This study aimed to establish a fully 3D modeled immersive virtual reality (IVR) system for primary school students learning about plants and evaluate teachers' perceptions of the usage of the system and pupils' flow experiences and learning attitudes. There were 5 teachers with expertise in science and IVR experience who were first interviewed to understand their consideration of the limitations of teaching about plants in the classroom. The framework and script of the learning content for the IVR system, as well as the user interface and function were then comprehensively described. Another 10 teachers were invited to evaluate the appropriateness of the system for fifth-grade students to learn about plants. These teachers generally expressed positive attitudes towards exploiting the IVR system for their teaching. Moreover, there were 37 fifth-grade students contributed to the evaluation of the system. The results indicated that the IVR system was capable of offering the pupils perceptions of antecedences to achieve flow such as task challenge, clear goal, instant feedback, well control, and playability, and aroused their flow experiences, particularly regarding autotelic experience and concentration. This study also verified the relationships between the pupils' flow experiences and learning attitudes. The crucial roles of flow perceptions including playability, challenge, and autotelic experience in the pupils' learning attitudes were further identified. According to the results of the evaluation from the teachers' and students' perspectives, several practical and academic implications of this study are proposed.