneiki is an oil cultivar with small fruit, which makes hand picking slow. Our profile of Koroneiki olive oil covers the variety in more depth.
Why early harvest costs yield but gains polyphenols
An olive builds oil and loses phenolic compounds as it ripens. The two curves move in opposite directions.
In October, a green olive has reached full size but has not finished filling with oil. It also holds a high level of phenolic compounds, such as oleuropein, which protect the fruit. Milled at this stage, it gives less oil per kilo, but that oil is greener, more bitter, more peppery and higher in polyphenols.
By December, the same olive is darker and fuller. It gives more oil and is easier to process. Its phenolic content has fallen, and the oil tastes rounder and milder.
Picking early is a deliberate trade. The grower gets fewer litres from the same trees and must pay for slower, earlier work. In return, the oil can reach polyphenol levels that later fruit rarely matches. That is why early-harvest oil costs more. It is also why the EU health claim threshold of 5 mg of hydroxytyrosol and its derivatives per 20 g of oil is easier to reach with green fruit (European Commission, 2012). Our article on early-harvest olive oil and quality explains the chemistry.
How the weather shifts the calendar
No two seasons run to the same dates. Growers time the harvest by the fruit, not the calendar.
- A warm spring can bring flowering forward. A cold or wet spring can delay it and reduce fruit set.
- Heat during flowering can dry the flowers and shrink the crop before any fruit forms.
- A dry summer slows fruit growth and oil accumulation. Mild water stress can concentrate phenolic compounds. Severe drought cuts yield and can harm quality.
- Early autumn rain swells the fruit with water. This can change the timing of harvest and the extraction at the mill.
- Olive fruit fly pressure varies with temperature and humidity. Damaged fruit can raise acidity, so a heavy fly year can push growers to pick sooner.
- Altitude matters too. Groves on higher ground often ripen later than those near the coast.
Olive trees also tend to alternate heavy and light crops from year to year. Our harvest season diary describes what a season looks like on the ground.
When fresh-harvest oil reaches customers
Oil milled in late October or November is not on your table the next day. A few steps come first.
- Milling. Olives should be milled within hours of picking. EU rules reserve the term "cold extraction" for oil obtained below 27°C (European Commission, 2022).
- Settling or filtering. Fresh oil carries water and fruit particles. Removing them helps the oil stay stable.
- Testing. Samples go to a laboratory for grade and polyphenol analysis.
- Bottling and shipping. Once results are back, the oil is bottled and sent to market.
For a careful producer, this usually means new-season oil reaches buyers in winter, a few weeks to a few months after harvest. If you want the freshest oil, look for the new harvest month on the label from around the turn of the year. Our guide to how long olive oil stays fresh explains what happens after that.
How Pomoni does it
Pomoni follows this calendar from Greek groves of Koroneiki trees. We pick early, while the fruit is still green, and mill within hours using cold extraction. Every batch is tested by HPLC before it is sold, and the certificate is published on our testing and certifications page. The harvest month is printed on each dark glass bottle, so you can see where your oil sits in the year. Find the current batch on the Pomoni high-phenolic olive oil page, and read more about Greek olive oil.
Frequently asked questions
When is the olive harvest in Greece?
The Greek harvest usually runs from late October to January. Early harvest of green fruit happens in late October and November, and the main harvest follows in November and December.
When do Koroneiki olive trees flower?
Koroneiki trees usually flower in May. The weather during flowering has a large effect on how big the harvest will be.
Why is early-harvest olive oil more expensive?
Green olives hold less oil than ripe ones, so the same trees give fewer litres. The grower also picks earlier and more slowly, which costs more.
When can I buy olive oil from this year's harvest?
New-season oil usually reaches shops in winter, after milling, filtering and testing. Check the harvest month on the label to be sure.
Sources
- European Commission. Commission Regulation (EU) No 432/2012 establishing a list of permitted health claims. 2012. eur-lex.europa.eu
- EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific opinion on health claims related to polyphenols in olive. EFSA Journal 2011;9(4):2033. doi.org/10.2903/j.efsa.2011.2033
- European Commission. Commission Delegated Regulation (EU) 2022/2104 on marketing standards for olive oil. 2022. eur-lex.europa.eu
- International Olive Council. Trade standard applying to olive oils and olive pomace oils, COI/T.15/NC No 3. internationaloliveoil.org
