The Royal Horticultural Society has calculated that its annual Britain in Bloom competition “saved the UK more than £23million last year”.
In 2012, community gardeners carried out nearly £8million worth of free labour.
Bloom volunteers also raised £5million through sponsorship and £10million through private investment and local fund-raising activities.
The RHS consulted 76 Bloom groups, who between them planted 20million plants last year, and look after two million acres of public space – that’s five times the area of London.
RHS community horticulture manager Stephanie Eynon said people still think of Bloom as being about hanging baskets brightening-up rural villages.
“But these new survey results illustrate how the campaign is so much more than that.”
Volunteers said the campaign had improved the environment, increased civic pride, cut crime and helped local economies to flourish.