What makes this cellar in Vertus different

In Vertus, at the southern end of the Côte des Blancs, Doyard-Mahé ages its Champagnes in a cellar dug in 1970 beneath the Moulin d'Argensole. This cellar has a particularity few Champagne cellars share: it is ringed by underground springs. That is what gives our bottles a singular ageing — and it is the heart of the visit, which we open by appointment.

A cellar ringed by springs

The slope of Vertus is made of belemnite chalk, a soft, porous rock that can hold up to 300 litres of water per cubic metre. Beneath the Moulin d'Argensole this chalk is permanently crossed by underground springs and water flows — the place is not called “Chemin des Sept Moulins” (Seven Mills Lane) by chance: it took water, and plenty of it, to turn seven mills.

Water has one very simple but decisive physical property: it takes an enormous amount of energy to change temperature. A body of water circulating around a cellar therefore acts as a natural thermal flywheel. Outside, the year swings from −5 °C to 35 °C. Inside the cellar, almost nothing happens.

What that changes, concretely

A slower second fermentation, finer bubbles

The second fermentation in bottle — the prise de mousse — is the moment when Champagne makes its bubbles. At a constant 10-12 °C the yeasts work slowly: six to eight weeks instead of a few weeks in a warmer cellar.

That is not a detail. The slower the fermentation, the more finely the carbon dioxide dissolves and binds to the wine's proteins. The result in the glass: very fine bubbles rising lightly to the surface to form a persistent collar. Yeasts that suffer no temperature shock also avoid producing the stress aromas that blur the freshness of the fruit.

Humidity protects the bottle

In air saturated to 85-95 %, nothing dries out. Bottling corks and crown caps keep their elasticity, the seal stays perfect, and there are none of those micro-ingressions of oxygen that age a wine too fast. A dry cellar, by contrast, draws moisture out of the cork, which eventually lets the gas escape.

Resting on the lees, free of disturbance

Once the sugar is consumed, the yeasts settle at the bottom of the bottle: these are the lees. They then break down slowly, releasing mannoproteins, amino acids and peptides. This is where notes of brioche, toast, hazelnut and dried fruit come from, along with the round texture that softens acidity.

The chalk returns to its first calling

There is a kind of loop in all this. The chalk of the Côte des Blancs is made of the skeletons of marine organisms accumulated in the Cretaceous, when Champagne lay beneath the sea. In contact with the springs, that chalk becomes again what it always was: a sponge and a mineral filter. The cellar is the meeting point of rock and water — and it is this purity of air that lets the mineral, saline side of our blanc de blancs come through.

Visiting the cellar

The visit takes you down into the 1970 cellar: bottles undergoing their second fermentation, riddling racks, bottles on laths resting in the dark. The different stages of production are explained before moving on to a tasting of the estate's cuvées. Every step of production is set out on our craft page.

• Hours: Monday to Friday, 10 a.m. – 12 p.m. and 2 p.m. – 5.30 p.m.; Saturday 10 a.m. – 12 p.m.
• Groups: 2 to 20 people, by appointment only.
• Address: Moulin d'Argensole, 28 Chemin des Sept Moulins, 51130 Vertus — twenty minutes from Épernay, on the Champagne tourist route (Côte des Blancs loop).

To book, use the reservation form or call +33 3 26 52 23 85. To understand the terroir around the cellar, read also Vertus, Premier Cru of the Côte des Blancs.