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Understanding Fertilizer Labels

August 15, 2012

Have you ever wondered what the three numbers on the bag, box, or jug fertilizer you use on your plants or lawn mean? Well here is a brief overview on understanding what these numbers represent.


The three numbers are the [N] Nitrogen, [P] Phosphorus (Phosphate), & [K] Potassium (Potash) percentages by weight in each bag.

For Example:
A bag of 24-5-11 is made up of 24% Nitrogen, 5% Phosphorus, & 11% Potassium

  • Nitrogen: Helps to produce more chlorophyll which helps make the plant grow more rapidly. It also helps to develop a darker green color in the plant.
  • Phosphorus: Helps with root development, flowering quantity, & bloom size.
  • Potassium: Helps the plant guard against disease. It also helps aid the plant with drought & cold tolerance.

These number don’t add up to 100%

Now you might be saying to yourself, these percentages do not add up to 100%. Well, you are right! The rest of the bag is made up of other nutrients and fillers that help make sure the product is spread at an even rate.

An experienced gardener may be able to look at a nutrient problem a plant might have and be able to diagnose what that plant is lacking, but until you are able to do that, have your soil tested if your plant looks unhealthy. This can be done through your local Cooperative Extension Office.

Download the full Article (.pdf) and learn how to calculate fertilizer nutrient amounts.

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