A porous, soft bed of mineral wool intended for cultivation purposes and preferably having the form of a disc (10) or mat. It can for example consist of rockwool, measures being taken so that the bed is easily moistened by water. Recesses (12) are made in connection with at least one of the two main surfaces of the bed for accumulating and spreading a wetting agent (18). The recesses can for example have the shape of round holes or slots, which are uniformly distributed across one main surface of the mineral wool bed. A plurality of bed discs (10) or mineral wool can form a package, the discs being piled on top of one another so that the recesses (12) in a first disc are closed by a second disc facing said recesses.
