Modeling the phenological development of plant is predicting the occurrence time of plant developmental stages such as emergence, flowering or maturity. The simulation of crop development is important to investigate the effects of environmental conditions, genotypes or crop management. In spring season, it is essential to predict the bolting time of radish because bolting induces poor-quality product problems. It is known that bolting in radish is not only driven by temperature, but also by vernalization. We used two curvilinear mathematical functions to figure out the relationship among growth rate, vernalization and temperature. We recorded the number of days to first visible floral bud which indicates beginning of bolting stage from field experiment serially sown with four different sowing dates in spring season using a temperature gradient chamber for model parameterization. Moreover, we tested the model performance using different periods with datasets which were independent from those used during the parameterization process. As a result, it showed the general trends observed in the parameterization dataset.