What is Grape Cluster Counting & Why It Matters to Winemakers

Even though school is out during summer, it’s math time in the vineyards.

June and July are the months where grape cluster counting takes place. Grape cluster counting literally means walking through vineyard rows counting grapes to determine if the year’s harvest will be small, average, large or somewhere in between.

How Grape Cluster Counting Helps Winemakers

Elena Robledo, whose father was our first employee at Jordan back in 1973, is the cluster counting guru at Jordan. She walks every vineyard, with clipboard in hand, stopping at every tenth grapevine in a row and counting each cluster of grapes on that vine. Once she reaches the end of that vineyard row, she moves ten rows farther and begins counting again. Counting the clusters on every tenth grapevine in a row gives the winemakers a sample of statistical significance to estimate the potential crop size for the vintage’s harvest. During this time, Rob Davis, our winemaker, also visits every vineyard and examines the size of the clusters. If the grapes are smaller than usual or the clusters are loose, the weight of grapes could be below average, which also affects how much juice can be pressed from the fruit once it arrives at the winery during harvest. On the flip side, very big clusters could mean much more juice inside the grapes, so knowing the exact weight of the clusters is just as important to a winemaker as knowing how many bunches are hanging on each grapevine.

After cluster counting, if the crop size is above average or the grapes are not growing uniformly (a balanced vine is the key to a balance wine), our winemaker will make the decision to sacrifice some grapes, dropping fruit to the ground is a quality winegrowing practice called veraison thinning. Once the estimated crop size is confirmed, winemakers have the ballpark numbers needed to plan out tank space for fermentations, order barrels and determine staffing for harvest.

Because Jordan sources grapes from five vineyards in Russian River Valley for Jordan Chardonnay and about a dozen in Alexander Valley for Jordan Cabernet Sauvignon, it takes Elena a few weeks to finish grape cluster counting. While the winemakers and cellar crew (including Elena’s son, Danny,) are busy with bottling during late June and early July, Elena is content to spend her days enjoying the cool mornings of Northern Sonoma County crunching numbers.

We think she has a pretty awesome office this time of year.