The factors that have the greatest influence on harvest timing include the grape variety, weather conditions and ripeness.
Annual grape harvest in Europe and North American starts in August and for the most part ends in October. For countries south of the equator, like Australia, New Zealand, South America and South Africa, grape harvest spans from February to April.
In both hemispheres however there is one exception to these general guidelines. Late harvest ice wines are made with grapes that remain on their vine until they are frozen. This ensures that once picked and pressed, the grapes will produce a juice with a high sugar concentration. This process can occur up to a few months past the traditional harvest time for that region. *Read “Ice Wine” to learn more about these sweet treasures.
A wet winter alongside a dry spring and summer with cool nights and temperate days are weather conditions ideal for growing grapes. Right before the harvest and for is duration, dry weather is essential or the wine will taste watery.
As a general rule of thumb, grapes that are grown in cool climates have a higher acidity, are described as crisp and tangy and have a light body, while warm climate wines are characteristically smoother, softer in acidity, have a fuller body and have more luscious fruity flavors.
When it comes to ripeness, it is the grape’s levels of tannins, sugars and acids that are tested to determine the grapes ideal maturity level. Ideal levels of each of these components differ depending on the qualities the winemaker wishes their wine to possess. These factors can be heavily influenced and put at risk by varying weather conditions
There are two routes a winemaker can take to harvest grapes, traditional hand harvesting or mechanical harvesting. While very time consuming, hand harvesting offers a more precise technique, protecting the grapes from damage and ensuring the skins stay undamaged.
Mechanically harvesting on the other hand is a far more time and cost efficient technique and is well suited for large vineyards that are on flat ground. There are a few disadvantages to mechanical harvesting however. The machines collects the grapes by beating the vine with rubber sticks until the plant drops its fruit onto the machine’s conveyor belt. Unfortunately, the machines can’t easily distinguish between ripe, rotten and under ripe grapes. These must be sorted through in the winemaking facility. Furthermore, the machinery puts a lot more pressure on the grapes leaving the skins at risk of maceration. This may cause an unintentional coloring of the juice, or oxidation that causes a loss of the wine’s ultimate aromas!