Brian McCollum, Michigan.com

Jason Mraz wanted to get his hands into some Detroit dirt.

The smooth-rocking singer-songwriter popped in this afternoon on Plum Street Market Garden at MGM Grand Detroit, a 1.7-acre urban farm on the edge of downtown.

Mraz, a gardening aficionado who has an avocado farm at home in California, spent a couple of hours snipping lettuce, spinach and vegetables destined for area farmers markets, overseen by the Keep Growing Detroit (KGD) initiative.

"When I hit the road (to tour) for eight months, I miss it," said Mraz, who will play the Fox Theatre tonight in support of his album "Yes!" "I don't want to lose the skill or stop learning, so I get involved with other gardens, urban farming organizations and tree-planting organizations."

Joining Mraz for volunteer work at the farm were about 20 fans who had won the opportunity via a radio contest. Also on hand was Mraz's girlfriend, Christina Carano, who grew up in Royal Oak and Berkley.

The publicity was welcomed by the nonprofit KGD, which works with local gardeners and entrepreneurs while advocating for a day when most of the fruit and vegetables consumed in Detroit are grown locally.

Mraz was the Plum Street farm's most notable celebrity visitor yet, said KGD co-direct Eitan Sussman.

"I'd love to see more of it," he said. "We appreciate the draw. We're super-dependent on the volunteer support."

Mraz does gardening and farming drop-ins at many of his tour stops, but said he recognized the unique role of urban farming in Detroit's revitalization.

"I think this is very symbolic of what's growing in Detroit, and how Detroit is growing," he said. "It's been a city of industry in the past, and who says it can't be a city of agriculture and creativity? It can be whatever it wants to be, and right now there's a lot of passion in this, right here."