They call it Kennington’s answer to Sissinghurst and it’s the kind of place that makes people who live in cities feel they can breathe again. Just 10 minutes’ walk from the concrete jungle of the Elephant and Castle, the Roots and Shoots training scheme has transformed a derelict civil defence site into a bower of bliss.

Launched 13 years ago by the Lady Margaret Hall Settlement, which runs a number of other community projects in south London, Roots and Shoots has become a model training scheme for young people with learning disabilities, offering a two-year course in horticulture and woodwork, basic literacy and numeracy. Armed with these skills and the confidence that comes from achievement in a supportive environment, they go on to work in parks and gardens or retail centres like Homebase and BQ.

The project’s director, Linda Phillips, who describes herself as a gardening obsessive since the age of three, says the wasteland they rented from the Greater London Council for Pounds 25 a year, back in 1983, was surrounded by corrugated tin and filled with rubbish. There were two buildings from civil defence days and a solitary white lilac. It took a JCB to hack through the mass of fittings and reinforced concrete before top soil could be added and planting begin.

From the start, Linda was determined the garden should be beautiful as well as useful and this countrified corner of Vauxhall has the charm of a cottage garden, combined with the purposeful air of a busy nursery dispensing plants and advice to the neighbourhood and creating a wonderful outdoor classroom for schools. There are greenhouses and cold frames in the yard where a barrage balloon once came down and an ambulance station houses the workshop where rose arches, window boxes and garden furniture are made.

The Sissinghurst comparison is not too fanciful; the walls may be London prefab rather than Tudor brick, but they are smothered with the heavenly-scented ‘Mme Alfred Carrire’ and the Himalayan musk rambler, Rosa brunonii. Other roses have also been chosen for their fragrance: Rosa Banksiae and ‘Louise Odier’, for example, and the orange-scented ‘Veilchenblau’. Honeysuckles festoon the entrance - the garden boasts six varieties - with passion flower and jasmine tangled in their branches. There’s even a nuttery, a small copse of “Kennington cobs” and a spreading walnut tree which yields a sackful of nuts each autumn.

Visitors are amazed by the variety of trees - a superb Acacia dealbata, at its best in May when the National Gardens Scheme open day takes place, a Jacquemontii birch with its gleaming white bark, and a golden catalpa, rescued by a volunteer and now thriving in its new home.

Much in the garden has “just happened”, says Linda - the result of gifts from the project’s many supporters - so there are gorgeously random beds of plants with special associations, as well as more planned spaces such as a fuchsia walk and a variegated thyme garden, humming with bees.

Last month the wildlife meadow was parched from the drought, but bright with poppies, chicory, burdock and thistles. A pond, dug out and lined by trainees six years ago, is now fringed with yellow flag irises, rununculus, and water mint; home to frogs, newts and dragonflies and the occasional visiting duck from St James’s. Butterflies have already discovered the bog garden, planted this summer with salad burnet, clary, mullein and moisture-loving plants.

It all sounds like a lifeline for local schools, many of whose pupils live in the surrounding tower blocks. “It’s a breath of fresh air,” says Glenda King, a teacher at Walnut Tree Walk primary school. “It’s close, it’s safe and the children love playing in the long grass.” On their last visit they learned about bee-keeping from the retired policeman who looks after the hives and the day ended memorably with honey sandwiches.

Children from Ethelred nursery school also visit almost every week for nature walks, pond dipping, minibeast hunts and to bring life to projects on growth, shape, colour and texture. In what headteacher Ginnie Jones describes as “a very happy co-operative arrangement”, the trainees undertake work placements at the school and look after its small garden.

Roots and Shoots attracts visitors from all over the world who come to see how it helps young people with special needs learn new skills and cope with everyday life. Despite its achievements and highly-valued role in the community, the loss of public funding has left it facing a financial crisis and dependent on charitable trusts to keep going. With the future uncertain, the decision to plant an English oak in the meadow last year was an expression of their determination to stay. It’s reassuring to see it growing into a healthy young tree.

Roots and Shoots, Vauxhall Centre, Walnut Tree Walk, London SE11. Tel 0171 587 1131. Gardens of England and Wales Open for Charity Pounds 3.50 and Scotland’s Gardens Scheme Pounds 2.50 available from bookshops.