MOUNTAIN MUSE
Issue Fifteen | Mountain Grown Fruit
Growing wine at elevation is a high-stakes, high-reward endeavor. Steep terrain, volatile weather, and the need to do everything by hand deter most from trying. Yet the wines that result—powerful, finessed, and deeply expressive of place—are what compel Stonestreet to embrace the challenge.
High-elevation viticulture is especially uncommon in California, where only 3% of wine grapes are grown above 1,000 feet. Of the 15% of California’s vineyards that are classified as coastal, only 5% are situated on mountains, ridges, benchlands, and hillsides. And within Sonoma County, where 60,000 acres are planted to grapes, only 5–10% of this acreage sits at 1,000 feet in elevation and above.
The quality and longevity of mountain-grown wines is precisely what drove Jess Jackson and Barbara Banke thirty-one years ago to establish Stonestreet Estate Vineyards on the western edge of the Mayacamas Mountains. Today, Stonestreet farms 170 micro-vineyards that start at 400 feet and rise to 2,400 feet in Christopher’s Vineyard.
Taking on mountain viticulture requires a resilient and adaptive mindset. Steep, narrow slopes preclude the use of tractors, requiring all vineyard work to be done by hand. The thinner soils are also more susceptible to erosion due to high winds and the vertical drop of the slopes. Weather can shift quickly and unpredictably, and the growing season is generally shorter. Additionally, farming at elevation does not guarantee freedom from fire danger, a lesson Stonestreet learned firsthand during the 2017 Pocket Fire, which destroyed vegetation and killed wildlife on the mountain.
The daunting challenges of high-elevation viticulture attract a unique type of wine professional. Our viticultural team, led by Gabriel Valencia since Stonestreet’s inception, is made up of farmers who have tended to our vineyards for 25 to 30 years and have developed an intimate knowledge of the land. Working with Gabriel, our winemaker, Kristina Shideler helped identify and map our estate’s 170 micro-vineyards. These vineyards comprise 26 soil types, a multitude of microclimates, and vineyard exposures from every compass point to form one of the most diverse wine estates in the world.
The team’s collective knowledge of the mountain is integral to the quality of our wines, as it allows us to farm in harmony with the land. From grape to glass, our hands-on approach results in powerful, structured Cabernets and complex, textural Chardonnays that illuminate with astonishing finesse our estate’s varied geology, elevated topography, and climatic diversity.
Below are some of the conditions that explain the favorable effects of elevation on wine quality. Several of these apply to high-elevation vineyards in general, while others are unique to Stonestreet:
- More intense sunlight and lower atmospheric pressure produce smaller, more intensely flavored grapes. For every 1,000 feet increase in elevation, UV rays increase by 10–12%. To protect themselves from this radiation, the grapes develop thicker, darker skins—leading to wines with more concentrated flavors, vivid color, and powerful tannins. The grapes are also naturally smaller at elevation due to lower atmospheric pressure, resulting in a greater skin-to-juice ratio and intense flavors.
- Wider temperature swings slow the ripening process and aid acid retention. When temperatures drop at night—by as much as 50 degrees on our mountain—the ripening process slows down. This allows the fruit to mature slowly and develop complex flavors while preserving acidity. As Kristina notes, we can harvest the grapes at Stonestreet when they are moderately ripe but have lower sugar levels (and consequently lower alcohol levels), culminating in elegant, finessed wines.
- The inversion layer allows cultivation of cool-climate Chardonnay. Stonestreet’s Chardonnay plantings, which start at 800 feet and rise to 1,800 feet in the Upper Barn Vineyard, sit mostly within the inversion layer. Morning fog moderates the heat and sunlight until midday. Kristina credits this mesoclimate with Stonestreet’s ability to grow vibrant, textural Chardonnays that we would not otherwise be able to do in the warmer climate of Alexander Valley. “It is particularly rare to find Chardonnay grown at elevation like that of Upper Barn or Broken Road,” adds Kristina, “Their acidity is so beautiful.”
- Excellent drainage forces the vines to dig deep for water and concentrate their energy on fruit development. Because of well-draining rocky soils on very steep grades, the vines must dig deep to find water and nutrients. Yields are smaller, but have great flavor as the vines thrust all of their energy into developing the fruit.
- The parent material (the rocks beneath the soil) at Stonestreet is more exposed at elevation, building character in the fruit. Soil and the rock beneath it shape how vines grow by controlling how roots spread, how water drains, and how nutrients are held—factors that ultimately influence a wine’s acidity, pace of ripening, and the formation of its aromas. “Where else do you see clay next to schist next to volcanic material?” marvels Kristina, noting that Stonestreet’s complex soils and parent material originated in the tectonic and volcanic activity that gave rise to our mountain millions of years ago. “At Stonestreet, the rock is exposed, and the vines are right next to it. I think that accounts for the high character of our single-vineyard sites.”
- Stonestreet’s great diversity of exposures at elevation fosters complexity in the wine. Our mountain estate features every aspect from northeast to southwest. These different exposures create a plethora of microclimates at different elevations. We match the clones to the specific soil and microclimate of each block and then vinify each parcel separately. This meticulous approach gives Kristina a veritable “spice box” for blending wines—whether it is a block that expresses the bay laurel, wild chamomile, or sage growing on the mountain, or a parcel that captures the salinity of our ocean breezes.
- Stonestreet’s proximity to the ocean encourages freshness in the wine. Pacific Ocean breezes funnel through the Petaluma Gap—a break in the Coastal Range—into our vineyards, which are located just 23 miles from the coast. This natural air conditioning helps prevent disease, fungus, and mildew, while also causing the grapes to develop thick skins and hold onto their acid.
The proposed Pocket Peak AVA is designed to celebrate these unique and favorable aspects of mountain viticulture. Pocket Peak will include a delimited area comprising high-elevation vineyards within the Alexander Valley AVA that share elevated topography, steep grades, higher precipitation, and varied soils, acknowledging their differences from those vineyards located on or near the valley floor. Chris Jackson, Stonestreet’s second-generation proprietor and co-author of the petition, says that “Pocket Peak is home to profound wine stories yet to be told.”
No one is more ready to tell those stories than Kristina. “Our wines showcase this place,” she says. “I want to reveal the vineyard sites, reveal the mountain. You’re not going to change the wines—they have definite personalities, but how can you guide them along so they’re at their absolute best? I’m never going to get bored. It’s a pursuit of mastery.”
As Kristina unearths new facets of the mountain through her winemaking, we hope that learning more about high-elevation viticulture will connect you to our mountain and its singular wines even more.
