The Coursey Graves estate vineyard is a place where the distinction between rock and soil is blurred. Vines grow in volcanic soils created 5 million years ago. The Hambright “soil” is composed of weathered basalt and andesite gravel, cobbles, and stones. Across the landscape are boulder outcrops hinting at the igneous bedrock just a few feet below the surface.
It's difficult to farm here. Shallow, stony, free-draining soil with low fertility prompts fine root development. Vines struggle to establish. They are small; their yields are naturally limited. But the result is berries with intense color, texture, and flavor – grapes destined to be iconic wines.
Maritime Climate
Our terroir is greatly influenced by its maritime climate. Onshore breezes sweep across the Petaluma Valley to meet the mountain. The cool, drying air ventilates the vineyard, slowing fruit ripening, and establishing a balance between color, aroma, texture, and sugar.
Above the marine layer, 1500 feet above sea level – a privileged position – and on the southwestern slopes of the mountain, vines thrive in unimpeded, intensified sunlight. Ideal growing temperatures are compelled by thermal inversion, a phenomenon that upends standard models of air movement. During the day, hot air sinks into the valley, while cooler air is trapped above. At night, it reverses. Warm air rises to the vineyard, encouraging the biosynthesis of compounds paramount to complexity of flavor and aging potential.
Generative Farming
We practice and promote Generative Viticulture. We look beyond just the crop, actively encouraging biodiversity, soil biological activity, carbon sequestration, water-cycle efficiency, and resilience to climate change.
We seek to enhance synergetic relationships that promote the health of our agroecosystem. Multi-species pasture crops are planted during vineyard dormancy to promote carbon sequestration, water retention, soil stability, and microflora and fauna life. Small additions of aged compost are placed below irrigation drips for a slow and targeted release of organic matter and micronutrients. We build and protect a diverse ecosystem, maintaining resources to attract and retain natural predators.
The vineyard is just one part of the agroecosystem. We don’t employ certification systems that are measured by rules and compliance. We are motivated by the health and fertility of life above and below ground. It is paramount to a vibrant terroir.