WASHINGTON — On the South Lawn of the White House just over a year ago, 10-year-old Endya Colbert dangled a worm directly in front of Michelle Obama’s face. Endya’s mother, Chala Colbert, has a photograph to prove it.

It was a brisk day for the first lady’s final spring planting, but Endya, whose elementary school in New Orleans offers a gardening program, assured Michelle — yes, the student felt certain they were on a first-name basis — that the worm was a sign of healthy soil.

The current first lady, Melania Trump, is settling into the White House and has yet to officially embrace her predecessor’s seasonal ritual: leaving the White House — often at a sprint — waving toward a crowd of miniature green thumbs, all of them in sneakers soon to be matted with mulch.

Some supporters of the White House Kitchen Garden — the 2,800-square-foot foundation of Mrs. Obama’s Let’s Move! campaign to reduce childhood obesity — have expressed doubts that the vegetable patch could weather a blustery presidential transition.