How To Read Fertilizer Label Numbers

Reading fertilizer label numbers can be a daunting task when trying to find the right formulation. Sure, it looks intimidating, but follow these instructions to solve the fertilizer labels mystery.


Three Major Numbers

There are three large printed numbers on every bag of fertilizer required by law. These numbers represent the percentage of the three nutrients that are required for healthy plant growth. The numbers, for example, 24-20-10 would represent the percentages of nitrogen, phosphorous and potassium – in this order.


What Do They Mean?

The first number, “24,” represents the percentage of nitrogen in the bag. Nitrogen is a necessary element that helps produce chlorophyll. The second number represents how much phosphorous is in the mix. This aids in root development.  The “8” represents the percentage of phosphorous and the higher the amount of percentage will dictate its use as a fertilizer used in sowing new lawns or planting new trees. The third represents potassium percentage. Potassium helps plants ward of disease and aids in protection during drought periods and cold weather. When selecting fertilizer, a high potassium formula would be applicable at the beginning of winter and summer to protect plants from extreme changes in temperature.

The three numbers never add up to 100 percent because there are fillers and other additives present in every bag of fertilizer.