miracle grow nutrients are fine in soil, just use 1/4 as much as directed, and ease it up only when your plants demand more. Using miracle grow as directed on the box will burn the living shit out of your plants, except Shake-n-Feed. that time release pellet shit works pretty good, with that you can follow the label. shake some pellets into your hand, when they cover an area the size of a dime, sprinkle them onto the plant's soil surface, then just water normally. I've used this one for years with good result.
the liquid fertilizers are extremely potent, and will burn your plants at the concentrations directed on the packet. they do work though, and are pretty cheap.
if you use one type, dont use the other.