Instead, a heavy clay and limestone base dominates this area, resulting in poorer-draining soils, delayed ripening, and higher acidity levels in the wines.
These factors mean that, over the last few decades, many Saint-Estèphe's winemakers have increased their emphasis on Merlot, as it performs better on clay-rich soils than Cabernet Sauvignon. Because wines from here have traditionally been rather austere and tight in youth, Merlot also serves to soften the texture. Clay soils ability to retain moisture can come in handy during the occasional drought-like summers that have been known to bring a Bordeaux vintage to its knees. Other grapes permitted are Cabernet Franc, Carmenère, Côt (Malbec) and Petit Verdot.