After years of studying the complex relationship between wine quality and place, and understanding the importance of "terroir," Phelps has developed estate-owned vineyards in the premiere growing regions of Stag's Leap, Rutherford, Oakville, Oak Knoll and the eastern foothills of Napa. In Sonoma County, an ambitious project was undertaken in 1999 to purchase land and develop vineyards along the western frontier of the Sonoma Coast, and today Phelps has 80 acres of Pinot Noir and 20 acres of Chardonnay planted in Freestone. A small winery in the midst of the Freestone vineyards is currently under construction.

Varietals produced annually at Phelps include Napa Valley Cabernet Sauvignon, Backus Vineyard Cabernet Sauvignon, Insignia (one of California's most successful first growth luxury blends), Chardonnay, Sauvignon Blanc, several Rhône-style wines, and a luscious dessert wine made from Scheurebe.