Due to its vigorous vegetative growth and high fruit production, kiwifruit has increased nutrient demands. Adequate and balanced nutrition is essential to achieve robust development, rich fruit set, and satisfactory fruit growth in terms of both size and weight.

Winter dormancy until bud break

From leaf fall to bud break, the kiwi enters a dormancy phase. During this period, the buds accumulate the necessary chilling hours to complete their development, ensuring smooth flowering and abundant fruiting.

At this time, the vines do not exhibit significant nutritional demands, while the root system remains dormant due to the low temperatures, preventing active absorption of nutrients and water from the soil.

From bud break to flowering

With the rise in temperature in mid-March, the buds gradually open, and the growth of leaves begins along with the longitudinal increase of the shoots. At the same time, the root system becomes active and starts absorbing nutrients and water from the soil.

In late March, as vegetative and root development progresses, the formation of reproductive organs begins in the axils of the developing leaves. This process is completed by mid-May, with the start of flowering.

High sunlight, adequate irrigation, and balanced nutrition with Nitrogen, Phosphorus, Potassium, and essential micronutrients like Iron and Zinc promote strong root system development and robust vegetative growth. These factors also enhance photosynthesis and the production of nutrients for the development of inflorescences and the formation of perfect flowers.

Nitrogen (N) – Stimulates growth, enhances photosynthesis, supplies the necessary proteins to the buds, completes the development of flowering buds, and reduces flower drop.

Phosphorus (P) – Promotes the development of the root system and the growth of vegetative and reproductive organs.

Potassium (K) – Encourages the growth of roots and leaves, increases photosynthesis, improves water absorption, and protects the crop from diseases and adverse weather conditions.

Micronutrients such as Iron (Fe) and Zinc (Zn) positively affect the development of emerging shoots and enhance the photosynthetic activity of the leaves.

From flowering to rapid fruit growth

The reproductive phase begins in mid-May with full bloom, and is completed by the end of May with the fertilization of all flowers.

The first stage, extending until early July, is characterized by intense cell division and seed formation. At the end of this period, the vigorous shoots are removed as they compete with fruit growth, while differentiation of buds for the next spring’s flowers begins.

During the next four weeks, fruit development is a combination of cell division and elongation, with a major accumulation of water. By early August, the kiwi reaches 50% of its final size, and the seeds are fully developed.

At this time, sufficient water and timely nutrition with Nitrogen, Phosphorus, and Potassium maintain active photosynthetic activity in the leaves, which is crucial for fruit development and achieving high, quality yields.

Nitrogen (N) – Enhances flowering and fruit set, increases the number and size of fruits, supports seed formation, and promotes chlorophyll synthesis.

Phosphorus (P) – Provides the necessary energy for flowering and fruit set, and participates in cell division during early fruit development stages.

Potassium, Magnesium (K, Mg) – Strengthen photosynthesis and improve the production and transfer of photosynthetic substances to the developing fruits.

Boron, Calcium (B, Ca) – Increase pollen fertility, promote fruit set, support cell division, and contribute to the structural integrity of the fruits.

From fruit growth to ripening

After the period of cell division, until mid-August, the fruit growth rate slows down, and their increase is mainly due to starch accumulation. At this point, the fruits reach 60% of their final size, exhibit maximum acidity, and the seeds start to change color.

As development continues, kiwis reach their final size by mid to late September, thanks to the rapid accumulation of carbohydrates and proteins, facilitated by intense leaf photosynthesis and starch breakdown. Ripening follows, and the fruits are harvested in October when they have fully developed their organoleptic characteristics.

Nitrogen (N) maintains active photosynthetic activity in the leaves and boosts the increase in size and weight of the fruits. However, excessive application should be avoided, as it may delay ripening, reduce sugar concentration, and shorten the post-harvest shelf life of the fruits. In contrast, the crop’s need for Potassium (K) is particularly high during this period, as it plays a decisive role in metabolism, transport, and accumulation of soluble substances in the fruits, positively affecting their size, weight, and quality (brix). Phosphorus (P) promotes uniform ripening, while Calcium (Ca) helps maintain plant tissue stability, enhancing post-harvest shelf life.

Post-Harvest Stage

After harvest, significant quantities of nutrients, primarily carbohydrates and amino acids, are transferred from the leaves to the trunk and root system of the kiwi plant. These stored substances are vital for initiating and ensuring the normal development of the vegetative growth and flowering the following spring.

Applying nutrients during this period, especially after a high-yield season, strengthens the vine’s reserves and supports robust growth and good fruiting the following year.