Mr. Ruskey has grown coffee on his farm for more than a decade, but it is only over the last three or four years, as his coffee started winning high scores in taste tests, that other farmers have begun to try their hands at growing it. Still, Doug Welsh, roastmaster at Peet’s, notes that the number of coffee bushes growing in California today is 30 times what it was 13 years ago when Mr. Ruskey started, or about 14,000 plants.

“We probably roast more coffee at Peet’s in one day than is being produced on all the farms growing coffee here, but I’m looking at this as a cup half full,” Mr. Welsh said. “It’s early days, but I think it could at least get to be as big as the Hawaiian coffee business.”

(There are roughly 800 coffee farms in the Hawaiian Islands producing as much as nine million pounds of unroasted beans a year; California produces only hundreds of pounds. Globally, 12 billion pounds of coffee are consumed each year.)

These growers aim to appeal to the premium coffee market. More than half the adult coffee drinkers in America reported drinking a specialty coffee daily, according to the National Coffee Association, or roughly twice as many as in 2010.

“People are shifting away from the way my grandparents drank coffee, which was at breakfast and made from whatever coffee was on sale — it was simply fuel,” said Peter Giuliano, chief research officer at the Specialty Coffee Association. “They’re willing to pay for something unusual.”

A pound of dried green specialty coffee beans can sell for as much as $120 in today’s market, according to Andy Mullins, a retired technology executive who has planted coffee on his property east of Santa Barbara. “You should be able to produce a pound for under $30, which is a superb profit margin,” Mr. Mullins said. “The only places that see better margins than that are software companies.”