A sustainable solution to frost?

by Gemma Hadley

As we head to mid May, the traditional moment for frost has pretty much passed – but the question of how vineyards can best manage the increasing threat of frosts and protect vines nearing bud-burst during Spring remains front of mind in Bordeaux, as across all of France.

Major freezing events like those in 2017, 2019, 2021 and 2022 appear to be on the rise – with certain areas in 2020 also seeing significant losses. In 2017 many vineyards in the Right Bank lost their entire crop, while the 2021 vintage saw a harvest volume 20% below the 10-year average, according to the  Conseil Interprofessionnel du Vin de Bordeaux (CIVB). Sauternes was particularly badly hit, losing 51% of the crop that year. After the devastating losses of 2021, the French Government pledged €1 billion in aid to help frost-affected vineyards and farms, and the cost of fighting frost is becoming a huge issue.

Images of candle-lit vineyards and rows of smudge pots and nets have become perennial. Some properties even enlist helicopters and wind turbines. However, as many vineyards commit to sustainable viticulture, growers are now looking towards more ecological solutions.

Frost nets
Estates such as Liber Pater have experimented with frost nets, but these for now are forbidden for appellation wines by INAO rules. Similar issues exist with any form of drop cloths or sheeting. But finding alternatives that minimise environmental impact is tough. Wine Protect, a company dedicated to finding sustainable solutions, hopes to step into the breach with the development of ‘cloches antigel’ or ‘anti-frost covers’.

These anti-frost covers are placed on the top trellising wire above the vines, protecting them from the elements in a similar way to nets by providing a barrier between the vines and freezing air, without coming into direct contact with the vine. Produced in France from recycled material, they are capable of protecting vines from temperatures down to -6°C.

As weather patterns become more chaotic, there is evolving debate surrounding how producers can counter environmental hazards while adhering to AOC regulations. But unlike vineyard nets and sheeting, Wine Protect’s ‘cloches anti-gel’ comply with The National Institute of Origin and Quality (INAO), which is responsible for the implementation of AOC regulations.

This is because the cloches are not seen to affect the structure of the vine or the biology of the soil, and so in theory maintain the integrity of terroir. According to creator Déborah Ducamp, the 100% recyclable cloches made from recycled plastic need no energy source to work, don’t need monitoring, can withstand wind of up to 70km/h, and require just one annual installation and removal. Each one can reportedly last for up to 15 years. Their dark colour is designed to retain the heat of the sun, although there is also a translucent version that allows the UV rays to pass through, and a solar-powered version is currently under development. In this case, automatic temperature sensors will trigger the activation of heat-radiating bulbs, providing heat to frost-threatened buds for up to 8 hours.

Based in the Médoc, Ducamp founded Wine Protect three years ago with her brother Morgan Alamé who is an electrical engineer and her husband Mathieu Ducamp (part of the technical team at Château Mouton Rothschild). The company also works with environmental engineers and robotics experts, and is backed by Bernard Magrez’s ‘Start-Up Win Incubator’ programme.

Finding protection without excess costs
The growers in Bordeaux are spending increasing sums of money to protect vulnerable vineyards, but the reality is that many of the current solutions come with a large carbon footprint. The use of helicopters or wind machines to circulate air, electric heating, spraying and lighting also come with large financial costs, and create noise issues with neighbours, with several instances of winemakers being challenged in courts over their use, to the point that the French National Assembly earlier this year debated protecting winemakers against these challenges.

Candles are often seen as a less invasive and energy-intensive method of prevention, yet they present their own issues. While they burn for up to 8 hours, the bougies are labour-intensive as hundreds are needed per hectare every night during the early spring. At around €10 per bougie, the cost can be eye-watering (these cost €6-10 per item, depending on quantity, but are reusable). Many of these candles are paraffin-based, releasing harmful gases and toxic fumes.

“This project was obvious to me, living in the Médoc and being confronted with the problem of frost every year. I wanted to develop an ecological and sustainable solution,” says Déborah Ducamp.

In 2022 small-scale tests saw positive results and an increasing interest in the concept. This year large-scale testing has been carried out on six vineyards in Pessac Léognan, St Emilion, Sauternes and Médoc.

Despite no incidences of major frost this spring, results have been extremely promising. Château Smith Haut Lafitte, an organic certified Cru Classé de Graves, is one of the properties that is reporting successful trials.

There are issues – for one that they are unwieldy to store, and take two to four people 8 hours to install across a hectare of vines planted at 10,000 vines/ha (“during the day,” says Ducamp, “no more sleepless nights during frost season”), and they are unsightly compared to solutions such as small infra-red lights installed across the wires, which is another new solution being developed by Belgian company Frolight Systems.

Ducamp accepts that ‘development will be necessary to make it more straightforward for vineyards internationally to adopt, especially from a logistics and storage perspective’ – but there is great potential for the ‘cloches antigel’ both here in Bordeaux and further afield.

“There is no perfect solution,” she says, “but we’re trying to get closer to it”.