Grapes are one of the most varied of all fruits; they come in a host of different colours, flavours and sizes. They can be grown in almost every part of the world, treated and pruned by all sorts of methods and used in a multiplicity of ways. Although they are easy in pots under cover these do not give the yields of open ground plants. Unfortunately here in the UK we are on the very margin of successful outdoor cultivation. The changeable nature of the infamous British weather makes grapes a difficult crop. But modern varieties are making it much less of a gamble. And for once the amateur has an advantage as some of the best modern varieties are hybrids not allowed for commercial planting.
The newer grapes are not (yet) GMOs but simply conventional crosses that are so successful that they have had to be banned commercially to protect established vineyards. To be fair many are crosses with N. American species which may apparently give their wine a different overtone some describe as foxy! None the less they can be staggeringly productive; I once made eight gallons / four crates of wine from the produce of one Strawberry vine growing over a pergola, true it had an odd taste but after the first glass or three it didn't seem to matter. Indeed production is not often a problem with grapes it is quality that is difficult to achieve.
Grapevines are only too willing to grow, and crop, some of them are amongst the most vigorous climbers and yielders you'll come across. Ancient vineyards grew them clambering over huge trees which must have made picking difficult. The later Romans certainly used the 'modern' practices of remarkably hard pruning, training and supports to keep the crop off the ground at a convenient height and to control the vigour. Modern varieties are just as vigorous, if not more so, and they will happily produce masses of growth and many hundredweight's of berries. As in Classical times the skill is in getting sweet ripe ones.
I have tried dozens and dozens of different grape varieties, growing and pruning regimes and conclude that the site is everything. Grapes must have maximum exposure to as much sun as possible and the crops are much poorer quality where this is not given! I have grown the same varieties in many places around my garden and by different methods. And it is always a struggle as my garden has a slope to the North and therefore it gets less sun than it could. So I have a big handicap and here in Norfolk I am also as far North as outdoor vines are considered feasible anyway without extra protection. However I find that as long as they are given full sun many of the modern varieties usually do very easily. And with the benefit of a wall, fence or shelter belt behind them then these crop well almost every year. My light free draining soil helps but vines will also grow in heavy wet ground though then they will probably make even more growth. To be sure in Britain I doubt you ever need worry much about feeding vines growing in most soils for at least the first decade or so.
Spacing and support is almost any you can conceive. The closer together vines are grown the more pruning you have to do. On the continent many are grown at about a metre or so apart each way and trained to a vertical post. As they are cut down to stumps each winter they can be constrained like this but the few buds retained can be lost in a frosty spring. While dormant vines will take hard frost, it's the young growths that suffer. In milder but erratic Britain we are usually better planting vines further apart retaining a bigger framework supported on wires with more buds left on thus guarding against frost damaging all of them. Winds can knock off young shoots and strong supports are needed to support any vines, and where winds are a problem then good supports are critical as a dropped vine is hard to deal with.
It does not seem to matter much which of a multiplicity of different pruning regimes you undertake. Grapevines are so forgiving and so vigorous that any mistakes are soon rectified. They need winter pruning to control their size and to select for good fruiting wood, and summer pruning to control vigour and ensure cropping. Grapes fruit on wood made the previous year so any shaped framework may be built up and then all growths from that are reduced to three buds or less each winter. In the spring when the buds break then all others appearing from odd places are rubbed off. Once the flowers appear (usually between the third and fifth leaves) then bare shoots can be removed or stopped to prevent the multiplication of non-fruiting wood. Once the fruit trusses are set then the best are selected and all others removed and their shoots stopped. All shoots may be stopped if the vines get too vigorous but doing so can weaken the crop. All shoots need tying to supports if you wish to pick or net the crop. Much time can be spent training vines!
The first few years really ought to be used to build up the strength of the vines and form the basic frame. De-flower them completely the first year, the second year leave only one bunch on just for verification and each year thereafter restrict cropping by removing trusses after they've set. This is critical; more than one bunch per square foot of foliage is greedy and may risk the whole crop, thinning down the number of bunches greatly improves the rest as they then ripen more uniformly and sooner! Leaving very heavy crops on will lead to late and patchy ripening, mould and misery. Parsimony will bring success.
Frost damaging the opening buds, shoots and flower buds is the first problem and is fairly easily avoided by hanging sheets over the vines. Once growth is well underway and straggly this becomes tricky but then very late frosts are less likely and vines are not early flowerers often waiting till July. Once the flowers are set then the next problem is mildew, this threatens anytime but especially when the soil is dry and the air damp. Bordeaux, sulphur and sodium bicarbonate sprays are available to organic gardeners but the best solution is to grow the more resistant varieties.
After the mildew threat has been avoided the ripening berries become subject to all sorts of moulds, most of which are not a problem in hot dry sunny weather! In cold damp wet weather moulds and botrytis are insurmountable -and I let the chickens have the crop once I am sure the year is a write off. A better site would improve my hit rate no end so be warned!
If the moulds and mildews fail to stop the crop then the birds and wasps move in. Fortunately the wasps only threaten the earliest crops except in very mild autumns. The birds are the crops worst enemy for sure and netting is the only way to keep them off the ripening grapes. I've tried individual bags over each bunch which keeps the birds and wasps off but then almost ensures rotting! Light frost does not seem to damage grapes which may ripen for several weeks afterwards but hard frosts destroy them.
As to variety; well Boskoop Glory is a star performer and has proved most reliable, it has a black glutinous berry and is very tasty, probably the best bred so far. The Strawberry grape and Schuyler are amazingly productive but have an odd eyeball like texture to the berry, their juice is fine but the wine is odd. Marshall Joffre and Leon Millot are also very vigorous and produce masses of small bunches early in the season of black grapes good for juice or wine with a deep strong red colour. Triomphe d'Alsace is similar and I think by far the best of the three. Together they have proved capable of producing generous amounts of very palatable red wine in a good summer. Similar but with bigger bunches and berries and to my mind not quite so good a flavour is Seibel 13053 which is also called Cascade, this is pretty vigorous but not in the same league as Marshall Joffre. Siegerrebe is the most delicious rose coloured grape with a wonderful bouquet, it is a bit prone to mildew and does not like chalky soils but the flavour is worth any effort. A lovely golden grape is Chasselas D'Or but this only does for me under cover I have seen it thrive on warm walls where it is very reliable and sweet. For the true white grapes the most reliable heavy cropper is Seyve-Villard 5/276, this likes a chalky soil and makes a lot of rather acid juice good for mixing with others. It's often grown with Mueller-Thurgau as the two make a good wine together. Mueller -Thurgau also called Riesling Sylvaner is atrociously prone to mildew but can make a tasty sweet juice. Madelaine Angevine and Madelaine Sylvaner try hard but are definitely runners up being respectively subject to mildew and botrytis. There are some intereting Russian varieties Gagarin Blue and Tereshkova which are heavy cropping purplish berries with a coarse peppery taste liked by some. And many other newer varieties are arriving so these should all be very much worth trying.
It had always been my dream of having my own small vineyard, or at least enough vines to make some celebratory plonk. I managed this with a vengeance and filled my own cellar, but now I find I prefer drinking the unfermented juices. Whereas to produce a good vintage required some skill, to just drink the delicious juice takes no effort at all. And although some varieties have flavours that are too strong for wine they are fine when drunk as juice. Equally it is hard to grow large grapes outdoors for eating but when small sweet wine making grapes are juiced they make gorgeous nectars and you don't have to chomp through the pips and skins. They are even dried slowly to make my own scrumptious raisins and sultanas, and for this the Muscat varieties such as Siegerrebe are unsurpassable. And of course the young leaves are used in cooking. Even the prunings are useful as they burn really well and smell divine on a bar-b-q.