Dr Katrin Wilhelm is a senior researcher in environmental science, heritage and wellbeing, working across the Department of Psychiatry and the School of Geography and the Environment. Dr Wilhelm is also a tutor at Regent’s Park College. Here she outlines the findings from the study, funded by the National Institute for Health and Care Research (NIHR) Oxford Health Biomedical Research Centre, which was published in the journal Wellbeing, Space and Society.
Behind the high fences of a psychiatric intensive care unit (PICU), safety tends to come first and nature tends to come last. These are among the most tightly controlled spaces in mental healthcare, designed to manage acute crises in some of the most vulnerable young people in the country. Yet a growing body of research shows that access and exposure to green space can ease stress, support recovery, and help staff cope in demanding workplaces. A new study from the University of Oxford asked a simple but provocative question: could biodiverse planting and therapeutic gardening be brought into a Child and Adolescent Mental Health Services (CAMHS) PICU without compromising safety?
A barren starting point
The Meadow Unit at the Warneford Hospital is a Tier 4 Child and Adolescent Mental Health Services (CAMHS) psychiatric intensive care unit, a short-stay ward for young people in acute mental health crisis who need intensive, highly supervised care. Like many such units, it included an outdoor space, but it had limited use or therapeutic role. The outdoor space adjoining the ward was a sloping patch of compacted, poorly draining soil with minimal planting. Staff described it as "barren" and "depressing" a space that offered little sense of refuge, and even less sense of supporting recovery or wellbeing.
Growing together: co-production in practicE
Marc Thomas, a member of the facilities team at the Trust, now in the Department of Psychiatry, planning the garden alongside Laura McCarthy, Green Spaces Co-Ordinator at Oxford Health NHS Foundation Trust.
Rather than arriving with a finished design, the co-research team treated the outdoor space as something to be created together. Over seven sessions from January to July 2024, medical and non-medical staff, ex-service users, estates colleagues, geography-psychiatry researchers and a therapeutic horticulturalist from the Oxford Health Arts Partnership shaped the garden as a group. They discussed what mattered: colour, scent, herbs for cooking, places to sit, things to touch.
Every plant had to pass a strict safety test - non-toxic, no ligature risks - and also withstand poor soil and awkward drainage caused by an anti-climb roof. Within those limits, the team chose layered planting designed to enrich biodiversity and invite pollinators, while remaining safe and manageable. Estates staff improved the topsoil and installed a cladded path to handle water run-off and allow mud-free access. On planting days, consultants, researchers, nurses, receptionists and ex-service users worked side by side in the soil, discussing where the lavender should go.
Team members Shannel Paulin, Laura McCarthy and Anna Henry start planting.
What staff and patients noticed
As the months passed, the space changed and so did how people talked about it. Staff began noticing worms in the improved soil and bees among the flowers. One co-researcher described the unexpected delight of finding "loads of worms," a small but telling sign of how sensory engagement with living soil could shift mood. Another reflected: "It was so barren out there and depressing… so actually having some wildlife there, some plants, some bees, it adds some humanity."
Not every young person could safely enter the garden, but even a view mattered. One staff member recalled a patient in longer-term segregation who became quietly absorbed in watching a flowerbed develop outside their window over the summer: "something to focus on, something to look at." The room's glass window down to the floor meant, as one observer put it, "the outside became the inside"; a different "horizon" within the same secure architecture. For staff, the garden offered what one co-researcher called "a way out of the pressure cooker" and the garden project a collaborative, non-clinical activity that temporarily softened hierarchies. Not everything was straightforward: some plants were pulled up, and ongoing stewardship proved essential.
What the team learned: Hybrid Green Spaces
Working in this small fenced in outdoor space led the researchers to name something they call Hybrid Green Spaces, which are therapeutic environments that deliberately blur conventional boundaries: between built and natural, inside and outside, patients and staff, care and operations. Their framework identifies three axes along which this hybridity can do meaningful work: risk management (showing that nature can be integrated safely through careful species selection); spatial co-production (turning a neglected corner into a place people actively shape and return to and identify with); and power dynamics (creating moments where staff and young people meet around a shared living task, rather than a diagnosis or incident).
The team argues that if NHS green spaces are treated as core therapeutic infrastructure instead of a peripheral amenity, even the most secure units could begin to support what they call "ecological collective flourishing": caring for living systems that, in turn, help care for us. Underpinning this is what we describe as an eco-biomedical model, a framework whereby living environments and human-nature-health connections are explicitly at the heart of clinical design, treating human mental health and ecological health as part of the same system rather than separate concerns. It is a replicable model, and one that the NHS, facing both workforce pressures and sustainability targets, may have good reason to take seriously.
We would like to express our sincere gratitude to the project’s co-researchers, including the PICU medical and professional support staff, ex-service users, estate services, and all Patient and Public Involvement (PPI) contributors whose invaluable insights and lived experiences significantly shaped our research outputs and this paper. Their active participation and perspectives have enriched the development of the project, ensuring its relevance and impact.