SANTA MARIA, Calif. — Organic leaf and lettuce sales remain on a rising arc, prompting some conventional growers to continue to diversify in the category.

Sales of organic salads grew 13.8% in the past year, according to Nielsen’s Dollar Volume Index.

The salad numbers, for the 52 weeks ending May 28, reflect broader growth in organic produce. According to the Organic Trade Association’s most recent survey, overall sales rose 12% last year.

“The organics business is on the rise,” said Dave Johnson, vice president and co-owner of Santa Maria-based Pacific International Marketing. “Everybody overreacted to the economy and went too far one way, backing off organics. But now it’s settling down and moving back up.”

Up enough to help prompt a plant expansion at Pure Pacific Organics, a Gonzales, Calif., subsidiary of Pacific International Marketing. The plan is to add 30,000 square feet to a facility that had 22,000 when it opened in May 2010.

“It will probably take us into October to finish,” Johnson said.

Doug Classen, sales manager at The Nunes Co., Salinas, said his company offers organic counterparts to all of its conventionally grown commodities.

“Organics have been an area of considerable growth for us,” Classen said. “We started a couple years ago with organic romaine and romaine hearts, celery and celery hearts. Based on the reception, we’ve steadily increased our product line.”

The Nunes products carry the Foxy label.

To the south, Oxnard, Calif.-based Deardorff Family Farms in July established a year-round supply of organic leaf lettuces and celery through a marketing agreement with Salinas-based Crown Packing.

Deardorff had launched its line of organic commodities in January. The leaf lettuces and celery are grown in Oxnard from December to June, and the Salinas connection will provide product in the remaining months.

Most of the Salinas production will pack under the Deardorff Organics label. Some will appear under Crown Packing’s Bunny label.