This easy-to-use tool helps you determine how much fertilizer your lawn needs throughout the year. Whether you have cool-season or warm-season grass, get precise application rates and an annual fertilization plan to keep your lawn healthy and thriving. Refer to the instructions on your bag of fertilizer to determine N-P-K and Nitrogen Rates and this tool will calculate how much fertilizer you’ll need.
Fertilizer Calculator
What is this? The bag will usually state something like "Apply X pounds of fertilizer per 1000 square feet." This tells you how much of the entire fertilizer product to apply based on your lawn size.
You will need 0.00 lbs of fertilizer for your lawn.
At this rate, you will apply 0.00 lbs of phosphorus and 0.00 lbs of potassium per 1,000 sq ft.
Annual Fertilization Plan
Select your grass type to view the fertilization plan.
Additional Information About Application Rates
When applying fertilizer, always consider the specific needs of your grass type and the time of year. Over-application can lead to nutrient runoff, which may harm the environment. It is recommended to split the total nitrogen application into multiple smaller applications throughout the growing season to ensure even growth and reduce stress on your lawn.
Cool-season grasses benefit most from fertilization during early fall and late spring, while warm-season grasses respond best to applications during late spring and summer.
Read the Label
Always follow the label instructions on your fertilizer bag, and avoid exceeding the annual nitrogen limits for your grass type to promote healthy growth and avoid potential damage. Keep in Mind: Applying fertilizer can lead to increased lawn growth, which means you should be prepared to mow more frequently to maintain the lawn’s appearance.
If you are unsure about the correct fertilizer or rate, contacting your local agricultural extension office for or a lawn care center can help. Soil testing can provide valuable insights into nutrient deficiencies and help tailor your fertilizer plan more accurately to your lawn’s needs.
What to Look for in N-P-K Levels
For cool-season grasses like Kentucky bluegrass, fescue, or ryegrass, a good N-P-K fertilizer ratio to look out for is 20-5-10. This provides a higher nitrogen (N) level to promote lush growth, phosphorus (P) to support root development, and potassium (K) for stress tolerance, especially during active growth in the cooler months of spring and fall.
For warm-season grasses like Bermuda, zoysia, or St. Augustine, a typical recommendation is 16-4-8. This blend supplies ample nitrogen to fuel growth during the warmer months with phosphorus and potassium to encourage strong roots and resilience during hot conditions.
Warm VS Cool Season Grass Types
Cool-season and warm-season grasses are two types that thrive in different temperatures. Choosing the right one depends on your climate.
Cool-Season Grasses
- Best in cool weather (spring and fall) with temps from 60°F to 75°F.
- Found in northern regions like the Pacific Northwest, Midwest, and Northeast.
- They grow best in USDA Zones 3-7 and stay green most of the year, though they might go dormant in hot summers.
Examples: Kentucky bluegrass, fescues, and ryegrass.
Warm-Season Grasses
- Thrive in hot weather (summer) with temps from 80°F to 95°F.
- Common in southern areas like the Southeast, Southwest, and parts of the Midwest.
- Suited to USDA Zones 8-11, they turn brown in winter when it gets cool but bounce back in the heat.
Examples: Bermuda grass, Zoysia, and St. Augustine.
Finally, be sure to check whether a license or certification is required to provide fertilization services in your state. Where I live in Idaho there is no special certification required for fertilization of customer lawns, but that may not be the case where you live. Most states require an applicator’s license or other certification for handling and applying herbicides even if combined with fertilizer. Make sure to research your state’s requirements to ensure compliance before offering these services to customers.
About the Author: Brett Lindenberg
