This year, opening day for major league baseball is the earliest ever. But if Yankee Stadium's head groundskeeper had his way, it'd be two weeks later.

"I wish it was the second week in April," Danny Cunningham said during a recent trip to the stadium. "Right field is just thawing out. It's been frozen over there."

"We don't have a heating system in the field," Cunningham added.

The March start gives teams additional off days throughout the season, days they can use for extra rest, or to reschedule rainouts. The sod—bluegrass, grown in sandy conditions in South Jersey—got an even earlier start. It's been down since January, and, in the lead-up to opening day, it was covered with sheets of grayish plastic that serves as a germination blanket.

"It's like a mini-greenhouse," said Cunningham, "it traps heat, buffers the nighttime temperatures, and allows the grass to breathe in the process."

In the weeks before opening day, workers were power washing seats, clearing drains, and fixing up the rest of the field. The infield is a mixture of clay, sand, and silt. Home plate and the pitchers mound are a hard clay mixture, and the warning track is lava rock from Colorado.

"It's got that crunchiness to it," said Cunningham. "So when the players walk on it they know they're on a warning track. If you're not looking down when you're looking at the ball, it's good to know where you are by feel."

But opening day for baseball is not opening day for Yankee stadium. The New York City Football Club has been playing games on the field since early March, and over the next six months, workers will convert the field back and forth. Cunningham oversees it all. But there's one field duty he hasn't performed in the 31 years he's worked at the stadium: YMCA.

"I've never done it," said Cunningham. "No, that's for the younger guys, the dancers."

For more, listen to Kate Hinds's WNYC segment on the stadium's groundskeepers and opening day.