Plant architectural models have become essential tools to understand how plants access and optimize environmental resources during their development. However, using such models at larger scales, e.g. in population models, remains a great computational challenge. A continuous approach has been developed, based on the continuity equation of meristem quantity. It integrates the elementary developmental processes such as expansion, tropisms and branching rate as independent terms of the equation. A semi-Lagrangian method was developed to solve the equation on discretized domains that were allowed to deform as a result of growth. The approach was applied to a simplified case of density dependent growth in a population. The models presented in this study, still under development, indicate that more efficient whole plant architectural models could be developed using this principle. Potential applications include individual based population modelling or the design and engineering of more efficient crops.