Hydroponic systems are built to sustain plant life without the need for soil. In a hydroponic system, a nutrient solution is fed to the roots of the plant through a potting medium such as Perlite, or the roots hang in the nutrient solution without a potting medium. A basic indoor hydroponic system needs adequate light, a reservoir for the nutrient solution and water, and something to hold the plant.
Measure the piece of foam board so that it will fit inside the container, toward the top. Leave enough room over it for the nutrient solution and water.
Cut holes in the foam board big enough to fit the plastic cups, which should be placed 1 to 2 inches apart and protrude 2 to 3 inches from the bottom. Fill the cups with Perlite and place your plants into the growing medium.
Fill the container with the nutrient and water solution mixed to the specifications on the nutrient solution bottle and according to the plants you are growing. Fill to the the level where the foam board rests.
Place the foam board onto the top of the container and place the plastic cups into their holes. Place plastic wrap over the top of the cups until the plants begin to sprout.