There is a huge variety in the types of soils where vineyards are planted. Sand is good for drainage, loam holds moisture, organic matter aerates, and rocks add minerals. As a grapevine’s roots grow, searching for water, they take up molecules and minerals from the soil that help the plant to thrive. It is those same molecules that contribute to the chemical reactions that create individual grape flavors based on location, or “terroir“.
Soil is just one aspect of terroir, which makes up all of a site’s contributions to its grape’s flavors: soil, temperature range, hours of sunlight, rainfall (or its lack), winds, fog, grade, and elevation.
“However omnipotent climate and soil may seem, they cannot be considered apart from the variety of the grape being grown. A climate too warm for pinot noir is one that can be perfect for syrah. Varieties respond differently…[and] great wine can only result when a grape variety is tuned in…to its environment.”
~ Karen MaNeill
Generally speaking, Cabernet Sauvignon, Zinfandel, Sangiovese, and Syrah prefer heat, and Pinot Noir, Riesling, Gewürztraminer, Pinot Gris, and Chardonnay prefer cool weather. But if a winemaker’s goal is to create wines that pull all the elements of terroir together, then grape varieties that work well with the vineyard’s soils and climate will be planted, as the amount of grapes grown from each vine will be limited—by pruning—so that the flavors will be concentrated.
“We do know this: For every vineyard, there is a breaking point—the point where too many grapes will cause the vineyard to be out of balance and where the subsequent quality of the wine will plummet.”
~ Kaen MacNeill
So that’s the dance: to balance the vines and weather, soils and inclines, knowing that it’s the wise combination of all these elements that will create great wines.
For further reading, try Karen McNeill’s “The Wine Bible”, and “Wine Grapes: A Complete Guide to 1,368 Vine Varieties” by Jancis Robinson.