Over the week of 11-17 April, the four gardens are running activities that show the benefits of keeping healthy in the garden. Other gardens, charities and businesses are also signing up to take part.
Bunny Guinness, landscape architect and author of the book Garden Your Way to Health and Fitness, is supporting National Gardening Week this year.
She said: 'The wonderful thing about gardening is that, unlike repetitive exercises at the gym, it can provide all-over body fitness – raking, weeding, digging and other gardening tasks all use different muscles and test your body in different ways.
"National Gardening Week will highlight how enjoyable it is to keep fit in your garden, and how it can bring tangible benefits to health."
RHS Garden Wisley, Surrey is running a wide range of events throughout the week, including mothers' fitness classes, a preview of the film Painting the Modern Garden: Monet to Matisse, and a talk by gardening charity Thrive.
At RHS Garden Rosemoor, Devon, author Matt James will speak on 12 April about garden design, inspired by his new RHS book How to Plant a Garden. On 16 and 17 April Rosemoor will hold a Greening Grey Britain & Get Fit Gardening Weekend, with a t'ai chi drop-in demonstration and advice on how to improve grey front gardens.
At RHS Garden Hyde Hall, Essex, horticulturists will be on hand every day at 11am to talk to visitors on why they love their jobs and how it keeps them healthy. At 2pm Stella Phillips, a local health and wellness expert, will be talking about health, nutrition and offering the chance for visitors to practice t'ai chi.
RHS Garden Harlow Carr, North Yorkshire will be holding t'ai chi sessions at 10am each morning, tours of the Kitchen Garden and outdoor cookery demonstrations of healthy recipes with herbs. Garden manager Katherine Musgrove, who left office work for the world of horticulture, will talk about the links between health, happiness and horticulture in her role.
All four RHS Gardens are opening for free on National Open Gardens Day on 15 April. Wisley is also running a full day of events including a boot camp for mothers with babies, sessions with Coventry University exploring tool design and the physical effects of gardening, and tree-climbing demonstrations by the arboriculture team. Designer Adam Frost will also be at Hyde Hall to meet visitors.
Other gardens and charities taking part include Knoll Gardens, Wimborne; Kent Association for the Blind Sight Centre; and Lindengate, Wendover. Gardens can register here to take part in National Gardening Week.