The Cognac production area lies at a junction where a microclimate and rich, diverse soil meet to produce the conditions that are favorable for the cultivation of vines used to make the spirit. The microclimate is a result of the influence of the Atlantic Ocean on the land. It is characterized by being ‘softly tempered,’ with ample amounts of sunlight and sufficient rain, and an average annual temperature of 13.5°C (48°F). This microclimate, combined with the special soil, is considered ideal for the production of high quality wines.
The secret of Cognac lies in the soil. Although the soil produces a wine that is not particularly good, it is nonetheless ideal for distillation. The soil itself is extremely diverse, ranging from open country chalky soils, to plains with red clay earth, to green valleys. Quality variations in the soil are based on the amount of chalk present, the hardness of the chalk, and the amount of clay mixed in with the chalk. For example, more chalk in the soil increases its quality; the softer the chalk, the better; and the less clay in the soil, the better its quality. Chalk in the soil is important because it retains humidity (moisture). Also, the chalk-flecked soil reflects light and so helps to ripen the grapes. Grand Champagne has the softest chalk and the least clay; therefore, it is considered the best soil and produces the highest quality Cognacs.