I would only use the tinniest amount of miracle grow in conjunction with good nutes. The problem with miracle grow is most of the nitrogen is not in a readily available form. it must be processed by beneficial bacteria in order to be available to the plant. this means miracle grow will quickly put the salt content of your soil through the roof. so if your going to use miracle grow get a soil ph meter, costs like 10 bucks and you can keep an eye on the buildup.