Marking the heart of summer on the Central Coast, July brings us long, warm days, plenty of Packers baseball action, and endless excuses for gathering with friends over a glass of wine. In the vineyard, however, the passing Dog Days are not quite so leisurely, for they trigger dramatic changes that influence the future and quality of the developing grapes.
A critical period in the viticultural timetable, mid-summer signals the onset of véraison (pronounced vuh-rey-zhun), a French term for which there is no precise English equivalent. The word comes from the French root “vér,” meaning “truth,” and describes the do-or-die phase during which the vines transition from active growth to the business of ripening their fruit.
Perhaps ancient growers associated the word véraison with the maturing fruit because this is the time when grapes begin to assume their true color. Though all new grapes are as green as their tender stems and shoots, when véraison sets in, they soon differentiate into the golden, purple, and blue-black berries we know and love.
During véraison, the skins of red varietals, such as Pinot Noir and Syrah, blush ever darker, while the so-called white grapes, such as Chardonnay and Pinot Gris, turn from apple-green to yellowish- or golden-green. This color shift serves as a sign that the hardworking vines have begun magically turning sunshine into the liquid sugar that yeasts will later convert into carbon dioxide and alcohol during fermentation.
“Summer is like a solar farm for making booze,” Wes Hagen, winemaker for Clos Pepe Vineyards, wrote, describing grape vine activity in his New Vineyard blog at winemakermag.com.
By July 9, Hagen reported, “the clusters have closed and are preparing to change color and soften over the next few weeks. The clusters are basically full-sized at this point … tiny berries with thick skins, which will give the Clos Pepe wines their characteristic flavor and verve.”
From early June, when the grape vines flower and—if luck and weather cooperate—set a crop of tiny berries, until véraison, the fruit grows due to rapid cell division and expansion, increasing daily in volume and weight. As summer progresses and the stress from high heat and a diminishing water supply set in, cell division slows, causing the size of the grapes to remain relatively stable.
Called the “lag phase,” this slowing marks the dividing line between active growth and ripening, the process that builds the chemical environment necessary to bring grape seeds to maturity (which, after all, is the reproductive goal of the vines). When véraison occurs, the accumulation of sugars (sucrose and fructose) in each grape dramatically increases, acid content declines, and berries actually begin to lose a little of their mass as soil moisture dwindles.
Green shoots, which appeared just after bud break, start to harden and turn brown on their way to becoming canes. This is a good thing, for should they continue to grow, vital energy will be diverted from the grape clusters, which need all of the vine’s resources to fully ripen.
Viticulturists admit that the trigger for véraison remains unclear. They acknowledge that it seems to be intimately tied to the maturing seeds inside each berry, but face a conundrum when considering that seedless grapes follow the same developmental path.
In his July 16 blog entry, Hagen confirmed seeing “the first hints of véraison,” right on schedule. As véraison progresses, the herbaceous odors of youthful berries fall away and ripening clusters emit ever more tempting wafts of fruity aromas that draw hungry birds and animals.
Hagen noted, “nets going up soon,” a reference to the fine-gauge netting that growers drape over their vineyards at this time of year.
“We’ll drop a few tons [of fruit] on the ground at véraison,” he added, “to keep all clusters ripening consistently.”
Jeff Newton, co-owner of Coastal Vineyard Care Associates, begins thinning clusters several weeks before véraison, aiming for a load of just two to four pounds of fruit per vine. When véraison is about 85 percent complete, he directs his crew to cut away any green berries remaining, in order to narrow the ripeness range of the hanging fruit, and ultimately to produce a better wine.
Roughly 45 days after véraison, that critical juncture in the growing of grapes, the berries may have shrunk a bit, but their sugars, hopefully, have developed nicely. If their chemistry has settled into a proper balance and all the numbers add up, they are ready for harvest, the next step of their journey into our waiting glasses.
K. Reka Badger’s wine glass is ready and waiting. Pour her some comments or ideas at rekabadger
This article appears in Jul 23-30, 2009.