Facts about wine grapes
The types of grapes used to make a wine are probably the single most important factor in the taste of the wine. However, the flavors of a wine are also affected by how old the vines are, what types of soils the vines are grown in, exposure to sunlight, climates and microclimates, how the grapes are handled and fermented, types of yeast used, whether the wine is aged in wood, etc.  The common grapevine of the Old World is Vitis Vinifera, native of Central Asia, now cultivated world wide, but brought to prominence originally in France, particularly Bordeaux, and the Rhone.   Cabernet Sauvignon, Merlot, Pinot Noir, Chardonnay, Sauvignon Blanc, etc., are all examples of Vitis Vinifera.

One of the main North American vine species, Vitis labrusca is found primarily in Canada and the northeastern United States, although some grapes of this species are grown in South America. The Concord variety is the best known, followed by the Catawba and the Delaware. Grapes from this species have a pronounced musky, grapey, foxy quality that clearly separates it from Vitis Vinifera.

Major red wine grapes of the world

Major white wine grapes of the world

Growing Conditions
Grapes, although primarily a temperate-zone plant, can be grown under semitropical conditions. They are not adapted to the cooler parts of the temperate zone, where growing seasons may be too short to allow the fruit to reach maturity or where low winter temperatures (less than -7 C [20 F]) may kill the vine or its fruitful buds. Vitis vinifera is more susceptible to damage from winter conditions than is Vitis labrusca.

Climate strongly influences the composition of mature grapes. A major cause of the variation among grapes from different areas is the differing quantities of heat received by the vines during the growing season. Other important factors include differences in night and day temperature, hours of sun, and soil temperature.  Grapes begin their growth cycle in the spring when average daily temperature is about 10 C (50 F). To reach maturity, they require a certain amount of heat above 10 C during the growing season. This amount of heat, called the heat summation, is calculated by totaling the number of degrees of average daily temperature over 10 C for each day of the growing season. A heat summation of about 1,800 is required for successful growth. If the heat summation is less than required, the grapes will not ripen; they will reach the end of the growing season with insufficient sugar and too much acidity. This condition, frequently occurring in the eastern United States, Switzerland, and other cool regions, can be corrected by adding sugar to the crushed grapes. Where the heat summation is much greater than required, as in the central valley of California, the grapes mature earlier, with high sugar levels, and with less acidity and color than those produced under cooler conditions.

Factors influencing the heat summation of a vineyard and, therefore, grape composition include exposure (in Europe, best from the east), air drainage (preferably from the slopes to the valley), soil temperature (above 10 C during the growing season), and soil moisture content (not too dry at any time and not waterlogged for more than short periods).  Seasonal conditions also can be critical, especially in regions of low heat summation, as found in parts of France and Germany. When the growing season in such areas is warmer than usual, the fruit produced is riper and better balanced than is usual in cool seasons. In warm regions the sweeter dessert wines may benefit from somewhat low heat summation, resulting in less berry raisining (moisture loss) and giving the fruit better color and acidity than is achieved when the growing season is excessively warm.