AbstractThe water loss from tall fescue cv. S170, perennial ryegrass cv. S24, Italian ryegrass cv. RvP and timothy cv. S352 when dried as a thin layer under controlled conditions at 20°C and r.h. 50% is described. Comparisons were made on six occasions between mid‐April and mid‐June. Tall fescue dried faster than the other species and the time to reach a water concentration of 0·2 g water per g dry matter varied little between the six harvests. In contrast, the drying time for the ryegrasses and timothy increased to maximal values in mid‐May and then fell. Drying time was dependent on the initial water concentration of the grass, the ratio of leaf to stem and on the amount of true stem exposed to the drying environment. The practical implications in relation to haymaking are di