Site selection is extremely important for growing the more cold-tender grape varieties, although American types such as Concord and Niagara thrive in most places in Pennsylvania that meet the criteria outlined in Getting Started. Site evaluation criteria for temperature are outlined in Table 6.1, and grapes are classified by hardiness in Table 6.2. An ideal site for the cold-tender varieties should also have 160 or more frost-free days.
After choosing an appropriate site, the most important decision a prospective grape producer must make is the selection of appropriate varieties. Variety selection is determined by at least two primary factors. The first is the purpose of the grapes. Although Concord makes a wonderful juice and jelly, it makes a wine of limited appeal; in addition, many people dislike seeds in their fresh-eating grapes. On the other hand, Concord is wonderfully adapted to our climate in Pennsylvania, having good pest resistance and cold-hardiness. European grapes (Vitis vinifera) such as Chardonnay or Cabernet Sauvignon have excellent winemaking characteristics, but they are susceptible to a whole host of diseases and are more cold tender than native grapes. In many cases, French-American hybrid grapes offer a good compromise for wine production because they have good winemaking characteristics as well as better horticultural traits than their European cousins. Table 6.3 and Table 6.4 delineate characteristics of wine and table/juice grape varieties.