Guenoc Valley is a small, inland AVA in the larger Lake County AVA in California. The area can be found just north of the Napa County boundary and roughly 15 miles (24km) south of Clear Lake. Despite covering an area of around 4500 acres (1820ha), Guenoc Valley is home to just one winery, Langtry Estate.
The single Guenoc Valley estate was first established in the 1880s by the English stage actress Lillie Langtry, famous for having been the mistress of the Prince of Wales (later King Edward VII). The area became an AVA in 1981 and was the first with only one winery within its limits.
This mountainous wine region is one of the warmest in California. The Mayacamas mountains that lie between the valley and the Pacific Ocean create a rain shadow, making Guenoc Valley drier and hotter than the regions on the western side of the mountains (including Sonoma Valley and Napa Valley). Careful site selection is vital due to the climate being relatively harsh for viticulture, and only the very best areas are chosen for cultivation.
The vines are planted on ridgelines up to 1400ft (426m) above sea level to take advantage of the cooler environment that altitude brings. Altitude is central to winemaking in Guenoc Valley: it brings significantly cooler nights, allowing the grapes to develop complexity while retaining acidity. Vineyards can also be found in the valley, where small, sheltered microclimates provide a cooler environment for the vines. The intense summer heat means grapes must be harvested early, before the sugars get too high and the acidity drops.
The hilly terrain is largely volcanic in origin (much like the nearby Red Hills Lake County AVA), and the shallow gravel and loam soils are well suited to the production of premium wines. Free-draining and rich in magnesium, these soils cause the vines to dig deep into the ground in search of sustenance, making them stronger and healthier.
The vineyards of Guenoc Valley produce full-bodied, concentrated wines from a wide variety of grapes; Petite Sirah, Cabernet Sauvignon, Sauvignon Blanc and Chardonnay are the best known.
