Re: What chemicals in Miracle-Gro help plants grow?

Miracle-Gro contains mineral nutrients that the plant requires. The label on 
the the package list the minerals nutrients it contains. The three main ones in 
Miracle-Gro are nitrogen, phosphorus and potassium. 

There are 14 mineral nutrients that plant scientists accept that all plants 
require including calcium, magnesium, sulfur, iron, boron, manganese, copper, 
zinc, molybdenum, chlorine, and nickel. Chlorine and nickel are not added 
purposely as fertilizers because they are present in adequate amounts due to 
contamination.

Some plants species also require other mineral nutrients, such as sodium and 
silicon.