Hydroponics is a method of growing plants in a nutrient water solution. Hydroponic systems vary greatly in their complexity, depending on the scale of production and the type of plant produced. Growing vegetables hydroponically is useful for growing vegetables year-round or when gardening space is limited, such as on a porch or balcony. Leaf lettuce is suitable for growing in a simple 1-gallon hydroponics system made with a few easily obtained materials.
Wash and rinse the 1-gallon container well. Be sure to rinse several times if dish soap is used.
Add 1 teaspoon of hydroponic fertilizer to the washed and rinsed container. Add approximately 1 quart of water (tap water is fine) and swirl to dissolve the fertilizer. It is acceptable if some fertilizer settles to the bottom of the container. Continue filling the container with water until you reach about 1½ inches from the top.
Wrap the container, excluding the opening, in aluminum foil to keep algae from growing in the nutrient solution.
Add soil-less growing medium to the net pot, but do not it pack too tightly. Place the net pot with growing medium in the opening of the hydroponics container. Be sure it is a snug fit. The bottom half of the net pot should rest in the hydroponic solution. Capillary action wicks the moisture throughout the growing medium.
Plant 1 or 2 lettuce seeds ¼ inch down in the moist growing medium. Carefully add a teaspoon of water if the medium is dry.
Place the hydroponics container in a sunny location away from rain or wind. Leave the container alone for 5 to 6 weeks while the lettuce grows (the lettuce seeds should germinate in 2 to 4 days). No additional water or fertilizer is necessary for this method, according to the University of Hawaii Extension Service.