Legally the Cognaçais can use a number of grape varieties, although the choice is largely theoretical. The Ugni Blanc accounts for over 90% of the total area, with the rest being Folle Blanche and Colombard. Cognacs rise to fame was based on two varieties – the Folle (later known as the Folle Blanche), and the Balzac, both of which were despised by local wine makers. In the 18th Century the Colombard, which made sweet wines from the Borderies cru, also rose to prominence. Today the Colombard’s inclusion in modern cognacs is limited, as it finishes very short and fails to last on the palate, as opposed to the best cognacs with their great depth and finish.
The Folle Blanche prospered during the 18th & 19th centuries. The wine it produced was so acid as to be virtually undrinkable, but was ideal for making cognac. After the Phylloxera it was found that when grafted onto the American rootstock it flourished too vigorously. The bunches were too tightly packed and the grapes in the middle were susceptible to grey rot which could not be accessed with sprays.
So the Ugni Blanc triumphed. As the name implies, it was originally an Italian variety, the Trebiano Toscano from the hills of the Emilia Romagna near Piacenza. In France it is the most widely planted vine, but it’s popularity is in marked contrast to it’s quality making a highly acidic and short wine (ideal or course for distillation). The vines were pruned hard to reduce yields, but with improved viticultural techniques yields have risen sharply. Even with a high level of regulation by the BNIC, 8 hectolitres of pure alcohol per hectare are produced every year, and most growers could increase on this by up to 50%. There are problems though – the grapes ripen late and produce a weak wine. In hot summers they run the risk of becoming too rich, with strengths of up to 12% making flabby cognac, as was the case in the 1989 vintages.