Planting seeds: First lady Michelle Obama and Assistant White House Chef Sam Kass understand the importance of teaching kids to play in the dirt. (Tim Carman/The Washington Post)

This afternoon, school children from Fairport, N.Y. (the Girl Scouts of Western New York), Washington D.C. (Bancroft and Harriet Tubman elementary schools), Ames, Iowa (Mitchell Elementary), Chester, Pa., (Stetser Elementary) and Greensboro, N.C. (Sumner Elementary) assisted the first lady as she and the White House kitchen staff planted a wide variety of seeds in the garden for the fourth straight spring. Dozens of media members hovered over every detail as if this were more than a photo op with children ferried in from vital swing states.

“We want you guys to grow up healthy,” Obama told the children. “The garden is a good way to start the conversation, because vegetables and fruits are a big part of a healthy diet. A lot of time when you grow your own vegetables and fruits, they taste really good. They taste better than a lot of stuff you’ll get in a grocery store. Trust me. My kids have done it.”

The effectiveness of the first lady’s directives — eating healthfully and planting your own food — are hard to quantify, especially on obesity, which looks to be holding steady. But there’s some evidence that the gardening message has been heard loud and clear. Last year alone, notes Michael C. Metallo, president and chief executive of the National Gardening Association, the organization received more than 10,000 applications for just 346 grants for school gardens.

“There’s a tremendous amount of interest in this, and we’re not even coming close to meeting it,” Metallo says. “Now whether or not Michelle Obama has something to do with it.. . . I think you can infer something, but we have nothing directly.”

What’s more, there are “people’s gardens” in “all 50 states, three U.S. territories and eight foreign countries,” according to the USDA, which launched the initiative in 2009, the same year as Michelle Obama’s first kitchen garden planting.

By definition people’s gardens are, notes the agency, “required to have three components in common. They must benefit the community, in some cases by creating recreational spaces and in others by providing a harvest for a local food bank or shelter. They must be collaborative — that is, the garden must be created and maintained by a partnership of local individuals, groups or organizations. And third, they should incorporate sustainable practices.”

The White House Kitchen Garden would seem to qualify as a people’s garden. Come harvest time in the fall, most of the garden’s produce goes straight to Miriam’s Kitchen, the nonprofit (located blocks from the White House) that feeds the District’s chronically homeless. Steve Badt, director of kitchen operations for Miriam’s Kitchen, says the White House has brought the organization about 500 pounds of vegetables every fall since 2009.

“They must have a lot of pressure to pick a different charity every year. . . I’m always expecting to get the call” to say the White House has selected another group, Badt says. “Hopefully one of the reasons they pick us is that we’re in the neighborhood . . . . The produce in their garden is directly helping the homeless that they see everyday at their gate.”

Miriam’s Kitchen, Badt says, gets fruits and vegetables from a number of farmers markets in the area, but the produce may be stuff that the farmers can’t sell — or those slightly damaged or deformed items known as seconds.

“The difference with the White House garden. . . . Everything is prime,” notes Badt. “There are no seconds. . . The salad greens we get from the White House are just picked. They’re perfect.”

Incidentally, Michelle Obama’s book devoted to the White House Kitchen Garden was originally scheduled to hit stores April 10. It’s now expected to drop on May 29. The book, “American Grown: The Story of the White House Kitchen Garden and Gardens Across America,” has also changed its subtitle, as noted by Obama Foodorama. It was originally titled “American Grown: How the White House Kitchen Garden Inspires Families, Schools and Communities.”

No word on why the title changed, and a call to the publisher, Crown, was not immediately returned.

In the meantime, here’s the day in Tweets and photos from the White House planting this afternoon.