What makes Napa Valley such a renowned area for growing wine grapes? It all comes down to the dirt. There are more than 30 types of soil in Napa Valley. The chemistry of this soil is the most important factor of what the French call “terroir," the distinctive tastes and aromas that an area’s specific conditions impart on the wine.
An understanding of Napa Valley’s geography can go a long way in helping you choose wines from the region that you know you’ll love. Here’s a basic rundown of Napa’s microareas and the flavors their conditions give the finished product, using that perennial favorite, cabernet sauvignon, as an example:
St. Helena: St. Helena climate and soils are very different from those of the surrounding regions. While the western hills warm and protect the area, breezes from the Pacific do reach here earlier than they do other regions. Cabernets from this area are ripe, round and fruity, with a “chewy” feel on the palate.
Rutherford: One of the least mountainous areas in the Napa Valley, Rutherford’s soils don’t drain as much as do the hillier vineyards, meaning that soil minerals remain in the area, and even grow more concentrated over time. The cabernet is earthy and high in tannins.
Spring Mountain: An extreme area for wine-growing, with sparse soil that drains quickly and is blasted all day and all night with chilly temperatures. The cabernet from Spring Mountain is as extreme as its conditions, rich, powerful and concentrated.
Yountville: The soil types here are varied, with a mix of sand, loam, silt, and others. The area is cooled by breezes from San Pablo Bay, not far away, meaning that the grapes can mature on the vine for a bit longer. The resulting cabs from this area will be smooth and boldly fruity, with dark berry aromas.
Mount Veeder: This mountainous area is above 2,400 feet above sea level, very high for vineyards. The steep slopes mean that soils are thin and vines are stressed for nutrients. That results in smaller crops from this area, but the grapes that make is are intensely colored and powerfully flavored, with great complexity. Wines from this area are great candidates for the cellar.
Howell Mountain: This region is similar to Mount Veeder, but since its temperatures run a little warmer, its cabernet is even more bold and concentrated.
Stags Leap area: The vineyards here are located in hills that cool off every afternoon. This, combined with its well-drained soil, gives the area’s cabernet highly perfumed, velvety wines big on flavor but soft on tannins.