Campbell Soup Company is buying Ferndale’s Garden Fresh Gourmet for $231 million. Both companies announced the sale Tuesday. Garden Fresh has grown rapidly since Jack and Annette Aronson started the business in 1998. Today, it makes the top-selling brand of refrigerated salsa in the United States. Aronson’s business partner and Vice Chairman Dave Zilko says Garden Fresh wasn’t for sale when Campbell executives approached him a year ago. He tells WDET’s Pat Batcheller they convinced him they shared Garden Fresh’s values and commitment to making fresh, local food.