Lawn Care

Fertilizer Facts

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

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

Example: A 40-pound bag of 10-6-4 fertilizer is 10 percent nitrogen (4 lb of N), 6 percent phosphate (2.4 lb of P), and 4 percent potash (1.6 lb of K).

Trivia Notes (interesting, but not essential information):

	Phosphate is a chemical form of phosphorous.
	Potash is a general term for any of several chemical forms of potassium.
	K is the chemical symbol for potassium, which derives from a Middle English transliteration of the Arabic words, "al" + "kali", meaning "the" + "ashes". You may recognize this combination to be "alkali." Potassium was made from calcined plant ashes. The symbol "K" is for "kali", the "ashes". To "calcine" ashes means to heat them to a very high temperature but below the melting point. Calcium and potassium are alkali metals.

Nitrogen Fertilizer Guide for Lawns

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

Turf

Monthly Application Rate
lb N per 1000 sq ft yard

Bahia grass

Bermuda grass

Centipede grass (see note)

Fescue, tall

½ to 1

Kentucky bluegrass

½ to 1

Kentucky bluegrass / fine fescue

½ to 1

Kentucky bluegrass /tall fescue

½ to 1

Kentucky bluegrass /tall fescue /fine fescue

½ to 1

Kentucky bluegrass /perennial ryegrass

½ to 1

St Augustine grass

Zoysia grass

	Dates suggested are for the central piedmont of North Carolina. For western NC, dates may be 1 to 2 weeks earlier in the Fall; for eastern NC, 1 to 2 weeks earlier in the Spring and later in the Fall.
	For bermuda grass, centipede grass, St. Augustine grass, and zoysia grass: In the absence of soil test recommendations, apply about 1 lb of potassium per 1000 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) in August.
	Centipede grass should be fertilized very lightly after establishment. An additional fertilization in August may enhance centipede grass performance in coastal locations. Avoid using any phosphorous on centipede grass after establishment.

Fertilizer Rates

A typical lawn feeding is 1 pound of nitrogen per 1,000 square feet of lawn. Here are some common lawn fertilizer formulations and the amount of each needed for 1 pound of nitrogen.

Fertilizer bag reads	Amount of fertilizer 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 percent.

To find out how much of this 24-6-6 fertilizer it takes to apply 1 pound of nitrogen per 1000 sq ft, divide 1 pound by 0.24.

1 pound divided by 0.24 equals 4.17 pounds
This calculation says you would need approximately 4 pounds of this fertilizer for each 1000 sq ft of your lawn.

If your lawn is 5,000 sq ft, multiply 5 time 4 pounds. The result is 20. You would need a 20-pound bag of 24-6-6 fertilizer to cover your lawn.

Mowing Guide

The proper mowing height and sharp mower blades reduce weed competition and promote healthy grass growth.

Turf	Desired height (inches)
Centipede grass	¾ to 1
Tall fescue	2½ - 3½
Perennial ryegrass	1½ - 2½
Kentucky bluegrass	1½ - 2½
Fine fescue	1½ - 2½
Bermuda grass	¾ - 1
Zoysia grass	¾ - 1½

Grasscycle! Leave grass clippings on the lawn. They return nutrients to your lawn and reduce the need for additional fertilizer.

You can reduce the amount of nitrogen you add to your lawn by a third if you recycle you grass clippings.

More often enough so that you never have to remove more than one third of the height of the grass when you mow. If you need to remove more than a third, then mow twice.

The grass blades process the soil nutrients and return them to the roots to make the roots grow. If you keep your grass tall, a better root system will develop to help grass survive a hot dry spell.

Have a lawn question?

	Visit the North Carolina State University Cooperative Extension Service Turf Files web site, or
	Email the Guilford County Horticultural Agent, or
	Call the Telephone Hotline.

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Most of the information presented on this web page is from Bulletin AG-597 published by the
North Carolina Cooperative Extension Service in June 1999.