Answer: Pruning grapevines seems more complicated than pruning fruit trees or roses when you first start but gets easier as you gain experience.
If you fail to prune your grapevines they will go completely berserk. It doesn?t take long for a vine to reach 30 or more feet and vines can be quite unproductive at that size. Pruning encourages new wood to grow and the grapevine fruits only on new wood. Pruning should thin out old non-productive wood and encourage the vine to put its energy into new fruiting wood. When done correctly pruning allows the vine to have the proper amount of year old cane ready for the following spring?s production.
A few terms describing a grapevine may help you understand. The main support for all vines is the trunk, growing laterally from the trunk are ?arms.? There are commonly two arms, but sometimes several more. Coming from the arms are ?canes.? Located on the canes are ?buds? (these are little nodes that give rise to the new wood on which fruit develops). If you leave too many buds there will be little or no fruit and lots of bushy vine. If the cane is pruned quite short, to two or so buds, it is called a ?spur.? Do not count buds closer than one-quarter inch from the base of the cane. With pruning, what you try to do is to ?balance? the vine so that fruit production and vine growth are ?balanced?; that is, provide enough green leafy growth to support the fruit crop and allow the correct mixture of sun and shade to insure good grapes.
When starting vines put the vine in the ground with a post and let it grow until its next dormant period. This allows the vine to settle in and establish a sound root system. During the next dormant period select the dominant cane and remove all the other canes at their base. Prune this dominant cane back leaving two or three buds on it. In the growth period of the second year, when the dominant cane bud shoots have grown about 12 inches, select the dominant shoot (cane) from these and cut all others off. This will become the vine?s trunk. In order to develop the lateral arms, pinch the tip off dominant cane about six inches above the level you want the arms to finally be. When sturdy lateral canes (to become the arms) have developed, remove all other buds and canes. In the vine?s third year the training period is largely complete. It is now in its permanent form and ready for production. It is important to remove all fruit from young vines early each summer when the vines are in their formative years. Fruit bearing before the vines are sturdy and mature may reduce its productivity for many years to come.
There is a difference between training and pruning. While it is true that we prune to train vines, desirable fruit production is dependent on good training and proper yearly pruning. Pruning grapevines is done when the vines are totally dormant. All grapevines need some support for the fruit bearing canes. Usually wire or cable on strong vertical stakes is sufficient.
Pruning grapevines requires that the previous season?s growth be thinned. To do this look at the arms mentioned above and selectively cut out canes, leaving about six inches between each. So called ?cane pruning? involves pruning every other cane so that there are bout 10 to 15 buds per cane. The alternate canes are then pruned to leave only two buds; you will then have one long cane and one short cane, or spur, alternately. Thompson Seedless grapes must be cane pruned because the first 3 to 6 buds on each cane of this variety are virtually fruitless. The short spurs will send out canes for next years crop. All varieties can be ?cane pruned? but Thompson Seedless must be.
?Spur pruning? is less complicated in that all selected canes are pruned to two or three buds. Red Flame, Tokay, Emperor, and Black Manucca table grapes as well as the common wine grape varieties can all be spur pruned.
The real secret about grapevine pruning is to know how much to remove and how much to leave. If you still have questions, there are many books with diagrams available at bookstores and local libraries. Best wishes with your grapevines!
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