Harvest, the Birth of a New Vintage

First published in the print edition of Good Wine Magazine, 2013.

Harvest indicates the end of the summer, and the beginning of autumn. In this period the life of the grape comes to an end. Each year the grapevine goes through an annual fruit production cycle. In a hot climate, a grape’s life cycle may be as short as 130 days, whereas in cooler regions grapes may live over 200 days. The plant started its growth cycle a couple of months earlier in spring. In the Northern Hemisphere bud break starts around March. From that moment the grape goes through a sequence of stages known as flowering, fruit set, and veraison (the beginning of ripening), before being harvested. The harvest starts just before the falling of the leaves, at the time the fruit is optimally ripe. In the Northern Hemisphere this will typically be in September. However, depending on the climate of the region, harvest may be as soon as mid-August in warmer regions, or as late as begin November in cooler regions. In the Southern Hemisphere, in comparison, bud break takes place in September, and harvest will typically find place between March and April, with outliers to February and May.

The single most critical aspect of harvest is timing. The timing is determined by the ripeness of the grape. One of the most important features of a good winemaker, is to pick the grapes at the right moment. In order to know the right moment of picking, it is crucial to understand something about the processes taking place in in the grape. Traditionally, ripeness was often merely expressed in sugar grape concentration, which is directly related to the alcohol potential of the wine. Nowadays, a number of different aspects are taken more and more into account. The most important aspect is the balance between natural sugars and acids. Other aspects that are related to physiological ripeness are; skin color, pulp texture, seed color and ripening, flavor, and phenolic changes with regard to tannins in red wines. A grape is considered ripe when it is physiologically mature. The aim is to pick the grape at the best moment. This is not predictable, however. Factors such as weather conditions, site, and viticultural techniques all have an impact these relationships. A favorable condition to obtain optimal physical ripeness, for example, is to have large diurnal ranges. This means large differences between day and night-time temperatures. The heat of the day makes sure sugar is accumulated in the grapes, whereas the cooler night temperatures help to retain acidity, resulting in a perfect balance. Another example of how optimal ripeness can be achieved, is by canopy management. Canopy management are the techniques used to improve the exposure of leafs and fruit to the sun. In a cool climate for example, winemakers prefer to expose the grapes directly to as much sunlight as possible in order to build enough sugar, whereas in hot climates the aim is to try to protect the grapes form sunburn by creating shadow with the help the leafs. Obtaining the optimal ripeness dependents on a series of complex decisions that have to be made through out the annual cycle.

At the moment the grapes are found being ripe, harvest begins. Picking grapes is sometimes regarded as romantic and delightful - proven by numerous poems and paintings that have been made since ancient times - but in reality grape picking is back-breaking work. The best vineyards are located on steep slopes, and the fruit zone is usually close to the ground, often between 60 to 100 cm. As every bunch needs to be cut separately it requires very intense and difficult labor. Fortunately, recent technologic advancements facilitated the replacement of the traditional manual harvest by mechanical harvest. Mechanical harvest is done by harvesting machines mounted on tractors driving between the rows. Most machines work by striking the grapevine to remove the fruit and catching it with horizontal conveyor belts. Machines with optical sensors also exist. The advantage of mechanical harvest is that it can replace manual labor. If optimally used it reduces the costs of winemaking as well as the time needed to harvest. Harvesting machines are faster and grapes can be picked at either time of the day or night. Those advantages, however, go together with a number of disadvantages. Harvesting machines, for example, can’t be operationalized on very steep slopes. On steep slopes manual labor is still required. Importantly, mechanical harvesting is often believed to have a negative effect on the quality of the wine. Most of the machines work quite rough, breaking the grapes, hence exposing the juice to oxidation, which results in lower quality wines. Another disadvantage is, that it’s difficult for machines to select unripe or rotten grapes out of the bunches. Manual picking has the advantage that grape selection can be done directly in the vineyard, whereas most machines are not capable of doing this. Despite the existing disadvantages, technical innovations are implemented continuously, making mechanical harvesting more and more interesting and widespread. I expect that advanced harvesting machines will be introduced into most of the vineyards in the upcoming decades.

Having this said, the time has come to leave the vineyard and enter the cellar. As harvest is the end of the grape’s life, but the beginning of the wine, it is crucial to acknowledge the importance of the harvest in the process of winemaking. Harvest is a period of transition. All the work that has been done in the vineyard during spring and summer comes to an end. All what follows in the cellar is already determined by what happened during the growing season, because the production of good wine starts in the vineyard. Remember, that good wine can’t be made from bad grapes. It is at this moment, once the grapes enter the cellar, that a new vintage is born.