Single Application Fertilizer Calculator for NJ Homeowners with Established Lawns
For lawn situations other than Established Lawns, we recommend
Soil Testing to determine your soil needs.
Step 1
Estimate the total size (in square feet) of your lawn using tape measure, or number of paces (eg. 13000 square feet). Do not use commas.
Step 2
Insert Nitrogen application rate. For Established Lawns, NJ Law allows no more than 0.9 pounds of Nitrogen per thousand square feet. Use decimal equivalent - Do not use fractions.
Step 3
Insert the first number in the analysis of your bag of fertilizer. (eg. 15 - 0 - 10) This number corresponds to the percentage of nitrogen in the bag. The second number corresponds to the percentage of phosphorous and the third number, potassium.
You may apply pounds of fertilizer per one thousand square feet.
You may apply pounds of fertilizer for your entire lawn.

Designed by Jason L. Gray. Texas A&M. Special Thanks to Marilyn Hughes.

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Make Your Life Simpler
Calculate your lawn fertilizer needs for an established lawn while complying with the 2011 NJ Fertilizer Law which restricts the amount of nitrogen you can apply to your lawn per application as well as per season.

Once new fertilizer formulations required by the law come out, figuring out how much fertilizer you can put down should be simple – follow the directions on the package and you will be in compliance with the law.
Fertilizer companies have until 2013 to comply with label and content requirements.

For completeness, let’s go through the actual numbers:

For a single application - Don’t apply more than 0.7 pounds of water-soluble N per 1,000 sq. feet of turf. Don’t apply more than 0.9 pounds of total N per 1,000 sq. feet of turf.

For the year’s total application - Don’t apply more than 3.2 pounds of N per 1,000 sq. feet of turf per year.

Keeping track of fertilizer you’ve applied over the year might seem tedious, but once the new formulations are released this should be less of a burden.


When to Fertilize
Fertilize lightly in spring and early summer, little to none in summer, and heavily in fall. A heavy fall fertilization program produces the healthiest turf throughout the year. Applying high rates of N in spring and summer stimulates excess leaf growth at the expense of root growth. This forces you to mow more often and reduces turf quality. High rates applied in spring and summer can also stimulate disease, weed, and insect activity.

The Amount of Fertilizer Can Vary
The amount of lawn fertilizer that should be applied annually depends on a number of factors.
  1. Homeowner desires: A dense, dark green lawn requires more fertilizer than a thinner, lighter colored lawn. Applying more fertilizer annually also means more mowing and irrigation. (Note that over application of fertilizer can also lead to more nutrients leaching to groundwater or in runoff to surface waters.)
  2. Location: More fertilizer is needed to maintain the same turf quality in the warmer regions than in the colder regions because the longer growing season.
  3. Species: Certain types of zoysiabuffalograss, or tall fescue require less annual fertilizer than species such as Kentucky bluegrass or perennial ryegrass.
  4. Weather: Wet weather stimulates growth and requires more fertilizer than dry weather. The same is true for an irrigated lawn vs. a nonirrigated one.
  5. Soil type: Turfgrasses grown on a very sandy or very heavy soil requires more fertilization than on a silt loam soil.
  6. Age and quality of existing lawn: New lawns need more fertilizer for the first few years to enhance density as does rebuilding a neglected or thin lawn.
  7. Clippings: Clippings should always be returned to the lawn; removing clippings for composting or mulch necessitates more annual applications of fertilizer.
Manually Calculating the Pounds of Fertilizer to Apply
Determining the amount of fertilizer to apply when you are given the fertilizer rate in lbs N/1000 sq ft:

Desired rate in lbs N/1000 sq ft
% nutrient
Total fertilizer needed/1000 sq ft

Total fertilizer needed/1000 sq ft
Area to be
in sq ft
lbs fertilizer needed to treat the area
For example, how much fertilizer do you need to apply to a 20-0-0 fertilizer at 0.9 lbs N/1000 sq ft to a 5000 sq ft lawn?
0.9 lbs N/1000 sq ft
4.5 lbs 20-0-0/1000 sq ft

4.5 lbs 20-0-0/1000 sq ft
5000 sq ft
22.5 lbs of 20-0-0 to treat a 5000 sq ft lawn at rate 0.9 lb N/1000 sq ft

Adapted from Purdue University