The Southern Oregon AVA (American Viticultural Area) is, not surprisingly, located in the southernmost part of Oregon, beginning near Eugene and extending 125 miles (200km) south to the Californian state border. Southern Oregon incorporates two smaller AVAs, the Rogue Valley and the Umpqua Valley. Many different grape varieties can be grown here, including the Pinot Noir that Oregon is noted for, along with Syrah, Riesling and Tempranillo.
Viticulture in Southern Oregon takes place in a huge range of terroirs, as the region is located in a series of river and mountain valleys at the meeting point of the Klamath, Coast and Cascade mountain ranges. Generally, the AVA is warmer and drier than the Willamette Valley in the north, because the high Southern Oregon Coast Range blocks out much of the Pacific Ocean’s coastal influence. Distinct mesoclimates exist, however, and ocean breezes are channeled into the vineyards via the region's many rivers.
Altitude is fairly important viticulturally in Southern Oregon, and many vineyards can be found on slopes reaching as high as 2000ft (600m) above sea level. Here, they can enjoy warm sunshine during the day followed by much cooler nights. This diurnal temperature variation throughout the growing season helps to extend the ripening period, leading to the development of varietal character along with acidity.
The meeting of the three mountain ranges has led to a huge array of soils, with more than 150 different types identified in the Umpqua Valley alone. These soils come from metamorphic, volcanic and sedimentary origins, with vineyards usually sitting on alluvial sandy loams on the hillsides. In the Rogue Valley, alluvial gravel is more common, and many vineyards sit on river terraces above the area's many rivers. In general, these soils are free-draining and low in fertility, which is excellent for premium viticulture: the stressed vines produce less vegetation and put more energy into producing high-quality grapes.
Oregon's first winery was established in the Applegate Valley in the 1870s, but commercial viticulture didn't really take off in Southern Oregon until the American wine renaissance of the 1960s and 1970s. Since then, the industry here has grown steadily. Southern Oregon became an AVA in 2004, giving the previously established Rogue and Umpqua Valley AVAs a united front under which to market themselves.