Performance of lettuce (Lactuca sativa) grown in soilless media in vertical hydroponics
Florida growers use several types of hydroponic production systems to grow a wide variety of vegetables. One popular soilless media system in Florida is a vertical one of leafy greens such as lettuce (Lactuca sativa). The soilless media used in this system has traditionally been perlite and or coconut fiber, however, higher cost of these media has led to the need to research composted pine bark as an alternative medium choice. A research trial evaluating four soilless media materials or combinations was conducted at the Suwannee Valley Agricultural Extension Center near Live Oak, Florida in 2013 and 2014. ‘Tropicana’ lettuce was transplanted into VertiGro® pots for three crops, two in Spring 2013 and one in Spring 2014. The media treatments were: coconut fiber, composted pine bark, perlite plus coconut fiber on the top two inches, and composted pine bark plus coconut fiber on the top two inches. The yield and quality of lettuce at harvest was recorded with no significant differences among any of the four soilless media evaluated in two of the three plantings. However, during the first planting, coconut fiber produced the highest yield followed by composted pine bark plus coconut fiber. The lowest yields were found with perlite plus coconut fiber, and composted pine bark alone. These results suggest composted pine bark may be an acceptable media in a lettuce crop grown in a VertiGro® production system.