Vegetation has large applications in bio-engineering practices. Root system provides an additional reinforcement whose effects depend on the biotechnical properties. This study evaluates the changes in the additional root cohesion under different conditions of plant-growth, e.g., exposure to light, water and nutrient availability. These determine different root system development in terms of root length, density, root diameter profile, total number of roots. A root topological model is used to simulate the root architectures, which are then coupled with a Root Bundle Model to estimate the additional root strength. Finally, this study proposes a rigorous method to compute the additional root cohesion from the tensile strength.