This study details the development of a plant STEAM education program aligned with the Grade 6 elementary school Korean national science curriculum, using a regionally linked curriculum as its design framework. The primary objective was to investigate the plant program's effectiveness in enhancing elementary students' environmental competencies. Ninety-one Grade 6 students, divided into an experimental class (n = 46) and a comparison class (n = 45), participated in the study. Data were collected before and after the program through an assessment tool designed to evaluate environmental competencies, in addition to collecting field notes and student learning outcomes, which were subjected to qualitative and quantitative analysis. The results revealed significant improvements in students' environmental competencies, with notable enhancements in exhibiting environmental sensitivity and displaying a sense of environmental community. This study offers an illustrative model showcasing the integration of plant-related, STEAM, and a regionally linked curriculum in education.