Blending grapes broadens the flavor of a wine

Making wine from a blend of grapes is a tradition that dates back centuries. In France's southern Rhone Valley village of Chateauneuf du Pape, just north of Avignon, winemakers use up to 13 varieties of grapes, including white ones, to make the heady red wine for which the village is famous.

In Bordeaux, tradition mandates, and the law allows, as many as five varieties, mainly merlot, cabernet sauvignon, and cabernet franc, with smaller amounts of petit verdot and malbec. In the 19th century, the Bordelais included a sixth variety, carmenere, but opted not to replant it after phylloxera, the vine-destroying insect, devastated the vineyards.

The custom of blending wine made from several grape varieties probably originated as an economic insurance policy, analogous to financial planners' advice to diversify. Merlot and cabernet sauvignon, for example, have slightly different growing cycles. Merlot blooms earlier in the spring, which puts it at a higher risk for frost damage, but it ripens sooner, decreasing the risk the grapes will be damaged by rain in the fall. Cabernet sauvignon blooms and ripens later, protecting it from frost but subjecting it to rain during harvest, which can dilute flavor. As a result of these inherent differences, a spring frost or bad fall weather is less likely to decimate the entire crop if the farmer has planted a mixture of grape varieties. As it turns out, wine made from a blend of cabernet and merlot grapes is usually better than wine made exclusively from one of those varieties, so producers embraced the practice.

In California in the 1970s, it was considered bad practice to blend wines. Some of California's greatest red wines still are made entirely from cabernet sauvignon grapes. More and more, however, winemakers are adding a little merlot to cabernet or vice versa to broaden the flavors of the wine.

As long as the wine contains at least 75 percent of one variety of grape, it can be labeled with that name. Once no one grape reaches that percentage, though, regulations prevent the winery from using a grape name. In that case, wineries use proprietary names, such as Insignia (by Phelps) or Opus One (by Mondavi).

Franciscan Oakville Estate, another leading Napa Valley producer, labels its Bordeaux blend Magnificat. Composed of 73 percent merlot, 22 percent cabernet sauvignon, and 5 percent the remaining three Bordeaux varieties, the 2000 Magnificat is a gorgeously layered, amazingly supple wine. It is aptly named. Franciscan Oakville Estate, Magnificat, 2000. About $45.