When to cut back vines?

Strictly speaking, of course, it is not the wine that is pruned, but the vine, i.e. the vine. Pruning is an important factor for the yield of the vine and thus later for the quality of the wine.

Without pruning, the vine would grow uncontrollably and form new lateral "stocks" with shoots and buds every year. This expansion in area would lead to high yields and lower wine quality. Pruning therefore regulates the number of buds on the vine from which new shoots can form. By limiting the number of new shoots, one also reduces the number of grapes and thus increases the wine quality: the fewer grapes a vine bears, the more extract each individual berry contains and the more substance the wine later has. The effect of pruning on the quantity and quality of the grapes depends on the grape variety, the training system and the location, age, health and growth behaviour of the vine. The sprouting and growth behaviour of the vine is in turn influenced by the arrangement of the shoots.

The so-called one-year-old wood, i.e. the shoots of the previous year, is always pruned. In addition to leaves, tendrils and shoots (the later grapes), each shoot also forms new buds. These buds already carry all the plants for new shoots, but are initially enclosed by bracts and filled with fine woolly hairs in the cavities. This allows the bud to overwinter protected from the cold (which is why it is called winter eye) and then sprouts the following year.

Pruning takes place during the Winter dormancy of the vine, i.e. between leaf fall in autumn and bud break in spring; in the northern hemisphere this phase is between December and March. In so-called winter pruning, by far the largest part (80 to 90 percent) of the one-year-old wood is usually cut away completely in January and February , leaving an average of two one-year-old shoots per vine. For frost-prone In the case of grape varieties and in such locations, as well as in the case of young vineyards, pruning is often delayed until March. The one-year-old shoots that remain are then pruned again so that exactly enough eyes remain for the shoots that develop from them to reach an optimal strength and length and the physiological balance of the vine is guaranteed.

Apart from winter pruning, there are other occasions to prune the vines: On the one hand, it may be necessary to prune the vines unscheduled after hail or frost damage. On the other hand, the so-called green harvest often takes place in the course of the growing season: thinning as a special form of pruning, in which grapes are cut away from the vine during the growth or ripening phase in order to increase the quality (extract) of those that remain.

Terminology:

• Foliage = leaves of the vine
• Tendrils = attachment organs of the vine
• Shoots = young shoots of the vine
• Eyes = buds of the vine, from each of which a shoot grows
• Shoots = inflorescences of the vine from which the grapes develop
• Nodes = nodes on the shoot from which leaves, tendrils, eyes and shoots develop
• Internodes = Shoot axes of the vine between the nodes