Sémillon is an important cultivar in two significant wine producing countries. In France, Sémillon is the preeminent white grape in the Bordeaux wine regions. The grape has also found a home in Australia; whereas today the country’s major white varieties are Chardonnay and Sauvignon blanc, early in the country’s viticultural development it was Sémillon, at that time mislabeled as Riesling, that was the most significant white variety.
In France, the Sémillon grape is grown mostly in Bordeaux where it is blended with Sauvignon blanc and Muscadelle. When dry, it is referred to as Bordeaux blanc and is permitted to be made in the appellations of Pessac-Léognan, Graves, Entre-Deux-Mers and other less-renowned regions. In this form, Sémillon is generally a minor constituent in the blend. However, when used to make the sweet white wines of Bordeaux (such as those from Sauternes, Barsac and Cérons) it is often the dominant variety. In such wines the vine is exposed to the “noble rot” of Botrytis cinerea which consumes the water content of the fruit, concentrating the sugar present in its pulp. When attacked by Botrytis cinerea, the grapes shrivel and the acid and sugar levels are intensified.
Due to the declining popularity of the grape variety, fewer clones are cultivated in nurseries causing producers to project a future shortage of quality wine. In 2008 17 Bordeaux wine producers, including Château d’Yquem, Château Olivier, Château Suduiraut and Château La Tour Blanche, formed an association to grow their own clones.