Agree with all of the above.
I, personally, am organic and choose not to use chemical fertilizers. These are commonly salt-based and, in the long-term, are detrimental to soil biology and soil health. As Gumbo suggested, read the ACT thread in the "Compost" forum. It elaborates on this subject much more (yeah, it's a long thread, but it holds a lot of great information).
If you want to go the MG route, go easy on it. If the plants are just transplanted, you may even want to use less than the packaging recommends. Once they larger and approach the flowering stage, you might want to cut it out completely.
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