A man who has lived among plants for 30 years is  expected to have a green thumb. But Patrick Blanc has opted for the pinkie instead, with a disturbingly long nail slicked over in glittering emerald polish. He is a radiant evergreen, bedecked in Peter Pantone snakeskin shoes, khaki safari trousers, and a lime disco shirt, with mesclun highlights in his blond hair. Even his vice is green: He smokes menthols. Frankly, it wouldn’t take a genius to pick the botanist out of a lineup.

Getting your hands on him is another matter entirely. The creator of the “plant wall,” a living canvas for indoor and outdoor vertical space, is in high demand. His trademark technique for a top-down, no-fuss, no-muss irrigation system, not to mention the 30 years of botanical research on three continents under his belt, have made him an urban garden guru. Recent creations include the hip Pershing Hall hotel and the Fondation Cartier in Paris, the swanky Siam Paragon mall in Bangkok, boutiques in New York and Paris, and restaurants in Los Angeles and beyond. With the lavish opening of the Jean Nouvel–designed Musée du Quai Branly in Paris in June, where he created a lush, 8,600-square-foot façade with 15,000 plants, big-scale commissions are flooding in.

Blanc’s work began, however, with homes—notably his own, a tropical rainforest doubling as an apartment on the outskirts of Paris, in Créteil. Even as major jobs began to elbow out most private commissions, some homeowners managed to persuade Blanc to create outdoor vertical gardens, seeking to add a “rural” element to their city views. The indoor vertical garden—Blanc’s true calling as a low-light specialist—however, had to wait until 2004, when Jean-Marc Dimanche phoned  up from his 4,400-square-foot home, which was under  construction in the Left Bank’s 14th arrondissement, with an idea for the 20-by-23-foot interior wall that  was beginning to take shape.

“I told him I’d found the perfect spot, and he said, ‘Fantastic! I’ve finally found a loon like you crazy enough  to put the wall inside his house!’” Dimanche remembers. The adventure had begun. Two years on, it is hard to imagine the space without its forest canopy, a canvas of the living with some 150 tropical, low-light species assembled in harmony. It begins as a field of texture  near the ground, then runs through violet and amber arcs of flowers and other ruddy blooms, broadening out near the ceiling into trees that overhang the room like  a sheltering forest. It strikes an easy balance with both the raw elements of the home (concrete, metal beams,  a transparent glass elevator that pierces the heart of  the five-story structure) and the charming bric-a-brac  of a family’s everyday existence (country-kitchen stools, orchids coaxed into bloom, battered leather armchairs that sigh beneath your weight). The effect, Dimanche agrees, is “very calming.”

Though he always kept a flat in Paris to be close to the communications agency he runs, his wife, Vivette, and their children moved from outside Rambouillet,  an hour’s drive from the city, where they had renovated a longère, an ancient, low-lying elongated house nestled into a garden. “Basically, when we moved our house shifted 90 degrees, and so did the garden,” Dimanche says. “This house, for us, has meant a whole new life, a new lifestyle,” adds Vivette. “It’s not a purely conceptual house. It’s all about le vivant, le vécu,” she explains, the living, the lived experience.

For all its urban delights, Paris is one of the densest world capitals—two million residents packed into only 40 square miles—and it just cries out for a green manifesto. Blanc’s plant walls may be part of that, producing spaces that don’t deny the urban grid but weave it into the realm of the living. From homes and museums Blanc now wants to move on to the city’s least attractive spots—parking lots, public housing, train stations, “all those places where we don’t expect living things.” “The plant wall is not a criticism of the city,” he adds. “I’m only trying to reconcile it with nature.”