Modular tank (1) for intensive culture of green roof comprising an upper compartment adapted to receive a culture substrate, a lower compartment adapted to receive a water reserve, and at least one block (2) porous capillary allowing the water of the lower compartment where it is stored to migrate by capillarity to the upper compartment, this at least one porous capillary block being characterized by its open porosity material and having a tortuosity which allows to slow the release of this water by adapting it to the increasing the suction tension of the plants, its elongated shape and its total volume sized to be able to store at least 0.05 times the water capacity that the lower compartment is able to receive. In addition to the tortuosity of the material which hinders the return of water, the invention also comprises specific braking means of the water rise placed between the at least one porous capillary block and its water contact surface with the culture substrate. , These means leaving a water contact that according to a maximum of two generatrices (4) along the at least one block in its greatest length. Bac modulaire (1) pour culture intensive de toit végétalisé comportant un compartiment supérieur apte à recevoir un substrat de culture, un compartiment inférieur apte à recevoir une réserve d'eau, et au moins un bloc (2) poreux capillaire permettant à l'eau du compartiment inférieur où elle est stockée de migrer par capillarité vers le compartiment supérieur, cet au moins un bloc poreux capillaire étant caractérisé par son matériau à porosité ouverte et possédant une tortuosité qui permet de freiner le relargage de cette eau en l'adaptant à l'accroissement de la tension de succion des plantes, sa forme allongée et son volume total dimensionné pour être apte à stocker au moins 0,05 fois la capacité d'eau que le compartiment inférieur est apte à recevoir. En plus de la tortuosité du matériau qui freine la restitution de l'eau, l'invention comporte au
