Winter pruning is one of the most important tasks carried out in the vineyard and consists of cutting the old wood and the green parts of the vine after the grape harvest. Its purpose is to prepare the plant for the following year’s production, therefore the decision the right moment to prune has a special relevance.
Pruning requires that temperatures drop and the vines begin to go dormant. It is a very specialized task that can only be done by hand and will be conditioned by many factors: the type of soil, the slope and orientation of the vineyard, traditions and, sometimes, legal regulations, the type of wine expected from the vineyard… however, there are factors that are critical in determining the timing of pruning.
Climate and weather risks
Pruning can be started after the temperature in autumn and winter drops, when the plant is dormant and the plant sap is static. Pruning should be done during these months, and before the new shoots appear.
Spring frosts are a common risk in certain regions such as Mosel or Rheingau in Germany, where the winegrower may decide to prune a little later to try to delay budbreak and reduce the probability of damage from these frosts. Temperatures in warm regions allow greater flexibility when pruning, but it must be done before budbreak and before the vine sap begins to activate the new vegetative cycle.
The grape variety
Not all varieties start the vegetative cycle at the same time, even if they are in the same vineyard. Chardonnay or Pinot Noir are early budding varieties. In order to delay budbreak, some winegrowers tend to prune them later than other varieties, especially in cold areas such as Chablis or Champagne. On the other hand, medium or late budding varieties, such as Grenache, can be pruned later or earlier without major concern.
Availability of resources
It should be borne in mind that pruning requires qualified and adequately trained workers according to the type of pruning required, this implies money and human resources that in some countries/regions are scarce. In Spain it is common for the best teams of pruners to go from one vineyard to another, hired by the different companies, making a journey that can start in Ribera de Duero, pass through Rioja and end in Catalonia.
On the other hand, in family or very small wineries, it is usually the same people who must carry out the work in the vineyard and in the winery, having also other products to harvest. In these cases, pruning is done after the main winemaking processes have been completed and the other products have been harvested. This is what happens in small Barolo or Txakoli wineries.
The size of the vineyard and the type of vine training
Given the size of some vineyards, the pruning of all the vines may take several weeks. In these cases, the pruning calendar will be defined by the number of days/weeks required for the correct pruning of all the hectares of the vineyard.
In addition, the vineyard distribution system and the type of training of the vines also have an influence; in this sense, the pruning of trellised vines is faster than the pruning of bush vines.
In conclusion, pruning is one of the main and most strategic tasks in vineyard management, with different factors affecting the decision of when to prune. Each of these factors must be considered together with the rest, being fundamental: to know the vineyard very well, the irrigation to which it can be subjected, the quality of the crop to be obtained and to manage the available resources very well.
By Teresa Guilarte. Sommelier, WSET educator and Co-founder and Head of training at Artean Wines