During the first two or three years, vines which are to be given the form of horizontal cordons are treated exactly as for vertical cordons, that is, they are pruned back to two buds each winter and the growth forced by disbudding into a single cane during the summer.
As soon as a well-ripened cane of the required length is obtained, it is tied to a wire stretched horizontally along the row at from fifteen to twenty-four inches from the ground.
For this system of pruning, the rows should be twelve to fourteen feet apart and the vines six, seven, or eight feet apart in the rows. As the cordon or trunk of each vine should reach the next vine, it will have to be six to eight feet long. The best shape is obtained when the trunk is all formed one year from a single cane. It is necessary, however, sometimes to take two years for the formation of the trunk. In any case, the cane first tied down should reach at least half way to the next vine. The following year a new cane from the end of this should be used to complete the full length of the trunk.
In attaching the cane to the wire, it must be bent over in a gentle curve and care taken not to break or injure it. The proper form of the bend is shown in Figs. [27] and [35]. Sharp bends should be avoided.
Fig. 35. Unilateral horizontal cordon with half-long pruning.
The cane should be placed on top of the wire, but should not be twisted around it. The end should be tied firmly and the rest of the cane supported by strings tied loosely in order to avoid girdling when the cane grows.
In the following spring, most of the buds on a good cane will start. If the cane is short jointed, some of the shoots should be removed and only those shoots allowed to develop which are conveniently situated for permanent arms. If the vines are to be short pruned, the arms should be developed every eight to twelve inches from a few inches beyond the bend to the extreme end. For long pruning, the arms should be farther apart, twelve to twenty inches. Shoots starting from the top of the cane and growing vertically upwards are to be preferred.
As the shoots develop, the strongest should be pinched repeatedly, if necessary. This will tend to force the growth of the weaker shoots and to equalize the vigor of all. At the end of the season, there should be from five to ten canes growing on each cordon of full length. These canes are then pruned back to two or three buds, or a little longer for long-pruned varieties.