There’s a palpable energy in wine country this time of year, as the wineries and winemakers consult with vineyard professionals to decide the ideal time to bring in grapes from the fields. Deciding on the right time to harvest the fruit requires taking many factors into consideration, and it’s the most important decision made in the vineyard. Grapes are at their peak for only a few days, and uncontrollable events like weather can change plans in an instant. Vineyard workers and machinery must be ready at a moment’s notice, and when it’s time to go, it’s go-go-go. Because different parts of a vineyard can become ripe at different times due to sun exposure or grape variety, it’s common to have several passes through a vineyard during harvest.

The typical Napa Valley visitor or local may never actually see anything resembling harvest activity, largely because vineyard staff are busy picking while the rest of the region is sleeping. Berries are gathered during the night or early morning while it’s cool enough that the grape maintains a stable sugar level until it arrives at the winery, and so that workers avoid picking for hours under the glaring sun.

Many grapes are still harvested by machine, but hand-picking is gentler on the grapes and allows harvest workers to leave out undesirable fruit. Wine producers usually harvest their best wines by hand, especially in areas where it’s difficult for machines to navigate. Machine harvesting is faster and less expensive—one reason why certain wines are priced higher than others.

Harvest timing largely comes down to sugar content. White varieties are picked before red varieties, to retain desired acidity, and grapes for dessert wines are harvested last for desired sweetness. The longer the berry remains on the vine, the riper and sweeter it becomes. Desired sugar levels vary pending on the variety and style of the wine, but one thing to keep in mind is that level of sweetness translates to strength, and the higher the sugar content, the higher the alcohol content in the wine.

There are some general guidelines for harvest timing. At the end of summer, when the grapes began turning color and ripening (veraison), the clock began ticking. Around 30 to 70 days from veraison, grapes first began to be tested by taste, sight, and smell, until it was deemed time for the more scientific method of testing sugar content, known as Brix. Determining the best Brix level is one of the most critical choices in the grape growing and winemaking process.

Once picked, the harvested fruit is delivered to the winery as quickly as possible. Different varieties get different treatment upon arrival. Red varieties may be lightly crushed but are then fermented with the skins, while grapes destined for whites and rosés spend little to no time with their skins. All fruit ends in a fermentation vessel for a period, after which it may or not age, depending on the wine.

Now that the fruit has been brought inside and has begun its journey into becoming wine, it’s time for the vineyards and the vineyard teams to take a break, before the next season begins.

Layne Randolph, Inside Napa Valley Magazine, October 2019