After assemblage the wines are put into barrels and transferred to the ageing cellar which is kept at constant levels of temperature and humidity.

Grand-Puy-Lacoste selects barrels made from fine-grained Allier oak for its delicate and subtle tannin. Two-thirds of the barrels are new each year, with one-fill barrels completing the total. The Château limits its purchases to just three trusted cooperages.

Depending on the year, ageing will last from 16 to 18 months, with gravity racking every three or four months. All work is done with the greatest respect for the classic methods which have produced the Médoc's finest wines.

During the entire period of ageing, the mysterious alchemy between wine and wood is at work. Great care is constantly taken to follow the wine's development right up to the time of bottling.