I. Introduction & Background Patients in secure settings often have little access to outdoor therapeutic environments. Psychiatric Intensive Care Units (PICUs) prioritise safety, producing sterile, low-stimulus outdoor areas. We present a micro-case from the Warneford Hospital CAMHS PICU, where staff, ex-service users, researchers, estates teams and arts partners co-designed a biodiverse therapeutic garden within safety protocols. The project asked: 1. How can secure units integrate biodiverse green spaces? 2. Do such spaces expand therapeutic potential? 3. Do they re-shape staff–patient relationships? IV. Future of Psychiatry • This PICU micro-case opens a testable pathway for nature-integrated psychiatry. Hybrid Green Spaces suggest that biodiverse environments can mediate risk, space, and power in secure care. • The next phase is to test whether such environments improve recovery, care practices, staff wellbeing and retention, and contribute to climate-resilient green estates. • The long-term ambition is a model in which psychiatric green estate is designed, evaluated and funded as an active component of care.