|Type||American Viticultural Area|
|Part of||California, Lake County, North Coast AVA|
|Other regions in California, Lake County, North Coast AVA||Benmore Valley AVA, Clear Lake AVA, High Valley AVA, Red Hills Lake County AVA, Big Valley District-Lake County AVA, Kelsey Bench-Lake County AVA|
|Size of planted vineyards||340 acres (140 ha)|
|Grapes produced||Petite Sirah|
The Guenoc Valley AVA is an American Viticultural Area in Lake County, California, United States, about 15 mi (24 km) north of the town of Calistoga. Guenoc Valley AVA was the first American Viticultural Area designation granted to an area with just a single winery.
Guenoc Valley is a small inland valley comprising an alluvial fan of Arroyo Seco and Conejo Loam series soils isolated from surrounding areas by rocky ridges. Its geographical location also affects the climate. Guenoc Valley has slightly less rainfall than the nearby Middletown area. Guenoc Valley receives approximately 45 inches (114 cm) to 50 inches (127 cm) of rain per year, while Middletown receives approximately 60 in (152 cm) per year. Guenoc Valley also experiences slightly greater seasonal temperature extremes, being warmer in the summer and colder in the winter. Also, due to the surrounding ridges, fog is generally less severe than in Middletown. For these reasons, the United States Department of the Treasury Alcohol and Tobacco Tax and Trade Bureau determined that Guenoc Valley possesses geographical features which distinguish the area viticulturally.
Guenoc Valley has a long tradition of viticulture and wine production. In 1888, Victorian actress Lillie Langtry established a wine estate in the Guenoc Valley, at the southern end of the county in the 1800s. It wasn't until the late 1960s and the 1970s that farmers who wanted to diversify started planting grapes again, mostly in nearby Big Valley.
On the site of Lillie Langtry's old estate, Guenoc and Langtry Estate Vineyards was revived by the Magoon family at about the same time. The now-deceased longtime winery president Orville Magoon sold his interest in the company in 2003 and retired to San Francisco with his wife, Karen Magoon. The winery and the 21,000 acres (8,500 ha) it sits on is owned by Malulani Investments Ltd., a real estate group that since 1964 has been the only shareholder and stockholder of Guenoc.
Guenoc Valley is a small inland valley of about 23,000 acres (9,300 ha), extending from upper Napa County. The wine appellation is defined by the rocky ridge surrounding it and is entirely contained within the boundaries of Lake County. The Guenoc vineyards sit at 400 ft (120 m) elevation. These vineyards are the first in the area to be harvested, as extremely hot days are common and over-ripening is a concern. The area also has very cool nights, preserving acidity and producing rich wines with elegant structure, making it a Climate Region III.
There are now 340 acres (140 ha) of vines surrounding the Guenoc estate. The winery works with Semillon, Sauvignon blanc and Chardonnay, as well as Malbec and Petite Sirah from the estate vineyards. Petite Sirah is the leading red grape in the appellation, followed by Cabernet Sauvignon, Merlot, Petit Verdot, Carmenère, Cabernet Franc and Malbec. Among whites, Langtry grows Chardonnay, Sauvignon blanc, Semillon, Marsanne and Viognier. Langtry also has the distinction of having some of the oldest vines in California, as a couple of Syrah vines dating back to the 1850s still grow at the Tephra Ridge Vineyard.