Growing Grapevines Outdoors Against a Wall
OUTDOORS AGAINST A WALL
Immediately after planting, cut the main stem down to about 60-75cm (24-30in) abovelevel, cutting to just above a bud. Insert a stout bamboo cane close to the plant, secure the cane to the wires and tie the vine stem to the cane. In the first season, tie the main stem vertically to the cane and pinch out its top when it reaches the topmost wire. Side-shoots will develop and the strongest of these should be tied to the horizontal wires to the right and left of the main stem (or rod as we should now call it). These side-shoots should be pinched out at a point just beyond five leaves from their base. All the other side-shoots should be pinched out.
In the following winter, cut back the main shoot by approximately half and cut back the lateral shoots to about 2-5cm (1-2in) from their bases.
The next season, the process is more or less repeated and you should, once more, only allow a single lateral shoot to develop from each of the stubs; carefully pinch out the weaker ones. In the second winter, cut back the lateral shoots again, and again shorten the main shoot — it will, of course, gradually be getting closer to the top of the cane.
In subsequent years,and fruit can be expected but it’s important not to be too greedy and allow too many to develop, as the individual bunches and fruit will be small. One per lateral shoot is ideal in the first year, two in the second and three in subsequent years. The shoot should, therefore, be pinched back to a point just above three leaves beyond the first, second or third flower cluster as appropriate. Side-shoots will then form from the laterals and these should be pinched out at just beyond one leaf.
In the winter, the laterals should be cut back regularly to leave short stubs and, when the main rod has reached the end of its allotted space, it too should be treated just like a lateral and cut back to the same point each winter
With a vine planted just outside a greenhouse, the main shoot should first be passed into the house through a hole cut into the end wall close to soil level. Thereafter, the basic training andis similar to that employed on outdoor , but the main rod must be directed along the greenhouse structure as explained below.
In a lean-to greenhouse, direct the rod up the side wall and then along the angle formed where the bottom edge of the roof meets the wall. The laterals are, in turn, directed up the slope of the roof. In a free-standing span house, the same system may be adopted, or else the rod may be pinched out when it reaches the top of the wall and so encouraged to branch. In this case, one branch is trained as before while the other is taken across the end wall and trained along the opposite side, effectively producing a two-armed cordon with the two sets of laterals tied up the two roof slopes and meeting at the ridge. Thereafter, the pruning is exactly as I’ve described for outdoor vines.
If you are growing grapes for dessert use, rather than for wine making, it’s important to thin out the fruit within the bunches so that the individual grapes will be large and plump. Use blunt-ended scissors and work upwards from the bottom of each bunch, snipping out about half of the grapes when they are around 5mm (1/4in) in diameter.