Harvest at night is an increasingly widespread practice, especially in warm winegrowing areas. When summer is very hot, temperatures do not drop during the nights and grapes can lose their aromatic properties. During the harvest, it is better to have an absolute control over temperatures since excessive heat may lead to must oxidations, pre-fermentative macerations or spontaneous fermentations.
Although night harvest can be practiced to pick any kind of grape, white varieties are the most suitable for it. They are more sensitive to light and heat because of their skin type, so certain difference in wine can be appreciated if it has not been exposed to that conditions.
One of the advantages is that harvest can be more efficient and reduce expenses. In case it is performed by hand, people who work at the vineyard do not spend hours in the daytime sun carrying out this meticulous task and they improve their efficiency. In the case of machine harvest, bunches do not suffer as much as if, when they are struck, they were also affected by heat. Furthermore, energetic waste employed in cooling the cold stores is less if grapes are already in cool temperatures.
Night harvest also has its disadvantages, as the lack of visibility that may hinder the farming and cellar tasks. The assortment by hand can be less selective due to the absence of light and the mechanic method absorbs leaves and petioles, residues that must be cleared in the tow with equally deficient light conditions.
More and more wineries are performing this harvest and take a chance on the entry of cool grapes into the cellar, preserving the fruit quality and avoiding unwanted reactions during fermentative processes.