Miracle-Gro also contains high levels of salt, which over time strip the soil of its natural nutrients and prevent plants from absorbing them as well, causing a type of “lawn burn.” Many consumers believe that more fertilizer will help their gardens even more, so overapplication and consumer misuse exacerbate theseClick to see full answer. Also question is, why Miracle Grow is bad?Miracle-Gro is a synthetic fertilizer that contains ammonium phosphate and several other chemicals that can be toxic to your soil and plants. D., says in his book Fertile Soil: “[Ammonium fertilizer] acidifies the soil, and thus it is probably more harmful to soil organisms than any other nitrogen fertilizer . . . .Likewise, what is special about Miracle Gro? ‘Miracle-Gro’ is a 15-30-15 fertilizer, meaning that that the powder within contains 15 percent nitrogen, 30 percent phosphorous, and 15 percent potassium. Nitrogen, phosphorous, and potassium are the three main nutrients needed by plants, the ones plants gobble up in greatest quantity. Keeping this in consideration, is Miracle Gro poisonous to humans? Miracle-Gro contains urea, which can irritate the mouth, throat, esophagus and stomach. Swallowing it can cause nausea and vomiting. According to the Manufacturer’s Safety Data Sheet for Miracle-Gro, if you accidentally swallow the product, immediately rinse the mouth out with water.Is Miracle Gro a good fertilizer?Each type of fertilizer, whether a liquid, dry or slow-release formulation, is designed to provide the nitrogen, phosphorus and potassium necessary for your plants to thrive. Depending on the type of Miracle-Gro, it can be a good fertilizer for tomatoes and vegetables.