Bordeaux is unusual in that its wines are created by blending different grapes. Other French regions, such as Chablis or Beaujolais, use 100 percent of one varietal. The red wines of Bordeaux rely primarily on three grapes—Cabernet Sauvignon, Merlot and Cabernet Franc—though Petit Verdot and Malbec are also permitted and grown in tiny amounts.
The whites—which make up only about 11 percent of the vineyard plantings—are based on Sémillon and Sauvignon Blanc, though small amounts of Muscadelle and other varieties are also grown.
The Bordeaux model is built around not only the desire to craft complex wines; by using different grape varieties that ripen at different intervals, they can better account for the vagaries of the growing season and adjust the percentages in a blend to give a wine more color, tannin or backbone.
Bottled as a stand-alone varietal and used as a blending grape, Cabernet Franc is used primarily for blending in Bordeaux, although it can rise to great heights in quality, as seen in the grand wine Cheval-Blanc.
In style, it can range from light- to medium-bodied to as intense and full-bodied as Cabernet Sauvignon and Merlot, with which it is often blended. It may be a Cabernet Sauvignon mutation adapted to cooler, damper conditions, budding and ripening earlier. Its currant and berry aromas and flavors often stray into herbaceous notes (also evident in unripe Cabernet Sauvignon) that become more pronounced with age.
Cabernet Franc is also an important grape in France's Loire Valley, where it's made into a lighter wine called Chinon. It is established in Italy and California, and Argentina, Long Island and Washington are picking it up.
The undisputed king of red wines, Cabernet is a remarkably steady and consistent performer. While it grows well in many appellations, in specific appellations it is capable of rendering wines of uncommon depth, richness, concentration and longevity. Bordeaux has used the grape since the 18th century, always blending it with Cabernet Franc, Merlot and sometimes a soupçon of Petit Verdot.
Elsewhere in the world—and it is found almost everywhere in the world—Cabernet Sauvignon is as likely to be bottled on its own as in a blend. It mixes with Sangiovese in Tuscany, with Syrah in Australia and Provence, and with Merlot and Cabernet Franc in South Africa, but flies solo in some of Italy's "super Tuscans."
In the United States, it's unlikely any region will surpass Napa Valley's high-quality 100 percent Cabernets and Cabernet blends, which typically follow the Bordeaux model of smaller portions of Merlot, Cabernet Franc, Malbec and Petite Verdot.
At its best, unblended Cabernet produces wines of great intensity and depth of flavor. Its classic flavors are currant, plum, black cherry and spice. It can also be marked by herb, olive, mint, tobacco, cedar and anise, and ripe, jammy notes. In warmer areas, it can be supple and elegant; in cooler areas, it can be marked by pronounced vegetal, bell pepper, oregano and tar flavors (a late ripener, it can't always be relied on in cool areas). It can also be very tannic if that is a feature of the desired style. The best Cabernets start out dark purple-ruby in color, with firm acidity, a full body, great intensity, concentrated flavors and firm tannins.
Cabernet has an affinity for oak and usually spends 15 to 30 months in new or used French or American barrels, a process that (when properly executed) imparts a woody, toasty cedar or vanilla flavor to the wine while slowly oxidizing it and softening the tannins. Microclimates are a major factor in the weight and intensity of Cabernets. Winemakers also influence the style, as they can extract high levels of tannin and heavily oak their wines.
Merlot dominates the Right Bank of Bordeaux, though not the Médoc and Graves. Though it is mainly used for the Bordeaux blend, it can stand alone. In St.-Emilion and Pomerol, especially, it produces noteworthy wines, culminating in Château Pétrus.
It is a difficult grape to grow, as it sets and ripens unevenly, but can be found in many places in the world, including Italy, California (where it dates to the early 1970s) and Washington state, which may have a slight quality edge with Merlot over California.
Several styles have emerged. One is a Cabernet-style Merlot, which includes a high percentage (up to 25 percent) of Cabernet, with similar currant and cherry flavors and firm tannins. A second style is less reliant on Cabernet—softer, more supple, medium-weight, less tannic and featuring more herb, cherry and chocolate flavors. A third style is a very light and simple wine.
Like Cabernet, Merlot can benefit from some blending, as Cabernet can give it backbone, color and tannic strength. It also marries well with oak. As a wine, Merlot's aging potential is fair to good. It may be softer with age, but often the fruit flavors fade and the herbal flavors dominate. There is also an unrelated Merlot Blanc.
This white has a notable aroma, often described as "grassy." In Bordeaux, it can be found all over, as part of a blend in the dry whites of Pessac-Léognan, Graves and the Médoc; it also shows up in the sweet wines of Sauternes and Barsac.
Sauvignon Blanc grows well in a variety of appellations, marries well with oak and blends well with Sèmillon. The pure varietal is found mainly in France’s Loire Valley, in Sancerre and Pouilly-Fumé. New Zealand has had striking success with Sauvignon Blanc, producing its own perfumed, fruity style. In the United States, Robert Mondavi rescued the varietal in the 1970s by labeling it Fumé Blanc, and his winery and others have enjoyed success with it.
The key to success seems to be in taming its overt varietal intensity, which at its extreme leads to pungent grassy, vegetal and herbaceous flavors. Many winemakers treat it like in a sort of poor man's Chardonnay, employing barrel fermentation, sur lie aging and malolactic fermentation. But its popularity—which ebbs and flows—comes from the fact that it is a prodigious producer and a highly profitable wine to make. It can be crisp and refreshing, matches well with foods, costs less to produce and grow than Chardonnay and sells for less. It also gets less respect from vintners than perhaps it should. But even at its best, it does not achieve the kind of richness, depth or complexity Chardonnay does.
The wine drinks best in its youth, but sometimes will benefit from short-term cellaring. As a late-harvest wine, it's often fantastic, capable of yielding amazingly complex and richly flavored wines.
On its own or in a blend, this white can age. With Sauvignon Blanc, its traditional partner, this is the foundation of the sweet wines of Sauternes and Barsac and of most of the great dry whites found in Graves and Pessac-Léognan. These are rich, well-balanced, honeyed wines with complex fig, pear, tobacco and notes.
Sémillon is one of the grapes susceptible to Botrytis cinerea, or noble rot, which shrivels the grapes and concentrates their sugars, yielding luscious dessert wines. When blended into Sauvignon Blanc, it adds body, flavor and texture. When Sauvignon Blanc is added to Sémillon, the latter gains grassy herbal notes.
Australia's Hunter Valley uses Sémillon solo to make a full-bodied white. In South Africa it used to be prevalent, but it has declined drastically in importance there. In the United States, Sémillon enjoys modest success in California and Washington, where it can make wonderful late-harvest wines.