French Winemakers are Setting Their Vineyards Ablaze to Save the Harvest
When temperatures plunge across some of the most famous wine regions in France, winemakers set hundreds of fires to fight the frost.
When temperatures plunge across some of the most famous wine regions in France, winemakers set hundreds of fires to fight the frost.
Spring Frost is a Serious Threat to Burgundy and Bordeaux
Spring frost is one of the biggest risks faced by vineyards across Bordeaux, Burgundy and the Loire Valley. Italy’s Piedmont and various regions throughout Tuscany, including Montalcino, also face similar threats. Warmer winters and earlier springs mean vines produce new buds, just weeks before the freezing temperatures hit. As young shoots are vulnerable, they’re susceptible to frost damage, which prevents grapes from fully developing later in the season. Not only does this reduce the yield, but it also means a single night of frost can decimate months of hard work.
Source: Pexels
Thousands of Paraffin Wax Candles are Lit
Large paraffin wax candles, or bougies as they are locally known, are lit throughout the vineyard to stave off frost. Hundreds of candles are delicately placed between the rows of vines, working well into the night to ensure that the crop is protected. When the candles are lit, they warm the surrounding air to 2°C to 3°C, which is just enough to stop the buds from freezing.
Protecting one hectare costs €3,000 on average, which pays for 200 candles. During severe frost, up to 500 candles per hectare may be required.
As the expense is so great, producers often reserve this method for highly prized plots. This includes Premier Cru and Grand Cru plots; however, historic appellations, like Pommard and Meursault, are also known to adopt this practice across whole vineyards.
The Ancient Technique That Still Saves Grapes
Some vineyards use older, more traditional methods. Instead of using paraffin candles, they burn hay bales, old vine cuttings, or straw. Although the fire generates warmth, the primary purpose isn’t to create heat but instead to create a blanket of smoke. The smoke produces a cloud that slows down the rapid warming of the morning sun.
Ironically, sunrise is the most dangerous time for fragile crops. Frost-covered buds that thaw quickly experience cellular damage. Intracellular freezing, or cell culture, happens when the water inside active bud cells crystallises. As the ice crystals expand, they burst the cell walls, causing tissue death.
A secondary process, osmotic dehydration, happens when the ice that forms on the outside of the cell draws water out, dehydrating the plant.
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The Surprising Science of Ice Protection
The most interesting anti-frost method adopted by wineries throughout France involves spraying water onto the vines. As temperatures fall, sprinklers spray the buds, which then freeze. As temperatures plummet, the freezing process releases heat.
Exothermic reactions mean that the bud stays at 0°C; however, the system must continue running until the temperature rises above freezing. This makes the method only suited to wineries that have a reliable water supply that can serve the entire plot continuously. Some of the wineries that rely on those methods include the estate of Pierre Brocard, Réaut, and G.H. Mumm, all of which are located in the region of Champagne.
Domaine Stéphanie Michelet in Chablis also uses aspiration to protect select parcels, saving nascent shoots from freezing temperatures.
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A Battle that is Fought Every Year
Dramatic scenes like this become more common as more unpredictable weather patterns affect European vineyards. Earlier bud growth, when combined with late cold snaps, means that frost protection is becoming an annual ritual.
Even though there are spectacular photos of owners setting their vineyards ablaze, every flame signifies an exhausted worker who is pulling 24-hour shifts to protect the grapes that will eventually become some of the most celebrated wines in the world.