What size is your plant and what size pot is it in? Does the soil have any vermiculite or perilite added for aeration? The Miracle Grow could definately have done it. It can easily burn the plants if you use a bit too much. How long ago did you use it? If recently, then you want to flush it with plain water. Water it until the have the pot size has flowed out of the bottom of the pot. Just stick with plain water until the growth starts looking healtier and then you can fertilize it again, but I strongly recomend organic fertilizers. Nothing can replace what mother nature created.