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Tuesday, September 10, 2013

What makes Sonoma County special for wine grapes

Trivia question: What is the size of Rhode Island, can have a 40 degree difference in daytime temperatures, and has more soil types than France?
Answer: Sonoma County.

Wine grapes can be grown almost anywhere though most is between the 30th and 50th degree latitudes in both the Northern and Southern Hemispheres. Countries as seemingly different as Brazil and Switzerland have sizable grape production.

So what makes Sonoma County special? In a word, diversity.

First, Sonoma has the right climate (temperature, rainfall, sunlight, wind) and good soils. There's the warm and dry growing season with cool nights that's just right for premium grapes. For soil good drainage is important. Rich soils are actually a detriment as they promote vine growth at the expense of the best grape growth.

But it's the diversity that makes Sonoma special.

Image from


A micro-climate exists in a very small area of differing weather. With the latitude and long hours of sun this part of California is naturally quite warm during the summer and into the autumn, however the cool Pacific waters lap on the western edge of the county. This "fight" between hot, dry air and the heavier cool, moist air is what really sets Sonoma apart.

Temperatures and winds can change noticeably in just a few miles. It can be 100 degrees in the hottest inland areas and only 60 at the coast.

Why does this matter to the grapes? Some wine grapes do better in a cooler area with less sunlight while others what the heat. This means Sonoma County can grow all the major wine grape varieties within a few miles of each other.


Gravelly, stony, volcanic, clay, it's all here. Vineyards run from down almost at sea level to 2,600 feet. It's not unusual for a single vineyard to have multiple soil types.


Sonoma County is the birthplace of the California wine industry. The wine industry here was huge by the late 19th century. The local grape growers have learned a lot about producing top quality grapes over time.

Sonoma has everything from valley dry-farmed Chardonnay to mountain Cabernet grown in volcanic rock. There's that diversity again!

Bennett Valley in Sonoma County
An area surrounded by ancient volcanic peaks
with the marine layer of cool air influencing the growing season