Heavy Winter Rain and Its Effect on the 2006 Growing Season

One of the questions I have most often been asked in 2006 is: “How is the rain affecting the vineyards and growing season?”

The short answer is that heavy rain is not a problem while vines are dormant i.e. before the start of the growing season (approx March 1) unless soils are severely eroded. Fortunately, this is preventable. Before our Santa Cruz Mountains vineyards were planted, for example, we installed a system of surface trenches, inlets and underground drains that collects water and moves it downhill to natural runoff areas.

California vineyards typically benefit from some of clearest weather patterns anywhere in the world. Notwithstanding, rain does become a problem when it occurs during the growing season  at the beginning (April May) or near the end (September October). Both scenarios threaten successful harvest because cooler temperatures usually accompany rain, thus truncating the number of sunny days needed to adequately ripen grapes.

Experts estimate that between 110 and 140 days of clear weather are needed to effectively ripen fruit; actual numbers depend upon specific regions and grape varieties.

To underscore the importance of growing season duration, we look to the Heat Summation Method, a general classification devised by UC Davis professors in the 1930s. With photosynthesis (vine growth and sugar production) only occurring above 50 F, their approach measures the number of degree days per season offered by a given area. Region II (2,500 to 3,000 degree days) is the second coolest of the five classes, is similar to Frances Bordeaux, and includes portions of the Santa Cruz Mountains and Monterey County. Region III (3,000 to 3,500 degree days) is as warm as the Rhne Valley and includes parts of Napa Valley and Paso Robles.

Ripeness is a very relative term, but most winemakers would agree that fruit maturity is simply not a function of sugar content. Before harvesting, we consider a number of criteria including grape variety, vine appearance, the condition of seeds and stems, and most importantly, the smell, taste and color of the grapes and their juice.

In addition to shortening the ripening cycle with cooler temperatures, wet growing seasons challenge vines with potential mildew on the shoots (early) or fruit (late), and large leaf canopies. At Cinnabar, we apply sulfur, an approved organic fungicide, to control mildew, and maintain proper vine balance with hedging and leafing to improve wine quality. Hedging is the process of trimming the top of the shoots that exceed a certain length while leafing is the removal of leaves around grape clusters to increase sun and wind exposure.

As with any business so dependent upon Mother Nature, weve learned to take constructive measures to counter the effects of the occasional challenge, thereby producing wines of the highest quality, year after year … or more precisely, growing season after growing season!

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