The common, edible grapes of vineyards and orchards belong to the Vitis genus, consisting of sixty to seventy species and many more cultivars. Grapes are important fruits, much esteemed and cultivated for eating out of hand, wine making and drying as raisins.
The botanical name Vitis is the ancient one for the wine or vineyard grape of the Old World. Vitis are usually vigorous, woody, perennial vines, some hardy, some not, and often with extensive stem systems, generally climbing by tendrils. They have undivided, more or less palmately-lobed leaves. Tendrils, forked or not, may develop opposite every leaf or all except every third leaf. Panicle-like clusters of flowers occupy some tendril positions. The fruits, technically berries, have been cultivated for several thousand years.
Three distinct types of grapes are cultivated in the northeastern United States. Each has many varieties which are best adapted to specific regions and are managed differently. Vitis labrusca are American grapes and include cultivars that are hardy in zones 5A and colder. Vitis vinifera are European grapes and significantly more sensitive to cold. French-American grapes are hybrids of the two, producing good wines with less cold sensitivity than the vinifera grape plants and, in many cases, less susceptibility to pests and disease.
In New York State, Vitis vinifera is the dominant species for wine making. Early attempts to cultivate vinifera grapes outdoors in the northeast United States failed miserably as the plants are very sensitive to cold temperatures and wet conditions. The harsh winters of our climate were thought not suitable for growing grapes until trials were undertaken in the Finger Lakes area of New York State. The microclimate proved perfect for growing these grapes when some precautions are taken to protect the vines in cold weather.
Established in October of 1982, the Finger Lakes AVA (American Viticultural Area) is the largest wine-growing region in New York State with approximately 11,000 acres of labrusca (American), French-American and vinifera (European) grapes and just over 100 wineries. The region compares itself to that of Germany’s Rhine region due to similarities in growing conditions. Neighboring states in the Northeast have established commercial wine production as well.
Vinifera grapes probably originated in the Transcaucasian region of western Asia and are considered native to southern Europe. These are the grapes of antiquity, of the classics, to which reference is made in the Old and New Testament of the Bible. Vitis vinifera cultivars are renowned for producing some of the world's great wines including Reisling, Chardonnay, Cabernet Sauvignon and Gewurztraminer.
There are numerous grapes derived from Vitis labrusca that grow well in the New York area. Each has unique characteristics of fruit size, flavor, yield and harvest time.These native grapes are commonly called American bunch grapes and include the popular cultivars 'Catawba', 'Concord' , 'Delaware', 'Ontario' and 'Niagara'.
The most important element of successful grape cultivation is choosing the right plant to grow. There are grapes that will grow in most areas of the Northeast but carefully consult with your nursery or catalog information for cold tolerance before selecting your cultivar. In zone 6b, many northern vinefera grape varieties, such as 'Reisling' and 'Cabernet Franc', will succeed, while in zone 6a, hardier vinifera and semi-hardy to hardy labrusca grape plants, including the five, popular cultivars mentioned above, are more appropriate. Particular cultivars also require specific, minimum numbers of consecutive, frost-free days, so northern areas with shorter growing seasons have a more limited selection. Vitis labrusca 'Fredonia' and Vitis 'Bluebell' are popular choices in northern New England.
The home gardener should select a planting sight that provides plentiful sun and protection from the wind; a southern exposure is ideal for a long season of fruit production. Hillside is an advantage for air-drainage; do not select a site in a frost pocket. Well drained, sandy soil is optimal with a pH range of 5.5 to 6.5. Rows of plants should be oriented north to south as far as possible.
Vitis will not grow straight without support so a trellis or arbor should be set up for the plants early in the first year of planting. At a minimum, a stake should be present for support at the time of planting. Your support system will allow you to keep the growth of your plants in check and will optimize fruit bearing conditions.
Plants are sold as bare-rooted plants or grafted plants. (Only Vitis vinifera cultivars require grafted roots as they are susceptible to root louse.) After preparing your soil for proper pH and drainage, plant out grapes as early as the soil can be worked. Dig a hole for the plant with room to fan out the roots and deep enough for the roots to lay two to three inches below soil level. Space plants a minimum of 8 feet apart. Trim away excessively long roots and all but the strongest cane from the plant, which will become its trunk. This primary cane can be cut back to 6 to 8 inches and tied to the stake or support system.
Keep the planting site watered and free of weeds. Deer and rabbits can destroy young plants so try to protect your vines from these pests. Once new growth reaches ten inches, remove all but the strongest shoots as well as any flowers from the single vine to allow it to focus its energy on cane growth this first season. Continue to tie the strong shoots to the support system. No fertilizer is needed in the first year, but thereafter a 10-10-10 formula is recommended.
Grape pruning and training is important because when grape plants are not pruned, vines become very dense, diseases become hard to control and fruit quality declines. Grapevines require yearly pruning. Generally 90% of fruit bearing vines of the previous season plus some new growth is removed during plant dormancy.
Pruning is not difficult and can be done anytime during the dormant season. The goal of pruning is producing an optimum crop. The more buds left at pruning, the more fruit will develop. However, if too many fruits are left on through the season, fruit will be small and, even worse, may not ripen. Fruit will grow only on one year old wood so pruning should focus on removing canes that have already borne fruit and removing enough of the new growth to make the plant manageable and the fruit production vigorous.
As a general rule, big vines grow more buds and therefore more fruit than small vines. Keep new growth on the vines near the center of the vine.
Harsh winters occasionally damage trunks; new trunks (renewals) should be selected from the suckers growing from the base of the vine. For some varieties that are particularly sensitive to cold, renewal must be undertaken every year and as many as four trunks of different ages may be left during the growing season. The multiple trunks allow one or more to die back in the winter without killing the plant.