Bernie Rothenberg, 98, pulled eight colored balls from his jacket pockets and gripped a pitching wedge in his weathered hands.

“I’m addicted,” he said, hitting the balls across the modest playing field outside Building 624 in Stuyvesant Town in Manhattan on Wednesday. “I come out here every day, all year. I’ve played in the snow and had to wait till it thaws to find the balls.”

This was not a golf course — there are none in Manhattan — but rather Mr. Rothenberg’s practice range: a play area less than half the size of a football field and covered with artificial turf, outside his building. Over the past decade, Mr. Rothenberg has installed himself as the resident golf pro for this modest village green wedged between the red brick buildings and lined with benches and tall trees, near the eastern end of 20th Street. “This is Bernie’s course, the Rothenberg Golf Club,” said one resident, Alan Lacher, 69, a retired tax lawyer who calls himself “Bernie’s worst student.”

“There’s a whole stable of students who have been looking to Bernie as their coach for years,” Mr. Lacher said. “He’s down here, no matter the weather. He’s indomitable.”