Any true wine geeks out there? OK it’s a little long for our blog, but it’s one of the best summaries of what makes the Calistoga area (an official American Viticultural Area, or AVA) such a great place to grow wine grapes. This was written for a local journalist by winemaker Cameron Parry, and provides a link to the actual petition – authored by Bo Barrett – that led to government approval of the AVA. Here goes, hope you like it:
The Calistoga AVA has a lot of great sloping/hillside and higher elevation vineyards and the well recognized concentration that they bring, along with a relatively small amount of “flat” valley floor land. That valley floor land has a lot of alluvial influence, so even though it is flat, it is not that heavy – lots of stony, well drained soils. There are 3 different soil origins, and numerous classified soil types, which bring in a great complexity as well. But, it’s not just the dirt! One of the most defining features of the Calistoga AVA is the influence of Mt. St. Helena, which acts like an air pump: drawing air up (pulling cooler air in from the Knights Valley gap) during the day as the mountain warms, and sending cool air sliding down slope at night. This near constant air movement helps keep temperatures in check and reduces the mildew pressure. It also contributes to a large diurnal swing (as much as 40 degrees a day on a regular basis), which (without getting into too much grape physiology) helps preserve the natural acidity in the grapes resulting in wines with great balance, complexity, and longevity. Many people think that Calistoga is the hottest of the AVA’s in Napa, but in reality the hottest part of the valley is just north of St. Helena. The other often overlooked aspect of the Calistoga AVA is the orientation of the valley. Most of the Napa valley runs about 340°, but right around Larkmead Lane, the valley turns West by about 20-25°, running about 305°. The result is that the Calistoga AVA has a very different solar exposure than the rest of the valley. The result, here at Chateau Montelena, is that we see earlier ripening/earlier harvest dates than many other locations, which often means that all of our fruit is in before the fall rains. Somehow we also seem to have better solar capture even in the “difficult” years, meaning that we always get ripe fruit.
Much of this is outlined in the TTB petition that Bo wrote back in 2003, so that would be a great reference as well.