This study was conducted in order to elucidate the problems in organic greenhouse cucumber growing. Two dosages of farmyard manure (15 or 30 tons ha(-1)) were tested during autumn and spring seasons of 2003 and 2004. Fruit samples were analyzed for their quality parameters (color and total dry matter content of fruits and total soluble solids, EC and pH of fruit juice) at three weeks intervals during the harvest period. Generally, there were no significant differences with respect to fruit properties between manure dosages in both growing seasons. Higher yield was in the farmyard manure application of 15 ton ha(-1) (5.92 kg/m(2)) compared to the application of 30 ton ha(-1) (3.95 kg/m(2)) in autumn season, whereas higher total yield (17.84 kg/m(2)) was obtained from the plants grown by the application of 30 ton ha(-1) farmyard manure in spring, but the difference between treatments was not statistically significant.