Domenico Winery + Osteria

What Happens During Wine Harvest Season

Harvest is the busiest and most exciting time of the year at any winery. It’s when all the magic happens. The grapes are picked and turned into seductively delicious wine. As much as that sounds simple, wine harvest season is a little more complex than that.

So, what exactly happens during a wine harvest season? If you’re a wine lover, you’ve got to know the basics of the wine harvest season. It will only make you appreciate your wine even more.

When is Wine Harvest Season?

Generally speaking, the wine harvest season in California can run anywhere from August to November.  The exact dates all depend on how the grape’s ripening status, something that winemakers pay very close attention to. That’s because the time grapes are picked depends on a few variables, with the main ones being grape type, weather, and winemaking styles.

So, how do winemakers determine that it is the right time to pick? Well, winemakers use a handy unit of measurement called Brix. Brix is the measurement of sugar is in the grapes. The amount of Brix will give the winemaker an estimate of alcohol levels in the wine when fermented until dry.

How? Well, the amount of sugar in the grapes is what the yeasts will eat up and convert to alcohol. The conversions from Brix to alcohol range from .55 to .66, but on average fall around .55 to .59. So, 23 Brix will produce a wine somewhere around 12.6 to 13.6 percent alcohol (aka one gram of sugar is roughly a half a gram of alcohol.) The exact number can’t always be determined as yeast strains and grape types affect the way the wine ferments.

freshly picked white wine grapes in the vineyard

What Happens in the Vineyard During Wine Harvest Season

A winemaker’s job during wine harvest season is just as much in the vineyard as it is in the winery. During harvest, winemakers are constantly visiting the vineyards to make a solid judgment on the right time to pick. Winemakers have to weigh a lot of factors, like grape type, location of the vineyard, and the current or even upcoming weather.

This means that sometimes winemakers have to make hard decisions during wine harvest season. For example: if there’s a major rainstorm coming on Saturday, but the ideal day to pick would be Monday, the grapes will need to be picked before the storm. There’s no arguing with nature.

There are two main happenings in the vineyard during wine harvest season: taking Brix and grape picking.

The winemaker will take Brix measurements from the vineyards by taking grape samples. These grapes are crushed and their juices are tested with a refractometer. This tool will give the winemaker an estimate of the grapes Brix levels.

Once the winemaker determines that it is time to pick grapes, the picking time is scheduled so that the winery knows fruit is coming in. Grape clusters are picked typically by hand, but large-scale wineries often mechanically harvest grapes.

The grapes are usually picked in the early morning or even at night. Picking grapes during the day rarely happens, as it’s much too hot for the grapes and those picking them.

grape picking at night with the Domenico team

Harvesting grapes at night with the Domenico Crew!

Into the Winery

After picking, all the grapes are loaded up in bins and brought immediately to the winery. Grapes cannot sit around. They can actually begin fermenting in the bins, especially if they’re sitting out in the hot sun. This can totally damage the aromas of the grape. No winemaker (or wine drinker!) wants that. Also, you have to remember that harvest happens mostly during late summer and early Fall. Temperatures in California during this time are still pretty hot.

Processing the Grapes: To Crush, To Destem, or to Press…?

Once the grapes arrive in the winery, they aren’t all processed the same. White grapes and red grapes are usually treated a little differently. Within these categories, there are also different winemaking styles.

For white wines, the grapes are sorted, move through the crusher/de-stemmer, and sent directly to the press. White wines do not usually undergo maceration (although this depends on the grape type and winemaking style!) Many winemakers often add dry ice to the pressed grape juice. Keeping the juice cold will help preserve the aromas of the wine.

White grapes are also processed first, as they have less pigment. If red grapes are processed first, it could completely discolor a white wine whose grapes are processed after. This organization is very important, as there are typically grapes coming into the winery at various times during the days and weeks of the wine harvest season.

With red wines, there’s definitely more variability on what happens to the grapes in the winery. Red grapes often undergo more diversified treatment in the winery. This is due to red grapes having more pigment and a funky little thing called tannin.

destemmed grapes going into the crusher

Most red wine grapes go through the de-stemmer, the crusher, and then grape skins and all go into a vat or bin to ferment. Some grapes may only be destemmed, leaving the grapes uncrushed. From here, grapes can be foot stomped or undergo carbonic and semi-carbonic maceration. This is where grapes actually ferment from the inside.

Finally, there’s whole cluster fermentation, a process where red wine grapes are not processed at all and left to ferment in bunches. You can foot stomp these too, although it is does require some serious leg muscle (yes, it’s harder than Soul Cycle.)

What Happens After the Grapes are Processed

No matter the grape type, once they’re processed accordingly, they all are off to ferment. The fermentation process can begin with the winemaker inoculating the grape juice with yeasts or relying on ambient yeasts to conduct fermentation. As much as a broken record as we may sound, the yeast choice all relies on the winemaker.

You may be wondering, when does it all end? Well, grapes are coming into the winery at various times. So, there are grapes fermenting while new grapes are just getting crushed. Wine harvest season does not settle down until all the grapes are successfully fermented to desired dryness. Then, winemakers will transition the wine appropriately in terms of aging, a topic that deserves a whole post on its own.

Did you know: you could be part of a wine harvest too? With Bacchus Winemaking Club, not only can you make your own wines but also participate in the harvest process of your grapes. While you may not be able to pick the grapes (we have a team for that!) you can assist Dominick in the winery as you craft your future wines together.

Curious about Bacchus Winemaking Club, harvest, or what the Domenico team is up to? Don’t ever hesitate to reach out to us, via email or through Instagram. We’d love to chat all about wine!