Lettuce (Lactuca sativa) is one of the most commonly grown hydroponic vegetables. Hydroponics is a method of growing plants without soil. Plants may be grown in a nutrient solution only (liquid culture) or they may be supported by an inert medium (aggregate culture). In both systems, all of the plants' nutritional needs are supplied through the irrigation water. Hydroponics is a highly exacting and demanding system that requires a greater amount of production knowledge, experience, technical skill and financial investment than many other greenhouse systems. A grower must be committed to meeting the daily demands of production to be successful.