PurposeEnvironment concerns and climate changes have led organizations to reorient their processes with a focus toward sustainability. Organizations recognize that incorporating greening in HR practices has the potential to address environmental concerns. The present study aims to focus on investigating the relationship between green human resource management (GHRM) practices and environmental performance (EP). It is premised that the adoption of green human resource practices facilitates the development of a green organizational culture (GOC) that helps the organization to gain strategic business advantage with respect to the competitors. The literature suggests that the adoption of green human resource practices among organizations is at a nascent stage. The present study focusses on understanding the mediating role of three dimensions of GOC, that is, degree, diffusion and depth in the relationship between green human resource practices and EP that has not been addressed in the empirical literature.Design/methodology/approachThe present study developed a model consisting of GHRM practices as an independent variable, the three dimensions of culture (degree, diffusion and depth) as mediators, and EP as the dependent variable. The study followed a quantitative exploratory research approach. The sample consisted of 278 employees from private and public sector organizations located in India. The hypothesized model was analyzed using structural equation modeling (SEM).FindingsThe study found the green human resource practices to be significantly related with EP of the organization. Results of parallel mediation confirmed that the “degree” dimension of GOC played a significant mediating role in the relationship between green human resource practices and EP of the organization. The other two dimensions of GOC, diffusion and depth, did not have a significant mediating role in this relationship. The findings of the study have been explained in the context of social identity theory, resource based view and ability–motivation–opportunity theory.Practical implicationsThe study provides practical insights for researchers and managers who seek to adopt sustainability objectives in the organization. The findings have the potential to encourage human resource managers to adopt green human resource management practices toward promoting a culture of greening in the organization. The importance of developing and measuring EP targets for industry leadership is also emphasized.Originality/valueThe originality of the study lies in classifying and understanding GOC in terms of three dimensions, that is, degree, diffusion and depth, following the model proposed by Harris and Crane (2002). The three dimensions help in assessing the current level of GOC. This assessment promotes the judicious application of resources by the organization and adopts green practices to foster the organizational EP.