Miracle-Gro Plant Food is a concentrated mixture of nutrients, supporting the growth of flowers, vegetables, lawns and houseplants. While the ingredients vary slightly between "Organic" and "All-Purpose" options, many of the same nutrients exist in all Miracle-Gro fertilizers. The Miracle-Gro Plant Food mixtures have a series of three numbers on the bag, showing the percentages of the three main ingredients producing that particular blend.
The three numbers on packages of Miracle-Gro Plant Food indicate the amount of nitrogen, phosphorus (phosphate) and finally potassium (potash) in the fertilizer. These three ingredients are known as the primary macronutrients in plant growth. For example, the series "24-8-16" on bags of Miracle-Gro All-Purpose Plant Food means the mixture has total nitrogen of 24 percent, total phosphorus of 8 percent and 16 percent available potassium.
Essential to chlorophyll and all proteins, nitrogen plays a big role in photosynthesis. In addition to contributing to the photosynthesis process, phosphorus is a factor in the development of sugars and starches. Potassium is absorbed by the plant in great quantities and is responsible for proteins and photosynthesis. Potassium is crucial to what is thought of as the "immune system" of the plant, keeping it healthy and preventing disease.
Largely responsible for plant metabolism, micronutrients aid in the production of sugars and the regulation of other nutrients. These ingredients include boron, copper, iron, manganese, molybdenum and zinc. Helping these micronutrients blend with the soil, a "chelating agent" known as ethylenediaminetetraacetic acid also aids in photosynthesis and the transportation of oxygen.
Added to water at a ratio of 1 1/2 tbsp. of Miracle-Gro per 1 1/2 gallons of water for outdoor plants, this potent fertilizer promotes growth by replenishing the nutrients in the soil that are absorbed by the plants. The directions recommend wetting the leaves of the plant and soaking the soil to feed the roots. When used indoors, a dilution of 1 tsp. of Miracle-Gro per gallon of water is recommended for soaking the soil to the roots. It is not necessary to wet the leaves of indoor plants with the fertilizer. For best results, the directions suggest applying the fertilizer every 7 to 14 days.