Understand nitrogen, phosphate and potash on a fertilizer label, calculate an example rate and use soil-test guidance before feeding your lawn.
Coast to Coast GrassOriginally published May 3, 2023Content revised September 24, 2026 · Editorial approach
Grass texture, photographed in natural light. This is an illustrative photograph, not a species-identification image. Photo credits.
Make the plan fit your lawn.
Weather, soil and product formulations vary. Use local conditions and current product labels when deciding what to apply and when.
Potash is the label term for potassium expressed as K₂O equivalent. The 5 means 5% soluble potash by weight, not 5% elemental potassium. This is a label-reading example, not a fertilizer recommendation.
What the three numbers mean
The fertilizer grade lists percentages by weight: nitrogen (N), available phosphate (P₂O₅) and soluble potash (K₂O). The second and third numbers are oxide-equivalent label expressions, not percentages of elemental phosphorus and potassium. A 10-0-5 bag contains 10% nitrogen, 0% available phosphate and 5% soluble potash.
Separate the recommendation from the arithmetic
If local guidance calls for 0.5 pound of actual nitrogen per 1,000 square feet and a suitable product contains 10% nitrogen, the calculation is 0.5 ÷ 0.10 = 5 pounds of product per 1,000 square feet. For 2,000 square feet, that example becomes 10 pounds of product. This demonstrates units; it does not recommend that rate, timing or product for your lawn.
Choose from the soil report and grass
There is no universally best “balanced” ratio for every lawn. Ask your laboratory or extension office how the soil results, species and season translate into nutrient recommendations; soil testing alone may not set every nitrogen decision. Nutrients already sufficient in the soil may not need to be added. Follow current local fertilizer requirements as well as the label.
Make an application plan
Measure turf without beds or paving, check the analysis, and calibrate the spreader for the product. Bag spreader settings are a starting point, not proof of the amount actually delivered. Keep material off paved surfaces and out of water, and avoid application to frozen or snow-covered ground. Save the product, area, amount and date in a short log.
A pale lawn is not a fertilizer test
Shade, moisture, roots, grass type and disease can affect appearance. Feeding cannot repair every cause of thinning. Start with the soil-sampling guide or patch diagnosis checklist when the cause is unclear.
Sources and local guidance
University guidance supports the species facts and care principles here. Rates and dates in a regional source apply to that region; they are not national prescriptions. Use your local extension office for cultivar, soil-test and treatment decisions.
COAST TO COAST GRASSJANUARY - DECEMBER / REUSABLE EACH YEAR
N-P-K Fertilizer Numbers: A Lawn Owner’s Guide
Understand nitrogen, phosphate and potash on a fertilizer label, calculate an example rate and use soil-test guidance before feeding your lawn.
Before you start: Use months as reminders; local weather, grass growth and establishment stage take priority. Move freeze preparation ahead of your first local freeze, even if earlier than shown.
01
January
Read past results
Match each soil report to the lawn area and grass it actually describes.
02
February
Read N-P-K
The grade shows nitrogen, phosphate and potash percentages. It does not tell you how much your lawn needs.
03
March
Sample suitable ground
Avoid contaminated spots and follow lab directions; wait if soil conditions prevent a useful sample.
04
April
Map separate areas
Keep distinctly different soil or management areas separate when the lab recommends it.
05
May
Interpret the recommendation
Ask how results translate into the grass’s nutrient and pH needs.
06
June
Measure before applying
Use actual turf area and the current label; a bag’s grade is not an application rate.
07
July
Investigate pale patches
Check roots, moisture and shade before assuming a nutrient deficiency.
08
August
Plan justified amendments
Only add lime, sulfur or nutrients for a clear recommendation and suitable timing.
09
September
Keep an application log
Record material, amount, area and date when any recommended work is done.
10
October
Check local restrictions
Fertilizer rules and seasonal limits vary; verify them before applying.
11
November
Protect dormant ground
Avoid fertilizer on frozen or snow-covered soil and keep material off paving.
12
December
Plan the next test
Use the laboratory’s retesting interval rather than changing pH repeatedly without evidence.
Observe the cause
Choose the right growing window
Keep a short photo and care log
Use current local advice and product labels for treatments. New seed, sod and plugs need establishment care. This is a planning guide, not a monthly application schedule.
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Use a soil recommendation and the current fertilizer label, then measure the lawn and calibrate the spreader.
The spreaders are alternatives. This checklist does not prescribe a fertilizer, application rate or frequency.
Spreading / Whirl / 71074
Scotts Whirl hand-powered spreader
Consider for: Small areas and occasional granular applications.
Hand-crank operation; adjustable arm support. A compact option when storing a wheeled spreader would be awkward.
Check before buying
You carry the loaded hopper. Check material compatibility and calibrate for the actual product; bag coverage is not a universal hopper capacity.
