dude your plants will grow... they just won't be that awesome... your plants will grow and then when it's time to bud they will say "ok what can i use here to make buds?" and if theres nothing but water and light then they will do their best to flower using just that... but if you listen to the people on this forum who have grown before, they will all tell you GIVE THE PLANT WHAT IT'S HUNGRY FOR!!!!
or if you don't really like smoking pot and your just trying an experiment to see if you can grow something that your able to smoke... then yeah, fox farm soil, a cannabis seed, light, and water... you'll get something out of that but for me sounds like a waste of 3 months.