MOST HOMEOWNERS leave their roofs to the elements—moss pads, pigeons, the occasional trespassing squirrel. Doug Christie, however, sees his as agricultural space: Atop Anderson Roofing Company, his Portland business, you’ll find a kaleidoscope of bright red, burnt orange, and lime green heirloom tomatoes. Each evening after work, Christie trades his shingle shears for a watering can and heads to his rooftop Eden to gather the day’s harvest of more than 30 heirloom varietals, many of which sport Seussian names like Prudens Purple, Caspian Pink, and Eva’s Purple Ball. “I’ve got a primeval urge to farm,” he explains. “All my relatives are farmers.” For the past 12 summers, Christie has hand-harvested as many as 3,000 pounds of tomatoes, which he donates to friends, co-workers, and Carlyle restaurant. ?(In fact, in 2007, Carlyle started making a seasonal dish, Doug’s Caprese Salad, out of them.) In return for his heirlooms, most of which come from seeds that are at least 50 years old, Christie receives the occasional meal on the house—a kind of gentlemen’s agreement that recalls the simpler era in which many of his prize tomatoes first appeared.