What is the yeild?

If im groiwng 3ft plants what kind of yeild can i except

What kind of light and what do you feed them?

Think of it as an engine, with each factor of cultivation representing a single piston, sure the engine will run if some of the cylinders are misfiring or not firing at all, but to yield the most power from that engine, all cylinders must be firing in sync and at maximum capacity. So if you a very good grower you can go by what the people that sell the seeds say on the back of the pack.

The sun is the light and and mircale grow allpurpose plant food

I would say unless you are very experienced you should expect 1-1.5oz. per 3 footer.