Ingredients in Miracle-Gro Plant Food

Many people who use the Scott’s Company line of fertilizers called Miracle-Gro believe that this plant food causes miraculous growth in their vegetables, roses, ornamentals, houseplants, and lawns. This synthetic fertilizer is advertised to “give you the beautiful garden you've always wanted.” One of its selling points is that it contains no potentially harmful inert ingredients such as industrial waste and heavy metals, according to the book, "Fateful Harvest."

Ammonium Phosphate

Ammonium phosphate is a commonly used ingredient in chemical fertilizers because of its high concentration of phosphorus, an essential plant nutrient. Ammonium phosphate can contain as much as 46 percent phosphorus, according to If it is used improperly, ammonium phosphate can cause irritation to the mucus membranes, according to Cameo Chemicals, so be sure to observe product warnings on Miracle-Gro packages.

Main Nutrients

All plant food packages show a listing of the three major nutrients that they contain. These nutrients are nitrogen (N), phosphorus (P) and potassium (K), expressed as the N-P-K ratio. All-purpose Miracle-Gro has an N-P-K ratio of 15-30-15, which gives it a large concentration of all three nutrients. Other Miracle-Gro products have differing ratios that help to support the type of plant for which they are intended. For example, Miracle-Gro Continuous Release Rose Food contains an N-P-K ratio of 9-18-9: the smaller amount of nitrogen helps to promote more flowers.


Urea is the common name of ammonium cyanate, which was the first synthesized chemical. Many plant foods include synthesized urea because it contains large quantities of nitrogen. Human and animal urine contains urea, notes

Potassium Chloride

The white crystalline chemical powder known as potassium chloride is one of Miracle-Gro’s ingredients. As a plant nutrient, potassium chloride causes increased plant growth and productivity of flowers or fruit. It can cause skin, eye, gastrointestinal and respiratory irritation if it’s consumed or used inappropriately, according to the J.T. Baker Chemical Company website.

Keywords: plant food, fertilizer Miracle-Gro, chemical synthetic, Miracle-Gro ingredients

About this Author

Barbara Fahs lives on Hawaii island, where she has created Hi'iaka's Healing Herb Garden. Fahs wrote "Super Simple Guide to Creating Hawaiian Gardens," and has been a professional writer since 1984. She contributes to Big Island Weekly, Ke Ola magazine, GardenGuides and eHow. She earned her B.A. at UCSB and her M.A. from San Jose State University.