Hydroponics is the science of using sterile medium to grow plants, eliminating the use of soil altogether. Light and nutrients can be controlled in hydroponic containers, which is why such flowers and plants grow faster than those planted in the soil, and can be grown indoors in winter as well. There are many types of hydroponic containers you can make at home with a few inexpensive tools. One of the simpler ones that does not require any special skills or expertise uses a fish tank.
Scrub the fish tank thoroughly with hot soapy water. The tank should have no cracks and be waterproof. Then paint its exterior dark blue or black to prevent microscopic bacteria and algae that thrive in light from growing inside. Allow it to dry thoroughly.
Measure the opening at the top of the fish tank and mark the measurements on styrofoam. You want the styrofoam to float over the water at the opening. Cut over the marks with a serrated knife. Cut the foam a ¼-inch narrower on all sides so you can add or remove things from the tank easily.
Place the pots on the foam, spacing them 3-inches apart, and trace their bases with a pen. Carefully cut over the circles with a knife. Also check the size of the air tube and cut a tiny hole at one end of the foam for it to pass through. Place the tank in a sunny location indoors, or suspend a grow light over it with S-hooks to supplement lighting, if necessary.
Attach the air tube to the air stone and place the stone in the base of the fish tank. The air stone replenishes oxygen in the tank to maintain a certain level.
Fill the fish tank with water until it is three-fourths full, and follow the manufacturer's directions for adding hydroponic nutrient solution to the water.
Lower the styrofoam sheet through the opening in the tank, so it floats on the water. Extend the air tube through the hole in the corner of the foam, and attach it to the air pump. Place the air pump on a flat surface next to the fish tank.
Fill each pot with growing medium and plants, and carefully insert it into a hole in the styrofoam. The pump and air stone will work together to produce oxygen bubbles in the fish tank, which the plants' roots will absorb.