Using a float system to grow hydroponic lettuce for sale at local green markets in southeast Florida

Abstract

A float system was used to grow hydroponic lettuce (Lactuca sativa L.) for sale at local green markets. Lettuce seedlings were grown in horticultural grade rockwool cubes. In 2001, four floats measuring 4 ft × 8 ft × 8 inches were used. Each float was lined with 6-mil clear polyethylene sheeting and filled with 125 gal of water to which soluble fertilizer containing 20%, 8.8%, 16.6%, and 9.6% N–P–K–Mg, respectively, was added. Thirty-six holes were drilled into 2- inch-thick sheets of foam insulation measuring 4 ft × 4 ft. By the 2007–08 season, a total of 27 floats had been made and an average of three floats were being planted each week (216 plants per week). The newer floats were 5 inches tall and held 80 gal of water.