If you use Miracle Grow your set for a long time. About 3-6 months..kinda bad when its time to flower and you have all the wrong nutrient levels in your soil. Thats why ppl dont reallty like it. MG has all the stuff in it that your plant needs chemicaly up until flower. If you plan to go the synthetic route then use that 10-10-10 but my opinion is to use FFOF or Kelloggs Patio plus and make your own soil using manure, blood meal, bone meal, perlite or dolomite.
I have a 24 foot area im working with.. I could go bigger but I think Im pressing my luck already.
I added:
4 bags or cow poo
1 bag of blood meal
some garden compost
and then im adding the patio plus and roto tilling it with a hand held tiller do hickey..
we will see how it works..presonally i like organic but its up to you..just know that the MG will last along time and probly give the wrong nutes to your plant when its time to flower