The vineyard that grows the grapes for Vilarnau Gran Reserva Brut Nature Vintage is located in Espiells, in the highest part of the municipality of Sant Sadurn d'Anoia. This has an exceptional microclimate because it is surrounded by the coastal range and the Montserrat mountains. Alluvial soils exist.

The four different varieties are processed separately. The harvested grains are first cooled to preserve the aromas of the skins and to prevent oxidation of the grape.

The first fermentation lasts about a month at a controlled temperature of 15°C. Following that, the four distinct grape varieties are blended together. Following that, the wine undergoes a second fermentation in which yeasts convert it to cava.

Vilarnau Gran Reserva Brut Nature Vintage is aged in the bottle for 36 months before being sold.

Vilarnau is a small family winery in Sant Sadurn d'Anoia with a history dating back more than 50 years and all of their products span over 50 hectares in Spain.