Solano County AVAs

The AVA covers the whole of Solano County, which sits on the Sacramento Delta and enjoys temperature-moderating influences from the same San Pablo Bay that is so important to viticulture in nearby Napa Valley. Viticulture is mostly confined to the western part of the county, where the Vaca mountain range provides a multitude of suitable mesoclimates for the production of premium wine.

Solano County boasts the second oldest American Viticultural Area (AVA) in California, second only to the Napa AVA. The two sub-AVAs of Solano County can be found in this part of the region: Suisun Valley AVA and Solano County Green Valley AVA (so-called to distinguish it from Green Valley in the Russian River Valley) and also shares Wild Horse Valley AVA with Napa County. Some additional wineries can be found in the north near Davis and in the very west near the boundaries of the Clarksburg AVA of Yolo County.

Solano County enjoys a maritime climate due to the close proximity of the Sacramento Delta. Ocean breezes and fog from both Suisun Bay and San Pablo Bay help to cool the vineyards, which extends the growing season and leads to grapes that produce balanced wines with good acidity and phenolic ripeness.

The soils across Solano County are largely alluvial, having been deposited on the flat valley floors over many years by rivers that run through the area. The soils have differing levels of fertility, and the shallower sandstone and shale types found in the foothills of the Vaca mountains are generally considered to be the most suitable for vineyard cultivation. Free-draining and with limited fertility, these soils cause the vines to struggle for water and nutrients, which results in smaller berries with more-concentrated flavors.

Viticulture in Solano County began in the 1860s, when European settlers made their way to California in droves to find their fortune during the Gold Rush. However, the period of Prohibition in the 1920s spelt the end of winemaking in the region for the next 50 years. Recovery came during the American wine renaissance of the 1970s, when pioneering vignerons began to look at the potential of the region for the production of quality wine.

Today, Solano County has a thriving wine industry, and the county's location just outside of San Francisco means that it is becoming a popular destination for wine tourists. It also has a large number of vineyards operated by contract growers, who sell their produce to winemakers. Grapes from the area are often used in regional Californian blends.

Suisun Valley AVA

Established as an AVA on November 23, 1982.  The Suisun Valley AVA is located just east of the Napa Valley wine region in the Coast Range.  The valley is approximately 3 miles by 8 miles, and contains about 15,000 acres.  Suisun Valley is a region in the California Coast Ranges that is bordered on the east side by the Blue Ridge of the Vaca Mountains, and on the west side by the Howell Mountains, which are also called the St. George Range. The valley is located almost entirely in Solano County with a northern terminus near the county line with Napa County, and a southern terminus at Suisun Bay in the estuary where the Sacramento River enters San Francisco Bay.

Elevations on the valley floor range from 100 to 200 feet above sea level, rising steeply to 1,122 feet at Okell Hill on the north side, and to 2,162 feet on the west side at Twin Sisters, a twin summit that is the high point of the Howell Mountains, as well as a prominent landmark in the valley. Blue Ridge on the east side of the valley exceeds 2,000 feet elevation for much of its length.

Suisun Valley has a semi-coastal Mediterranean climate with a cool wet season from November to April, followed by a warm dry season. Moist winds blow inland from San Pablo Bay and Suisun Bay at the headwaters of San Francisco Bay almost continuously from May through October, which minimizes frost danger. Mean rainfall averages about 20 inches a year in the southeast part of the valley to 30 inches in the northwest, with nearly all rain falling during the wet season. The climate is classified as mid-region III under the University of California, Davis system.

Sedimentary rock composed of sandstone and shale makes up the bedrock that is buried beneath the fill of the valley floor. Similar sedimentary rocks crop out in the hills that border the east and north sides of the valley. By contrast, mainly pyroclastic breccias and tuffs, with some interbedded volcanic flows, make up the Howell mountains that border the west side of the valley. Suisun and Green Valley Creeks drain the northern uplands and create an alluvial fan that covers most of the valley floor, and builds out to the south into the Suisun Marsh.

Soils developed on the alluvial fan, where most of the vineyards are located, range from a very thick layer of Sycamore silty loam that covers most of the fan on the valley floor, to thinner Rincon and Brentwood clay loams that develop where the fan laps onto the valley margins, and drainage is somewhat better. Dibble and Los Osos soils that cover sedimentary bedrock in the eastern and northern foothills, and Hambright and Toomes soils that cover volcanic bedrock on the west side generally are more conducive to grazing cattle than growing grapes.

More than 3,500 acres of the valley are currently planted as vineyard, and whilst perhaps best known in the last twenty years for Petite Syrah, the other most popular planted varietals are Cabernet Sauvignon, Chardonnay, Petite Verdot, Zinfandel and Sauvignon Blanc. Overall, there are more than twenty varietals of wine grapes represented in the valley.

Solano County Green Valley AVA

The AVA was established on December 28, 1982.  The Solano County Green Valley AVA is a small AVA at the very western edge of Solano County located to the southeast of the Napa Valley AVA, Green Valley is about 1 mile wide and 4 miles long.  The AVA is located in a small, north/south-oriented valley about 12 miles northeast of San Pablo Bay. It lies in the southern foothills of the Vaca Mountains and is just eight miles from Napa township.

The valley is close to San Pablo Bay and thus has a maritime climate.  The valley's temperate maritime climate is well suited to the production of high-quality wine grapes. Warmth during the day is replaced by cold fog in the evenings, giving the grapes a chance to cool overnight. This extends the ripening period, leading to a good balance of ripeness and acidity in the berries.

Most of the vineyards are planted on the valley floor and benefit from moist, cooling winds in the summer afternoons.  The valley's orientation and proximity to the cooling winds and fog from San Pablo Bay creates many of the same favorable climatic conditions as Napa and Sonoma valleys.

The alluvial soils here are deep and free draining, with the majority of the 800 acres of vineyards planted along the valley floor, which slopes gently down toward Suisun Bay. These soils allow for root systems to penetrate deeply into the ground, creating healthier vines and higher-quality grapes.

Solano County Green Valley AVA wines hold a reputation for striking a balance between quality and affordability. Popular varieties throughout the area include Zinfandel, Sangiovese, Cabernet Sauvignon, Merlot and Syrah.

Solano County Green Valley AVA is considered an "up-and-coming" area of wine production.  There are currently just a few wineries operating here, but given the valley's short distance from San Francisco and the neighboring Napa Valley, this is likely to change.

Wild Horse Valley AVA

Designated an AVA on 29 November, 1988. The Wild Horse Valley AVA has borders that overlap both Napa County and Solano County and is partially contained within the Napa Valley AVA. The appellation's southerly location results in more hours of sunshine than other locations in Napa Valley or nearby Green Valley. The proximity to San Pablo Bay results in a cooler climate, making Wild Horse Valley attractive for the cultivation of grapes like Pinot Noir.

The Wild Horse Valley AVA features two distinct subregions. To the west, the area is cooled by San Pablo Bay, although the elevation keeps the area above the fog line. The eastern half, being protected by the slope of the ground, is much warmer. The soil type is generally volcanic throughout the entire AVA.

Grapes were first planted in the area in the 1880s. The current vineyard plantings date back to 1980, with commercial production starting in 1985.