In viticulture (grape-growing), veraison is the onset of ripening. Veraison (pronounced, veh-ray-zuhn) marks the stage in vine ripening when the grapes go from little, hard green berries to softer, colored grapes. The term is originally French (véraison), but has been adopted into English use. The official definition of veraison is "change of color of the grape berries".
This time of year is highly anticipated. We have been monitoring weather, searching and waiting for the first signs of color in the clusters. These two pictures were taken about one week apart in our vineyard.
When the little berries begin, the acid content is much higher than sugar. During veraison, the sugar content increases and acid decreases, making the berries softer and plumper, looking more like actual grapes. This is a pretty important stage in winegrowing. Veraison is a physiological stage in the vine life cycle that is marked by a change in the appearance and hardness of the grape berry. Till now, the grapes looked like little green peas. Veraison takes them from this stage to actual grape stage. For white varieties, this means that they become a softer, transparent yellow-green color. For red varieties, it’s more obvious, taking the grape from bright green to red or purple. Up until now, the berries are very firm. Once they get through veraison, the berries are pliable and this elasticity is one of the only ways to observe veraison in white wine grapes.
As a general rule, once grapes complete veraison, they will be ripe and ready to harvest in about six weeks. Veraison typically takes 5-7 days to complete. The interval from veraison to harvest is different for each varietal, and is largely dependent on heat accumulation and crop size. Merlot takes fewer heat units to ripen than Cabernet Sauvignon and Syrah.
In the case of both white and red grapes used in winemaking, the onset of veraison marks the end of grape skin cell division. Once it is finished, the grape skin cell number is fixed. A smaller number of skin cells generally mean smaller berries. A small berry has a better skin to juice ratio that ensures a better concentration of flavor and structure, something that’s very important in quality winemaking.
From this point on, the berries just keep ripening to become the perfect grape for our future wine and the busy time begins!