I just had the opportunity blind taste three bottles of California red wine. To start the blind tasting, I did not know the varietal type but was told it was a single varietal wine. And, I was informed that one bottle was from the California Central Coast, one was from Paso Robles and the other was from Napa. It turned out that they were all California Merlot. But, each of the three bottles tasted very different. So, why is this?

One simple answer is - Terroir (p. Te-war). This is a French word that’s derived from their word for earth which is “terre.” It describes the interaction of soil, climate, terrain and grape variety in a specific site, and how they each imprint the wine, making each wine from a specific site distinct.

Here’s an overview of the various components that define a terroir:

Varietal Type

There are multiple types of Merlot grapes, often referred to as various clones. And a quick survey says there 12 certified clones of Merlot in France, approximately 30 registered clones in California and hundreds of clones of Merlot throughout the world. So, there is great variety within the Merlot family of grapes.

Soil

Throughout the world, there is tremendous differences in the types of soil, rock and minerals. Soil definitely affects the flavor of wine while the jury is still out on the topic of rocks and minerals affecting a grape’s flavor. But, many believe that minerals play a defining role.

Terrain

The geological features of a wine-growing region (e.g., mountains, valleys) as well as surrounding plants and large bodies of water (e.g., rivers, lakes and oceans) affect how a wine tastes.

Climate

Wine regions can vary significantly in climate from cool and foggy to hot and sunny. Warmer climates typically generate higher sugar levels whereas cooler climate wine grapes generally have lower sugar levels and higher acidity.