Almost every single red wine produced in Bordeaux is a blend of several grape varieties. This is in part because of the varying climate. Different grapes react differently to changes in weather: some may have thick skins that are more resistant to rot, while some others might ripen earlier or later in the season. The wine maker's job in Bordeaux is to mix these different varieties based on the weather in that given year, so as to produce the best wine possible. This method has been perfected over many generations of Bordeaux wine makers. While there are technically 14 grape varieties permitted under the AC regulations, in reality only 5 black grapes and 3 whites are ever used:

Cabernet Sauvignon

Cabernet is the classic black grape variety of Bordeaux. In the Médoc, it makes up 75% of the blend in wines. Throughout Bordeaux however, Cabernet Sauvignon makes up only 29% of the planting, because it produces relatively lower yields. The wines made from Cabernet Sauvignon in Bordeaux are quality wines high in tannin. The classic aroma is of blackcurrants, but if the grapes do not ripen fully, it will have more of a vegetal quality, too tough to drink unless softened by blending with Merlot. It grows best on drained, warm, gravel soils.

Cabernet Franc

This grape is grown mainly in Saint-Emilion, and somewhat in the Médoc and Graves. It has larger yields that Cabernet Sauvignon, but less body. The typical flavors are herbaceous and stalky, and the wine matures more rapidly than Cabernet Sauvignon. It prefers the same type of soil as Cabernet Sauvignon.

Merlot

Merlot produces a medium yield of full-bodies, moderately tannic wine. It can add softness, richness, and body to Cabernet Sauvignon in blends. The most important areas for Merlot are Saint-Emilion and Pomerol, where it is grown on limestone soil. By itself, Merlot doesn't have enough character to make a successful wine, unless it is grow in very low yields. When a Merlot wine like this is produced, it is still always blended with Cabernet Sauvignon or Cabernet Franc to add fruit aromas, color, and tannin.

Malbec

Malbec in Bordeaux is mainly used for basic, easy to drink red wines, in areas like Bourg and Blaye. Its popularity is small and is on the decline.

Petit Verdot

This black grape is used only as a small additive in blends, to add tannin, color, and notes of spice to very fine Bordeaux wines.

Sémillon

Sémillon is the most planted white grape in Bordeaux. Because of its thin skin, it is very prone to rot. This makes it an excellent candidate for botrytized sweet wines. It produces full-bodied wines with a gold color.

Sauvignon Blanc

Sauvignon Blanc is the exception to the rule that all Bordeaux wines are blends. In Bordeaux it does have the classic Vegetal and grassy aromas. It is sometimes blended, usually with Sémillon, where it provided high acidity to contrast with Sémillon's potential flabbiness.

Muscadelle

Muscadelle has a distinctive grape flavor and is used as an important but minor element in sweet wines.