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09/01/2010

The Perfect Grape: How growers Know When to Harvest

Figuring out when to harvest their grapes is one of the most important – if not the most important – decisions a wine grape grower makes all year. Months and months of tending the vines, making sure soils are healthy, determining watering regimes, etc. culminates in the crucial decision of choosing precisely the right time to pluck those grape clusters from the vine.

Of course perfect ripeness is what growers and winemakers look for. But what defines ripeness? Can you tell by how the grapes look or taste? Is there some kind of measurement that can be taken objectively? The answer is that it’s both of these things.

“It takes all of the senses – except perhaps hearing – to determine if the grapes are ready for picking,” says Neil Roberts, who oversees 3000 acres of vineyards in the Paso Robles growing region as the owner of Roberts Vineyard Services. “The color of the grapes and their seeds, the firmness of the fruit, the sweet, ripe aromas – all of these come into play. But of course the greatest arbiter of ripeness is taste, and since every grape variety has a unique taste and flavor profile that relates directly to the wine, learning when different types of grapes taste ripe takes experience.”

Experience is key, but there are some objective measurements for ripeness as well. One of the most important of these is the amount of sugar – known as degrees Brix – present in the grapes. The longer grapes hang on the vine the more sugar there is in the fruit (and the higher the degrees Brix). The objective is to pick when there’s enough – but not too much – sugar. How much is enough depends on the style of wine the winery is looking to make. Grapes for sparkling wines are harvested at relatively low sugar levels while those used for red and white table wines are harvested at higher levels; grapes that go into late harvest dessert wines are harvested at the very highest levels of all.

As harvest approaches, growers and winemakers walk their vineyard(s) weekly and even daily to check on the progress of the grapes. In addition to inspecting and tasting the fruit, they pluck grapes from different clusters, vines, vine rows and even blocks to make sure they’re getting a good cross section, then measure the Brix using a refractometer, a handheld device that can measure the grapes’ sugar content right there in the vineyard.

They’ll also take a sample of grapes to a laboratory where further testing will be done, including measuring acid and pH levels. Just like Brix, keeping an eye on these measurements is critical to the outcome of the wine. Too much acid (and inversely, too little pH) and the wine can turn out to be tart and astringent. If the acid level is too low (and pH too high) however, the wine can be flabby and unstructured, seeming more like grape juice than wine.

With all the tasting and testing that needs to be done (not to mention picking and delivering grapes to wineries!), harvest is by far the busiest time of year for growers in California. But if you ask most of them, they’ll also tell you it’s also their favorite time. Not only do they get to witness the culmination of the year’s labors, but the weather is beautiful and there’s a sense of excitement – and the scent of harvest -- in the air.

It’s no wonder then that California Governor Arnold Schwarzenegger has named September 2010 California Wine Month for the sixth consecutive year. There’s no better time to celebrate the rich history of grape growing and winemaking in California, and many of the Golden State’s wineries, wine grape growers and regional associations host events for consumers. From special tastings and harvest tours, to wine education classes and major wine festivals, consumers can participate in celebrations in all regions of the state. To find the most recent list of events this September, go to www.discovercaliforniawine.com/learn/september-wine-events and be sure to visit the site regularly because the list keeps growing!

Color, firmness, aroma and taste are all considered when determining if the grapes are ready to be picked.