Grapes are frequently prized fruit producing plants in the home garden. They need room in which to grow; they need annual and heavy pruning if they are to produce many fruits; they need spraying and fertilizing. In most areas, home-grown grapes are not difficult to grow, but they do need some sort of trellis or support. You have less opportunity to grow grapes, if you have a small garden.
They can be divided into 3 general classes as far as cultivation in the United States is concerned. Vitis vinifera is the European grape, many varieties of which are grown in southern Europe. In the United States they can be grown only in Calif., the Northwest Pacific Coast states and to some extent in Ariz. They can not be grown successfully elsewhere, but in those states they are almost the only ones grown, for they are superior to our Native American grapes and their many hybrids.
The second great group of grapes is derived from the native V. labrusca or Fox Grape, native to eastern North America. There are many hybrids of this type, some of them crossing with V. vinifera. One of the most popular of the V. labrusca hybrids is ‘Concord’, widely grown throughout the greater part of the country east of the Rocky Mountains and especially in the northern and northeastern United States.
The third group of grapes derived from V. rotundifolia, the Muscadine Grape, is grown only in the South where they will produce in the climate there and other grapes will not. Consequently, the home gardener selects the varieties he chooses to grow from one of these 3 groups, depending on the part of the country in which he lives.
Grapes prefer a sunny well-drained soil. Most of the commercial grape-growing areas in the East are located near large bodies of water which reduce the advent of frosts in the early fall, and give the fruit a chance to ripen fully. Areas near the Great Lakes, in Ark. and Mo. are in this category. Frost “pockets,” or low spots where early frosts occur, should not be used for planting grapes. Fortunately they will grow on a wide range of soils.
Many grapes are easily grown from hard woodcuttings and are then on their own roots. The home gardener can easily do this or he can layer stems on the ground. However, it is unfortunate that in many areas of the country, especially on sites of older vineyards, various diseases and insects take their toll of grapes by feeding on the roots. Recently there has been much work done in ascertaining which rootstocks arc “resistant” to these problems, and some excellent resistant rootstocks have been produced by various state and federal experiment stations. Popular varieties are then grafted on these so-called “resistant” root-stocks, with the result that the vines are far better able to grow in areas where disease and insect pests injure or destroy “own-rooted” types. It probably pays most home owners to play it safe and obtain varieties which have been grafted on resistant rootstocks.
Such plants should be watched carefully, for shoots from the roots if allowed to develop would produce grapes usually inferior to the clone grafted on them. All shoots coming from the rootstock should be removed; a rule to follow in growing any kind of grafted stock.
In New York at least, one of the best of the resistant rootstocks is ‘Couderc 3309′, but others are undoubtedly available in other areas. The local state experiment station would give the latest information on this score.
One-year-old vines are the ones usually planted either in the spring or in the fall, but, if planted in the fall special care might be taken in northern areas to mound the soil about the base of the vine to prevent them being “heaved” out of the soil by alternate freezing and thawing winter weather.
Vines are usually planted about 8 ft. apart and cut back to about 2 buds. Mulch might well be placed about the plant but no fertilizer should be used at planting time. One should remember that grapes are very susceptible to injury from overdoses of fertilizers or chemicals used in weed control. Extreme care should be taken in applying these materials.
Grapes must have a means of support. The old-fashioned grape arbor was one method of supplying this, but there are so many other ornamental vines now available that if an arbor is used in the garden, a vine more decorative than the grape is usually selected. Grapes are easily grown on a wire trellis consisting of 2 wires, attached to sturdy posts about 10 ft. apart. One wire should be about 30 in. above the ground, and the second about 36 in. above the first.
The vine is trained to a single stalk with a branch trained each way on the 2 wires, often referred to as the 4-arm Kniffin System. Although there are other methods of training grapes, this is by far the most popular system and the easiest one to use for the home gardener.
This is best done in winter or very early spring before the sap begins to flow. If the pruning is done late in spring the cut ends will “bleed” profusely and, although there is no evidence to prove this is harmful to the vines, certainly it does not seem to be desirable if it can be avoided by pruning while the vines are dormant. Pruning when the vine is in leaf just removes so many food manufacturing organs from the plant and this is decidedly harmful when done at this time.
Grapes are borne on shoots that grow from buds on 1-year-old canes. The whole idea is to allow just enough of these to develop to produce the number of grapes that the vine will reasonably support. If left unpruned, the vine will get very woody, clogged with dead wood, and will produce far too many small, poorly-developed bunches of grapes. To maintain a vigorous vine, reduce the old wood to a minimum and replace this with young canes.
Grapes grown in the home garden should not be picked until fully ripened on the vine. This brings up the problems in some areas of birds eating the berries before they are picked. We have been very troubled with this situation, but finally corrected it merely by throwing a large piece of saran cloth or netting over the 6 ft. trellis, covering the vines from ground to top on both sides. In this way, the grapes receive normal amounts of sunshine and air and one can check the ripening process. The cloth is put over the 2-wire trellis about 3-4 weeks before the fruits normally ripen. This is another good reason for growing grapes on a simple 2-wire trellis, for this is very easily covered, whereas a large arbor would not be.
Grape Insect Pests
Like other fruits, grapes require that a specific schedule for pest control be followed in order to produce a profitable crop. Early in the season flea beetles cat the buds, grape plume moth cripples the buds and cane girdler cuts off the new shoots. A dormant spray with insecticide kills the eggs of the plume moth and controls the grape scale and the cottony maple scale. Sprays of insecticide control the leaf-eating insects and the grape tomato gall which makes globular galls on the leaves and stems. Japanese beetle, rose chafer and the light-loving beetle have a strong liking for grape foliage. Insecticides give control without excessive residue.
Grape phylloxera, which is primarily a root aphid, nearly prohibits the culture of European grapes on their own roots. In America, American varieties or others grafted on them are grown. Spraying with insecticide helps to check the gall-making form on the leaves. The most important insect pest of the fruit is the grape berry moth. The first generation eats the leaves and buds and the second and third generations eat the berries. When preparing to pupate they cut and fold parts of the leaf to form a shelter. A single worm may infest several berries. Careful spraying with insecticide, especially when the berries are about half grown, is necessary.
Black rot is a serious fruit disease although it is also present on the leaves and canes. Infected fruit becomes hard and brown before it dries to the well-known mummies in which the disease overwinters. Destruction of infected fruit and sprays with fungicide just before and just after bloom is effective. Downy mildew infections on the leaves are controlled by the above treatment.
A regular schedule prepared by local authorities in pest control should be followed.