Grass seed will grow almost anywhere -- you may have seen it coming up through cracks in the sidewalk, for example. A fertilizer company once wanted to demonstrate the quality of its products so it sowed one of its parking lots in grass and it actually did quite well! As long as a plant has enough water and the proper nutrients, it will grow.
If you take things to an extreme you arrive at a technique called hydroponics. In hydroponics, plants are raised in a nutrient-rich solution. There are actually a number of advantages to raising plants this way, because you can precisely control the nutrients the plants get and eliminate most soil-borne diseases. To learn more, check out this introduction to hydroponics and the Hydrofarm Web site, which has a nice library page.
Here are some interesting links:
