THERE is a garden I know that is so magical that I have often made a detour on a dog walk to see it. It has a public right of way running through it that allows everyone to engage with the plot, while it somehow conveys the intimate feel of a loved back garden.

Soon enough, I found myself chatting with its creator, Steve. I was surprised to learn that he had come to live there by accident, at a difficult stage in his life, with no intention of making a garden. A therapist had suggested that he tried caring for a plant, as a way of taking the focus away from himself. And so the garden was born.

Steve is also candid about the fact that it would not have matured in the wonderful way it has without the interaction with, and encouragement from, passers-by of all ages. This story encapsulates, for me, the therapeutic aspect of horticulture. Gardening is about caring creatively; in so doing, you can exercise controls in what can seem a chaotic world, and provide time for mindful solitude, as well as sociability.

Gardens and gardening can have specific benefits for different groups of vulnerable people. Homebase, in partnership with the Alzheimer's Society, has commissioned the designer Adam Frost to make a garden for this year's Chelsea Flower Show. It will be called "Time to Reflect", and will draw attention to helping people with dementia, although Adam's aim is also to remind us how well-designed outdoor spaces can help us to stop and relax.

Any garden can provide the benefits of fresh air and exercise. Gardens adjacent to a care home for people with dementia may stimulate residents' reminiscences connected with their own garden in the past. It is a given that paths should be wheelchair-friendly, but they should also be fluid - perhaps in a figure of eight - and certainly avoid abrupt ends.

The route should be clearly marked by containers, specimen plants, or hard landscaping. Individual and shared seating allow for choice between solitude and company; and, in each case, plants should be available to smell, stroke, and study close up, Shelters from sun and rain are also important.

Greenfingers is a small but nationwide charity dedicated, as part of its "Rosy Cheeks" appeal, to building gardens at children's hospices around the UK. It has begun work on the 42nd project, at Chestnut Tree House children's hospice, in Sussex, a fully accessible magical woodland walk that will offer families who use the hospice a chance to spend precious time together in a natural environment away from the bedside. They are enjoying wonderful support: people are donating time, skills, and resources.

Garden centres across the country will be running special events and promotions on 14 March, as part of Garden Re-Leaf Day, to raise money for Greenfingers. If you find yourself with a bootful of plants after this, and your heart sinks at the work ahead, just remember: gardening is good for the soul.

gardenreleaf.co.uk