M M My Momma says, she says, Miracle Gro is of the Devil! But I gots some high quality H2O.
I custom mix what I use. Compost, vocanic sand, a smiggen of bentonite clay, perlite, composted manure, vermicompost, nosy people, etc... Since I stopped using MG, I stopped killing plants all the time. Funny, huh? Building up a soil foodweb in your soil whether in a container or in your garden makes for a far happier plant than some chemical salts that lack most of what plants need. This includes leveraging the strengths of helpers like mycorrhizal fungus, companions and mulch, even in containers. Peat is not a good choice either - lacks in nutrition seriously not to mention contributes to the destruction of our bogs. Even coir can be problematic - few coconut plantations are sustainable - they're planted at the expense of native jungles and are rarely organically cultivated. So - compost is king! Get a pile or bucket going!