John Little and I are standing in the middle of a lush wildflower meadow in Essex. It’s an idyllic scene: butterflies dance over the oxeye daisies, thyme blooms at our feet and the grass swishes as we push through it. I’m struggling to resist the temptation to break into a run of exhilaration, but it’s too dangerous. If I didn’t trip over the chimneys that protrude through the vegetation, I’d probably fall off the edge of the meadow. And it’s a 20ft drop to the ground below.

For Little’s wildflower meadow is situated on the roof of his house. “When I built the house, I just put the earth I dug out for the foundations on to the roof,” he says, “and sowed it with a wildflower seed mix. The sedums arrived by themselves.” The result is a softly fringed roof that changes colour with the seasons: blue and green in spring when the grape hyacinths and speedwells arrive; scarlet with poppies in summer; golden brown in autumn.

But there’s more to its benefits than mere attractiveness: it’s fantastically eco-friendly into the bargain. “Basically, if you have a grass roof, it’s as though your house didn’t take up any space because you’re replacing the land it stands on, just a bit higher up, which is great for biodiversity,” points out Little. “A grass roof absorbs water rather than letting it all run off. It’s great at keeping a building cool. And it helps your roof last longer,” he adds.

Evidence of Little’s passion is everywhere: a storage shed also has a thickly sprouting roof; even a derelict 2CV van, used as a play area by the children, has been covered with a thick wig of sedum.

On the face of it, Little is an unlikely sort of eco-campaigner. He lives in the Essex commuter belt near Thurrock, home of the mammoth Lakeside shopping centre. He left school at 17 and started to work for the family business, a small chain of shoe shops. But gardening, and specifically wild flowers, have always been his passion. “My grandfather had a garden, and I would help him out as a kid,” he says. “I used to sow wildflower seed in with his veg, which must have been annoying for him.”

When his parents sold their business in 1998, Little was out of a job. So, together with his brother, Robert, he formed the Grass Roof Company, and set about doing landscaping jobs.

In 2000, the local primary school, Horndon-on-the-Hill, which his daughter, Poppy, 9, now attends, asked for his help. One of the school buildings, a steel-built, south-facing structure, was intolerably hot in the summer. “They’d tried sticking things on the windows, but nothing worked, so they asked me if I could help. I suggested building a veranda roof and thought we might as well do a green roof on it while we were at it.”

Today, the school has several grass-roofed buildings and holds an annual Green Day. Twenty buildings in Thurrock, from home offices to bike sheds, now boast Little’s growing roofs, and such is the demand that he has brought out a DIY guide to creating your own, in partnership with green roof campaigner Dusty Gedge. “Green roofs are so easy,” says Little. “There’s no reason at all why they shouldn’t become a mainstream option.”

Little’s own garden reflects his liking for what he calls “in-your-face colour with minimum effort”. When he bought his four-acre plot with his wife Fiona in 1990, it consisted of scrubby grassland and a one-bedroom bungalow. They planted saplings of some 2,000 native trees around the edge of the garden, and dug a large hollow at the bottom of the lawn which, over time, has filled up into a shallow pond.

The scrubland was gradually converted, by means of kilos of seed mix, into a glorious carpet of wild flowers. Running down the hill, towards the pond, is a winding river of colour – scarlet poppies, purple viper’s bugloss and pink campions, above which tower the spikes of cardoons, teasels and Aaron’s rod.

The garden is not only intended to look good, however; it also acts as a laboratory for Little’s experiments. “Roofs are weird,” he says. “Some plants you’d think would do really well don’t work. Roofs tend to be dry, but plants that can cope with dry conditions normally have a very deep tap root. And it varies according to the substrate you use.” So some of the flowers are growing out of a base of crushed concrete; others must push their way through ceramic, or clamber over logs.

Behind the house, a prize-winning Scandinavian-style structure which Little built himself, lies a huge lawn, across which several plump rabbits are hopping. At our approach, they scutter into an impenetrable thicket of brambles, nettles and hawthorns, through which a winding circular path has been mown. Leaving this part of the garden as a wilderness was mainly a practical decision. “I can’t possibly get round it all,” confesses Little. Now, it’s a haven for birds, and the location of the family beehives.

It is no surprise that Little’s lush, eco-friendly and low-maintenance garden has had locals clamouring for the same. But his real interest is in the company’s most ambitious project on the Clapton Park estate in Hackney, East London. Since 2002, he and Robert have been responsible for maintaining the estate’s 120 acres of land. Where there used to be patches of dusty grass and scrubby rose bushes, there are now great sweeps of poppies, a communal herb bed, green-roofed garages and vegetable patches. “It’s encouraged people out of their flats and into the garden, so they meet each other,” he says. A garden modelled on this remarkable project won a silver gilt award at last year’s Chelsea Flower Show. “I think we were the first council estate to enter,” he says. “About half the judges got it, and the other half didn’t.” Shame on the stick-in-the-muds; because this return to the wild is undoubtedly the future of sustainable gardening.

To download a guide to growing your own green roof, go to www.grassroofcompany.co.uk

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