Vegetative awakening in fruit crops: effective fertilization

Even though differences exist due to latitude, altitude, and cultivated species-variety, fruit crops in Italy have already entered or are about to enter the vegetative awakening phase.

As is easy to imagine, this is a critical phenological stage, preceding the emergence of leaves and shoots, flowering, fertilization, and fruit set.

This phase has always required careful management—given spring’s natural climatic instability—due to the risk of more or less intense temperature fluctuations and variable rainfall. In recent years, however, climate change has introduced additional challenges. For instance, in 2025, many areas are experiencing cold snaps following periods of excessive warmth in February. These warm spells often induce premature budding, increasing the risk of damage to the crop if spring frosts occur.

During the vegetative awakening—also marked by increased root activity as temperatures rise—nutritional needs must be carefully monitored and managed, also considering the previous season’s outcomes and their impact on the accumulation of sugar reserves in plant storage organs.

Let’s briefly look at the key points to ensure effective—and efficient—spring nutrition for the main fruit crops. Nitrogen always plays a leading role at this time of year, but other nutrients also require targeted application.

For pome and stone fruits, nitrogen is essential in spring and summer for producing new tissues and supporting vegetative development, while phosphorus is crucial for flowering and root growth. Due to phosphorus’s well-known tendency to become insoluble, rendering it unavailable to plants even when abundantly present in the soil (phosphorus depletion), phosphate fertilization must be managed carefully.

Potassium, on the other hand, is indispensable for fruit ripening, as it plays a vital role in sugar metabolism. It positively influences not only Brix levels at maturity, but also fruit size and weight. Potassium is also involved in increasing resistance to spring frost and improving cold storage capacity.

Nitrogen requirements in pome and stone fruits extend well beyond winter’s end, lasting through the summer. Therefore, it is recommended to meet nitrogen demands through late-winter to early-spring applications of organic or organo-mineral controlled-release fertilizers.

The olive tree is evergreen, and although its main nutrient storage organs are the roots and trunk, the leaves can also temporarily serve this function during specific vegetative phases, redistributing nutrients throughout the plant according to need.

For olives as well, it’s advisable to split annual nitrogen inputs or use fertilizers with controlled, gradual nitrogen release, ensuring good nutrient availability from spring through summer to support vegetative activity and fruit set. Due to alternating yields, one should avoid excessive nitrogen applications at the end of winter following a productive year. Phosphorus and potassium are usually applied in late winter, often in a single application, and must always be incorporated into the soil.

Like olives, citrus plants are evergreen. For most oranges, mandarins, and clementines, flowering occurs between March and April, with harvest from November to January.

In spring, it’s essential to ensure adequate availability of nitrogen, which supports vegetative growth and fruit set, and phosphorus, which has a positive effect on both flowering and fruit development. Potassium begins to be absorbed more significantly in late spring, with a drop during summer months and a resurgence in autumn.

For wine grapes, fertilization strategies vary depending on soil and climate conditions, varieties, rootstocks, and specific oenological objectives.

Annual phosphorus and potassium doses are generally applied either in autumn after harvest (for heavy soils) or in late winter (for lighter soils). Nitrogen applications are always split into at least two treatments, one in spring and one in autumn. A similar approach applies to table grapes, although the amounts of nutrients applied may differ significantly from those used in winemaking.

Although considered a rustic plant with modest nutritional requirements, hazelnuts in commercial orchards must be properly fertilized. Spring fertilizer choices should reflect the crop’s particular need for nitrogen and potassium, with nitrogen playing a key role in late-winter fertilization.

Ortofrutta Special 12.7.5, an organo-mineral fertilizer, provides a mineral fraction with slow-release nitrogen, as well as phosphorus, potassium, meso-elements, and a significant amount of organic matrix made from a blend of highly humified, naturally fermented manures. The humified organic matter improves soil characteristics, protects nutrients through the chelating action of humic acids, enhances fertilization efficiency, and improves soil structure. Ortofrutta Special 12.7.5 also supplies secondary nutrients and micronutrients, although only magnesium, sulfur, and zinc are present in legally declarable quantities. Recommended for citrus, hazelnut, olive, and grapevine.

Agricomplex 7.5.14, in addition to the mineral fraction, provides the same secondary elements as Ortofrutta Special 12.7.5—magnesium, sulfur, and zinc—through its organic matrix, but with a different NPK ratio. Recommended for stone fruits, pome fruits, and grapevine.

Agrivigne Special 9.5.15 is also an organo-mineral fertilizer containing organic matter from highly humified manure. It delivers nitrogen, phosphorus, and potassium from sulfate, and is notable for its sulfur content. Recommended for stone fruits, pome fruits, and grapevine.