What Makes Napa Valley Special?


Thanks to the handful of readers who wrote back about yesterday’s post on the high price of Napa Valley wine. It was quite natural for them to wonder what makes this region special enough to justify the price. 

As you recall, the simple answer is supply and demand. So, why are Napa Valley grapes in such high demand? What makes the valley so special?

The short answer for that is “pure luck.” And, pure luck translates into a great combination of soil and climate for wine grapes. The growing conditions here are so favorable for growing wine grapes that a grower could almost do a sloppy job of farming and still get pretty good results.

But, the thing is that most growers and winemakers here aren’t content with “pretty good.” They want to grow/make wonderful wine! So, the third, key, element is people: People who are fanatical about what they do. Any winemaker will tell you that if the vineyard grows superlative fruit, she’s 90% of the way home. Her job is to try not to mess it up.

The fact that the valley is small and produces only 4% of California’s wine adds to our “luck” when it comes to demand.

If you look at the most famous winegrowing regions worldwide, the soils aren’t alike. Grapes are hearty and adaptable. But, they have some key things in common: the soils are usually well drained and not particularly good. You’ll find gravel in Bordeaux, chalk in Champagne and slate in the Mosel.

Our soils

Napa Valley soils are so diverse it boggles the mind.


Over the last 10 million years, massive collisions of the earth’s crust created our mountains and valleys. Repeated volcanic eruptions spewed forth rock, lava and ash, and created some of the small knolls you see as you drive through the valley. Changing sea levels sent flood waters washing in and out of the valley like the waves of the sea, depositing layers and layers of sedimentary clay and sand of vastly different ages. 

The valley is just over 30 miles long and one up to four miles wide at the widest point. So, the two very different mountain ranges that form the valley have a major influence on the composition of the valley floor.

The Mayacamas range, on the west side, was pushed up from the ocean floor as part of what’s known as the Franciscan Series but also includes volcanic deposit. The material is extremely varied which is why the various, famous alluvial fans aren’t alike. It’s heavily wooded and perpetually green.      

The shallow 100% volcanic deposit that makes up the Vaca range on the east side includes layer upon layer of volcanic deposit like compressed ash (tuff), volcanic glass, lava flows, volcanic mudflows, etc. The shallow soil and low rainfall, compared to the Mayacamas range makes it a dry home for scrub oaks and sage brush.


Of course, over the millenia the material of both ranges washed down and mixed together, to a degree, into the narrow valley floor. The Napa River, which bisects the valley running north to south, flooded and receded countless times over the millenia and left deposit of its own. 

Overall, the soils here are considered moderately fertile – a little better than we need – so the response is to be rather stingy with the water and fertilizer. Years can go by between boosting the nitrogen or potassium.


The San Pablo Bay, at the southernmost end of the valley is the key to our terrific climate. Most days of the growing season tend to be quite warm but, the breeze picks up late in the day and the fog moves in, in the evening, allowing the grapes to ripen slowly and evenly. The marine influence decreases as you move north through the valley, which explains why it’s a happy home for quite a number of different varieties. Heat-loving varieties dominate the middle and northern areas and varieties that do best in cool conditions are concentrated in the south. 

We all want the same thing

Every grower and producer, worldwide wants just enough sun to get the grapes ripe and not too much more. And, every region has its gripes. In Napa Valley we worry about too much heat. In Burgundy, they worry about not enough. Everyone worries about rain at harvest – best if it’s dry.

Thanks for writing! Cheers!

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