Understanding the Lawn Fertilizer Calculator
A lawn fertilizer calculator tells you how much product to apply to your lawn based on its size and the fertilizer’s nutrient content. Applying the right amount keeps grass healthy and green while avoiding the waste, lawn burn, and runoff that come from overdoing it.
Reading the N-P-K numbers
Fertilizer bags show three numbers — the percentages of nitrogen (N), phosphorus (P), and potassium (K). Recommendations are usually given as pounds of nitrogen per 1,000 square feet, so the calculator works back from the bag’s nitrogen percentage to tell you how much actual product to spread.
More is not better
Over-fertilizing can burn the grass, cause excessive growth that stresses the lawn, and wash nutrients into waterways. Applying the calculated amount evenly, and watering it in as directed, gives the best results. Splitting the annual feeding into a few applications across the growing season is gentler than one heavy dose.
Tips & things to know
- •Rates are usually per 1,000 sq ft of nitrogen.
- •Over-fertilizing burns grass and pollutes waterways.
- •Split feeding across the season for healthier turf.