Great wines begin in the vineyard—with the perfect location, climate, soil, and vines. However, great wines cannot be made without talented winemakers and vineyard operators. Once the land and vines have done their job and the grapes have been harvested, our team guides the grapes through the winemaking process.

Theorem Vineyards is just as captivating in the winter as it is during harvesting season. Below, our team has compiled a summary of how we turn grapes into ultra-premium wines.

What Happens in the Cellar

After harvest, we are busy making sure the winemaking process runs smoothly. Below is a list of some of the things happening during the winter months at Theorem Vineyards.

  • Clean Machinery: The first thing the team at Theorem Vineyards does after harvest is thoroughly clean the entire winery and machinery. This step is critical because it helps us ensure that any residual sugar particles, stems, seeds, and pulp are entirely scrubbed clean so that no bacteria can grow. Everything in our cellar has to sparkle like harvest never happened. We are serious about cleanliness.
  • Malolactic Fermentation: The next thing our team focuses on after cleaning our cellar is finishing fermentation. Once the primary sugar fermentation is complete, we start monitoring for secondary fermentation, which is also known as malolactic fermentation. This process consists of taking tart malic acid (think green apple) and turning it into softer lactic acid—the same acid found in milk. The process is complete by naturally occurring bacteria found on grapes. We keep wines going through malolactic fermentation at a slightly warmer temperature of 65 to 70 degrees.

According to our Assistant Winemaker Ward, you know malolactic fermentation is happening when “you hear a sound like bacon frying in the barrel.” All red wines and some white wines, such as Chardonnay and Viognier, undergo malolactic fermentation. When malolactic fermentation is complete, red wine develops a softer mid-palate and more rounded mouthfeel. Chardonnays, on the other hand, typical buttery notes from malolactic fermentation.

  • Composite Sampling: During malolactic fermentation, we perform weekly composite sampling to monitor Volatile Acidity (VA) and see the progression of the malolactic fermentation. Volatile Acidity isn’t necessarily a flaw in wine if it is present in small amounts; however, there is a threshold limit where flavors and aromas become impacted. Every week, we take composite samples and send them to the lab to be tested for specific characteristics. We take the same amount of wine out of every barrel and combine it. Every time we remove wine from a barrel, it opens space for oxygen. That is why we have to top the barrels with more wine to prevent oxidation. Every week, we lose 300ml-500ml of wine per barrel due to evaporation. Once malolactic fermentation is complete, the wine is moved into a cold room to begin the aging process. During this, composite sampling is only performed once a month and the barrels are topped up to remove oxygen headspace from the barrel.
  • Racking the Wine: We rack the wines by pumping the clean wine off the solids that have settled to the bottom of the barrel. The barrel is then turned over, and warm water is used to clean the inside and remove all the solid partials. After, we transfer wine from the stainless steel tank back into the clean barrels. When it’s time to bottle, we will rack them one more time and put the wine into the bottles.

What Happens in the Vineyard

Once the wine is aging in barrels, we start shifting our focus to the vineyard.

  • Plant a Cover Crop: If you were to look between the rows of our vines, you would see grass and other plants growing—this is called a cover crop. Cover crop helps with erosion and replenish nitrogen into the soils. The nitrogen released in this process is useful during the vines’ vegetative phase.
  • Pre-Prune: During the winter, we place a lot of our focus on the vines. The first step is to pre-prune by getting rid of all the long shoots so when it’s time to actually prune, it’s much easier. Pre-pruning is usually completed in January, and the actual pruning itself is completed early February. Pruning lays out the foundation for next years’ harvest since it influences the health, growth, and yields of the vine.

Wine Preparations & Planning

After the vineyard has been prepared, we start planning for the next bottling and harvest. This includes a variety of jobs to add the finishing touches to the last harvest and to prepare for the next harvest.

  • Planning for the Next Bottling: There are a lot of logistics that go into bottling wine. This includes preparing orders for glass bottles, corks, labels, capsules, and bottle trucking. The labels must also be approved by government regulatory bodies. Approval can take weeks or months to achieve.
  • Preparing for Next Harvest: Once the preparations for bottling are complete, we start to focus toward the next harvest. The first step is to order new barrels for the next vintage. Since some coopers are in high demand, we like to submit orders early. The number of barrels ordered is typically a guess based upon our projections for the next harvest. Unfortunately, there is no way to tell how big harvest will be until the actual harvest. There are lots of things that can influence the harvest size. So, while we wait for the fruit to mature, we will keep busy by cleaning our equipment, checking on the wine in the barrels and, hopefully, sharing our winery with new and old friends who come for a tour and tasting.

Schedule a Tour at Theorem Vineyards!

We invite you to come taste our wine and tour our vineyard. Theorem Vineyards is nestled on the northern slope of Diamond Mountain near Calistoga, 1,100 feet above sea level. This breathtaking location allows our wines to capture the beauty and spirit of this magical place. Our team works on every winemaking process with care, guiding the grapes to create timeless and captivating wines.

Experience our winter winery by scheduling an appointment today! Call us at (707) 942-4254.