Winemaking has been around for thousands of years. In fact, humans have been making wine since at least 4100 B.C. The history of wine reveals that great wine is a complex blend of nature, art, and science.

Although winemaking is a complex process, there are five basic stages needed to produce a bottle of wine.

Stage 1: Preparing for Harvest

Great wines begin in the vineyard. The location, climate, topography, soil types, and vines clones all factor into the final product. The maintenance and care of a vineyard—such as pruning, leafing and dropping of fruit—all play an important role in the quality of the wine. At Theorem Vineyards, we walk the rows frequently during the growing season and monitor the vines from bud break to véraison and to, eventually, harvest. As harvest approaches, we begin weekly grape sampling to track sugar levels and taste the grape skins to gauge tannin profile. Sampling allows us to determine the optimal harvest time. This meticulous approach to maintaining the vineyard requires significant time and effort but it results in a more complex and age-worthy bottle of wine.

Stage 2: The Wine Grape Harvest

Winemaking starts with the annual harvest. This can be accomplished by either mechanical or hand-harvesting. We choose to hand harvest annually to select the best grapes for our high-quality wines. We drop any clusters the ground that is below standard. Grape harvest usually begins early in the morning around 2 a.m. Large tractors with mounted lights allow the vineyard to be well-lit while we start harvesting. We choose to harvest early in the morning when the ambient temperature is at its lowest so we can ensure the fruit is cold when it reaches the winery. All of these extra steps allow us to make the best possible wine each year.

Learn more about what makes Napa Valley ideal for top-quality wine in our Theorem Vineyard blog!

Stage 3 Processing

Once harvested, we take the grapes to the winery for processing. White grapes and red grapes are processed differently. If the grapes are white, they are loaded directly into a press and squeezed to release all the juice. The freshly pressed juice is then placed into barrels made of oak or stainless steel and moved into a cold room. After a few days, small bubbles will form. This is the start of fermentation.

The red grapes process begins with destemming. This is when we remove the stem from the individual berries. The berries then pass through an optical sorting machine that takes pictures of the fruit. If the images detect anything below our set standards, it will send out a small burst of air to eject the berry. The berries then move into a tank where they begin cold soak. Cold soaking keeps the grape and the “must” cold to prevent the yeast from fermenting. The purpose is to carefully extract color and flavor from the skins first.

After cold soak, we introduce yeast to kick-start the fermentation process.

Stage 4: Wine Fermentation

Fermentation is when the yeast converts the natural sugar into alcohol and carbon dioxide. There are a variety of techniques and technologies used to accompany the different kinds of grapes. At Theorem Vineyards, we do pump-overs. This is the process by which we mix the tank by taking the red wine from the bottom of the tank and pumping it back to the top. This helps extract tannin in the wine and provides oxygen to keep the yeast happy. We taste the fermentation daily until it reaches optimal tannin level and all the sugar has been converted into alcohol. The final step is to drain all the wine and dig the “must” out onto another tank. We load the must into the press, and the remaining wine is pressed out and blended back with the free run wine.

Stage 5: Age the Wine

The next step is to transfer the wine into barrels for aging. Aging wine in oak barrels blends natural oak tannins and grape tannins to produce the perfect balance. At Theorem Vineyards, we prefer to use French Oak for our aging process because we like the aromas and flavors they impart into the wine.

After 18 to 24 months, or when the winemaker feels the wine is “ready,” it’s time to bottle the wine.

Stage 6: Bottle the Wine

Wines are usually bottled through a mechanical bottling line. Some wineries rent mobile bottling rigs that can be transported for the season while others have equipment onsite. The process includes filling and topping with nitrogen to displace oxygen that might be lingering on top of the filling line before inserting the cork.

See the Winemaking Process for Yourself at Theorem Vineyards

Come experience the process of winemaking while tasting and touring at Theorem Vineyards. Theorem Vineyards is nestled on the northern slope of Diamond Mountain near Calistoga. This breathtaking location allows our wines to take advantage of a unique blend of minimal fog, rich sunlight, and volcanic soil. Our grapes are harvested at just the right time to create a timeless Cabernet Sauvignon. Our winemaker Thomas Rivers Brown’s philosophy is to let the site dictate the way the wine is produced. This has made him one of Napa’s most celebrated winemakers. His wines have earned the highest acclaim, including more than 25 100-point scores from Robert Parker. Thomas has also been named Winemaker of the Year by Food & Wine Magazine.

Every stage in the winemaking process is complex We hope you will join us at Theorem Vineyards to see how our wines are produced!