A garden-sharing project could save the taxpayer hundreds of thousands of pounds and help improve the health of older folk.
The claims come in a report, Growing Friendships, which focuses on the Garden Partners scheme - hailed as the first project of its kind in the UK - that matches older garden owners with volunteers to share gardening jobs.
Since 2009, the scheme has helped more than 60 garden owners stay independent and remain in their homes for longer, said the Wandsworth branch of Age UK and NHS Wandsworth, which worked together on the report.
Horticulturist and broadcaster Christine Walkden said: "This cultivates soil and people. Bringing together people who need space to grow their own with older people with land to spare benefits mind, body and soul."
Garden Partners could help to reduce the high cost of health and social care for older people, the report said. Researchers estimated that as much as £30,000 per person each year could be saved through fewer GP and hospital visits.
Taking just those older people in the survey who reported improvements to their health, researchers calculated a potential saving in one year to the NHS of £113,748. If the estimate was widened, the potential annual saving could be £500,223.
An evaluation last year found that garden owners reported improved or stable health. A third reported improved mobility and activity levels, while more than half felt less anxious.
A huge boost, however, was the lasting friendships ushered in by sharing, said Garden Partners coordinator Sarah Jackson. "We are delighted at how successful the scheme has been," she said. "Older people are staying healthier and happier for longer and everyone benefits through being part of a scheme to which they all contribute."
NHS Wandsworth commissioner Andrew McMylor commented: "It is about seeing the bigger picture, not just the immediate health needs. Garden Partners has the potential to contribute to the quality of life and health of both older and younger generations."
View the Growing friendships report.
The average annual worth of each volunteer's time given to the project was £3,065.
With 43 volunteers participating in 2011, the total annual value of their contribution was £131,795.