GIVEN the chance to accompany a team of botanists on a plant-collecting expedition to South America, most gardeners would probably be satisfied with the experience. They wouldn’t come home and try to recreate the rain forest in Manhattan.

But Michael Riley isn’t like most gardeners. Mr. Riley, a former commodities trader turned plant expert who went on to become assistant director of the Horticultural Society of New York, was eager to move beyond potted plants in a way that hadn’t yet occurred to many others. It took a number of expeditions, a lot of research and more than a decade and a half, but by 2003 he had figured out how to grow a wall of plants inside his Upper West Side apartment.

“In the rain forest, I realized that plants didn’t need to grow in pots with labels,” said Mr. Riley, 64. “I wanted to grow plants in ways that were natural to them.”

With his partner, Francisco Correa, a Spanish teacher who is now 52, Mr. Riley attacked a corner of his living area, stripping the walls of plaster and affixing exterior-grade plywood to new and existing building studs. On top of the plywood went bitumen roofing to protect the walls. Cork bark was then stapled over that, and plants were inserted into pockets in the cork. Sprinklers and lighting were installed overhead, trenches were put in at the base of the walls to catch water that trickled down, and pools were added in the middle of the room to increase humidity.