Chenin Blanc

Could Chenin Blanc be a panacea to global warming? Maybe ... maybe not ... but with an ever-changing climate and more and more vintage unpredictability, a resilient grape like Chenin gives one lots of options. Smoke threatening the grapes? Pick early and make sparkling wine. Heat wave baking the region? Chenin Blanc retains its acidity better than many other grapes, so less of a worry. Impossible to locate a vineyard crew to harvest? Chenin makes great dessert wine if the winery cannot get a crew to pick until the next month. However you spin it, Chenin makes perfect sense for these uncertain times.

Working the Land:

Does soil influence the flavor of the final wine?

Traditionalists answer unequivocally “Yes!” Soil is a key element of “terroir,” the natural environment in which vines grow, along with climate (temperature, rainfall), topography (altitude, drainage, slope, aspect) and sunlight.

A more unorthodox view holds that the influence of soil on what you taste in the glass is a myth. Maynard Amerine and Ann Noble, two famous names at UC Davis, California’s premier wine school and research facility, conducted a study on the topic. Though the study is based on Chardonnay grapes, they concluded that the following holds true for all wine grapes: “no outstanding sensory differences were observed in wines produced from different soil type locations.” The key word is “sensory” (sight, smell, taste). They are not claiming that soil doesn’t affect vine behavior (yield, growth cycle, etc.). 

The subject is most certainly up for further debate. That said, here is a brief review of how Chenin Blanc, according to the classic view, expresses itself in the glass, based on the type of soil in which it is grown.

Limestone Soils

Limestone offers beneficial nutrients to grapes that help them grow better, resulting in sweeter fruit. It is special because it retains moisture in dry weather, but also offers good drainage in cool weather. The one negative effect of lime is that it causes iron deficiency in grapes, meaning that winemakers with soils high in lime content must fertilize frequently. With Chenin Blanc, limestone-based soils bring forth more acidity than weight. 

CA Locations: Central Coast between the Santa Cruz Mountains to the north and Lompoc to the south.

Calcareous Soils

Calcareous soils are formed from crushed and decayed shells and bones of sea creatures. These layers settle at the bottom of shallow oceans and, depending on how much heat and pressure they're subjected to, can be as soft as talc or chalk, or as hard as limestone or even marble. Of course, in order for plants to be able to access the calcium carbonate, it needs to be friable: soft enough for roots to penetrate. Calcareous clay, as is found in France’s Vouvray district, produces round wines with acidity.   

CA locations: Central Coast between the Santa Cruz Mountains to the north and Lompoc to the south.

Tuffeau Soils

A buff-colored, sandstone-rich, otherwise chalky limestone as found in the Loire, particularly around Touraine, and used in the physical construction of many of its glorious châteaux. Tuffeau is NOT to be confused with tuff, a type of volcanic soil found in Napa (Howell Mountain), Lake County (California), Madeira, Hungary (Tokaj), Alto Piemonte (Gattinara, Ghemme), Campania (Mount Vesuvius) and large swaths of Yellowstone Park.

CA locations: There is no significant source of tuffeau soil in California

Chenin Blanc ripens quite unevenly, and often requires strict hand harvesting to ensure quality. Less ripe grapes have more acid and are a perfect base for making sparkling wine. As the season extends, remaining clusters attain higher sugar levels, and some can become affected by noble rot (botrytis). These are selected for sweeter wines. In general, old, existing vines better control yields for quality fruit. The reality is that young vineyards want to be more productive, so one needs to control the crop by thinning fruit, while old vineyards are more naturally balanced. Indeed, there is a classification in South Africa for Chenin Blanc based on old Chenin vines (2016’s Old Vine Project). Mature vineyards can cope with dry seasons better than young vines by virtue of established root systems, resulting in the vines self-regulating for drastically reduced crops in dry conditions. Lower yields mean greater concentration, even at moderate ripeness. Finally, dry farming rather than irrigation is important as well. 

In California, there is not much in the way of clonal variety, especially when compared to Pinot Noir, Chardonnay or Zinfandel. Registered selections in California have been limited to those from regional commercial vineyards. Chenin Blanc FPS 02, 03, and 04 were derived from FPS 01 using heat therapy. FPS 05 was established from a different California vineyard. A comparative trial demonstrated that Chenin Blanc FPS 04 was the most productive. 

In the U.S., Chenin Blanc is mostly trained to a bilateral cordon and pruned to 12 to 16 two-node spurs. Additional numbers of spurs may be needed for large vines and to minimize tight clusters by increasing cluster numbers. Cane pruning reduces bunch rot potential with less compact clusters