How Do We Know When to Harvest Our Grapes?
Updated: Jul 27, 2019
There are many factors that help determine when it’s time for harvest, but all viticulturists use a mix of science and intuition to make their decision. Achieving the right balance of sugar, acidity and tannins during the ripening process of the grapes will result in a wine with great equilibrium.
From a scientific perspective, the sugar and pH levels must be optimal before harvest. The yeasts need the right amount of glucose to convert the juice into wine. Brix is a measurement of the sugar content of the grapes. Ideally, Brix levels should be between 24°-26° for red grapes and 22°-23° for white.
We also measure the acidity to know if the grapes are ready. As the fruit ripens and sugar levels increase, pH rises and acidity drops. We need to maintain certain levels of acidity so the wine is well-rounded, so we strive for a pH of around 3.2-3.4.
One must also consider the physiological changes of the vines. Fernando checks the color and texture of the grapes, stems and seeds. Grapes that are ripe will have bright, plump fruit. Stems and seeds will be brown. The seeds should also be hard but easily chewed.
Finally, intuition comes into play throughout this whole process, but especially when we taste the grapes. When the grapes are at their peak, they will taste sweet, be slightly acidic and the tannins will be notable. The characteristics of each variety will also be easily distinguished.
In summary, determining the ideal moment to harvest requires science and intuition. Taking all this into consideration and making a precise decision about when to pick grapes allows us to bring out the full qualities of our terroir and make the best quality wine.