Plant-based concretes are increasingly used as building materials thanks to their insulating properties and their reduced environmental impact. However, existing studies show that it is still impossible to predict their mechanical performances from their initial formulation. This article presents the first results of a project which aims to control the mechanical performance of plantbased concretes and to define compatibility indicators between mineral binders and plant particles. In this study, the impact of six plant species on the hydration kinetics of Portland cement and pozzolanic cement is evaluated by isothermal calorimetry. The addition of plants leads to shifts in the heat flux curves, which are very variable according to the nature of the vegetal and of the binder. These results are generally attributed to certain components of the plants, such as sugars and phenols which have a retarding effect on the setting of cements.