For the past couple of years I've been playing with Miracle-Grow products (potting soil, plant food, tomato food) on my tomato plants. What I've found with all of these products is that the plants absolutely grow like crazy (I've had staked tomato plants reaching as high 8 - 10 feet. Problem is that while the plants themselves experience tremendous growth, they don't seem to yield quite as much fruit as their slower growing, non-Miracle-Grow infused peers. I tend to just get big plants.
I was discussing this with a life-long produce and dairy farmer one day and he told me he went back to conventional fertilizers after experiencing the same thing with some experiments he tried.
Jeffery Rehm