Simulation models have the potential of greatly enhancing decision‐making by farmers and researchers in Nigeria. These models however, need to be adapted before use. This study was conducted to test the phenology module of CERES‐Maize model version 3.5 under varying N rates as a step toward adapting the model in the Southern Guinea Savanna of Nigeria. Data on seven late‐maturing cultivars of maize ( Zea mays L.) grown under 0, 30, 60, 90, and 120 kg N ha −1 in the field for two seasons were used for running the model. There was a linear relationship between N rates and days to silking and maturity with R 2 values of > 0.70 for most of the cultivars, indicating that N strongly influenced phenology. Predictions of days to silking at high N rates (90 and 120 kg N ha −1 ) were close, with most prediction errors of <2 d. The highest deviations in the calibration results were 4 and 2 d for 90 and 120 kg N ha −1 , respectively, while in the validation results, they were 1 and 2 d. Similarly, days to maturity were closely predicted by the model at high N rates with <2‐d deviations for most predictions. At low N rates, however, there were greater deviations in model predictions. This shows that the CERES‐Maize model can be reliably used for predicting maize phenology only under nonlimiting N conditions. Thus, a N stress factor needs to be incorporated into the model for more accurate phenology prediction in low‐N tropical soils.