The day after the grisly Hamas attack, Mr. Swissa, the strawberry grower, faced a reality: There was no one to do the vital preparation work to ensure his strawberry plants would thrive and be ready for the winter harvest.

He decided to scale back production, but he still needed volunteers to save part of his crop.

After they failed to show up on a recent Monday, he reached out to a nonprofit. Word spread rapidly across social media that he was “desperate” for volunteers.

By Tuesday morning, he had received 2,000 calls and 3,000 text messages. More than 150 people, including a busload of high school students, reported to the fields.

Mr. Swissa barked orders at them to little effect. Then several adults appointed themselves crew leaders, divvying up the tasks among different teams.

“I knew nothing about this work before this morning,” said Ofer Buchnik, a software engineer who brought along his teenage son to volunteer. Under the sweltering sun, they stretched long plastic sheets over rows of tiny strawberry plants, and deposited bags filled with soil alongside them to hold them down.

“We thought we would pitch in one day, but we see there is great need,” said Alon Shachar, a team leader, adding, “I’ll be back tomorrow.” Others also said they planned to return.

By early afternoon, most of one field was ready, with strawberry sprouts poking out of the ground.

Mr. Swissa was beaming. “Israel has to fight the war and bring back the hostages,” he said. “Farms need to keep working to feed our people.”

Then a volunteer, Schlomit Eliakim, her fingers deep in the dirt, shouted out: “What will happen when we have to return to our jobs? That’s the big question.”