BACKGROUND: Hospitals can improve how they learn from patient safety incidents. The Green Cross method, a proactive reporting and learning method, is one strategy to meet this challenge. In it, nurses play a key role. However, describing its impact on learning from the users' perspective is important. AIM: This study aimed to describe nurses' experiences of learning from patient safety incidents before and 3 months after implementing the Green Cross method in a postanaesthesia care unit. STUDY DESIGN: A qualitative study with an inductive descriptive design with focus group interviews was conducted before and 3 months after implementing the Green Cross method to assess its impact. The data were analysed using qualitative content analysis. The study was conducted in a postanaesthesia care unit in a Norwegian hospital trust. RESULTS: Before implementing the Green Cross method, participants indicated limited openness and learning, including the subcategories 'Lack of openness hampers learning', 'Adverse events were taken seriously' and 'Insufficient visible improvements'. After implementing the Green Cross method, participants indicated the emergence of a learning environment, including the subcategories 'Transparency increases learning', 'Increased patient safety awareness' and 'Committed to quality improvements'. CONCLUSIONS: Implementing the Green Cross method in a postanaesthesia care unit positively impacted openness and nurses' patient safety awareness, which is crucial for learning and improving quality. RELEVANCE TO CLINICAL PRACTICE: The Green Cross method could be useful for organizational learning and facilitating learning from patient safety incidents through transparency, discussion and involvement of nursing staff.