Harvest refers to the time of year when grapes intended for wine production are picked (this does not include table grapes). Depending on the region, it can take place between August and October.
How is the harvest date chosen?
Generally, the harvest takes place about one hundred days after the first vine flower appears, that is, when the fruit reaches maturity. Grapes are harvested once they are ripe, but ripeness can be influenced by many variables, such as sun exposure, grape variety, or altitude.
It should be noted that several types of ripeness must be taken into account. A date must therefore be found that roughly corresponds to all three at once:
- Technological ripeness: this determines the wine's acidity and sugar concentration (and therefore its alcohol content).
- Phenolic ripeness: this corresponds to the degree of berry maturation. It therefore determines the quality of the coloring compounds and tannins.
- Aromatic ripeness: this determines the concentration of varietal aromas.
To check the ripeness of the grapes, berries are collected from each plot. Some are analyzed, while the others are tasted. A prefectural decree then sets the official start date of the harvest: this is known as the harvest proclamation.
Dates vary by region but generally correspond to the following times of year:
- Late August: Provence, Languedoc-Roussillon, Corsica. As a general rule, the harvest takes place earlier in the south.
- Early September: Rhône Valley, Beaujolais.
- Mid-September: Loire Valley, Burgundy, Bordeaux, Rhône Valley, Jura, Bugey, Savoie, Centre, Southwest.
- Late September: Champagne, Alsace.
- Early October: Cognac, Charentes, Lorraine.
Other types of harvest: beware of confusion!
There are other types of harvest, which do not correspond exactly to the definition of the classic harvest but nevertheless bear the same name.
Green harvesting: During July, some winegrowers decide to remove some grapes that are still green from the vines. They are removed by hand in order to relieve the vine, so that it has fewer fruits to nourish. This results in lower production by volume but better quality. Removing grapes allows those that remain to increase their concentration and promotes their ripening. However, care must be taken not to carry this out too early, as the remaining grapes may tend to grow larger than normal, producing the opposite effect to the one intended.
Late harvest: Some regions choose to harvest later, in mid-October, to obtain riper grapes with a higher sugar concentration (for white wines only). This is particularly the case in Alsace for varieties such as Gewürztraminer and Riesling, and in the Southwest with Jurançon. This also affects the color of the wine, which takes on a more pronounced straw-yellow hue.
There are other exceptionally late harvests in Alsace, Austria, Germany, and Canada, which take place in December or January. This produces what are known as ice wines. The grapes must be very ripe, and the juice in the berries must have frozen (temperatures must therefore be between -6° and -12°). The grapes are then pressed while still frozen and left to ferment. This produces a very sweet wine, which should be served at a temperature of 6° as an aperitif, with dessert, or with cheese. As the harvests are late, more grapes are lost and harvesting costs more because of the cold. This makes ice wine a precious, rare product that is difficult to access because of its price.
