Plants need mineral nutrients to grow. If we can supply the nutrients to the the plant by other means there is no need of soil. We can do it by supplying nutrients through water. This method is called Hydroponics.

In Hydroponics, plants are grown with roots submerged in a nutrient solution, with the stem and upper parts of the plants held above the solution.
With this system, the main considerations are:

1. provision of a suitable container,
2. suspension of the plants above the water,
3. provision of a suitable nutrient solution and
4. proper aeration of the water solution.

To learn Hydroponics follow this link Hydroponics learning center - Greentrees Hydroponics