Happy harvest time, everyone! Yes, September is high harvest time in many parts of the world. This is a very important time in the wine production cycle. Vineyard managers must determine the exact time to pick the grapes- too early and they may be too acidic; too late and they may be too sweet. Warmer climates can start harvesting earlier (warmer weather=faster ripening), as early as July in some places, including Cyprus and Texas. Most other areas in the Northern Hemisphere harvest in late August to early October.
So why is harvest timing so important? Harvesting grapes is the foundation of the winemaking process. If harvest goes badly, the wine yield might be low or the quality could suffer. Grape growers have to consider two very important factors in determining when to harvest. First, and probably most obvious, is the ripeness of the grape. The grapes need to be picked at the right level of ripeness to ensure the wine will have the right balance of sweetness and acidity. Different grapes ripen at different times, with white wine grapes usually picked earlier to maintain acid levels, red grapes picked next, and grapes for sweet wines picked later to ensure maximum sugar levels. While some wineries will adjust sugar and acid levels during the winemaking process, others will not intervene, so it’s incredibly important to pick the grapes at the right time. Experienced grape growers can tell if a grape is at the right sugar level just by tasting it. There are also devices called refractometers that give a precise measurement of sugar levels to help grape growers make the decision. When determining ripeness, grape growers must also consider the physical ripeness of a grape. The grapes must be the right size and color, and the tannins must be ripe.
Another vitally important part of timing the harvest is the weather. While fall is an exciting time when temperatures are dropping and leaves are changing colors, it can also be unpredictable. A heavy rain, early freeze, or a hail storm could wipe out an entire crop. The implications of this are obvious- if the grape crop is destroyed there won’t be any wines made that year.
Timing the grape harvest is an art based in science. Although the decision is rooted in measurements, forecasts, and history; great grape growers know their land and their vines, and follow not only the weather forecast and sugar measurements, but their own instincts.
Wine harvest time is often considered one of the best times to visit a vineyard because of the many colors of the trees, vines bursting with grape clusters, and all the exciting activity. Those of us in Texas have largely missed the harvest, but there’s still time if you’re in other parts of the country. Many wineries offer parties to those who help with the harvest- you often get to help pick grapes, eat breakfast, drink wine, and even stomp the grapes! It’s hard work but the wineries reward their volunteers handsomely.