May in the Olive Grove: the flowering that defines the harvest.
- Azeite a Norte Blog
- 12 hours ago
- 4 min read
After April sees the development of the inflorescences, May arrives in the olive groves of Trás-os-Montes as the decisive month—it is now that the olive tree blossoms and, in a few crucial days, a large part of the olive production that will come in the autumn is defined.
May is the month of full bloom, of pollen carried by the wind, of tiny flowers that will transform into fruit. It is also the month where the olive grower can do nothing but observe, wait, and trust in the work done in the previous months.
Flowering: a critical time of year
Olive flowering in mainland Portugal generally occurs between the beginning of May and mid-June, being later in inland regions. In Trás-os-Montes, full bloom typically takes place in the second half of May, although this can vary slightly depending on altitude and the climatic conditions of each year. (RCAAP)
Olive blossoms are small, inconspicuous, yellowish-white in color, and grow in clusters (the inflorescences that develop in April). Each inflorescence can have between 10 and 40 flowers, but only a small percentage—usually less than 5%—will develop into olives. (Espaço Visual)
Flowering is extremely rapid: each individual flower remains open for only a few days. The full bloom of an olive tree lasts between 5 and 15 days, depending on the variety and climatic conditions. It is a narrow window of time where everything has to go well. (Olive Knowledge)
Pollination: the crucial role of wind
The olive tree is an anemophilous species—pollinated by the wind. It does not depend on pollinating insects like bees, but rather on the wind that carries pollen grains from the male flowers to the stigmas of the female flowers. (Espaço Visual).
For this reason, weather conditions during flowering are absolutely critical:
Moderate wind: favors pollen dispersal and effective pollination.
Heavy rain: washes pollen from flowers, preventing pollination.
Very low temperatures: delay or inhibit pollen release.
Excessive heat: can dehydrate flowers and reduce their viability.
Excessive humidity: hinders pollen dispersal and favors fungal diseases.
That is why May—a traditionally unstable month in Portugal—can be a source of great anxiety for olive growers. A few hours of heavy rain at the wrong time can compromise months of work and an entire harvest.
Revenge: when the flower transforms into fruit
After successful pollination, fruit set begins—the process in which the fertilized flower transforms into a small fruit. The flower's ovary develops, the petals fall, and a tiny green olive emerges.
Fruit set is the moment of truth: only now can one see how many flowers will actually become olives. An olive tree can have thousands of flowers, but only 1% to 2% of them will develop—and even of those, many will fall in the following weeks (a phenomenon called "June fall" or "physiological fall"). (Artigo)
Factors that influence revenge (Agrisc):
Pollination quality (weather conditions during flowering)
Nutritional status of the tree (March fertilization was crucial)
Water availability (water stress drastically reduces fruit set)
Previous year's yield (alternation phenomenon: years of high production alternate with years of low production)
It is during fruit set that experienced olive growers begin to make the first crop estimates: they observe the number of flowers that have set, assess the distribution of small fruits on the tree, and anticipate whether it will be a year of high or low yield.
May in the villages: the month of the first pilgrimages
May is traditionally the month that marks the beginning of the cycle of pilgrimages and popular festivals in Trás-os-Montes and Alto Douro. After the winter months and the Lenten solitude, rural communities celebrate the arrival of full spring with festivities that blend devotion, conviviality, and the affirmation of identity.
May to Feel
For those visiting Trás-os-Montes and Alto Douro in May, this is the month to observe the olive groves in bloom—a unique sensory experience. The sweet fragrance of the flowers, the discreet hum of the wind in the branches, the sight of fields covered in wildflowers and olive trees laden with small white clusters.
It is also the ideal month to understand the fragility of olive growing: a storm in May can compromise an entire harvest, a late frost can destroy the flowers, and excessively strong winds, or the absence of them, can harm pollination.
At this time, olive growers observe the sky with anxiety and hope. May is the month when nature decides—and the olive grower simply waits.
Olive tourism experiences in May allow you to witness this critical moment in the cycle and understand the dependence of olive growing on natural elements—discover more at . azeiteanorte.pt/experiencia
The month that guarantees nothing, promises everything
May teaches us humility. All the work of the previous months—the careful pruning of February, the meticulous fertilization of March, the beginning of budding in April—now depends on a few days of favorable weather conditions that are completely beyond human control.
It is the month that reminds us that olive growing, however much it evolves technically, remains hostage to the elements. And that the wisdom of Trás-os-Montes of not counting the harvest before the harvest is more than prudence—it is knowledge accumulated over generations.
In the olive grove of May, covered in discreet flowers that the wind carries from tree to tree, we learn that there are processes that cannot be rushed, forced, or controlled.
They can only be respected.
🫒 Follow along with us the olive tree's cycle month by month—in June, we will see how the newly formed olives face physiological drop and begin their development.
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