This is part one in an ongoing series about the basics of winemaking. After you’re done with this one check out the other sections! Basics of winemaking Part 2: Harvest, Basics of Winemaking Part 3: Crush and Fermentation, Basics of Winemaking Part 4: Pressing and Basics of Winemaking Part 5: Barrel Aging .
When most people think about winemaking they jump ahead to everything that takes place at the winery, after the grapes come in off the vine. But truly great wine absolutely starts in the vineyard. The French even have a whole concept built around that notion, terroir. Great wine doesn’t just grow anywhere; wine production is limited to between the 30th and 50th parallels of latitude in both the northern and southern hemispheres.
To focus on the grapes themselves they are by and large from the species Vitis Vinifera. Name any of the international grape varietals that you have ever heard of and they are probably of the Vinifera species. There are other species of grapes including some Native American species that are also made into wine but they don’t have the same complexity and finesse as the vinifera grapes and there for are not very well know. A grape berry consists of 75% pulp, 20% skin and 5% seeds. The pulp is the most important part; it is the juicy center of the grape that will eventually become the wine. This pulp contains mostly water and sugar but also small amounts of that ever-important acid, some minerals, pectin compounds, and very small amounts of vitamins. But growing that little grape is a convergence of many different factors.
Climate is the first of these factors. Grapevines thrive in temperate regions where a long warm growing season will allow them to develop. This is the reason for the 30th-50th rule. It is not because countries or regions outside those boundaries don’t appreciate wine or don’t know how to grow it. It is just simply either too hot or too cold for grapevines to survive in their climate. Grapevines start to grow when the temperature reaches above 50°F, anywhere below that they remain dormant. When temperatures begin to rise into the 63°-68°F range the vines will begin to flower and it is these flowers that will eventually become the grapes.
Climate in general is important but it typically applies to an entire region. Within that region there are smaller microclimates that have their own temperature variations and those small differences in temperature can dramatically affect the grapes that are grown in that smaller region. These microclimates can come from such factors as the proximity to an ocean or other bodies of water and the presence of mountains to the slope or orientation of a vineyard.
Within the issue of climate is the issue of sun exposure. Sun is what ripens the grapes but the climate and or microclimates of the vineyard site will dictate whether that sun exposure is maximized or minimized. Generally in cooler regions the best vines are planted on south facing slopes to take advantage of the sun exposure and ensure ripe fruit in an otherwise cool environment. Grapes grown in warmer climates however don’t have to struggle to ripen and are therefore typically planted on north facing slopes. Intense sun can back the acidity out of the grapes; by shielding them from the sun it allows the grapes to ripen more slowly without getting sunburned.
Another factor in determining where to site your vineyard is kind of an interesting one, stress. On the surface stress would seem like a negative in the grape growing process and something that winemakers and vineyard managers would try to avoid. In reality though vines that are under stress actually produce better wine. Obviously you don’t want them to be in sever stress that they shut down or die, but an endurable amount of stress forces the grapevine to struggle. When the vine is forced to struggle the plant concentrates its sugar into a limited number of grapes and as a result those grapes will have more complexity and a greater concentration of flavor.
Temperature swings tie into both climate and stress. These swings help to create a balance in the grapes and they can occur either daily or over the course of the seasons. Wine regions that are relatively hot during the day benefit from cooler nights, which shuts down the ripening process for a while and helps the grape vines preserve their natural acidity. This break time everyday extends the overall ripening time of the grapes leading to more complexity and mature flavors. Season temperature swings are important because the grapes need precise cues for bud break and grape development. The ideal situation would be a definitively cold winter followed by a definitively warm spring and summer. Too many random warm days during the winter can lead to an early bud break which means the vines would come out of dormancy before normal and potentially during unstable weather. Too many cool days during the summer months can likewise confuse the grapes and interrupt the ripening. Or, worse yet, rain during or right before harvest can be very damaging to the grapes and cause issues with mildew.
The final two factors to consider are water and soil. As vines grow they search for water. Dry topsoil encourages roots to burrow deeper into the ground to find their water in a more stable and consequently more nutrient rich environment. Vines with this kind of developed root system are able to withstand drought and other environmental stressors. This is basically the concept behind dry farming and an example of one of the ways that stressing a vine can lead to better wine. This is also why the best soil for vineyards are those that are well drained. Another important aspect of soli is its ability to reflect and or retain sunlight. In cooler regions this can be an incredibly important factor, the soil can reflect the limited sunlight back onto the grapevine to help to ripen the grape. Or the soil can retain the heat from the day and help the grapes continue to ripen even in the cold nights.
All these factors and considerations need to be in place to grow the grapes that may one day make that special bottle of wine. And all of these factors contribute the flavor and complexity of that wine long before they are harvest and before they make their way into the hands of the winemaker and the winery.
Check out part 2 of this series, Basics of Winemaking Part 2: Harvest