Pruning Grapes – What is the Purpose?
Anyone who has the green thumb knows how important pruning is. This not only provides an aesthetic ideal for the plants, but it also keeps the plants productive as well. Pruning grapes or pruning grape plants are no exception. In fact, horticulturists are saying that grape plants must be pruned to about 90% most of the time. Although this may sound drastic, cultured grapes gain more benefits from trimming off the parts that are no longer productive. Otherwise, the entire plant can grow in volume substantially, with its runners trying to establish more areas where the plant can expand to. This is a sign of the plant's good health, but it also lessens its chances of increasing its fruit harvest.
As a rule, grapes emerge only from one year old wood, and only on stems that have been established from the last season. Everything else, like the new threads of runners, or the older wood, or the stems from two seasons ago, will only hinder the new flowers from blossoming. Fewer blooms mean fewer fruits. Additionally, too many stems and runners can effectively block out the sunlight, especially if these are climbing on supports that create their own canopies. And all grape farmers know that these plants are dependent on full sun exposure most of the time. Without long periods under the sun, the grapes can become stunted in growth, or ripen slower, or be subjected to fungal rot. The practice of pruning grapes is therefore essential in increasing both the potential fruit harvest and the amount of natural illumination that the plants are supposedly to receive.
Pruning grapes must be done carefully, so as not to endanger the overall health of the plants. For starters, it is imperative that only the sharpest pruning tools should be used, to minimize the shock on the plants' systems. Hacking away at the branches and stems or ripping off runners by hand can cause a lot of damage. If the plant survives this poor treatment, (and a lot of plants do not) it will devote most of its growing time to reconstructing itself again, rather than develop its flowers and fruits. So, it really pays to be gentle when it comes to pruning grapes.
Pruning grapes should only be done when the plants are dormant. The time after the harvest season is the best. Most mature grape plants should be pruned yearly to keep the one year old stems from being drowned out by the older stems and branches. Runners or the trailing vines that creep up on almost all the surfaces of the climbing subsidies must be likewise trimmed off, to keep the energy of the plant within a certain core. These runners are used by the grape plant as a means of anchorage. But these are also used as a natural means of expanding its growing area … a trait that most wild grape species still carry. However, since the plants are now being cultured, it is essential to limit the growth of the runners so that the grape plant has more energy in fruit production instead.