(CNN) Back in February, ahead of a Golden State Warriors game at Oracle Arena, Don Nelson was asked what he's been up to since he retired from coaching.

The answer from the ex-NBA coach, who last coached for the Warriors in 2010, made everyone in the room burst out laughing.

"I've been smoking some pot," Nelson said. "But I never smoked when I played or coached, so it's new to me."

Turns out, he now does that every day.

In an interview with HBO's "Real Sports with Bryant Gumbel," Nelson revealed that he grows marijuana on his farm in Maui. His pot, called "Nellie Kush," is not for sale, as it's for his personal medicinal use. He did not specify what condition he was treating.

"You've got to treat it like a baby," Nelson, 79, said to Gumbel. "You've got to water them. You've got to have music for them. You've got to bless them. It's a whole process, I'm telling you."

HBO, like CNN, is part of WarnerMedia.

Nelson retired from coaching as the NBA's winningest coach. He coached four teams over his 30-year career, but he was best known for his time with Golden State, where he won 422 games. Nelson is largely credited with building the groundwork for the modern dominance of the Warriors, including drafting Stephen Curry in 2009.

His imprint on how the game is played today is felt elsewhere, too. He was the first coach to give a 7-footer the greenlight to shoot from three-point range. He was the first to introduce the concept of sacrificing height for pace-and-space small-ball basketball -- notably with the "Run TMC" trio of Tim Hardaway, Mitch Richmond and Chris Mullin -- that now dominates the NBA.

And he just might be the first retired NBA coach to grow his own marijuana.