The hydric and nutrient element nutrition of cucumber plants (cv. Alaska) cultivated in a green house on rockwool, was studied by following the daily net uptake by the plant of nutrient elements and water and the changes occurring in the nutrient solution and drainage solution in order to stablish the actual demand of the plant for each nutrient element and the relation between the uptake of each ion with the uptake of other ions under the agriclimatic conditions of this experiment. The accumulative uptake of water and nutrient elements by plants over the whole cultivation period, from 18 days after transplanting, fits quadratic curves, since the absorption rates increase constantly as the plant develops (positive quadratic term). The slopes of the curves corresponding to nutrient element uptake increased in the following order: nitrate > potassium > calcium. The results demostrate that water uptake is closely related with sulphate, phosphate and sodium ion uptake. The absorption of nitrate was related to the uptake of calcium, magnesium and chloride; the potassium uptake was related to the uptake of ammonium and the calcium uptake is related with nitrate ion uptake.