Abstract This paper is the first of three on the coffee production system consisting of (1) the coffee plant, (2) coffee berry borer (CBB) and (3) the role of CBB parasitoids. A previous simulation model of the coffee plant was developed using data from Brazil where coffee phenology is characterized by distinct seasonal flowering ( Gutierrez et al., 1998). In contrast, flowering in Colombia is continuous with low seasonality. To capture the differences in coffee phenology and growth in the two climatic regions, the Gutierrez et al. (1998) model was modified using new data from Colombia. The modifications to the model include: (1) The effect of solar radiation on floral buds initiation; (2) An age structure population model to track the daily input and development of the floral buds; (3) The effect of leaf water potential on breaking dormancy in flower buds, and hence on the timing and intensity of flowering; (4) The incorporation of both the vegetative and the reproductive demands to predict the photosynthetic rate. (5) The effect of low temperature on photosynthesis and defoliation. Other aspects of the model were re-interpreted and refinements made to generalize its structure for use across coffee varieties and geographic areas. The model, without modification, realistically simulates field data from Brazil and two Colombian locations having different varieties, patterns of rainfall and hence flowering phenology. The model will be used as the base trophic level for incorporating CBB and high tropic levels effects, and for the analysis of management options in the coffee production system.