When is water deficit usually scheduled in vine growth?

• A. During dormancy.
• B. Between fruit set and veraison.
• C. After harvest.
• D. Only at veraison.

Answer: (B)

Water deficit is used in a strategic, growth-stage–based way to influence grape composition. The most effective window is during berry development—from fruit set up to veraison—when the berries are expanding and still accumulating sugars and flavors. Imposing mild water stress then helps restrain vegetative growth and reduces berry size, which increases skin-to-juice ratio and concentrates sugars, acids, and phenolics, improving overall wine quality.

Dormancy is a period of little vine growth, so water status then has little impact on fruit quality. After harvest, the season has ended and the vine needs to recover, so deficits aren’t used to shape the current vintage. Only at veraison would focus on that single moment miss the opportunity to influence berry growth and composition during earlier development. That's why scheduling the deficit between fruit set and veraison is the best answer.