During 2011 at Simon Fraser University, the Faculty of Education hosted the implementation of a pre-service teacher education program with an emphasis on sustainability and environmental learning. This cohort, termed SEEDs (Sustainability Education in an Environment of Diversity), enrolled 32 teacher education students in an intensive 12-month teacher certification program composed of equal parts campus and field-based seminar experiences and practicum placements in a variety of K-12 school classrooms. While reflections on the overall experience from students and community stakeholders were positive, the potential of the model (with students, Faculty Associates, and School Associates fully supporting each other) was not fully realized. Stakeholders involved in the development and implementation of the SEEDs module were left feeling melancholy as we discovered "dark matter" in our difficulties with implementing a true community of practice for environmental learning hosted within the structure of a large and diverse teacher certification program. This paper focuses on the reflections of SEEDs students, instructors, and courses facilitators working in the program, but more importantly recounts the constraints faced by the community as it attempted to reconceptualize the dominant (hegemonic) approach of teacher development common in Canadian teacher certification programs.