“Mental health is defined as a state of well-being in which every individual realizes his or her own potential, can cope with the normal stresses of life, can work productively and fruitfully, and is able to make a contribution to her or his community.” (World Health Organisation 2014)
Approximately 1 in 4 people in the UK will experience a mental health problem each year
In England, 1 in 6 people report experiencing a common mental health problem (such as anxiety and depression) in any given week 
“Spending time in the natural environment – as a resident or a visitor – improves our mental health and feelings of wellbeing. It can reduce stress, fatigue, anxiety and depression. It can help boost immune systems, encourage physical activity ….. It can combat loneliness and bind communities together.” HM Government 
Losing our connection with Nature
18% of the UK adult population spend time in nature less than once a month, some people never. 
Three-quarters of UK children spend less time outdoors than prison inmates, who are legally entitled to 1 hour a day outside.
“Social and therapeutic horticulture (STH) is the process of using plants and gardens to improve physical and mental health, as well as communication and thinking skills.” (Thrive, The Society for Horticultural Therapy)
There have been many projects, studies and academic reviews into the role of nature, and more specifically gardening, over the last 10 years, some covering a wide spectrum of the population and some focused on interventions for specific client groups.
A comprehensive review of nature-based interventions for mental health care commissioned by Natural England in 2016  concluded that meaningful nature-based activity especially in a social setting brings a raft of mental health benefits. These can be summarised as Psychological restoration and increased general mental wellbeing promoting Improved happiness, satisfaction and quality of life.
Of the projects included in the review STH formed the largest number with the most quantitative and qualitative data on the outcomes.
Ecominds: the mental health charity Mind funded 130 ecotherapy projects across England between 2009 and 2013. 12,000 people from all walks of life were supported by trained professionals as they took part in gardening, food growing or environmental conservation work. They found it improved their mental and physical wellbeing, helped them meet people, get more involved in their local community, learn new skills and develop new interests. 
One of the earliest reports into the benefits of nature specifically for people living with dementia was commissioned by Natural England in 2013 .
Greening Dementia concluded that evidence suggests that social interaction and access to the outdoor
s and nature is important for people living with dementia and that these activities have an important role in their quality of life.
Gardening or Therapeutic Horticulture?
Most studies differentiate between gardening at home and participation in a planned, structured STH programme led by a trained practitioner. In between lie community gardening projects. Overall the benefits are the same across all three of these but the needs of the individual drive which activity is most valuable at any given time. Gardening at home can maintain good mental health and build resilience in the general population. Attending a community gardening group can add the benefit of learning from other gardeners and social engagement, suited to some people at risk of social isolation and deteriorating mental health. A formal STH programme is designed to benefit individuals with specific needs, including learning disabilities, physical and mental health support needs and dementia, with activities chosen, adapted and assessed to achieve defined outcomes. Here, gardening and nature based activities are used as a medium to deliver the desired therapy and the health outcomes are the key objective.
The UK Green Care Coalition website carries information on the different types and applications of ‘green care’ including STH. The coalition was established in 2016 to promote the commissioning and use of Green Care services.
The 2017-18 Survey of engagement with the natural environment  indicates that 18% of the UK population spend time in nature less than once a month, some people never. The results also show that more people are frequently visiting nature than ever before and that health and exercise was the main motivation for spending time in the natural environment indicating increasing awareness of the wellbeing benefits. However in the group who rarely spent time in nature the only reason cited that has increased over time is ‘poor health’ which may suggest difficulty in accessing the natural environment from precisely those people who could benefit the most.
The survey considered the ‘natural environment’ to include green, blue and open spaces in and around towns and cities as well as the wider countryside and coastline, crucially away from home. Given the established wellbeing benefits of gardening whether at home, in a local community setting or through an STH programme tailored to participants needs and capabilities, there is surely scope for gardening to increase meaningful engagement with nature amongst this latter group.
- MIND Mental health facts and statistics, 2017 LINK
- A Green Future: Our 25 Year Plan to Improve the Environment, HM Government Defra, 2018 LINK
- Monitor of Engagement with the Natural Environment, Natural England, 2018 LINK
- Survey commissioned by the laundry detergent brand Persil, reported by The Guardian newspaper, 2016 LINK
- A review of nature-based interventions for mental health care, Natural England Commissioned Report, 2016 LINK
- Feel better outside, feel better inside: Ecotherapy for mental wellbeing, resilience and recovery, MIND, 2013 LINK
- Greening Dementia, Natural England Commissioned Report, 2013 LINK