Grapes have long been appreciated, not only as fresh fruit, but also for making wine. Varieties of white or black grapes are specially selected for their purpose, and growing grapes for wine-making in particular is a very specialized business. Soil and weather conditions as well as choice of variety or varieties can make all the difference. If there ever was a case for checking what other gardeners in your area are doing, this is it.
Grapes need a great deal of sun, and in cooler areas it is easier to grow them under glass, especially if they are for eating. Outside they can be grown in the open if they are trained onto wires, but they may well do better if they are grown against a warm, south-facing wall. From a decorative point of view they make excellent climbers to cover a pergola or arbour, when they provide a dappled shade that is perfect for sitting under. However, with vines climbing over such large structures it is not easy to protect the ripening fruit from the birds.
Patience is required because it will be at least three years before grapes in any quantity are produced, but once they are established the vines may live up to 50 years, so investment in thorough initial work will be well repaid.
There are several methods of training grapevines. They can be grown against a wall as single, double or multiple cordons; in the open on wirework the double guyot is a good method. Although pruning and training are not complicated, the formative work takes place over several seasons and it is worth consulting specialist publications to check on the best methods and techniques.
Grapes must have a warm, sunny situation. The soil must be very free draining, and if your soil is heavy it will need a lot of work before it can be used. South-facing hillsides, with a gravelly, lightish soil are perfect. Plant the new vines in spring at intervals of 1.5m/5ft. Apply a mulch of manure in spring. Water during dry spells.
Dessert grapes need to be thinned to produce large grapes. Bunches should be thinned to 30cm/12in intervals and then the grapes themselves thinned to allow them to swell and the air to circulate. Use long-pointed scissors for the thinning. Net to prevent fruit loss to birds.
Pruning and training
Whether they are grown under glass or outside, against a wall or as free-standing plants, vines need wire supports. Immediately after planting reduce the leader to 45cm/18in. From this the various basic shapes will be grown. Specialist books should be consulted for formative and established training and pruning methods for vines grown under glass. The guyot system of training and pruning may be used for outdoor vines.
Harvesting and storing
Pick the grapes when they are ripe by cutting the entire bunch from the vine. It is usual practice to cut a little of the woody vine stems on each side of the bunch in order to form a useful “handle”. A mature vine should provide about 7kg (15lb) of grapes. It is advisable to store the grapes in a container with a soft lining so that the delicate fruits are not bruised or damaged. Grapes are best eaten straight away, but they can be kept for a couple of weeks if a longer handle is cut and placed in a tall container of water so that the fruit hangs down outside the container.
Pests and diseases
Wasps and birds are two common nuisances, but scale insects, mealy bugs and red spider mite can also be a problem. Grey mould and powdery mildew are among the diseases.