This chapter focuses on the adequacy of the model to the reality of crop plants (herbaceous). The GreenLab model aims to compute biomass production and distribution among plant organs using source–sink parameters. This can be assessed in the form of graphs in which measurements on plants (plant crowns and organic series) are correctly fitted by the corresponding mathematical expressions of the model, using the parameters optimized by the inverse method. This chapter describes the use of the inverse method to fit model outputs to measured plant data. This process involves both directly measurable and hidden parameters, with the latter estimated from organic series data. Finally, this chapter discusses the application of inverse methods on cultivated plants and the integration of stochastic development for phenotypic variability. The analysis of organic series is essential for linking plant measurements to the model’s mathematical expressions, allowing for accurate growth modeling and parameter estimation across different developmental stages. Validation of the GreenLab model is established on various cultivated plants (maize, sunflower, rice, etc.).