That's because he gets the structure right. Bell's honed-down approach to a garden makes that more important than the dressing. Gardeners building up to show manicured wild gardens at the Chelsea Flower Show just wouldn't get his drift. There are no herbaceous borders and not many plants, but don't be fooled by the stony backyard belonging to Michael Craig Martin, a painter and lecturer at Goldsmiths College, London, or the Zen-like simplicity of the single plant on a roof for sculptor Anish Kapoor: these aren't trendy clones of down-sized Japanese gardens, but intelligent resolutions of difficult spaces for artists who want outdoor rooms with a view.
"Appropriate" is a mannerly word Bell uses a lot, but you understand what he means when he explains that he only visits Britain's most famous garden, Stourhead, on his computer. That way he can use his Photoshop program to airbrush away the rhododendrons - "a Victorian addition from the Himalayas and completely inappropriate" - which in his view disfigure William Kent's 18th-century design.
"Context" is a buzzword with architects, one that Bell takes to mean responding to the site. Sometimes getting the context right requires radical changes: in the US, he persuaded a famous client, Martha Stewart, who markets lifestyle on television and in her magazine Martha Stewart Living, to put most of her real estate on Long Island on the flight path for birds heading to Patagonia, by turning flowerbeds into marshlands set about with silvery paper-stemmed birch groves and flag irises. On other sites it can be as simple as a planting plan: Marco Pierre White's Mayfair restaurant, the Mirabelle, will be fragrant with mimosas and vines when it opens this month.
Reducing and simplifying is an exacting business. At first, it seems there is less and less to look at. But listen to the minimalist architect John Pawson - with whom Bell works - in his book Minimum (Phaidon): "As you go on attenuating, honing, you come to a point at which you go through a barrier and pass through into a kind of mirror world, in which you see ... not emptiness, but a sense of richness."
Jonnie Bell composes his gardens as if they were abstract paintings. First he frames them. The frame might be a barricade of espaliered branches fanned out on wires, a fence of figs or a screen of oak. Sometimes a lattice casts curious grid patterns of light and shade upon super-smooth flagstoned floors. Or he scours Scottish beaches for the right stones. Doors and gates are hinged to open silently and smoothly into secretive gardens. Only then does he plant anything.
His own garden in London, which he shares with Annie, this magazine's food writer, and their children, is a reed bed with big plashy bulrushes, home to toads and frogs but no newts yet. Bell likes it best in winter when the reeds snap and buckle and fold back on themselves like ancient Egyptian scrolls to puff wisps of wools across the yard.
Bell turned the tiny rooftop terrace belonging to Anish Kapoor into a meditative oasis with just a frost of white marble pebbles and a single fig tree rising out of an earthen pot. "It's a bog-standard ficus carica but it took me months to find one the right size and shape," he says. White on white like a blank canvas, except for that shapely tree with its sensuous summer-time promise of sun-warmed figs, this is a minimalist garden. To the uninitiated, that's as desirable as dining out on a single quail's egg. To the satiated it is soothing.
In a tiny 25ft by 6ft backyard belonging to Michael Craig Martin, Jonnie Bell made another abstract painting, this time in shades of grey with Scottish stones and an oak screen that silvers as it ages. He built the screen high to hide the back view of a pub but it has the effect of pulling down the sky into the space. Michael Craig Martin lives and works in this studio and calls his backyard garden his "outdoor room". What gives him the most pleasure in his light-filled studio is a constant awareness of the sun marking the hours of the day. Only one thing is missing. A tree. Bell, who writes scholarly appraisals of British trees for the quarterly Hortus, will take months to find exactly the right height of tree with a slender stem and an umbrella spread, because the wrong shape will jar in the composition.
He's just as picky about plants. "Too often, garden design is in the hands of plantsmen," he says. "People who pretend to be modern garden designers just can't resist chucking in a herbaceous border with great drifts of lilac and mauve. They don't pay that much attention to the site, or to what is indigenous." Instead of a planting plan, he handed a French client in Provence Virgil's Georgics to remind him of the seasons and when "to scythe, sharpen and sow". Then he opened up the views to the fields of lavender all around, and designed a steel gauze gazebo to set over a rustic stone retreat for shade, "just the ghost of a structure", he says. "The important thing for gardeners is never to colonise a place. Keep to native plants. If you colonise, you limit your horizons."
One of his heroes is Christopher Lloyd, who ripped out the tasteful rose garden at Dixter in Sussex, where Lutyens built a house, and planted 500 red hot pokers. "Quite a facer. Irreverent but refreshing," Bell says. That's why he doesn't like the minimalist tag planted in his gardens. He can be excessive too. But, generally, as you can see from these little London gardens furnished with stone and wood, less is more. More or less
Jonnie Bell can contacted on 0171-243 3181. Post-structural: the fence in Michael Craig Martin's garden (right) screens the back of a pub and draws light down into the space. Far right: Anish Kapoor's tiny rooftop terrace becomes an oasis of calm with a frost of white marble pebbles and a single fig tree. Kapoor's other small terrace (above right) is a moss-framed rectangle of black marble pebbles and a Gunnera manicata, which will grow huge in the summer, filtering a greenish light into the bathroom