What Affects Wine Quality? Your Guide to the Growing Techniques That Matter

What affects wine quality? The answer to this question isn’t so simple. A number of different factors, from the age of the vine’s rootstock to the vineyard’s climate, can dramatically impact how a wine tastes and how long it will last in your cellar. If the winemaker starts off with underripe, poorly grown grapes, then the resulting wine won’t taste elegant or refined, even if the producer ages the wine in the finest French oak. To invest in the highest-quality wines on the market, it’s a good idea to understand some of the growing techniques that affect wine quality, including climate, vine age, soil composition, pruning, weather, and harvest dates. By considering each of these factors as you shop for collectible wine, you’ll learn how to identify the best wines from the top producers–and be able to pick out unlikely gems from lesser producers as well.

Macroclimates Significantly Impact Wine Flavor

If you want to find out whether a wine was made under the perfect growing conditions, start with macroclimate. A macroclimate is a category that describes the overall weather patterns for a particular area. For instance, Germany as a whole tends to be cooler than Australia, so the types of wines that thrive in Germany may not thrive as easily in Australian vineyards. There are three macroclimates that most wine grapes are grown within: Mediterranean, continental, and maritime. Each of these macroclimates has different temperature patterns that are ideal for different varieties of wine grapes.

 

Mediterranean

Characterized by: Long, leisurely summer growing seasons, plenty of sunshine, and very warm temperatures.

Regional Examples: Australia and California.

Wine Styles Commonly Grown Here: Full-bodied reds like Syrah (Penfolds Grange) and Zinfandel (Ridge).

Wine Personality: Fruit-forward wines that are high in alcohol and residual sugar.

What Affects Wine Quality: This macroclimate is prone to drought. The best producers will have anti-drought measures in place, such as artificial irrigation, or old rootstocks that can reach into deep underground water tables.

 

Continental

Characterized by: Extreme weather conditions. Summers are very hot, while winters are very cold. Daily diurnal variations (large temperature fluctuations) are common.

Regional Examples: Burgundy and northern Rhône.

Wine Styles Commonly Grown Here: Light or medium-bodied reds like Pinot Noir (DRC La Tache), and white wines like Chardonnay (Ponsot Montrachet).  
Wine Personality: Tart wines with low residual sugar and low alcohol. They have a “greener,” less fruity personality compared to wine made in more moderate climates.

What Affects Wine Quality: Frost is common in the winter and spring, which may reduce crop size. Cool summer temperatures also may make the wine taste underripe and astringent. The best wines come from years where frost damage was minimal and summers were relatively warm.

 

Maritime

Characterized by: Close to large bodies of water, like lakes and oceans. Maritime climates have long growing seasons and pleasant, moderate temperatures that are neither too hot nor too cold.

Regional Examples: Bordeaux and Champagne.

Wine Styles Commonly Grown Here: Complex Cabernet Sauvignon (Margaux), and white wines like Sauvignon Blanc (Haut-Brion).

Wine Personality: Well-balanced wines that perfectly combine acidity with residual sugar. However, this is only true if the temperature remains moderate in the spring and summer and doesn’t become unusually hot or cold.

What Affects Wine Quality: Rainfall is a challenge for maritime winemakers. These regions receive plenty of rain, which can dilute the grapes. To pick out the best maritime wines, research how much rainfall the region received that year, and whether winemakers took measures to prevent excessive irrigation.

If you’re not sure how to categorize a particular region’s macroclimate, you can also use the Winkler index to determine whether a wine is well-matched to its climate. Look at the list of regions below to see which wines thrive best under which climate conditions:

Region I (very cool): Chardonnay, Pinot Noir, Riesling.

Region II (cool): Cabernet Sauvignon, Merlot, Sauvignon Blanc.

Region III (moderate): Zinfandel, Barbera, Gamay.

Region IV (hot): Malvasia, other North American grapes like Concord.

Region V (very hot): Table wine, especially wine made from native North American grapes.

With the scale above, you can quickly determine whether a wine was likely made in a region that will bring the best out of the grapes used.

However, macroclimate also varies by subregion. For instance, California overall has a Mediterranean macroclimate, but some smaller areas of California (like the Russian River Valley) have a much cooler macroclimate. In some cases, a grape variety is able to thrive in an unlikely area because of favorable conditions within a smaller region of one particular macroclimate. Here are two famous examples of the climate in a particular area determining what types of grapes thrive there.

 

As you can see in the examples above, a region’s overall macroclimate can’t tell you everything you need to know about what affects wine quality. You also need to think about whether subregions have unusual or unique climates that impact grape quality.

Different Grapes Thrive in Different Microclimates  

Microclimates deepen your understanding of what affects wine quality. Unlike a macroclimate, which is a general description of the weather conditions in the area, a microclimate is specific to the vineyard itself. So even though Napa Valley is relatively warm overall, some vineyards there have unique microclimates that change the personality of the wines made. For instance, Napa winemaker Carole Meredith has a vineyard that’s surrounded by woods, and as a result, its climate is cooler compared to the other vineyards growing around it. Here, she grows Mondeuse, a Savoie wine that is notoriously difficult to make in a warm region like Napa. Mondeuse thrives in climates that sit between continental and maritime; the grape requires a lot of sunshine, but it also needs cooling winds that prevent it from becoming too raisined. Because Meredith’s vineyard is cooler than the vineyards around it, she is able to successfully produce this rare French wine on the estate.

When you research specific microclimates for some of your favorite producers, you can easily see what makes them so successful. A vineyard’s microclimate may significantly differ from its overall macroclimate in temperature, the amount of sunlight the grapes receive, or the average annual rainfall. Factors like forest cover or bodies of water (such as rivers) can change the personalities of the wines grown in a particular region. If a vineyard is in a Mediterranean climate but sits next to a river, it will likely be cooler than other vineyards in the area, and may be better for growing Pinot Noir than, say, Syrah.

The Age of the Rootstock Is Essential

The age of the vines can also mark the difference between a low-quality wine and one that’s worth collecting. Winemakers have to wait three to five years after planting their vines before the vines will produce quality grapes. As these vines mature further, they begin producing higher quality grapes–in general, a 70-year-old vine will produce more complex grapes than a ten-year-old vine. The reasons for this are debated, but one reason is that older rootstock is sturdier, and can handle weather fluctuations more easily.

As vines get older, their roots grow deeper into the soil. In some cases, the roots grow so deep that they gain access to underground well water that younger vines simply can’t reach. During a drought, this is a benefit for old vines; they get most of the water that they need underground, even if rain never comes. The reverse is also true. If there’s too much rainfall, young vines tend to soak up the water in the shallow soil, producing diluted grapes. It takes much longer for this water to reach older, deeper rootstock, so their grapes will stay more concentrated in flavor.

As a result, wines made from old vines are also able to circumvent some of the more serious weather challenges that winemakers face. The wines produced by these vines are more consistent in quality over time, and are often more collectible and age-worthy because they produce grapes that almost always have an ideal balance between acidity and alcohol, regardless of the weather conditions that year. If you want to invest in the most reliable, high-quality wines, consider buying vintages made from vines that are at least 20 years old, preferably older. Penfolds’ Block 42 vintages, which are made from grapevines planted in 1888, are a great example of this.

What Affects Wine Quality? Complex Soil Types

The type of soil that vines are planted in can also impact the flavor and ageability of a wine. As a general rule, rocky soils do the best job of draining excess water from the vine roots, making this type of soil especially desirable in wet climates, like continental and maritime regions. Meanwhile, denser soils are a benefit for Mediterranean regions that frequently suffer from drought, as the soil can retain water and feed the rootstock steadily until the next rainfall occurs. Although the ideal soil composition varies from vineyard to vineyard, most top producers share one thing in common: they plant their vines in complex, multi-dimensional soils. The best winegrowing soils have a mix of rocky and dense components–this allows the soil to cling to water during dry seasons and drain the excess during heavy rainfall. Not enough soil drainage results in a thin, diluted wine; too much drainage causes the wine to become overly sugary and overripe in flavor. When you research a new producer, look at the vineyard’s soil composition to see whether it suits the climate, and whether there’s a good mix of rock and dense clay components.

The Weather Impacts Vintages

Climate and soil composition are slow to change–for the most part, they stay constant over the years, giving the wine its basic personality (fruity, acidic, or tannic). But the weather can vary year by year, which significantly affects wine quality. You can use information about macroclimate and microclimate to assess whether a grape variety is particularly suited to the region, but if you want to determine whether a specific bottle of wine is high in quality, then you have to look at the actual weather conditions for that vintage.

While the quality and flavors of the final wine will also depend on how the winemaker reacted to the weather conditions, generally, the hotter and drier the weather was that year, the more concentrated and high in alcohol the wine will be. The colder and wetter the weather was, the more acidic and herbaceous the wine will be. To analyze quality, think about the weather as it relates to the vineyard’s climate. If the wine is from a Mediterranean climate and the weather was especially warm that year, then that wine may be overly ripe and not collectible. However, if the summer temperatures were cooler than usual that year, then the wine may have a better balance of flavors. Pay close attention to weather reports for each vintage before you invest.

Pruning Gives the Grapes Protection

Winemakers can’t control the climate, soil, age of the vines, or the weather, but they can control pruning. Proper pruning practices can mean the difference between a high-quality vintage and a low-end table wine. In the winter, vines enter a dormant state–they shut down completely until the warmer spring weather arrives. At this point, winemakers have to think about pruning the budding leaves. If they leave too many leaf shoots on the vine, then the leaves will overtake the fruit, resulting in low grape yields. What’s more, the leaves will block out sunlight, causing the final wine to taste too astringent and underripe. If the winemaker leaves too many fruit buds on the vine, the grapes will crowd each other out, becoming too small. With fewer leaves, the fruit also doesn’t have enough protection from the sun, and may overripen. The best producers prune shoots and buds early and often, striking a balance between leaf cover and plenty of fruit spacing. In years when the weather is either too hot or too cold, winemakers can sometimes prevent fruit damage by adjusting their pruning standards for their needs (such as by allowing more leaves to grow than usual during an especially hot, sunny summer).

Also Essential? Harvest Dates

Another method that winemakers use to control the quality of their grapes is to adjust harvest dates based on the weather. Like pruning, picking the right harvest date for each grape variety is what separates high-end producers from lower-quality estates. In most cases, producers in warm climates tend to harvest their grapes relatively early in the season in order to prevent overripening. In colder climates, harvesting late can give the grapes a bit more time to ripen properly without losing acidity. And some wine styles are designed to be harvested especially late–Napa’s Far Niente Dolce is a white dessert wine that requires a lot of hang time on the vine in order to get those rich, very ripe flavors. Most bold dessert wines spend extra time on the vine (sometimes through November) in order to become as sweet and decadent as possible, whereas lighter styles, like Pinot Noir, tend to be harvested on the early side (typically in September) in order to preserve their acidity.

How to Find Information About Winegrowing Techniques

Learning what affects wine quality is only one piece of the puzzle. You also have to know where to find information like harvest dates, microclimates, and other details. Many high-end wineries offer tech sheets online which explain exactly what the weather conditions were like on the estate for a particular vintage, and what pruning or harvesting techniques were used to make the most out of every grape. However, not all wineries provide this detailed information. If you can’t find this information on the winery’s website, you may have to use your own research of the wine region and weather conditions in the area to determine whether the wine is likely to be high in quality. You may see that the grape is well-suited for the macroclimate, that the microclimate brings out features in the wine that you enjoy (like noble rot), that the vines are supremely old, and that the weather struck a perfect balance between sunlight and rainfall that year. If you have information like this, it’s reasonable to assume that the wine is probably worth buying, even if you’re not sure exactly when the grapes were picked or what pruning techniques the producer used.