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Pruning for Perfection at Clos de la Tech

Posted by CM Support
Sep 25, 2012 | Keywords: T.J. Rodgers  vineyards  viticulture  wine grapes  

This is the complete series of blog posts in which Clos de la Tech Winemaker T.J. Rodgers explains some of the most technically challenging and important aspects of Clos de la Tech’s grape production. To download a PDF of this series, click here.

“Great wine is made in the vineyard.” – T.J. Rodgers, Clos de la Tech Winemaker


When we started to make wine, we thought that becoming skillful winemakers would make all of the difference. Over the years, we re-discovered what the French have known for centuries—that “the wine is made in the vineyard,” as the old saying goes. Winemaking can add certain stylistic components to a vintage, but the basic quality of a wine is grown, not vinified. Below, we describe our state-of-the-art Pinot Noir vineyards with a focus on the special pruning techniques we employ to improve wine quality.


Typical California vineyards have 455 to 1,361 vines per acre, with rows planted a full 8 to 12 feet apart to accommodate a tractor. At Clos de la Tech, we plant 4,159 vines per acre—3 to 10 times more than is typical—with the vine rows only 3.5 feet apart. These vineyards are expensive to plant and hand-farm. The best French vineyards plant 4,047 vines per acre because they believe close-spaced vines concentrate the essence of the vineyard—the terroir (ter-whar), as they call it—in their wines. While close-spaced vineyards are just catching on in California, Clos de la Tech’s vineyards have been densely planted for 20 years.


Only the vineyard land itself and the types of vines planted on it are more important than proper vine pruning in determining wine quality. Almost all of the great vineyards in the world plant vines in rows of hedges with the “canes” (green shoots) positioned vertically between training wires. In early May, excess canes are removed from the vines to leave about one cane every four inches of vine row. This pruning produces a solid hedge of leaves without any leaf crowding—the right environment for flowering in mid-June. In June and July, the vines’ last spurt of green growth produces “laterals,” new shoots growing sideways from the middle of the canes. The laterals are best removed carefully by hand to create the perfectly pruned vineyard for “fruit set” in late June, the time when the flowers self-pollinate and transform into small grape berries. After that, we employ several special pruning methods to grow better grapes for dramatically improved wine quality.


Tipping is the special pruning process of removing the green tips at the top of each cane by hand. Tipping must be done at precisely the right time—when the flowers are just turning into small grape berries. When the cane tips are removed, they stop consuming energy, causing all of the vine’s energy to go to the flowers, which then produce more berries per grape cluster. A typical Pinot Noir grape cluster at Clos de la Tech has 240 flowers that produce about 80 berries. When tipping is employed, the number of berries per cluster increases to 100 or more. More berries do not necessarily produce higher yield, because the berries are more crowded in the cluster, forcing smaller berries to be formed. Smaller berries are known to produce superior wine tannin quality because they contain fewer seeds which produce bitter and astringent tannin and more skins, which produce pleasant, mouth-filling tannin.


Leaf stripping is another special pruning step to improve the quality of the grape clusters that is performed just after the small green berries have formed. It is another expensive manual process, in which some of the leaves covering the clusters are stripped off by hand. When direct sunlight then hits the grape berries, they produce natural sunscreen compounds to prevent sunburn. These compounds, with exotic names like quercetin and kamphaerol, are created by the berries with a biochemical mechanism similar to the one that creates tannin. Quercetin itself is flavorless, but it is known to be found in much higher concentrations in super-premium wines.


In one final nuance of leaf stripping, the grape clusters on the east side of the trellis, the ones that receive direct sunlight in the morning, are stripped of their leaves more completely, while the clusters on the west side of the trellis, which are subject to the hot afternoon sun, are left a little more shaded. Grape clusters receiving morning sun are known to make wine with superior color relative to wine made from clusters receiving direct sun in the afternoon when high temperatures decompose the color in red grapes.


Most vineyards in the world hedge their vines by cutting off the green growth at the top of the vines to create a square shrubbery-like profile to channel the energy of the plant away from green growth to the grape clusters. In some vineyards, especially in France, where it rains during the summer, hedging is performed continuously throughout the season. We view hedging as a necessary evil. It does a lot of damage to the plants. The ideal situation is to have vines that grow to their proper hedge height—and stop. While this is never completely achievable in the practical world, Clos de la Tech hedges only lightly, once per year, for two reasons. First, since our vines are closely spaced, we can import French vines that are genetically selected for low vigor. The California vineyards with wider vine spacing cannot use those low-vigor vines, which are bred for producing excellent quality crops, not for their ability to grow quickly and produce high yields.

The one benefit we do get from hedging is increased “hang time,” by keeping the clusters on the vine a week or more to ripen the tannins better. In California, sugar ripeness is easily achieved, but getting smooth, ripe-flavored tannin takes longer. By hedging our vines very short, leaving just 10 to 14 leaves on each cane, the vines create sugar more slowly, allowing the tannins to ripen better.


The second reason we need less hedging is that we do not water the grapes for most or all of the growing season. This “dry farming” technique is mandated by law in France. When our vineyards begin to dry out in late August, our vines typically end their green growth phase and “focus” on ripening their crop. By using low-vigor vines and dry farming most of the season, we have greatly reduced the amount of hedging we have to do at Clos de la Tech—and saved a lot of water. Our vines are typically watered with only 1.5 gallons of water, just five times per year. Scientists at U.C. Davis discovered years ago that very lightly watered vines produce better wine (albeit with lower yields) because the water-starved plants produce more bouquet compounds to attract birds to scatter their seeds as a survival “strategy.”

Paradoxically, hedging is the most common vineyard pruning practice—and the one that we try to avoid, while the other more advanced but expensive pruning techniques we use are employed in only a small percentage of the world’s best vineyards. Yet, the one time we hedge, we do so vigorously, and in doing so, produce silky tannins.


Whenever we have a heavy crop that yields over two tons per acre, we remove the excess clusters to improve wine quality. These clusters are removed only on the afternoon-sun side of the trellis to produce wine made mostly from the superior morning-sun clusters. California Cabernet Sauvignon crop yields routinely fall in the range of 4-5 tons per acre in the Napa Valley to 10-13 tons per acre in the Central Valley—two to seven times our yield. The concentration of flavor and bouquet in wines made from low-yielding, morning-sun bathed clusters is unmistakable.

– T.J. Rodgers

T.J. Rodgers is a member of the UC Davis Department of Enology & Viticulture Board of Advisors and Fellows. He designed, built and donated the advanced fermentation equipment used in the UC Davis Robert Mondavi Institute for Wine and Food Science.

Clos de la Tech Pinot Noir is currently available for purchase here.

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