The general pattern for the greater region is Mediterranean, and is great for grape growing. The nearby Pacific ocean dominates the climate, resulting in wet, cool winters, and 30-50 inches of precipitation which recharges the aquifer while grapes are dormant. Summers are warm to hot and very arid, allowing for a slow depletion of soil moisture which slows down vine growth at the perfect time, ensuring an ideally light-exposed crop, and the dryness greatly reduces pest and disease pressure. The Alexander Valley is cooled from south to north by marine air moving in from the Pacific Ocean via the Petaluma wind gap and the Russian River valley. The combination of enough heat to ripen the crop but a big enough cool down to preserve freshness and acidity are keys to wine quality.
ELEVATION & TOPOGRAPHY
Elevations range from 400 to 2500 feet. Stronger UV light causes thicker skins that add color, flavor, and structure. Late summer temperature inversion facilitates ripening despite lapse rate. Elevation adds another facet to the terroir of any site. Higher elevaton vineyards receive slightly more sunshine because the fog line burns off sooner—but their stressed soil conditions on the slopes extends the maturation a week to two weeks longer than the benchlands and valley floor. With these diverse terroirs, a mosaic of mature tannins that supply intense blackberry aroma and layers of tannin, giving broad flavors to the wine’s palate and contributing to a long elegant finish.
80% of the Alexander Valley vineyard parcels are grown in the valley’s benchlands and the majority of which are clustered in the middle of the valley at the base of the Mayacama Mountains planted to Cabernet Sauvignon. The quality comes not from the slope of the vineyard, but directly from the soil’s depth and composition.
Weathering, erosion, gravity, and water movement have further moved and settled things into a hodgepodge of soils that require testing and experience to match the right variety, rootstock, amendments and irrigation schemes to each site.