Fertilization aims both to replenish the nutrients removed through harvesting and pruning, and to support the tree’s needs for vegetative growth, flowering, and fruit set. The annual nutrient requirements of the cherry tree vary depending on the age of the trees, the variety, the earliness, the expected yield, as well as the specific soil and climatic conditions of each region.

Winter dormancy until bud break

During the winter months, the cherry tree enters a state of dormancy.During this period, the flower buds accumulate the necessary chilling hours required for their differentiation to be completed and for their smooth development in spring.

The tree does not exhibit significant nutritional demands, while the root system remains functionally inactive due to the low soil temperatures, resulting in the inability to absorb water and nutrients until the onset of bud break.

From bud break to the completion of flowering

With the end of dormancy, the flower buds swell and then the first blossoms emerge. This is followed by the appearance of the first leaves and, almost simultaneously with full bloom, the new shoots begin their longitudinal growth. At the same time, the root system becomes active and starts absorbing water and nutrients from the soil.

During this period, the tree meets its increased nutritional needs by utilizing the stored reserves from the previous growing season, as the root system’s activity and the photosynthetic capacity of the young leaves are not yet sufficient to fully support the demands of flowering and fruit set.

Nitrogen (N) – Contributes to the smooth and vigorous activation of the tree, supplying proteins to the buds and flowers while promoting leaf development, fertilization, fruit set, and cell division.

Phosphorus (P) – Supports the development of the root system and provides the essential energy for flowering as well as the structural elements necessary for cell division in young fruits.

Potassium (K) – Participates in metabolic processes and regulates the tree’s water balance, thereby facilitating the redistribution of stored substances to the developing organs.

Among the micronutrients, Boron (B) increases pollen viability and plays a critical role in successful fruit set, while Zinc (Zn) and Iron (Fe) are also important in meeting the enhanced demands of developing vegetation.

From the fruit setting stage to the hardening of the kernel

After flowering is complete, fruit development begins, while new vegetation develops, which significantly increases the tree’s overall water and nutrient requirements.

Η ανάπτυξη των καρπών οφείλεται αρχικά σε έντονες κυτταροδιαιρέσεις, οι οποίες καθορίζουν τον αριθμό των κυττάρων και επηρεάζουν άμεσα το τελικό τους μέγεθος. Παράλληλα, αναπτύσσεται το έμβρυο και αρχίζει ο σχηματισμός του πυρήνα, η σκλήρυνση του οποίου επιβραδύνει προσωρινά τον ρυθμό αύξησης και σηματοδοτεί τη μετάβαση στο στάδιο της διόγκωσης.

Nitrogen (N)requirements are particularly high, as this element supports germination, photosynthetic activity and initial fruit development. However, its application must be considered carefully to avoid fruit drop.

Potassium (K) begins to accumulate in the fruits, actively participating in the first metabolic processes of their development. At the same time, Calcium (Ca), in combination with Phosphorus (P) and Boron (B), are essential for the formation and stabilization of cell walls as well as for the formation of the nucleus.

Finally, Magnesium (Mg), Iron (Fe) and Zinc (Zn) enhance the photosynthetic capacity of leaves and contribute to reducing fruit drop.

From rapid fruit growth to ripening

After the hardening of the core, the fruits enter the swelling phase, during which their size and weight increase rapidly. This increase is due to water uptake and the accumulation of soluble nutrients, ensured by the intense photosynthetic activity of the leaves.

Balanced irrigation is critical during this period, as water stress can cause cracking in the fruits or a decline in production quality.

During this phase, the tree’s need for Nitrogen (N) decreases significantly, since an excessive application can lead to uneven and delayed ripening, as well as a reduction in quality and post-harvest shelf life. In contrast, the requirement for Potassium (K) is particularly high, as it promotes increased fruit size, sugar synthesis, and the improvement of taste and color.

Finally, foliar applications of Calcium (Ca) combined with Boron (B) enhance cell structure, reduce the susceptibility to fruit splitting, and improve post-harvest resistance and shelf life.

After Harvest

After harvest, the growth of the shoots continues, while simultaneously the differentiation of the flower buds that will produce next year’s fruiting takes place. The nutrients formed migrate as carbohydrates and amino acids from the leaves to the trunk and roots of the trees. These substances are crucial for the onset of vegetative growth and flowering the following spring.

Irrigation combined with the application of a certain amount of Nitrogen (N) after harvest is a critical cultural practice for the development of vegetative growth, bud differentiation, the smooth transition of the trees into winter dormancy, and vigorous growth with good fruiting in the following year.