Co-fermentation is the practice in winemaking of fermenting two or more grape varieties at the same time when producing a wine. This differs from the more common practice of blending separate wine components into a cuvée after fermentation. While co-fermentation in principle could be practiced for any mixture of grape varieties, it is today more common for red wines produced from a mixture of red grape varieties and a smaller proportion of white grape varieties.

Co-fermentation is the practice in winemaking of fermenting two or more grape varieties at the same time when producing a wine. This differs from the more common practice of blending separate wine components into a cuvée after fermentation. While co-fermentation in principle could be practiced for any mixture of grape varieties, it is today more common for red wines produced from a mixture of red grape varieties and a smaller proportion of white grape varieties.