9 Basic Guidelines of Fertilizing:
- Do a soil test to determine which fertilizer to use.
- Apply no more than 1-pound of fast-release nitrogen per 1,000-square feet in a single application.
- Use slow-release nitrogen whenever possible, especially on sandy soils.
- Apply only the amount called for based on your lawn’s square footage.
- Use a rotary spreader to apply quickly and evenly, and to avoid a striped pattern in the grass.
- Spreading a half-rate of fertilizer in two directions for each application helps prevent stripping.
- Apply fertilizer to dry grass, and water well immediately afterward.
- Sweep up all fertilizer that lands on paved or impervious areas to prevent it from washing into the storm sewer.
- The optimal time to apply fertilizers is when the grass roots and blades are actively growing.
Fertilizer Recommendations for North Grasses
Growth season for north grasses occurs during the early to mid-fall, when weed competition is minimal, and fertilizing produces healthy roots. This timing also allows plants to build upon needed carbohydrate stores with just a moderate amount of top-growth.
You should divide the annual amount of fertilizer and apply two-thirds in early fall and the remainder in mid to late spring, after the lawn’s initial green-up.
For low-maintenance lawns, apply 2 pounds of nitrogen per 1,000 square feet. Higher-maintenance lawns may need 3 to 4 pounds of nitrogen per 1,000 square feet. This may require an adjustment, given your specific growing environment, soil test results, the lawn’s condition, and the type of fertilizer you use. For example, Kentucky bluegrass and Perennial ryegrasses require more fertilizer than the fescues. Consult your local Cooperative Extension Service (CSREES) for recommendations.
Fertilizer Recommendations for South Grasses
Southern lawns growing warm-season grasses, such as Bermudagrass, Zoysiagrass, St. Augustinegrass, Seashore Paspalum, Bahiagrass, Centipedegrass, and Carpetgrass, are most active and grow most vigorously in the heat of the summer.
With warm-season grasses, the first fertilizer application should be made about three weeks after the initial spring green-up; then fertilize again later in the summer, but while the plants are still actively growing.
Low-maintenance lawns will need about 2 to 4 pounds of N per 1000 square feet per year; whereas higher maintenance lawns will need 4 to 6 pounds of N per 1000 square feet per year. These suggestions may require adjustment depending on your specific growing environment, soil test results, the lawn’s condition, and whether you use a slow or fast-release type of fertilizer. Wait until warm-season grasses become dormant before fertilizing areas overseeded for winter color. Consult your local Cooperative Extension Service (CSREES)
Common Nitrogen Fertilizers
The nitrogen fertilizers listed below are commonly available at nurseries and garden centers:
- Ammonium nitrate
- Ammonium phosphate
- Calcium nitrate
- Ammonium sulfate
- Activated sewage sludge
- Alfalfa meal
- Bone meal
- Composted manure
- Corn gluten meal
- Dried poultry waste
- IBDU (isobutylidene diurea)
- Methylene urea
- Poly-coated urea
- Soybean meal
- Sulfur-coated urea
Learn more: What is organic fertilizer?
Make sure to follow the manufacturer’s instructions; check the calibration of your spreader, as well as the square footage of your lawn, to ensure that you are applying the right amount of fertilizer. Remember, more is not necessarily better with fertilizers, applying too much may “burn” your lawn and promote thatch formation, disease, and insect infestation.
Keep in mind that over-watered lawns, those subject to heavy rainfall, and sandy soils are more prone to leached nutrients. The use of slow-release and water-insoluble fertilizers will help reduce leaching and keep nutrients available to the plants longer. Also, when mowing your grass, mulch the clippings back into your lawn. Grass clippings left on the lawn over the course of a year will return about 1 pound of nitrogen per 1,000 square feet.