NC State Extension Publications

 

Reduce runoff and trap pollutants with a healthy yard! Use care when gardening to protect streams, rivers, lakes, estuaries, and coastal waters.

Fertilizer Facts

Fertilizer labels always display three numbers in the same order, (i.e., 10-6-4). They represent the percent by weight of three important nutrients:

  • Nitrogen (N)—for green, leafy growth.
  • Phosphorus (P)—for root and bud growth.
  • Potassium (K)—promotes disease tolerance and drought tolerance.

Example: A 40 pound bag of 10-6-4 fertilizer has 10% nitrogen (4 pounds), 6% phosphate (2.4 pounds of P), and 4% potash (1.6 pounds of K).

Fertilizer Rates

A typical lawn feeding is 1 pound of nitrogen per 1,000 square feet.

Here are some common lawn fertilizer formulations and the amount of each needed for 1 pound of nitrogen:

Fertilizer Bag Reads Amount Needed for 1 lb of Nitrogen*
6-2-0 17 lbs
10-10-10 10 lbs
14-3-6 7 lbs
20-5-5 5 lbs
26-3-4 4 lbs
35-3-5 3 lbs
* Rounded to the nearest pound

For other formulations, follow this example using a fertilizer labeled 24-6-6:

  • The first number is the percent of nitrogen—24%.
  • To find out how much total product it takes to apply 1 pound of nitrogen, divide the 1 pound by 0.24.
  • 1 ÷ 0.24 = 4.17. This is equal to a little more than 4 pounds of product.
  • If your lawn is 5,000 square feet, multiply 4 pounds by 5. The result is 20. You would need a 20-pound bag of 24-6-6 to cover your lawn.

Nitrogen Fertilizer Guide for Lawns

This chart shows when and how much fertilizer to apply to your lawn, depending on the kind of grass you have.

Lawns need some nitrogen each year to remain dense and healthy. Many lawns will do fine with only 1 or 2 pounds of nitrogen per 1,000 square feet each year.

Monthly Application Ratea
Turf Jan. Feb. Mar. Apr. May June July Aug.b Sept. Oct. Nov. Dec. lb/nitrogen/1,000 sq ft/yr
Bahiagrass 12 12 1
Bermudagrass 1 1 1 1 4.0
Centipedegrassc 12 12
Fescue, tall 12 to 1 1 1 2.5 to 3
Kentucky bluegrass 12 to 1 1 1 2.5 to 3
Kentucky bluegrass/fine fescue 12 to 1 1 1 2.5 to 3
Kentucky bluegrass/tall fescue 12 to 1 1 1 2.5 to 3
Kentucky bluegrass/tall fescue / fine fescue 12 to 1 1 1 2.5 to 3
Kentucky bluegrass/perennial ryegrass 12 to 1 1 1 2.5 to 3
St. Augustinegrass 12 12 1 12 2.5
Zoysiagrass 12 12 12 1.5
a Dates suggested are for the central piedmont. For the west, dates may be 1 to 2 weeks later in the spring and earlier in the fall; for the east, 1 to 2 weeks earlier in the spring and later in the fall.
b In the absence of soil test recommendations, apply about 1 lb of potassium per 1,000 sq ft, using 1.6 lb of muriate of potash (0-0-60), 5 lb of potassium-magnesium sulfate (0-0-22), or 2 lb of potassium sulfate (0-0-50) to bermudagrass, centipedegrass, St. Augustinegrass, and zoysiagrass.
c Centipedegrass should be fertilized very lightly after establishment. An additional fertilization in August may enhance centipedegrass performance in coastal locations. Avoid using any phosphorus on centipedegrass after establishment.

Lawn Fertilizer

Excess nutrients damage the waters of North Carolina. Follow these tips to make sure you apply only the fertilizer you need.

  • Test your soil first! Order your soil test kit by calling your local Cooperative Extension center. You will be sent instructions on how to take your soil test. The soil test is provided free of charge by the NC Department of Agriculture & Consumer Services.
  • Use your soil test results. Your soil test results will tell you how much phosphorus, potassium, and lime that you need. Depending on the history of your soil, you may not even need to apply these nutrients!
  • Use the chart. The chart provided above will help you determine the amount of nitrogen you need for the type of grass you are growing and the time of application.
  • Recycle your grass! You can reduce the amount of nitrogen you add to your lawn by one-third if you recycle your grass clippings.

Control Erosion

In North Carolina, sediment is our biggest water quality problem.

  • Well-managed lawns control soil erosion.
  • Bare spots in lawns should be reseeded or sodded.
  • Exposed soil in garden areas or natural areas should be covered with some type of mulch such as straw, grass clippings, pine straw, pine bark, or leaf litter, especially during winter and just after tillage.

Mowing Guide

The proper mowing height reduces weed competition and promotes healthy grass growth.

Turf Mowing Height (in.)
Centipedegrass 34 to 1
Tall Fescue 212 to 312
Perennial ryegrass 112 to 212
Kentucky bluegrass 112 to 212
Fine Fescue 112 to 212
Bermudagrass 34 to 1
Zoysiagrass 34 to 112
  • Grasscycle! Leave grass clippings on the lawn. They return nutrients to your lawn and reduce the need for additional fertilizer.
  • Keep mower blades sharp.

Watering

  • In dry spells, allow an established lawn to go dormant, but water every 4–6 weeks.
  • If you want a nondormant lawn, then water when grass looks blue-gray and you leave footprints on it.
  • Early morning is the best time to water to discourage disease and increase watering efficiency.
  • Water slowly; wet the soil to a depth of 4–6 inches.
  • Avoid water runoff from the lawn.
  • Avoid light, frequent watering.

Urban and Suburban Lawns

Cement, gutters, and storm drains! Water that moves into storm drains dumps directly into streams. Fertilizers, oil, and weed-, insect-, and fungus-killers can all move into our waters through the storm drain system.

  • Keep fertilizer off paved surfaces! If fertilizer lands on hard surfaces, be sure to blow or sweep it up immediately.
  • Fill or empty spreaders on your grass, garden, or natural areas. This keeps the fertilizer off hard surfaces.
  • Do not apply fertilizer to frozen ground or dormant turf.
  • Do not use fertilizer as a de-icer.
  • Do not blow or sweep soil and materials into the storm drain.

Questions?

Have a lawn or garden question? Contact the master gardeners at your local Cooperative Extension center.

Acknowledgements

Adapted from Help the Chesapeake Bay by P. Riucciuti and L.L. May, University of Maryland at College Park, Cooperative Extension Service, Home and Garden Information Center.

Authors:

Department Extension Leader (Nutrient Mgt and Water Quality)
Crop and Soil Sciences
Professor Emeritus
Crop and Soil Sciences

Publication date: March 10, 2015
AG-597

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