pretty much i wanna know what in ferterlizer that makes plants grow

The three major plant nutrients are potassium, nitrogen and phosphorus. Most fertilizers contain these nutrients in differing quantities depending on the brand and what its put on. Also, there are other plant nutrients like sulfur, magnesium and calcium. A good fertilizer will have the proper balance of these for the plant you are trying to grow. You might also want to do soil tests to see what your soil might be lacking before you look for the proper fertilizer. Too much of these nutrients can be bad for plants.

Ironite also has acid to correct and balance the soil ph