Roots growth in granular materials resembles the formation of openmode discontinuities driven by the invasion of an immiscible phase. The root-soil interaction is studied in this work by means of complementary full field measurement techniques based on X-Ray Computer Tomography and finite element numerical simulations. High resolution X-Ray images captured the root tip geometry in detail and an analytical function was fitted to describe the root shape. Numerical simulations provided the evolution of the stress and strain fields in the soil around a root-shaped object as it swelled in the soil mass. These analyses show that the increase in the root internal pressure creates a zone of unloading and expansion ahead of the root tip, which facilitates cell multiplication at the root tip resulting in root growth.