The art of
growing grapes, or viticulture, has a long and illustrious history. The vine grows wild in the temperate regions of North America, western Asia, southern Europe and parts of North Africa and it is thought to have originated in Asia Minor. The vine is a perennial deciduous climber that clings to supports by tendrils. The leaves are hand- or heart-shaped and 4-8 in in size. The grapes most commonly grown by home gardeners in the northern part of the United States are the so-called American, or bunch, grapes, descendants of wild grapes. The blue, black, green, red and yellow berries usually have slip-skins (separable from the pulp) and ripen from mid-summer on. They are largely self-fruitful. Although American bunch grapes can be grown from zones 3-10, they do best in zones 5-7. Muscadine grapes are generally grown in the South (zones 7-9). These form much larger vines up to 90 ft long and produce fruits singly or in loose clusters. Several self-fruitful varieties are available but most varieties are self-unfruitful. Since the fruit of self-fruitful varieties is inferior to that of the self-unfruitful varieties, self-fruitful varieties are best used to pollinate the self-unfruitful varieties. Vinifera, or wine, grapes are descended from European grapes and are best employed in wine-making. A number of varieties, all with skins inseparable from the pulp, are eaten at table and are considered among the best grapes for this purpose. Some varieties are also used for raisins. All vinifera grapes are self-fruitful, producing berries in extremely large clusters. They grow best in California, but there are numerous hardy varieties that can be grown as far north as zone 6. There are also many new hybrid varieties resulting from crosses of American and vinifera grapes. These combine characteristics of the parents and are therefore difficult to classify.
Cultivation Grapes are sun-loving plants and must be grown where they will be exposed to the sun all day or at least for the greater part of the day. But the base of the plant need not be in full sun although it is essential that the upper part of the plant catches as much strong sunlight as possible. (Grapes growing wild in forests often take root at the foot of trees and soon clamber above the trees). The location selected for the vines should have good air drainage. In colder areas, protection from winter winds is necessary.
Soil for GrapesThe vines are fairly tolerant of a wide range of soils, although the soils must be deep and well drained, and not too sandy. The plants require a soil pH of 5.5-7.0. If there is any possibility that the soil may become badly waterlogged, a good drainage system should be installed. Two or three weeks before actual planting, prepare the soil by double-digging to break up any hard layers and to clear away perennial weeds. Dig in leafmold or well-rotted manure at the rate of about one wheelbarrow load per 20 square feet. Also rake in a balanced fertilizer such as 10-10-10 at the rate of 3 oz per square yard.
Planting Grapes Plant one-year-old vines in early spring before Staking and planting they start to leaf out. Dig large, deep holes; spread out the roots; firm them well; and water thoroughly. Then cut off all but one strong cane and trim this back to eight buds.
Maintenance Except for pruning and training, grapes do not demand a great deal of attention. In dry spells, they should be watered deeply, but, as the fruit begins to mature, the water supply should be reduced somewhat. This helps the maturation process and also inhibits succulent growth. In the fall, however, after the fruit has been picked, one heavy watering is necessary to help protect the vines from winter injury. Unless the plants are doing poorly, they need little fertilizer. Give each plant 2-4 oz of ammonium nitrate or a somewhat more balanced fertilizer in early spring. This should carry them through the growing season. Keep encroaching weeds pulled. An application of an organic mulch around the plants discourages weed growth in addition to supplying the necessary nutrients for healthy growth.
Training and pruning the training and pruning of grapes are matters of critical importance. The main purposes of training are to keep the large, fast-growing vines under control, to facilitate care and harvesting, and to expose all parts of the plants to the sun. The purposes of pruning are to maintain vigorous growth, to provide new canes for the next year, and to limit the number of fruit-producing buds so that the vines do not produce too much small fruit of inferior quality. Various training systems are used for all three types of grapes.
American bunch grapesFour-Arm Kniffin system This is the most popular method of training American bunch grapes since it gives good production and requires little summer tying of the vines. The trellis required consists of 4 - 6 in posts and galvanized steel wires. Space the posts 16 ft apart. Sink the end posts 3 ft into the ground and brace them with diagonal struts or guy wires. Sink the intermediate posts 2 ft. The posts normally extend 5 ft above ground, ...
to be continued
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