Grape Growing Tips and Advice

GRAPES

I once upset the home wine-making fraternity by saying that, as far I was concerned, wine comes from Vitis vinifera and nothing else. Perhaps I was stretching a point to make another, but the grapevine has undeniably provided mankind with more pleasurable drinking for more years than any other plant on the planet. It is easy to grow grapevines outdoors anywhere that experiences reasonably mild winters. But to grow them well enough to produce a dessert crop needs rather more care, and while you certainly can make wine from garden-grown grapes, your main problem will be one of having room to grow enough vines to make the exercise worthwhile. I shall concentrate, therefore, on growing outdoor and greenhouse vines for modest dessert fruit production.

 

HISTORY AND TYPES OF GRAPE

Grape growing for wine production was familiar to all of the ancient civilisations and, although the origin of the wild plant is unknown, it probably first grew in south-east Europe or south-west Asia. Grape growing spread northwards and westwards, reaching Britain and other more northerly parts of western Europe with the Romans. Since then, there have almost always been some vineyards in Britain although they have been restricted to the extreme south during periods of climatic cold.

The Spaniards took vines to North America although there are native American species, most notably Vitis Iabrusco, Vitis rotundifolia and Vitis aestivalis, that have contributed particular characteristics to some modern varieties. Others have been used to develop rootstock varieties, especially those that display resistance to the root aphid-like pest Phylloxera. This creature virtually obliterated European vineyards in the late-nineteenth century and was overcome only by using resistant American rootstocks onto which the best and most carefully selected European varieties were grafted. Although a tragedy at the time, it forced a rigorous weeding out of old and relatively useless varieties.

 

SOIL

Soil for grapes must be fertile, moist and well drained. They will not thrive in very thin, impoverished soils nor in waterlogged conditions, but vines tolerate fairly high alkalinity and some of the very best grapes come from limestone sites. Paradoxically, on chalky soils, more acidic grape juice is produced. Although it is possible to grow grapevines in containers, this is is really only satisfactory when they are trained specially as standards; full-sized vines, even those grown in greenhouses, are much better planted in the ground, preferably just outside the house with the main stem trained in through a small hole.

 

SITE

Grapes must have warmth. Almost all the major wine growing regions of the world lie between latitudes 30° and 50°. Whilst this embraces most of the United States, it excludes Canada, Britain and northern Europe which are too cold, and most of Africa and Australia which are too hot. Successful grape growing outdoors north of 50°N requires a locally warm, sheltered site and a south or south-west aspect, preferably fairly free from strong winds. The average summer temperature should be not less than about 19°C (66°F) and the average winter temperature not less than about -1°C (30°F). In gardens, grapevines will almost always be planted against a warm wall rather than free-standing and this is the method that I prefer.

 

GREENHOUSES

healthy greenhouse vine with the laterals spreading out along the structureThe main requirements for grape houses are that they should face south or south-west and have sufficient head room to enable the plants to be trained properly. Both free-standing and lean-to structures are suitable, although the lean-to has the added advantage of taking warmth from the adjoining building.

While a heated greenhouse would enable you to grow some of the finest-flavoured dessert grapes (among the so-called Muscat and Vinous groups of varieties), I don’t recommend this. They can be tricky to grow and, of course, the cost of heat towards the end of the season can be considerable. 1 advise choosing the more hardy varieties for which significant heating is neither necessary nor desirable, and for which the greenhouse should ideally be maintained at a minimum temperature slightly above freezing. Good ventilation is very important to minimize mildew and fruit-rotting moulds.

 

PLANTING AND SPACING

Grapevines are best planted in early winter when they are fully dormant. Prepare the planting position with well rotted manure or compost and a light dressing of bone meal, and plant to the depth indicated by the soil mark on the stem. Slope the soil away from the base of the stem after planting and top up with a mulch of compost, leaf mould or manure. The planting position should be 20-25cm (8-10in) away from the wall. Greenhouse vines are best planted in exactly the same way but just outside one end of the house then trained in through a hole in the wall. In most gardens and certainly in most greenhouses, there will be space for only one plant; grapevines are self-fertile so fruit production won’t be affected. Against a long wall outdoors however, where two or more plants could be grown, they should be spaced 2m (6ft) apart.

 

SUPPORTS, TRAINING AND PRUNING

The support for vines must be robust, as a plant in full leaf and fruit is both heavy and bulky. Against a vertical wall, horizontal wires should be used, spaced 30cm (12in) apart up to the top of the wall and anchored with vine eyes screwed in to wall plugs. Use 10 gauge — 3.15 mm (1/8n) diameter — plastic-coated training wire. In a greenhouse, the wires will need to be stretched along the length of the side walls of the house and also continued up the roof slope, secured to the glazing bars.

There are numerous systems for training grapevines, some developed for particular varieties, but I have found much the simplest, both in greenhouses and outdoors to be a basic cordon or simple espalier method. This is the system I have explained here. It is easy to understand (which is more than can be said for some of the commercial techniques), easily done and gives good, heavy crops.

 

FEEDING AND WATERING

The soil in which you grow your vines shouldn’t be allowed to dry out while the fruit are swelling, and so the plants should be mulched in autumn and spring and then watered copiously in the summer. Give about 34g per square metre (1oz per square yard) of a balanced general fertilizer such as Growmore or fish, blood and bone in spring and a proprietary liquid feed with high potash content every two weeks during the summer.

 

YIELDS

Yields and fruit quality will vary enormously with the warmth of the climate, care given to pruning, feeding and watering, the choice of variety and, of course, the space available. From a mature vine, well cared for and trained as a double cordon in a standard-sized 3 x 2.5m (10 x 8ft) greenhouse, it should be possible to obtain at least 50-60 bunches.

 

HARVESTING AND STORING

It’s almost impossible to tell by appearance whether grapes are ripe or not and much the best way is to test a single fruit to see if it tastes agreeably sweet. They should then be cut in bunches, not individually, with either scissors or snips. Cut out a short length of the shoot on which the bunch is borne to give a T-shaped ‘handle’ at the end of the bunch stalk. The grapes will keep fresh for about a week at room temperature or for about two weeks in a refrigerator.

A popular old method of storing involved special horizontal grape bottles, filled with water. The bunches were cut with much longer sections of branch attached, the branch was placed through the narrow neck of the bottle into the water and the grapes allowed to lie adjacent. In this way, and in the dark, the bunches kept fresh for several weeks and a similar system could be improvised today. Grapes can be frozen fairly satisfactorily but it is an extremely fiddly process, for each fruit must be sliced and the pips removed.

 

powdery mildew affecting leaves of grapesPROBLEMS

By far the biggest problems on grapevines are mildew and botrytis grey mould. Both are especially troublesome in greenhouses, and both are best combated by ensuring that, through adequate ventilation and pruning, the plants have a decent free flow of air around them.

 

Grape Varieties:

'Chasselas' grape varietyThe number of grape varieties in the world is legion. Most have been raised for wine production, and as any wine connoisseur will know, the juice from different varieties will result in wines of greatly differing character. There are many fewer varieties grown for dessert fruit production and fewer still that are suitable for greenhouse or outdoor cultivation in climatically marginal growing areas. It is the hardier dessert types that are recommended.

There are both black and white varieties, but while some types are suitable only for outdoor cultivation, others can be grown both outdoors and in greenhouses, while there are some that can only be grown indoors. Among the latter, the Sweetwater grapes are the easiest and most reliable, managing to ripen early before the temperature begins to drop in autumn. All other types of greenhouse grape really need some heat in the latter part of the season if they are to ripen successfully and for that reason, I don’t recommend them.

18. May 2011 by Dave Pinkney
Categories: Fruit & Veg, Soft Fruit | Tags: , | Comments Off on Grape Growing Tips and Advice

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