Greenhouse technology provides favorable microclimate for year round cultivation of crops. Floricultural production in the greenhouse is an attractive venture for subtropical India due to its economic and aesthetic value. However, production and quality of flowers suffer due to high summer temperatures. Hence, development of a reliable model to predict the microclimate of greenhouse is necessary to manage the crop production and to optimize the design. Experiments were conducted in two different shape and size of greenhouses to evaluate the microclimate and crop performance. A simple dynamic model was developed to predict air temperature, vapor pressure and canopy temperatures. Submodels of natural ventilation and crop transpiration constituted the sensible and latent heat transfers in the greenhouse. The model was validated for Gerbera crop cultivation during winter and summer seasons. Good agreement was found between the predicted and observed values of temperature with RMSE values of 0.73 degrees C and 0.87 degrees C during winter and summer seasons, respectively. Sensitivity analysis of the model showed that width of side opening and angle of roof vent influenced the model performance considerably. It was concluded that the model can be used as a design tool for prediction of microclimate in the greenhouse for floricultural production. (C) 2010 Elsevier B.V. All rights reserved.