Napa’s Nested AVAs : Spring Mountain District
"This unique combination of soils, geology, topography and flora sets Spring Mountain apart from surrounding regions."
- Eugene L. Begg, Soils Consultant
"Spring Mountain District earned its name due to the prevalence of natural springs all over the mountain. As the western-most ridge of the napa valley, it captures the most rainfall off the Pacific of all the Napa Valley AVAs. Loose volcanic soils allow roots to penetrate deep underground in an environment where vines grow with moderate nutrient and water stress, creating wines with rich fruit and balanced yet bold tannins."
- Andrew Schweiger, Schweiger Vineyards
Spring Mountain District is located west of St. Helena in Napa Valley, California, on the eastern slopes of the Mayacamas Range that separates Napa Valley and the Sonoma Valley. It lies approximately 30 miles east of the Pacific Ocean and 25 miles north of San Pablo Bay. The steep terrain of this region is primarily made up of eastern facing slopes with good drainage and elevation ranging from 400 to 2600 feet above sea level. Spring Mountain’s craggy façade mean that the vineyards tend to be small, spread out and surrounded by forest. This provides some shade and protection for the vines, as does the east-facing hills. The elevation also mitigates Napa Valley’s heat so in general Spring Mountain Cabernets are quite tannic and ageworthy as well as elegant and not overly fruity.
Cabernet Sauvignon is not the only grape grown in the Spring Mountain District. The region’s variegated topography and range of microclimates makes a happy home for a wide range of varieties, from Chardonnay and Riesling to Pinot Noir and Merlot. The southern half of the appellation is classic Franciscan Mélange – chunks of ocean crust are even apparent at high elevations – while the northern end enjoys similar volcanic soils to what is seen in the Diamond Mountain District. The unique character of grapevines grown on Spring Mountain result from a complex interaction of various geographical elements. While the steep, well drained soils of the area provide grapevines with sufficient moisture during the majority of the growing season, they also cause stress on the vines during the late summer and early fall, which limits grape yields and produces smaller grapes with higher flavor concentration.
Lying between the Spring Mountain appellation and the cold ocean current is a gap in the coastal mountains between Bodega and Tomales Bay and extending through the Santa Rosa Plain. Summer heat in the interior of California creates a low pressure area that draws cold air from the coast through this coastal gap and across the broad Santa Rosa plain. This on-shore air movement is bumped north by Sonoma Mountain pushing the cold air flow towards Santa Rosa Creek, the Northern Mayacamas Mountains, and directly at the Spring Mountain District AVA. The ridge of the Spring Mountain District is lower than Bald Mountain to its south and Diamond Mountain to its north. This lower ridgeline allows the cool, moist coastal air to enter the Napa Valley spilling down over forest and the vineyards that lie on the slopes of Spring Mountain and moderating peak daily temperatures
A typical summer afternoon on Spring Mountain is cool, sometimes with "waterfalls" of fog tumbling over the western ridge and down through the canyons of the district. Into the evening, the cool air settles to the valley floor creating a cover of fog and warm air is lifted to the higher elevations. Nighttime temperatures rise from this effect. Mornings warm more quickly on Spring Mountain than on the valley floor as most of the district lies above the morning fog line. The overall effect of this is moderately warm peak daily temperatures and moderately warm nighttime temperatures which keeps sugar accumulation in the berry in pace with flavor development.
Vineyards on the weathered volcanic and sedimentary soils of the Spring Mountain Appellation are usually planted to drought resistant rootstocks and trained to bilateral cordons with a vertical shoot positioned trellis. There is no one training and trellis system, however, that works on Spring Mountain. At present there exist both old, head-trained vineyards and vineyards on AXR rootstock with a California sprawl T-trellis. There are also newer vineyards on a quadrilateral divided trellis and on closely spaced vertical shoot positioned systems. All of these vineyards are capable of producing exceptional quality fruit if the vines are balanced between their crop load and vegetative growth.
The combination of low vigor potential soils with high winter rainfalls, cool springtime temperatures, and warm nighttime harvest temperatures produces a highly variable yet unique environment for premium wine grape growing within the Napa Valley AVA. Spring Mountain vineyards are known for their moderate production of grapes and wines with intense varietal fruit character and complex mountain tannins that differentiate them from the wines of other appellations in the premium wine-producing world.Spring Mountain produces both premium red and white wine grape varietals, including Chardonnay, Viognier, Cabernet Franc, Merlot, and Cabernet Sauvignon. Smaller acreages of Riesling, Pinot Noir, Zinfandel, Syrah, Petite Verdot and Malbec are also known for producing exceptional quality fruit and wines.
