Once calm is restored after the harvest, the ageing of the Grand Vin, now blended, continues for around 12 more months; at Château Phélan Ségur, the ageing is a fundamental step. The proportion of new barrels never exceeds 50%. Five coopers loyal to the property have contributed their know-how over many years. While complying with very precise technical specifications, the diversity of their respective products (origin of the wood, drying time, toasting, know-how) express themselves differently each vintage. Oxygen, oak tannins, and the aromas they bring are essential to the stabilisation of the wine and its development. Meticulous topping up of the barrels protects the wine from oxidation.