Four or five years ago, artists David Sleeth and Inga Dorosz bought a piece of property near Gorda, a remote town about 50 miles south of Big Sur. It was called “the etrog farm,” but it hardly looked like a farm. The 10 fruit trees on the land were nearly dead from years of neglect.

“The place had been abandoned,” said Sleeth. “We had a sense of what [the trees] were, but not really, and we didn’t understand the whole history of them.”

The couple began doing some research and discovered that they had inadvertently inherited an etrog orchard. So they set about nursing it back to life.

Though neither Sleeth nor Dorosz is Jewish, they learned through their research that “Judaism is very clear you can’t get rid of trees, especially those that are fruit-bearing,” said Sleeth. “Although the orchard looked dead, something about it really appealed to us.”

The etrog, or citrus medica, looks like a large, knobby lemon. Called a citron in English, it is one of the four species blessed during the festival of Sukkot, which begins at sundown on Sunday, Oct. 16. An essential part of the Sukkot ritual is holding an etrog in the left hand while shaking a lulav (single palm branch, held together with myrtle and willow branches) with the right. There are strict requirements for kosher etrogs that can be used in this ritual — they must be grown under rabbinical supervision, be mostly unblemished and have an intact stem. They also must not be a hybrid of different species.

Because of this, kosher etrogs command a high price, $80 or more for “premium” varieties. Most used in this country for Sukkot are imported from Israel, available online and through Judaica stores. There is only one known large-scale kosher commercial grower in the United States, located in California’s Central Valley.

In the Gorda orchard, Dorosz, who is a college art instructor, does most of the gardening work. She and her husband, also an artist, live off the grid and get their water from wells, making it more difficult and expensive to maintain the trees. But it’s something they can’t let go of.

“We’ve been told we’re silly to give so much water and attention to these fruits you cannot eat,” said Sleeth. “But there really is something amazing about them, maybe just what it’s teaching us now as we worry about water. Maybe just that part of what we need to do is to care for something outside of ourselves. It’s really rewarding.”

Last year when she was teaching at CSU, Monterey Bay, Dorosz talked about the orchard with a Jewish colleague, Seth Pollack.

“He got really excited about it,” Sleeth recounted. Pollack is a member of Congregation Beth Israel in Carmel, and he put an item about the locally grown etrogs in the synagogue’s newsletter. The congregation ended up buying around 10 of them for Sukkot last year.

Beth Israel’s Rabbi Bruce Greenbaum pronounced them “absolutely beautiful, much larger than the ones you normally get — they had a very nice shape with a beautiful color.”

They aren’t kosher, not being rabbinically supervised, but Greenbaum said his Reform congregation likes supporting a local grower as opposed to buying imported fruit.

“I would rather support our local farmers than those far away, even if they don’t have supervision,” he said, “though I realize an Orthodox rabbi wouldn’t accept the kashrut of these fruit.”

Etrogs are not a popular fruit crop, perhaps because demand for them is so low, peaking just once a year. They’re bitter, not good for casual eating. Also, growing perfectly unblemished fruit can be a challenge. One of the few places for consumers to buy their own etrog trees is through Four Winds Growers, based in Winters outside of Sacramento, which sells about 100 a year online and distributes its products to gardening supplies stores throughout the state.

The country’s largest, perhaps only commercial etrog grower is John Kirkpatrick, owner of Lindcove Ranch in the small San Joaquin Valley town of Exeter.

“There are other aspiring commercial growers, but no one is marketing them and doing a good job,” said David Karp, a researcher in the Agricultural Experiment Station at U.C. Riverside, which grows strains of etrogs experimentally.

Kirkpatrick was a citrus farmer of several generations standing when a yeshiva student cold-called him decades ago to ask if he might consider growing the Sukkot fruit.

Kirkpatrick’s curiosity was piqued, and he said he’d try to grow etrogs, even though he had never heard of the fruit — and was a practicing Presbyterian, to boot. Now his son Greg is mostly in charge, though the elder Kirkpatrick still has a say in how the business is run.

Greg said his dad “planted a few trees” after that initial conversation, and the business now provides about half the family’s annual income.

“We have about 4 acres under cultivation for the kosher trade, with our marketing partner in Lakewood, New Jersey,” he said. “We sell all of the highest-quality fruit to them, those that meet all the criteria for the blessing.”

Virtually all of the Kirkpatricks’ kosher etrogs are sold to buyers on the East Coast. Those that don’t pass the kosher test are sold for culinary use to make marmalade or citron-flavored liquor; some are sold locally to Berkeley Bowl.

Most kosher etrogs sold in California come from Israel via distributors in New York. That’s true, for example, of the etrogs sold at Berkeley’s Judaica store Afikomen, where a lulav and etrog set sells for $60. Rabbi Chaim Mahgel, who owns the store with his wife, said they sell about 200 sets a year.

U.C.’s Karp is one of those seeking to expand the commercial market for nonkosher etrogs. A professional pomologist, or fruit researcher, he also refers to himself as “the fruit detective.”

Riverside is growing two types of etrogs, he said. “The purpose is propagation by seed, as we want citrus nurseries to grow etrog trees for Jewish ritual use and offer them to the public.”

There’s a lot of money in citrus, which means there’s a significant amount of citrus smuggling into California. For several years U.C. Riverside and the U.S. Department of Agriculture have collaborated on a project called “Unforbidden Fruit” to prevent that illegal trade.

“People are bringing in whole trees from the ground,” Karp said, which may harbor harmful insects and can introduce serious disease to lemons, citrons and other citrus varieties. “It could cost billions of dollars for California growers.” Karp has traveled the world gathering information about the citron, in places such as Calabria, Italy, “where they grow a lot for Jewish ritual use,” and late last month to Brazil, where he attended an international citrus conference.

“Brazil doesn’t grow [etrogs] for Jewish ritual purposes, but it’s one of the largest producers of them for culinary purposes,” he told J. by phone from the conference. “They get huge like the size of a football, and then cut up and brined, soaked and candied. They are used in various Christmas confections here.”

Meanwhile, growing a fruit that is so meaningful to others has brought unexpected rewards to Sleeth, Dorosz and their two children.

“We’re a little bit agnostic,” is how Sleeth described his family, “but we love the experience of being present,” he said, referring to the practice of mindfulness.

When the couple harvested their etrog crop last year, a Jewish friend came with his shofar and “my youngest son was able to blow on it. It’s not easy, but you recognize the universal quality of all of this,” said Sleeth. “Caring for these trees has been a really amazing experience for us.”