BIG SUR, Calif. — Among the sleek guests who meditate and do Downward Facing Dog here at the Esalen Institute, the farmers appeared to be out of place. They wore baggy jeans, suspenders and work boots and had long ago let their hair go gray.

For nearly a week, two dozen organic farmers from the United States and Canada shared decades’ worth of stories, secrets and anxieties, and during breaks they shared the clothing-optional baths.

The agrarian elders, as they were called, were invited to Esalen because the organizers of the event wanted to document what these rock stars of the sustainable food movement knew and to discuss an overriding concern: How will they be able to retire and how will they pass their knowledge to the next generation?

Michael Ableman, a farmer and one of the event’s organizers, said the concerns were part of a much larger issue, a “national emergency,” in his words. Farmers are aging. The average age of the American farmer is 57, and the fastest-growing age group for farmers is 65 and over, according to the Census Bureau.

During their meetings, some of the farmers worried that their children would not want to continue their businesses and that they might have to sell their homes and land to retire.

Esalen is the birthplace of the human potential movement and a stunningly beautiful spiritual retreat overlooking the Pacific Ocean. When they were not in conference, the farmers wandered among floating monarch butterflies through Esalen’s farm and garden, rich with Calypso cilantro, tatsoi and flamboyant orange marigolds.

But the institute also holds conferences on major world and national issues. Mr. Ableman and Eliot Coleman, a Maine farmer, organized the intimate conference. Mr. Ableman, the author of “Fields of Plenty,” is writing a book about the gathering. Deborah Garcia, the widow of Jerry Garcia of the Grateful Dead and a filmmaker whose previous films include “The Future of Food” and “The Symphony of the Soil,” is making a documentary.

While the farmers here were proud of their anti-establishment beginnings, their movement has since gone mainstream, and organic farming has grown tremendously. Sales of organic food in the United States reached $31.5 billion in 2012, compared with $1 billion in 1990, according to the Organic Trade Association.

So the grandfathers and grandmothers of organic farming should be joyous, but they are not. Their principles of local, seasonal fruits and vegetables have been replaced in many cases by year-round clamshelled tomatoes for Walmart, Target and other stores. Some of today’s organic farmers have thousands of acres of single crops, which are flown to supermarket shelves, where they are sold at lower prices than many small organic farmers can afford to sell their produce.

Generally, the farmers at Esalen have less acreage and sell dozens or hundreds of varieties of fruits and vegetables at local farmers’ markets, to upscale restaurants and through so-called community-supported agriculture. C.S.A.’s, as these arrangements are known, consist of consumers who pay before the harvest for weekly deliveries of seasonal fruits and vegetables.

The sustainable agriculture these farmers practice goes beyond farming without synthetic fertilizer and pesticides. They adhere to a broader political and ecological ethos that includes attention to wildlife, soil, education and community. For most of them, the bottom line has never been their bottom line.

Many have done well, though not all organic farms succeed in the same way.

Some farmers operate a “debit card” C.S.A.; members make annual payments and buy at a discount only what they want. Jake Guest, who farms 70 acres in Norwich, Vt., said customers told him, “It’s like we’re getting free food.”

Stephen and Gloria Decater of Live Power Community Farm in Mendocino County, Calif., whose six Belgian draft horses help till the soil, operate “a participatory C.S.A.” with 200 households whose members split operating costs for the season and share the harvest with weekly baskets of organic food.

The proliferation of farmers’ markets has been a boon. Betsy Hitt sells her cut flowers, fruits and vegetables at one of 12 Saturday markets within 70 miles of her farm in Graham, N.C. Nash Huber, who farms in Washington State, sells his produce at seven farmers’ markets.

Some farmers have farm stands, some of which bring in $1 million or more annually. Another has a farmer’s cafe.

Farming an acre and a half of land in Harborside, Me., Mr. Coleman grosses $150,000, netting $30,000 annually. Tom Willey, with his wife, Denesse, grosses $2.8 million in direct food sales in the San Joaquin Valley. A few have had rough patches. But even they wax romantic about their love affair with the land.

“We went out of our way to give everything to the earth, and the earth gives back to us,” said Jack Lazor, who started his organic dairy farm in the 1970s. The earth doesn’t always give cash, though. He dropped his health insurance in 2008, because, he said, “We couldn’t afford it.”

All of the farmers were rebels. “We were told it was impossible to grow food without chemicals and pesticides,” said Mr. Coleman, who farms year-round, aided by his invention, a greenhouse on wheels.

They had few mentors or books to guide them. They went to schools like Tufts, Dartmouth, Cornell and the University of California. Some dropped out, protested the Vietnam War, occupied buildings or went to jail. They smoked marijuana and started communes.

“Every one of us broke the law,” said Frank Morton, 57, an Oregon seed farmer, with perverse pride.

When he was younger, Bob Cannard, 61, sprayed DDT and malathion, he said, and he passed out “many times” while working for his nurseryman father. Now Mr. Cannard lets weeds grow in harmony with his crops and is the main herb and vegetable grower for Chez Panisse in Berkeley, a temple of organic cuisine.

Mr. Ableman climbed out the window of his parents’ house when he was 16 and ran away. He was soon managing a 100-acre orchard, and then a 12-acre farm in Southern California, which grossed close to a million dollars. He now farms on Salt Spring Island, British Columbia, and travels to Vancouver to oversee urban farms he developed for people coping with addiction and mental illness. They are paid to work the land, and they sell their food to 30 restaurants and at six farmers’ markets.

Amigo Bob Cantisano’s dreadlocks dangle below his knees; he is tie-dyed down to his socks. Mr. Cantisano, 63, is the only one of the group at Esalen who has regular contact with industrial organic farmers. Some of them are Republicans in cowboy hats, he said, but they overlook his nonconformist appearance. He consults with companies like Sun-Maid, Sunkist and Earthbound Farm on how to improve yields and practice better sustainable agriculture.

Mr. Morton, who sells seeds through his Wild Garden Seed catalog, discovered at age 6 that food could be free but digging was hard. As a teenager, he said he “came to the realization that seed was the key to wealth and independence.”

Some related their marketing tips. Mr. Coleman, who sells his produce to 10 restaurants, said the endive variety called Bianca Riccia da Taglio would not sell until he renamed it. “Within two weeks, every lobster salad was sitting on a bed of golden frisée,” he said.

When farmers changed the name of Mandarin Cross tomatoes to tangerine tomatoes, sales soared. A farmer who had trouble selling her misshapen potatoes labeled them “Ugly Potatoes” and cut the price. They sold.

And many came looking for answers to the conundrum of retirement. Some have put their farms in land trusts; others said they tried to negotiate similar deals but failed. Like other family farmers around the country, some are finding that their children do not want to carry on their work.

Dru Rivers of Full Belly Farms in the Capay Valley in California was one of the few farmers whose children had returned to the farm, with their own ideas. A son is doing farm weddings and dinners. A daughter is operating a summer camp and running farm tours. In true hippie style, Ms. Rivers said: “I don’t want to die with one thing to my name. I want to give it all away. We have to do that to regenerate.” So she will give the farm to her children.

Norbert Kungl, 58, who farms in Nova Scotia, is concerned about the future of his land, which he says produces enough income for only one family. “I can’t find a cushion,” he said. “What options do I have other than selling to the highest bidder, which I do not want to do? These are questions that I have no answer for.”

Mr. Willey, 65, said he called a family meeting with his three children. “We made clear to them we have a very profitable business,” he said, but none were interested in carrying it on.

He understands why. “Farmers often work seven days a week and as many hours a day as the sun is up,” he said. “Young people looking into agriculture are not willing to make that drastic a sacrifice.”

Mr. Huber, who owns 25 acres and farms more than 600 acres on the north Olympic Peninsula in Washington State, said, “I think we’re looking at models that don’t work anymore.”

“I’m 72. I love what I do,” he said. “Obviously, I can’t keep doing it.” But young people “don’t have the financial resources to make it happen,” he said, with land in his area going for $26,000 an acre. “And they don’t have the knowledge, yet.”