There are probably enough south-facing garden walls and house walls in Ireland to supply the whole country's wine needs if they were all planted with vines! To rewardingly grow grapevines outdoors in Ireland is by no means such an impossible idea as most people might assume.
Naturally, vines can be grown and cropped in any part of the country in a greenhouse or conservatory, but not all of us have the possibility of availing of such a facility. It should be an encouragement to any would-be vine enthusiast that in many parts of the country a vine grown against a sunny wall outside can be productive. The grapes, when fully ripe, are delicious to eat and can be of far better flavour than any you could buy, and, incidentally, quite a respectable wine can be made from them. In the warmest and sunniest areas there are a few varieties which can even be grown entirely in the open, and which can crop and ripen most years, enabling the serious enthusiast to even plant a small vineyard!
It is, however, absolutely essential that a suitable variety is planted. The notion prevailing among Irish gardeners that grapes cannot be grown outdoors, may be due partly to attempts at growing the variety ‘Black Hamburg' outside - a venture almost certainly doomed to failure. Even for the greenhouse I would suggest that there are many varieties superior to this one, particularly if flavour is what you're after.
Growing vines on a wall
Left to its own devices, the grapevine grows to be a sprawling, rambling affair, and its vigorous shoots can easily grow more than three metres in one year in Ireland. Its stems are equipped with tendrils, rather like clematis, enabling it to bind itself to the likes of twigs and wires, but it cannot clasp itself onto a wall the way ivy can. For these reasons it is most easily and rewardingly managed when it is trained on a wire trellis.
In Ireland, generally, vines start growing around April on a wall and around May in the open. They make their most vigorous growth from June to August, growing by up to an inch per day, and they flower around June on a wall and in July in the open. Depending on the variety and on the location, grapes are normally ripe in October. However some early varieties on a warm wall can be ripe in August, while later varieties are sometimes not ready for harvest until November.
Both sunshine and warmth are of course very important to grapevines and only sunny walls facing south, south-east, or west should be considered. Vines grow well in any ordinary, reasonably fertile soil, as long as it doesn't get water-logged in the winter and isn't allowed to get bone dry in the summer. Feeding, if any, should be just enough to maintain healthy vigorous growth, and it is very important that vines are not over-fed. A good rule of thumb would be to plant around 1.5 - 1.8 m apart, but they could go as close as 1.0 m apart if desired. Remember that the young vine shoots can be damaged by spring frosts, although a wall vine will invariably escape frost damage, as the wall itself offers protection and shelter.
Vines produce their fruit along the bottom 40 cm or so of their current season's shoots (each shoot producing usually two, sometimes three, bunches of grapes), and the various methods of pruning and training them are all based on this principle. Correct pruning of vines is very important, in order to encourage heavy and regular cropping, but there is no great mystery to it once their growth habit is understood. There are essentially two methods of pruning and training vines, spur pruning and cane pruning.
For spur pruning, a permanent 'branch', known as a 'rod' or 'cordon', is trained, usually horizontally along a wire. From this rod the fruiting shoots grow and are usually trained vertically and allowed to grow to around 1.0 - 1.5 metres long before being 'pinched out'. These shoots, which are known as 'canes' once they are brown and have lost their leaves in autumn, are then pruned back during the winter to short 'spurs' consisting of two or three buds. The following year the fruiting shoots grow from these spurs.
With cane pruning, the fruiting shoots are allowed to grow from the buds along a whole cane from the previous year, rather than from spurs. The simplest form of this is called the 'Guyot' system. A Guyot trained vine consists basically of a short trunk and either one, or usually two horizontal 'arms', trained along a wire. Each winter all shoots are pruned away except two canes arising from suitably near the top of the trunk. These are pruned to around 70 cm long and are tied down to the wire, one cane either side of the trunk, in a 'T' shape. These two canes form the arms for the following season, and during the spring and summer, fruiting shoots then arise from all along these arms.
The Guyot system is the usual one adopted for vines grown in the open. Rows of vines would be planted, with plants around 1.2 - 1.5 metres apart in the row, and rows being 1.5 - 2.0 metres apart. The vines are trained on a wire trellis, consisting of a bottom wire for the Guyot arms about 50 cm above the ground, and several further wires up to a height of around 1.5 - 1.8 m to support the fruiting shoots. When the shoots are trimmed at the top wire of the trellis in summer, the rows of vines have the appearance of narrow hedges.
If your objective is to get abundant crops of ripe, tasty grapes from your wall vines, or even if you eventually wish to make a nice wine, then the choosing of a suitable variety is of paramount importance. It should be pointed out that the kinds of varieties best for growing outdoors do not produce big fleshy bland-tasting grapes like those from the local supermarket, but rather, quite small though sweeter, juicier and more flavoursome fruit. They are best eaten as one might eat a pomegranate, swallowing the seeds without chewing them, while savouring the rich juice! Without doubt the best variety for growing outdoors in Ireland generally, is 'Madeleine d'Angevine'. Its bunches of small round grapes are relatively early ripening and are deliciously sweet and juicy when ripe. It can also make a pleasant white wine, though for warmer sunnier areas one could afford to go for a later ripening variety, such as ‘Bacchus', ‘Schonburger', ‘Phoenix' or ‘Bianca'. These are all dual purpose vines, excellent both for eating and for wine-making.
‘Schonburger' has a particularly appealing pinkish mauve colour when fully ripe, as does ‘Siegerrebe', which is early-ripening and of quite exquisite flavour. ‘Phoenix' and ‘Bianca' are new mildew-resistant hybrid varieties, a boon to mildew-weary gardeners, who now have the possibility to grow healthy grapes, either in a greenhouse or on an outdoor wall without having to worry about spraying them.
It is certainly true that black grape varieties generally require more warmth and sunshine to produce ripe grapes consistently, but with a warm sunny wall, even black grapes can be grown outdoors. ‘Dornfelder' is a new German vine which produces particularly large bunches of juicy grapes. 'Dunkelfelder' on the other hand yields very small, but intensely blue-black bunches, and this variety's chief attraction is its spectacular scarlet-coloured autumn foliage, equally attractive in a conservatory or against a wall. There are also several good mildew-resistant black grapes: ‘Muscat Bleu' is rather late-ripening for outdoor culture, but has very good autumn colour; for reliability in cropping and ripening, try ‘Regent' or ‘Rondo'. All the above varieties are also suitable for wine-making, except ‘Muscat Bleu'.
There are of course many other varieties which one could attempt to grow, if one is lucky both to be living approximately south-east of a line drawn from Dublin to Cork, and to have a good sunny wall in a very warm sheltered locality. Grapes like ‘Riesling', ‘Chardonnay' or ‘Pinot Noir' might even be attempted with some success.
For an established vine of a suitable variety trained on a suitable wall, one may expect a yearly yield of between 1.5 and 2.5 kg of grapes per metre length of rod or cane. A 10 m long wall, planted with about six vines 1.5 m apart, could therefore yield 15 to 25 kg of grapes from about the third year after planting. If one wishes to ‘drink' one's grapes rather than eat them, this would translate to around 10-20 bottles of wine per year, and in a good year possibly even more!
(article by David Llewellyn)