EASY HOME HYDROPONIC PRODUCTION OF LEAFY GREENS

Growing plants on polystyrene panels floated on nutrient solution in shallow basins is suitable for home production of leafy vegetables and herbs. Polystyrene trays (0.58 x 0.38 x 0.06/0.04 m) floated individually in commercially available basins (0.4 x 0.6 x 0.22 m) on 45 L of nutrient solution were used to grow representative leafy types: corn-salad (Valerianella locusta L.) from seed and head lettuce (Lactuca sativa L., seven types) from transplants. Oxygenation, by fish tank devices, and nutrient solution concentration were based on preliminary trials, while plant density was further investigated in this trial, conducted in an unheated glasshouse in the cold season. Corn salad yield increased with plant density, to 2.4 kg/m² at 2000 plants/m². Overall leaf quality was generally good and decreased very little with density. Lettuce heads of 100 to 260 g were obtained, with weight decreasing with plant density, particularly for the heavier crisphead and romaine types. The best quality was shown by summer crisp and batavian types. Butterhead and lollo had higher nitrate concentrations, but were well under accepted limits. The amount of solution per tray was adequate to support one crop of corn salad, with slight pH alteration. Solution consumption was approximately 10%. For the longer cycle of head lettuces a refreshing of the solution was needed, through partial refill (5 L/basin) due to ion and pH changes. This type of cultivation is inexpensive and requires minimal care to raise several crops of vegetable greens from spring to autumn.