The olive tree's entry into the winter season coincides with the onset of dormancy, a complex physiological process in which the plant suspends active growth and reorganizes a broad spectrum of metabolic and structural functions.
Autumn 2025 is shaping up to be characterized by mild temperatures and evenly distributed rainfall. By December, the expected drop in temperatures will favor the beginning of the vegetative rest period, or quiescence (or ecodormancy). During this phase, the olive tree must fulfill its cold requirement (chilling requirement), which consists of theaccumulation of a certain number of cold units (CF, or effective chilling hours, for example about 200 hours at 7°C for some cultivars). This accumulation, regulated by environmental stimuli, is essential to complete the preparation of the buds and ensure subsequent differentiation into flowers in spring, thus allowing correct floral induction and vegetative recovery.
In this period the plant drastically reduces respiration, lowers transpiration and activates an intense accumulation of reserve carbohydrates within the woody and root tissues. The vegetative rest is governed by two phases: the first is theendodormancy o paradormancy, regulated by internal hormonal signals that block growth regardless of external conditions; the second is theecodormancy o quiescence, where growth is blocked only by environmental factors, such as cold or drought.
The completion of the cold requirement is the key environmental stimulus that allows buds to emerge from endodormancy, the “internal hormonal block” and to complete the process of floral differentiation in view of spring.
Even the root system, physiologically sensitive to temperature drops, maintains minimal functionality until the soil temperature does not steadily exceed 10°C, a condition which in northern regions can only occur starting from the second half of March.
Climate risks
Winter management of olive groves must take into account climatic instability. The real problem, in fact, is no longer caused solely by severe frost, but rather by the so-called “false springs”, periods when temperatures rise abnormally, reaching 15-16°C. These periods of mild weather induce the olive tree to prematurely restart its metabolic cycle. The subsequent return of cold weather, even if not severe, causes severe heat stress. The olive tree, sensitive to these fluctuations, suffers damage that can compromise the completion of flower differentiation, reducing the percentage of reproductive buds and, consequently, lowering the following season's production potential.
Pruning interventions
In the high humidity conditions typical of the period, pathogens such as Pseudomonas savastanoi (olive mange) to Spilocaea oleaginea (peacock eye) can survive and spread. Infections, often latent during the dormant period, can manifest themselves when vegetative growth resumes.
For this reason, winter is the ideal time for cleaning pruning, removing dead branches, suckers, and shoots. These procedures promote air circulation, reduce infections, and improve light penetration.
Cleaning pruning integrates perfectly with wood restoration interventions, such as slugging, caries removal, which aims to eliminate any dead or compromised tissue. Cavities are finished, and disinfection with copper-based products completes the process, protecting wounds and preventing new infections from wound pathogens.
Production pruning
In traditional and intensive systems, pruning is not optimally performed in the dead of winter. Once inadvisable due to the risk of severe frost on fresh cuts, it is now delayed for physiological reasons, such as slow healing.
- temperature dropsIn fact, slow down the healing process, increasing tissue susceptibility to wood-borne pathogens. Pruning should not be performed during abnormal temperature rises during "false spring" periods to avoid adding further stress to an already vulnerable plant with unstable metabolic processes.
The ideal time for pruning
Complete pruning, whether for training or production, which is a balancing act between vegetation and production, is safer to postpone it to the second half of February or MarchThis delay allows for work to be done at the phenological stage of "swollen bud," a time when vegetative activity is fully recovering; the risk of sudden temperature changes is reduced; the plant is physiologically more capable of healing cuts and effectively restoring its hormonal balance.
Pruning in super-intensive systems
In super-intensive systems, where pruning is predominantly mechanized, with trimming and lateral cuts, the intervention logic changes. Production efficiency depends on the stability of the canopy. Even in these systems, the most appropriate time to intervene remains during vegetative recovery to avoid slowing the regeneration of new shoots and the risk of infection in injured tissue.
Conclusions
Dormancy, often perceived as a passive phase, actually constitutes the central issue of the olive growing season, as it determines the basic conditions that will influence the quantity, quality, and stability of future production. Pruning, regardless of its method, is now optimally performed in the initial phase of vegetative recovery, when the plant is physiologically predisposed to support canopy reorganization and ensure effective wound healing.
AIPO Director
Interregional Association
Olive producers
