Green wing: Emma Townshend meets volunteers at Charing Cross Hospital's restorative garden

"I find," says Maggie with a smile, "that I take more and more interest in worms." Maggie Brennan is a horticultural volunteer working in a garden at the edge of Charing Cross Hospital, west London, and she is sitting with me, taking a brief break on this sunny cold day, trying to explain just what it is about gardening that she loves. "When you're gardening, you can really be in the moment," she adds. "Not worrying about the past, and what you did then, or fretting about the future. Lots of people don't really live in the present at all. Gardening brings you right back to the present, and centres you there."

Brennan is one of a team who come together once a month to renew this plot and take care of all the seasonal tasks: from pruning and clearing leaves to watering and feeding as spring progresses. The head of the team is Rosemary Creeser, who re-trained as a garden therapist after her own experiences of serious illness. Creeser is clear about the benefits of the open air and the earth: "It's learning to be present, it's learning to enjoy your time well."

Brennan agrees: "It's your feet on the soil, it's your hands in the soil, the blue sky, the green plants."

It's appropriate that she herself is a Maggie, for this garden surrounds the London Cancer Caring Centre run by the charity named Maggie's after its founder, Maggie Keswick Jencks.

The charity runs 11 centres at present, and this one, like all the others, welcomes patients from the hospital to a sort of clubhouse-cum-retreat for those affected by cancer, where staff are always on hand to help with any kind of question, and there's always a cup of tea and a biscuit on offer.

The Fulham building was designed by Richard Rogers; it nestles into its Dan Pearson-designed garden with confidence and a sense of luxurious peace that feels rather unexpected just beyond the NHS hospital car park full of shivering smokers. "People come to us as designers because our gardens have a sense of peace, and a spiritual quality," Pearson explains, having arrived to cheer along his team of volunteer gardeners by planting some new witch hazels. "They're gentle places, they make the building feel wrapped in greenery."

Brennan has particular reason to see the value of the centre, for she herself has had cancer, as have most of the other volunteers. Having survived the illness, they all remain gardeners. "I actually feel it energises you," explains a fellow team member, Maureen McCullum, "when you get back to roots, when you get away from civilisation. I worked in an office, miles away from the window. Now, I see all the seasons, and they're all wonderful. It makes you realise life will carry on."

Spring steers

Drudgery and March hailstorms can make you doubt it, but, as MacCullum says, life does go on. Here are some early spring picks from the Maggie's team:

Maureen McCullum recommends Viburnum odoratissimum: "They have beautiful leaves, so glossy, and the most fantastic fragrance." £11.50 a plant,

Maggie Brennan "Daphne. The first time I smelt it, it was just absolutely stunning, and there's something about cold air and scent this time of year." Try later-flowering Daphne tangutica Retusa. £20.49 a plant,

Rosemary Creeser "The building here is completely wrapped in Sarcococca hookeriana (below), underplanting the little birches, and it adds a wonderful evergreen weight." It smells delicious, too. £6.99 a plant,