Grand-Puy-Lacoste enjoys an exceptional terroir. The soil is gravel, the alluvial stones which ensure an excellent drainage of rainwater.

The originality of the Médoc's soil comes from two million years of history. Its gravel is the geological product of the quaternary era, when stones brought from the Pyrenees by the Garonne were deposited along the banks of its estuary, the Gironde.

Today layers of varying depth are composed of gravel mixed with sand and a little clay. They form "gravel outcrops”, separated by small streams called "jalles” in the local dialect which drain water to the Gironde. In Pauillac these vast and numerous outcrops are recognized as being particularly well-suited for top quality vine growing.

This gravely soil has the advantage of absorbing heat during the day and releasing it to the grapes at night, eliminating excessive variations in temperature and promoting even ripening in the grapes.

The vineyards of Grand-Puy-Lacoste are planted on very deep gravel, forcing the plants to develop an extensive root system to find the water and nourishment needed for growth. Because of the soil's poor quality, the vines "suffer for their beauty” and become more resistant with age, producing fully developed grapes with a fine sugar-acid balance. Cabernet Sauvignon is particularly well suited for this type of soil: it's a late ripening variety which needs a longer period to reach maturity than Merlot, so the heat given off by the gravel helps accelerate its growth.