Fertilizers are concentrated fertilizer particles of the major nutrients required by plants. Nitrogen, Phosphorous and Potassium are the three ingredients listed, in that order, in large numbers on the label. On the side label of the package, it will also state any other ingredients included. Calcium, magnesium, iron, micronutrients and the percentage of organic matter are common components of many specialty fertilizer products. The first number states the concentration of nitrogen in the package.
Nitrogen promotes leafy growth and is commonly associated with making the grass green.
A fertilizer with a high concentration of nitrogen, compared to the other ingredients, is useful for home lawns, deciduous and evergreen trees and to accelerate the growth of most plants. The second number states the concentration of phosphorous in the package. Phosphorous is also useful in vegetable production since it promotes flower set and heavy cropping. In flower production, phosphorous is required to produce robust blooms. The third number on the label states the concentration of Potassium.