Paso Robles Wine Country is centrally located between San Francisco and Los Angeles along California’s Central Coast. With a greater day-to-night temperature swing than any other appellation in California, distinct meso-climates, diverse soils and a long growing season, Paso Robles is a unique wine region blessed with optimal growing conditions for producing premium and ultra-premium wines.
The Paso Robles American Viticultural Appellation (AVA) is home to more than 200 wineries and 40,000 vineyard acres focusing on premium wine production. The distinct microclimates and diverse soils, combined with warm days and cool nights, make growing conditions ideal for producing more than 40 wine varietals from Cabernet Sauvignon and Merlot, to Syrah, Viognier and Roussanne, to Zinfandel, the area’s heritage wine variety.
The Paso Robles AVA’s western boundary is just six miles from the Pacific Ocean. The appellation lies on the inland side of the Santa Lucia coastal mountains in San Luis Obispo County, and roughly forms a rectangle 35 miles from east to west, and 25 miles from north to south. It extends from the Monterey County border to the north, to the Cuesta Grade below Santa Margarita to the south, and from the Santa Lucia Mountains to the west, to the Cholame Hills to the east.
The appellation comprises 612,000 acres of which more than 40,000 acres are in wine grape vines. It is the fastest growing and largest by far of three AVAs in San Luis Obispo County, and the main reason that the county ranks behind only Napa, Sonoma, and Monterey counties in planted acreage among the state’s coastal growing areas.
Paso Robles Wine Country is a land of diversity and contrasts that encompass river bottoms to rolling hills and flatlands to mountains. The major geographical features of the area are the Santa Lucia Range, the Salinas River Valley, and the Templeton Gap.
California’s Central Coast is geologically different from other California wine growing regions. Unlike others with deep, rich fertile valley soils, over 30 soil series are found in the Paso Robles AVA. These are primarily bedrock derived soils from weathered granite, older marine sedimentary rocks, volcanic rocks, and younger marine sedimentary rocks of the Miocene-age Monterey Formation featuring calcareous shales, sandstone, or mudstone. Soil diversity is the norm and a vineyard block may commonly contain several different soil types.
What is exceptionally unique about Paso Robles AVA soils is the predominance of desirable calcareous soils found throughout the region, and the high soil pH values of 7.4 to 8.6 that are not typical of California’s other viticultural areas. Due to geologic uplift, calcareous shale is plentiful on Paso Robles’ west side hills, where dense clay-based soils combine with relatively plentiful rainfall to make it possible for some vines to be dry-farmed without supplemental irrigation. More granular forms of broken down calcareous shale are found on the eastern hills and valley of the AVA. On both sides of the Salinas River, gently rolling hills are covered with sandy, loamy soils. In the watershed areas, particularly the Estrella River plain, loam, and clay are overlain with sand.