The study for the charity, Thrive, found time in the garden aided relaxation, improved social skills and gave a sense of achievement.

The three-year study by a Loughborough University team looked at over 900 gardening-based projects.

The team said results showed gardening was a valuable kind of therapy.

Building confidence

Groups involved in the study included those with learning difficulties and serious mental health problems, the long-term unemployed, victims of torture, and people with physical health problems and disabilities.

The research revealed that being outside in the fresh air, undertaking the physical exercise that gardening demands, working with nature and nurturing plants, all helped to improve clients' health and well-being.

Dr Jo Aldridge, one of the principal researchers, said: "Many of those who took part in the study were socially excluded and institutionalised in their daily lives.

"They had little opportunity to get out in the fresh air and work alongside others.