Spring and the Rebirth of the Vines

25 Mar 2024 / Viticulture

The beginning of spring coincides with the start of the vine's vegetative cycle. Although the common year has 12 months, in the vine cycle we can only glimpse some activity in 8, the first (in the northern hemisphere) begins in March with bud-break and the last in October with the harvest.

With the arrival of warm weather, the vines begin to awaken from the dormancy in which they were during the coldest months of winter, and the first phenomenon that heralds this awakening is the bleeding of the vine.

A bleeding is not always a sign of illness. When the eyes slowly begin to shed drops of sap, we have the first sign of awakening from a long sleep and the first pulse of life in the vine's new cycle.

This natural phenomenon consists of the release of a liquid (sap) through the pruning cuts on the trunks and branches of the vine, marking the resumption of activity by the plant. 

This sap is essentially made of water, nutrients, and minerals that have accumulated in the vine's roots and will now encourage the plant to produce new leaves, flowers, and shoots. This marks the start of vegetative growth and, subsequently, the development of the plant's organs, branches, shoots, flowering, and grape bunches. This phenomenon is called budding.

Types of budding
Budding can occur earlier or later, depending on the region, climatic conditions, and other factors. The specific characteristics of each grape variety also influence this process. In the Vinho Verde region, for example, one of the early budding varieties is Fernão Pires, while Trajadura is a late budding variety (on average 17 days after Fernão Pires).

This timing is important, especially in areas more prone to spring frosts, where late budding varieties should be selected so that the buds are not damaged, and the plant does not suffer production losses in the future.

The strong sensitivity of the first green organs to frost, even moderate frost, makes budding one of the most critical periods in the vine's vegetative cycle.

Six to thirteen weeks after budding, there is rapid growth of the vine's shoots, branches, and leaves, followed by flowering, which once again varies depending on the grape variety and weather conditions. 

The plant is in intense physiological activity: it absorbs water and nutrients through its roots, its leaves turn into small sugar factories through photosynthesis, the respiration that breaks down the sugars produces enough energy for cell multiplication and transpiration allows for the gas exchange necessary for photosynthesis. In the northern hemisphere, this process takes place from May to June, while in the southern hemisphere, from November to December.

Favourable conditions for flowering
The increase in temperature throughout spring will allow the vine to blossom smoothly. In addition, rain or strong winds are not desirable at this stage, as they can compromise the pollination of the vines and, consequently, their fruit set.

Fruit Set
Fruit set is the transformation of flowers into fruit, in the case of vines, into grapes. The setting rate can vary from 15% to 60%, meaning that not all flowers will turn into fruit, as those that are not pollinated will fall off.

Coulure and Millerandage
In cases where the setting rate is very low, this is known as Coulure, with some grape varieties more susceptible due to the low sugar content in the berries. If the berries grow without being fertilized and therefore have no seeds, the phenomenon is called Millerandage.

Both phenomena (Coulure and Millerandage) drastically reduce yields and are correlated with the climate during this critical phase of the grapevine cycle, pollination. After the flowers have fertilized and the berries have developed the ripening period is next.

At Aveleda, the members of the viticulture team are the true guardians of the vineyards and look after them every day with all the dedication and attention necessary to ensure that they grow healthy and produce grapes of excellent quality.

Discover more about the stages of Aveleda's vineyard cycle on our social networks or visit us at Quinta da Aveleda in Penafiel.

Written by Aveleda