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Lawn Fertilizer Facts

By Moira Clune ; Updated September 21, 2017
Lawn fertilizers keep your grass looking its best.

Lawn care requires more than just mowing and watering; lawns need a regular program of feeding and maintenance. Fertilizers provide the nutrients your lawn needs to grow and thrive.


A healthy, well-fed lawn is resistant to drought and disease, weed and insect invasion. A soil test will help determine what nutrients are present or missing from your soil.


Lawn fertilizers contain the components nitrogen, phosphorus and potassium, usually listed as "NPK." Nitrogen (N) promotes green, above-ground growth, phosphorus (P) feeds the roots and potassium (K) aids in photosynthesis and root development.

Fast or Slow Release Nitrogen

Fertilizers contain "fast release" or "slow release" nitrogen. The University of Illinois Extension suggests: "For lawns, fertilizers containing controlled-release nitrogen sources are suggested for most applications."

When to Feed

Lawns should be fertilized in spring and fall. Spring fertilizers help lawns "green up" quickly while fall fertilizers build strong roots for winter resiliency.


Several forms of fertilizer are available, including liquid and granular. Liquid fertilizers are fast acting, but granular formulas are easier to measure and apply.