The Grade Cellars
Overview
Estate
The Grade Cellars is a small, estate-focused Napa Valley winery located north of Calistoga on the same historic route over Mount Saint Helena that Robert Louis Stevenson described in The Silverado Squatters. Tom Thornton and Brenda Mixson purchased the 32-acre ranch in 1997 while living and working in New York City. They initially approached the property as a vineyard investment, then replanted the vineyard and developed it into an estate wine project. The first vintage was produced in 2004.
Climate
Winfield Vineyard sits in the Calistoga AVA at the upper end of Napa Valley, where warm, dry days are followed by cool nights. The site's mesoclimate is particularly influenced by its elevation and by maritime air entering the valley during hot afternoons, together with cool air descending from Mount Saint Helena. The resulting temperature swings are considered important to the vineyard's Cabernet Sauvign
Soil
Winfield Vineyard is located on a sloping mezzanine above the valley floor, at the meeting point of volcanic mountain geology and the valley's alluvial landscape. The vineyard soils are predominantly cobbly loam, with gravelly loam in the upper sections. Individual blocks are deliberately differentiated by soil type and moisture conten
Vineyards
Winfield Vineyard comprises seven distinct blocks of Cabernet Sauvignon on approximately 12 acres, at elevations of roughly 425–590 feet. The blocks differ in clone, rootstock, soil, irrigation program, and viticultural protocol. Block 1 is Cabernet Sauvignon clone CS7 on 110R rootstock in cobbly loam; Block 4 is CS337 on 101-14 in gravelly loam; Block 5 is CS337 on SO4 in gravelly clay loam. The winery has also planted additional Cabernet clones in Blocks 6 and 7.
Cultivation
The vineyard program is sustainable and fish-friendly. The owners worked with consultants to study the property, dig soil test pits, develop irrigation, and replant the vineyard. In 2023, the vines underwent cane conversion, and the property added water tanks in response to changing weather conditions.
Winery
The Grade Cellars produces estate Cabernet Sauvignon with a block-by-block approach. The winemaking approach avoids enzymes, flavor or color enhancements, reverse osmosis and spinning cones, with particular attention to tannin management and texture.
Family
The Grade Cellars was created by husband-and-wife proprietors Tom Thornton and Brenda Mixson. They met on a blind date while building careers in New York, Tom in architecture and Brenda in commercial real estate. After purchasing the Napa ranch in 1997, they gradually shifted from landowners and growers to producing their own estate wine. Their personal connection to the property and the shared experience of developing the vineyard are central to the winery's story.
Winemaker
Thomas Rivers Brown has been the winery's winemaker since 2012. He translates the character of the single vineyard, and even individual blocks, into the wines. His approach is meticulous and relatively non-interventionist, with a strong emphasis on reading the vineyard and managing Cabernet Sauvignon tannins during barrel aging.
Focus Point
• Small estate winery in Calistoga, Napa Valley.
• 32-acre ranch with approximately 12 acres planted to Winfield Vineyard.
• Seven Cabernet Sauvignon blocks with distinct soils, clones, rootstocks and irrigation programs.
• Property acquired by Tom Thornton and Brenda Mixson in 1997.
• First estate vintage in 2004.
• Thomas Rivers Brown has been winemaker since 2012.
• Sustainable, fish-friendly vineyard practices.
• French-oak ageing and careful tannin management.
Marketing materials
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The Grade Cellars logo
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