- Q & A
Chapter 1: The Key to Quality
VINES — THE KEY TO QUALITY
There is an old vintner's saying that great wines are "grown" in the vineyards. It is important then, in the learning of wine, to first grasp the importance of the raw material. In this case the grapes. No winemaker can "create" quality. The winemaker's duty is to take the grapes Nature provides and guide them on their course toward becoming wine. If you begin with the best grapes and employ great skill and experience, you have the potential to make great wine. The term here is "potential." There is an old axiom among winemakers, "You can make poor wine from fine grapes, but you can't make fine wine from poor grapes."
Nearly all of the world's vines are a combination of American, Vitis Labrusca, rootstocks to which have been grafted the so-called "noble" grapes of Vitis Vinifera varietals, such as Cabernet Sauvignon, Chardonnay and Riesling. Originally all vines were grown on their original rootstock. Unfortunately, this rootstock is susceptible to a louse called phylloxera, which literally eats the plant from the tip of the root up. We will discuss this topic in another chapter.
In order to make the best wine from each grapevine, many factors must be taken into consideration. The French call it terroir, which means the ecosystem of the vineyard. It comprises all the factors making the vineyard unique: soil composition, slope, temperature and rainfall at certain times during the maturation of the grapes, drainage, etc. Once the grapes are harvested, their potential has already been set.
The soil the vines are planted in is of paramount importance to the quality of the grapes. The red "terra rossa" soil, high in iron oxide and common to parts of the Napa Valley, Eastern Washington and the Sierra foothills, has been responsible, to some extent, for the hearty Cabernet Sauvignons produced in those regions. High granite soil found in Bordeaux and Italy produces a different but no less desirable grape. The very light, chalk-like and nearly white soil found in several areas of Sonoma, the Central Coast and Oregon has been proven to be ideal for Pinot Noir and Chardonnay. Riesling seems to like soils where roughly half the composition is stones and gravel.
Such viticultural intricacies have been known in Europe for centuries since, by trial and error, correct locations for specific varietals were found. Where Chardonnay did poorly, Cabernet thrived and vice versa. German red wines, with few exceptions, are light and flavorless. Their Rieslings, the grape that Germany's terrain is best suited for, are beyond reproach. California, with its short history of wine, was aware of these intricacies. Only in recent years, however, have California vintners made large strides in isolating these special terroirs in areas where soil and climate conditions are favorable to a specific varietal.
A century of winemaking is a very brief span of time. Once a vine is planted it requires 3-4 years in the ground before it can bear fruit, and very little at that. Vines do not reach full bearing capacity until they are 7 years of age. At such time the viticulturist can make a quality assessment. A red grape may yield a wine that will need to be aged for perhaps 3 years before the winemaker can make a firm quality assessment.
From the time the vine is planted until the time the final product is analyzed as being superior in quality, 7 or more years have elapsed. And, we're only talking about 1 wine, made from 1 vintage. It may take 3 or 4 vintages to get a "read" on the vineyard. In the meantime, a decade or more has passed. Usually, grape growers will have several "experiments" going at the same time (planting a row each of different grape varietals in the same vineyard to see how good the wine made from each can be), thus allowing them to make an evaluation after a few years using many different lots. All the while, however, no wine is sold; no income from these experiments is generated.
Vines, to survive, cannot tolerate either excessive heat or cold. To bear fruit of even ordinary quality, the temperature range is severely limited. For these reasons, viticulture (the growing of wine grapes) exists only in a very narrow range of latitudes worldwide and then only in areas where soils are suitable.
It has long been known in Europe that certain grapes thrive better in certain areas than others. The search for suitable climates in California was simplified in the 1960s when professors at the University of California, Davis devised a system for measuring ambient temperature during the growing season for vines. This is called the "Zone" system.
The minimum ambient temperature during the growing season when vines can be cultivated is 50 degrees Fahrenheit. The Zone system is based on heat summation expressed as "degree days." Degree days simply means that if the high temperature on a certain day is 70˚ F. and the low is 50˚ F., then the average temperature on that day is 60˚ F. Since the base is 50˚ F., the heat summation in excess of 50˚F is 10˚ F. and is expressed as "10 degree days." The total number of degree-days experienced in a particular location throughout the entire growing season, roughly March through October or about 200 days, denotes the Zone (sometimes called Region) in which that location falls.
To calculate degree-days, you take the average of the difference between 50˚F and the average temperature for that day. For example, a particular vineyard's 200-day growing season has an average daily temperature of 70˚F. The temperature is 20˚F over the base minimum of 50˚F per day. The important number in the zone system is the AVERAGE temperature. If the high is 80˚F and the low is 40˚F, the average is 60˚F. The difference between this average and the base (50˚F) is 10˚F and is calculated as 10-degree days. The average temperatures change as the season gets warmer. On a day that the high temperature reached 90˚F and the low 60˚F the average would be computed as 75˚F (the average between 60˚ and 90˚). The difference between 50˚F (the base number) and 75˚F is 25˚F so we add 25 degree days to the total. In April, May and June the high temperatures could average 70˚F. In July, August and September the high temperature could reach over 100˚. On a day where the high temperature reaches 100˚F and the low 60˚F, we take the average between 60˚F and 100˚F, which is 80˚F. 80˚F is 30˚F higher than 50˚F (the base number) so we add 30 degree days. At the end of the growing season (harvest day), we add up all the numbers for each day and categorize the vineyard by the following table.
|ZONE I||2,500 degree days or less|
|ZONE II||2,501 - 3,000 degree-days|
|ZONE III||3,001 - 3,500 degree-days|
|ZONE IV||3,501 - 4,000 degree-days|
|ZONE V||4,001-degree days or more|
If the average temperature throughout the growing season is 62˚F, the difference between that average and our base of 50˚F is 12. Multiply that by 200 days and you have 2,400 degree days or a Zone I (also referred to as Region I). If the average is 68˚F the difference between that and the 50˚F base is 18˚. Multiply 18 by 200 days and you have 3,600-degree days or a Region IV. As you can see it doesn't take much change over the growing season to have a dramatic impact on the Zone.
Many sensitive varietals, such as Pinot Noir, thrive best in the cooler climates such as Zone I. Chardonnay prefers a slightly warmer climate found in Zones I and II. Cabernet Sauvignon does best in significantly warmer climates like those found in Zone III. These zones were established after UC Davis conducted decades of studies. These studies are often used by viticulturists who wish to plant a specific varietal because they must first locate the correct soil conditions and then determine if the climate is compatible. They give the vineyardist a little more information from which to base an expensive decision other than pure luck. If the vineyard selection does not meet the criteria for the grape they wish to plant, they must either select another varietal or search for another location, assuming the highest quality grapes are their goal.
The Zone system is only a guide. It only takes into consideration the overall summation of heat in the vineyard and calculates that summation based on the highest temperature reached that day. It doesn't make allowances if a high temperature of 90 degrees was reached for 5 minutes or 5 hours. The vines, however, can sure tell the difference.
You would not base a very expensive decision solely on the Zone system with regard to what you would plant and where. Some grapes flower early, making them susceptible to early spring frosts. All the heat in the world won't save a dead grape. Some grapes ripen late, making them susceptible to fall hailstorms. It's tough to make wine from grapes shot with ice pellets. When the vineyard warms, when it cools, how hot it gets, its rain patterns, etc. are all very important considerations. The Zone system is a guide, which only addresses one of these concerns, the summation of heat in the vineyard. For this reason it is only a guide, not the whole enchilada.
Microclimates are small sections of larger areas which, due to some natural circumstance like proximity to a lake or hill or open to sea breezes, consistently provide climatic conditions different from the Zone they are located in. Therefore, a Zone II region might contain a small Zone I or Zone III within its boundaries. Microclimates can be as large as several miles in area, or as small as half a city block.
Vines reach full bearing age in about 7 years. For approximately the next 30-40 years they will sustain full yields as long as they are not ravaged by disease. For fine wine varietals, crop levels are decided upon in tons of grapes harvested per acre of vines. This averages between 3 and 7 tons per acre. The fluctuation depends on the varietal and the methods of pruning, watering, fertilizing and other actions, which affect vine growth. At 50 years of age the production of fruit by the vine gradually declines. At 60-70 years old it will produce less than half the quantity of fruit (though oftentimes very intense) of its younger years. At this point you are getting half as much wine as you once did. Most likely you can't charge twice as much to make up for the lost yield. This is why vines are replaced about every 50 years, even though they can live to well over a century.
A vine's yearly cycle begins early in spring, usually the first week of March. Since vines are deciduous, like many trees, they are dormant and without leaves in winter. With the first warming of the weather, sap, stored in the vine's root system, rises through the vine trunk and upward to its branches, called "canes." The length of these canes is controlled by viticulturists by pruning (cutting back) the vine during its dormant period. On each cane are many tiny nodules, called "buds," from which new growth is generated.
By controlling the number of buds on each cane through pruning, the viticulturist can control the number of grape clusters generated. This will affect the final yield of the grapes. To grow great Chardonnay grapes, it is generally thought that a yield of 3 to 4 tons per acre is desirable (although new techniques are allowing premium quality grapes to be grown at higher yields). Lower yields are achieved by cutting off grape clusters before they mature. This is referred to as pruning. If left alone, the vineyard would produce 7-9 tons per acre of very ordinary, flavorless grapes from which you would make ordinary, flavorless wine. The root system can only provide so many nutrients to the grape clusters. Generally speaking, each cluster will get its share as long as there aren't too many others on the vine in competition with it.
As the vineyard slowly lumbers out of winter and into spring, the sap in the vines rises, and the pressure increases. This forces the buds to swell until their protective cover splits and the first tiny leaf and floral cluster emerges. This is called "bud break." The "shoot" of new growth containing the first leaf, the floral cluster and additional tiny leaves then grows at a very fast pace, as much as 6 inches per day, forming new canes. Each cane, with its supporting leaves, will bare 1-2 bunches of grapes.
The cluster is actually a tiny flower pod which, when developed, will pop its cap and release a tiny flower. Since vines are hermaphroditic, or self-pollinating, each flower contains both the male and female elements for pollination, which is accomplished by gentle wind movements during early morning hours.
When the flower emerges, the vine has "bloomed." Pollination then takes place over a period of about 10 days and is so delicate that any rain, high wind, or even an extreme in temperature will prevent complete pollination and fruit development. As with each phase of winemaking, a delicate balance is critical. A gentle breeze is needed to carry pollination through its cycle. Too much wind will cause pollination to be sporadic. Too little will hinder complete pollination.
After pollination, called a "set," the vines then transform their flowers to miniature grapes, one of the great wonders of Nature. The green, buckshot-sized grapes, each of which is called a "berry," then enlarge rapidly in size, doubling in June and again in July. By the end of July or early August, in red wine grapes, a blush of color begins to occur, called veraison, a French word for color development as the grapes grow toward maturity.
These new vine canes, leaves and floral clusters are extremely delicate. The possibility of frost and freezing temperatures is a major threat, and if severe enough, can destroy the entire crop. Vineyardists use a variety of frost protection equipment (fans, heaters or even helicopters) during cold snaps to combat this threat. April is the worst month in terms of the possibility of frost damage. By May, the new canes have a length of 3 feet or more. The floral clusters at this stage look like miniature grape clusters with green "grapes" about the size of buckshot. These "grapes" are mostly made up of acid. Through the process of photosynthesis, the sun's rays transform that acid into sugar.
Depending upon the varietal, maturity will be reached between early September and the end of October. As the grapes ripen, their total fruit acid content decreases proportionally as their sugar content increases. When the balance between these two is correct in the view of the winemaker, the grapes will be harvested.
Grapes generally ripen in an orderly and predetermined pattern. Some reach maturity at the beginning of the harvest season (early varietals), others toward the middle of the harvest season (mid-ripening varietals), and the remainder at the end of the harvest (late-ripening varietals). Early varietals include: Pinot Noir and Chardonnay. Mid-ripening varietals include Sauvignon Blanc and Barbera. Of the late ripening varietals, Cabernet Sauvignon, Zinfandel and Riesling are usually the last to be harvested.
Sugar development in grapes is measured by winemakers in "degrees Brix," or percentage of sugar by weight. Grapes picked at 22.5 Brix contain 22.5% sugar. Acid is measured by volume and expressed as a percentage. A balanced Chardonnay might be picked at "22.5 Brix with .75% acid," a fine balance in Cabernet Sauvignon could be "23.5 Brix with .65% acid." These two figures refer to the balance of the grapes at harvest and prior to fermentation. After grapes are fermented into wine, a different measurement system is used.
Too often, however, a quality assessment of the grapes is done "by the numbers." These figures are only a guide to the quality of the grapes. The most important factor is grape maturity, and this can only be determined by an experienced vineyardist. Maturity refers to the complex acids, fruit components and essences that make wine so different from other beverages and contributes to the myriad flavors one enjoys. Maturity is attained when all these components are in the grape and will be present in the finished wine. It is immeasurable. It is determined through experience both of the winemaker and the grape grower, oftentimes just by tasting the grapes before harvest.
Another frequently used word to determine wine balance is expressed by the symbol "pH." This term is chemical shorthand for measurement of the acids contained in the total acid structure of a wine. A liquid that is neutral, that is neither acid nor alkaline base, would have a pH value of 7. Higher numbers indicate a higher base, or alkaline solution, while lower numbers indicate increasing acid. The pH value of fine wine generally ranges from 3.0 to 3.7, usually lower in white wines than reds. In white wines, a lower (better) pH will give the wine a very "crisp" taste. In red wines, a lower pH will affect its ageability and flavor.
Active acids, such as malic (found in green apples), one of the predominant acids in wine grapes, combine with citric (found in oranges and lemons) and other active acids to help lower the pH value. The acid content of wine is one reason why Louis Pasteur called it "the most healthful and hygienic drink there is."