The demand for sustainable solutions in the architectural field to face climate change challenges is rapidly increasing. Nature-based solutions (NBS) have proven to be an effective strategy by integrating vegetation into the built environment. In this framework, current research focuses on developing innovative tools to facilitate the understanding and adoption of tailored, context-specific NBS. This study aims to provide a decision-making tool intended for designers and final users based on a Microclimatic Matrix that addresses plant comfort in the design phase. The research was carried out as part of the “Nature-based Solutions for Mountain Villages” project (NBS4MOV) aimed at developing a green wall prototype designed to filter and reuse domestic greywater. The vegetation survival in this context highlighted the need for plant selection and system location guidance within specific microclimatic conditions and site exposition. The Microclimatic Matrix was developed using data collected from three mountain sites in Italy’s northwestern region (Sauze d’Oulx, Prarostino, and Cuneo), representing different altitudes (high, medium, and low altitudes). This digital model gathers microclimatic data (temperature, air humidity, irradiation, shading due to the presence of obstacles, and wind speed) to identify optimal conditions for the growth and comfort of pre-selected plants. Cross-referencing these data produced a summary table that allows designers and users to receive recommendations for plant species best suited to specific conditions. This work contributes to ecological and digital transitions, laying the groundwork for a scalable tool that promotes vegetation use in architecture for sustainable building and land regeneration.