"Calçots" are the second-year resprouts of the "Ceba Blanca Tardana de Lleida" landrace of onions. The evolution of three "calçots" populations has been modeled to help farmers to plan the optimal time to harvest. Four different models that essentially differ in the type of distribution of the fitting Gompertz function parameters (lag time, maximum growth rate and the maximum attainable number of commercial size "calçots") have been tested. The model that considers a multinomial distribution of the fitting parameters showed the best agreement with the experimental data.