When Frost Bites

A lot is said about Champagne’s extreme climate and the challenges of frost, but it’s hard to fully understand its devastating impact when you cannot see it for yourself. Sara Underdown gets first-hand experience during her recent trip to Champagne.

It's 5.20am on Rue du Marc in Reims, when a car approaches me from down the way. It’s Jean-Baptiste Lécaillon, chef de caves of Louis Roederer. This morning we’re off to see ‘frost fighting’ in Roederer’s massale selection nursery vineyards – baby vines – in Bouleuse around 20 minutes west of Reims in the Montagne de Reims. It’s been freezing in Champagne since I arrived earlier in the week. Temperatures plummeted to - 4 since the start of spring; snow fell, rain flowed and wind howled across the Marne.

It's frost season, and the fight is on from early April until the first week of May.

Lécaillon is one of the growers employing a range of frost-fighting resources to save buds during periods of higher risk. Here in Bouleuse, he uses heaters fired by sustainably farmed wood chips. There are 177 of them scattered across one hectare interspersed between rows of pinot noir. All is dark and quiet, and it’s easy to feel lulled by the serenity; but these little burners are all fired-up for battle.

“We have one of the largest collections of massale selection pinot noir in France. We started with just six clones,” says Lécaillon as we traverse the clayey loam at the bottom of the slope. "There are 160 individuals. When friends come from Burgundy, they say it’s unique.”

Amassing quality vine material is serious business at Louis Roederer. Today’s nursery is the culmination of twenty years’ work, cultivating cuttings from the estate’s best pre-clonal vines.

Amassing quality vine material is serious business at Louis Roederer. Today's nursery is the culmination of twenty years' work, cultivating cuttings from the estate's best pre-clonal vines.

Lécaillon’s ‘pursuit of taste’ mantra starts here, where he says the secret of winemaking is biodiversity to get ‘stronger and better’. Since becoming chef de caves in 1999, he has made Louis Roederer the region’s largest organically certified and biodynamic grower. More than two decades of viticultural improvements across the board have brought greater “character, intensity, phenolic ripeness and freshness” to their estate, he says.

Each year, frost poses a threat to Lécaillon’s prized collection of massale material because “as soon as you lose one of these, you lose their story forever.”

Champagne’s fight against frost is nothing new, of course. An extreme northerly climate sees temperatures plunge at spring which has all but annihilated crops over the course of history. In 1951, early bud break combined with devastating frosts affected 75 percent of vineyards. In 2003, almost half of the appellation’s chardonnay was wiped out and, in 2016, late spring frosts resulted in 20 to 80 percent loss in some areas. Then again, last year, yield was slashed by 30 percent. Adding insult to injury, frost almost always befalls further damage from mildew and hail.

Each year, frost poses a threat to Lécaillon’s prized collection of massale material because “as soon as you lose one of these, you lose their story forever.”

Frost occurs when the surface temperature falls below the freezing point, less than 0 degrees. New shoots contain water and, when the water freezes at a point typically below – 2 degrees, it destroys delicate cell structure.

‘Black frost’ is the one that bites hardest. The devastating impact of cold air is worsened by low humidity, so when the air settles on buds, it penetrates the molecules and destroys it from the inside, turning plants black. Last year, black frost occurred 10m above ground and brought temperatures of - 6 degrees to all of the coteaux, inflicting severe damage. What’s worse, there’s little that could be done about it.

‘White frost’, on the other hand, occurs every year - in varying degrees - with evaporation from soil. When the dew freezes and settles on the ground, humidity rises in the air. As temperatures drop to below zero, white frost occurs, forming tiny ice crystals on buds and leaves. If there is no wind, air becomes colder and more detrimental for plants. It is especially devastating in late spring, following development of shoots.

Wind machines can be an effective tool in artificially circulating air. In Avize, in the Côte des Blancs, Lécaillon protects their most valuable Cristal Rosé vineyards using generator-powered fans. Others choose sprinklers which - counterintuitively – offers protection by freezing water over buds, though some say there’s too much pollution from the water tables to make this a viable option. New technologies are also being trialled by some producers - the likes of Taittinger and growers such as Cedric Moussé in Cuisles, for example. Heat transfer lights, which are secured to trellising, emit subtle warmth and are said to be relatively efficient with a low carbon footprint.

Wind machines can be an effective tool in artificially circulating air. In Avize, in the Côte des Blancs, Lécaillon protects their most valuable Cristal Rosé vineyards using generator-powered fans.

But these are all band-aid solutions to a never-ending battle that goes deep into Champagne’s relentlessly extreme conditions, as well as climate change. Earlier budding, combined with late spring frosts, creates more challenges when defending plants during this critical time.

Biodiversity, regenerative and sensitive farming lends some hope, not in the least to make better wines, but as tools for managing a more extreme climate where frost is frostier, storms are stormier and heat is hotter.

For the past 20 years, cover crops have been at the centre of Lécaillon’s regenerative farming strategy to bring biodiversity to mono-culture vineyards. He continuously trials and monitors cover crops for frost resistance according to height and repartition. But adaption, according to season, is key. Lécaillon reduces their coverage in warm and dry continental years and increases them in oceanic years when there’s more rain.

Biodiversity, regenerative and sensitive farming lends some hope, not in the least to make better wines, but as tools for managing a more extreme climate where frost is frostier, storms are stormier and heat is hotter.

“They ensure vines are deep rooted and protected from extreme weather conditions.”

Low-lying crops are not ideal during periods of frost because they reflect away some heat, though mustard plants, with their emblematic spray of brilliant yellow flowers, offer some protection. At knee height and with relative density, they capture, store and release heat when temperatures plummet. Some growers, like Fabrice Pouillon in Mareuil-sur-Aӱ, are big believers in their frost-fighting benefits. Fabrice encourages lush plantation of cover crops incorporating five or six kinds, but mostly mustard. From a vantage point behind his coteaux champenois lieu dit, Carrière, you can spot his vineyards by the brilliant haze of yellow, as far as the eye can see, across Mareuil-sur-Aӱ and neighbouring Aӱ.

Delayed pruning can also help. For his more sensitive plots, Lécaillon slows down bud break, but only by one week - or ten days maximum.

“If you push the delay too much, after bud break, the vine’s reserves won’t be sufficient to feed a homogeneous bud break and you will end up with a very heterogeneous growth that could be dangerous for vines’ reserves in the following year,”  he says. “Knowing that our frost season can last from early April to mid-May, delaying 10 days will bring you to 20 April. And if you have a severe frost at the end of April, the vines will not be able to build their reserves. It’s a tool, but it’s not a magic tool.”

He’s also been converting to the Chablis method of pruning for the last six years, mostly because it’s less demanding of water, but there are some frost-resistant benefits.

“With Chablis, you have a vertical cane. Thanks to a vine’s acrotony [positioning of buds on a cane], you have a delayed bud break on one single cane. And in the case of late spring frost, a slight difference of temperature exists between the first bud and the last one. Moreover, in the case of frost damaged buds, it is much easier to renew a Chablis cane the following year than it is for spurs on a Cordon. With earlier budbreak, due to climate change, we need to rethink all of our practices to reduce the risks of frost damage,” he says, highlighting how plants can be saved - at least in part.

It’s 6.15am and the sun is starting to rise, it’s also the coldest part of the morning - I cannot even feel my toes. With the wood heaters doing battle, we are higher than freezing point (- 1.5 degrees instead of - 3.5 degrees) when compared with the adjacent, unprotected field.

“So it worked!” says Lécaillon to me the next day, once official data came in. All of this, for just one extra day of life, but absolutely necessary to preserve these unique pinot noirs that Lécaillon hopes will provide even more resilience into the future.

“In the Middle Ages, [pinot noir] had different weather conditions - frost, heat – but it has shown how it can adapt to the environment and climate through 1,000 years of mutation. That’s why it’s so important to give them ‘life’ because they are time machines,” he says.

Notwithstanding these efforts, for most, mustering the funds and capacity to fight frost with external resources – like burners and wind machines - isn’t at all viable. However, vineyard diversity and health supports adaption to the increasing demands of oceanic and continental pushes, including more extreme frosts.

So when frost bites, perhaps it won’t be as hard.

Words by Sara Underdown
Photography by Sara Underdown and Aurelien Ibanez