Learning about pruning Bordeaux vineyards is an essential part of vineyard ownership. It is the moment in the annual vineyard cycle where an owner or vineyard manager can exert the most influence over the agricultural process and eventual harvest. It can also be one of the most expensive line items in the annual wine making budget – why? Because each plant must be pruned by hand. I am sure that someone somewhere is working on a way to automate pruning but to date, the closest we have come to automation are electric secateurs. My guess is that there will always be a manual aspect to vineyard pruning because it is so precise and so important to get right.
With a small vineyard – up to 10 hectares it is quite possible that the owner will prune themselves, perhaps with the help of one other. For larger estates it is common that the whole team are trained in the art of pruning; this is partially because it is cost efficient to use team members at a time of year when there is not much else going on in the vineyard, but also because the owner (or manager) will have a certain culture that he or she will want to instil at the vineyard.
How many Vines can be pruned in a day. Watching a well-trained pruner is a humbling experience; they move precisely and quickly and can prune 600 to 700 per day without electric secateurs and up to 1500 per day with. If you are new to pruning (or a team member is new to it) starting off slowly is wise especially if using the electric secateurs which can cut through the trellis wires and leave an expensive fix to deal with. Expectations at the beginning should be around 500 vine plants a day early on – so on the basis that each hectare typically has about 5000 plants you can see that a hectare will take a single person alone about 10 days to complete. It is worth noting that Cabernet vines have harder wood which of course will affect speed and efficiencies.
There are two aspects to the pruning work. The first is the skilled side of vineyard pruning: that being to precisely cut in the right place on the plant. The second is the pickup of the branches that have been cut. This latter task requires no skill, so it is often outsourced to a different team or left for another day.
We are often asked when is the best time to prune? Across the Bordeaux vineyard region, you will see pruning ongoing during the winter months. In Bordeaux, pruning could start as early as the end of November and it will almost never be still under way at the end of March. There are, however, some logical reasons why in some cases pruning can be seen almost every day throughout these months. Imagine for the sake of argument that you have a Bordeaux vineyard estate with 100 hectares of vines and for the sake of this example we will split 50 hectares of Merlot and 50 of Cabernet. We can then assume that the total number of vines that need to be pruned will be 500,000 based on 5,000 plants per hectare. Let’s assume that we have a large team of 10 people and each of them are skilled and experienced being able to average 1000 plants per day – therefore 10,000 plants per day can be pruned by the team together. On this basis it will take 50 days to prune the entire vineyard from start to finish or 10 weeks if we assume that the team does not work on the weekends (which they often do in fact). Also, assuming that the Christmas and New Year holidays reduce work hours it might take about 12 weeks to complete a large estate in this way. This leaves the owner/manager with little choice but to start pruning as early as possible and use most if not all of the three-month Bordeaux winter season.
But what if you have a smaller estate of say 10 to 20 hectares and you have the choice to prune whenever you want. Given the option, what would be the best time of year to prune? The weather is increasingly dictating the answer to that question. Another reason might be the desire to leave the plant to rest dormant for as long as possible. Combined together, these two reasons support a later pruning start – perhaps late February starting after Valentine’s Day but completing (ideally) before 15th March. This will have the effect of delaying the plant from budding which is wise when we consider that springtime can send mixed messages to the plant, opening the risk of budding while there are still early morning frosts. In the case of the plant that has been pruned early December, it will have had less time to rest but also it will be ready to bud earlier following pruning. So, if we get some warm sunny days in February or March, the plant may start its annual growth cycle a little earlier and if there is a frost in March or worst still in April, it can damage the harvest as we saw in Bordeaux 2017.
After Pruning. Finally, once the plant has been pruned, its remaining branches need to be bent into place and attached to the trellis. The branches are attached with wire or biodegradable ties that secure the branch to the main trellis wires. This is much easier when it is wet than when dry – to be precise four times easier, since it is possible to bend 4000 wet branches compared to 1000 dry branches.
So what would be the perfect pruning cycle; each owner/manager should consider for a Bordeaux vineyard estate in 2021. Well, as we have seen above, for a large estate there may be no choice but to start early, and certainly before Christmas. But the ideal is to leave the pruning as late as possible.
In part 2 of our pruning review we will look at the history of pruning and interview an expert to understand some of the specifics of pruning in Bordeaux vineyards.
Written by Michael Baynes