In this study, in order to select most suitable design and orientation of greenhouse for humid tropical climate of Kerala, five similar, low-cost greenhouses having same floor area (75 m2) and different ridge heights of 2.85, 3.5m, 4.15m and 4.80 m in north - south direction and one in east – west direction (4.15m height) was constructed. In all the greenhouses and open field, four varieties of cabbage were cultivated to select high yielding variety of cabbage under the greenhouse. In all the greenhouses and open field, NS - 43 gave maximum yield and NS - 160 gave minimum yield. Statistical analysis of the yield data of NS - 43 revealed that maximum yield was obtained inside 4.15 m greenhouse oriented in north – south direction (1.799 kg) and minimum yield was obtained under open condition (0.469). In all the greenhouses, yield was more for the crops provided with organic fertilizer, but the difference was not significant. Greenhouses oriented in north – south direction and having ridge heights of 4.15 m and 4.8 m, were on par in the yield of cabbage. In all other cases, there was a significant difference in yield among the greenhouses and also between the greenhouses and open field. The yield under 4.15 m greenhouse was 3.64 times more than that of open field and a benefit - cost ratio of 3.07 could be attained. The study revealed that optimal greenhouse design suitable for Kerala homesteads is gable shaped structure oriented in north – south direction with a floor area of 75 m2 provided with roof and side ventilation. The structure should have a ridge height of 4.15 m, gutter height of 2.5 m, effective side ventilation not less than 30% and effective roof ventilation not less than 9%.