Hydroponics is useful in two main ways. First, it provides a more controlled environment for plant growth than soil thereby removing many unknowns from experiments. Second, many plant species produce more in less time and sometimes of higher quality, which under certain economic and environmental conditions, makes hydroponics growing more profitable to the farmer.

With hydroponics there are no soil-borne diseases, weeds to pull, or soil to till, and plants can be placed very close to one another. This allows a large amount of food to be produced in a small amount of space. Hydroponics is also very water-efficient as it uses containers or closed loop systems that recirculate the water, and therefore requires only a small fraction of the water used in traditional farming.

These qualities combine to make hydroponics useful wherever people wish to grow plants in a non-traditional manner. Science fiction writers have long speculated that hydroponics would allow space stations or spaceships to grow their own food. The same qualities make hydroponics ideal for those who wish to grow plants with maximum control over conditions, and maximum density.

Cite: Wikipedia