Practical Lawn Fertilizing: When, What, and How for Healthier Grass

Lawn fertilizing works best when guided by grass type and soil test results. Use slow-release nitrogen, prioritize fall feeding for cool-season grasses and late-spring through summer for warm-season grasses, and apply with a calibrated spreader while following label and local guidelines to protect water quality and avoid burn.

Why fertilize your lawn?

Grass is a group of plants and, like other plants, it needs nutrients to stay healthy. Regular fertilizing replaces nutrients that mowing, rain, and natural processes remove. The right feeding schedule and product will encourage root development, fill thin areas, and help grass outcompete weeds.

Know your grass: cool-season vs warm-season

Timing depends on your grass type. Cool-season grasses (Kentucky bluegrass, tall fescue, perennial ryegrass) grow fastest in spring and fall. For those lawns, the most important application is in early fall (late August-October) to build root reserves for winter and a greener spring.

Warm-season grasses (zoysia, bermudagrass, St. Augustine) are active in late spring and summer. These lawns typically get most of their fertilizer from late spring through mid-summer.

Local climate also matters. Check your state extension service for region-specific timing.

Choose slow-release and base decisions on a soil test

Slow-release (controlled-release) nitrogen sources reduce burn risk and provide steady nutrition. They feed grass over weeks to months rather than all at once.

Before picking a product, get a soil test. A basic soil test tells you soil pH and nutrient levels and helps you avoid unnecessary phosphorus or over-application. Many areas now restrict phosphorus in lawn products unless a soil test shows a need.

Seasonal, example approach

• Early spring: Address broad issues. Apply a pre-emergent herbicide if you have crabgrass history and soil temps reach ~55°F for several days (timing varies by region).

• Late spring to early summer: For warm-season lawns, apply a primary feeding as growth begins. For cool-season lawns, limit nitrogen in late spring to avoid excessive summer growth.

• Summer: Avoid heavy feeding of cool-season grasses; consider a light, slow-release feeding only if the lawn needs it.

• Fall: The priority for cool-season lawns. A late-summer to fall application promotes root growth and winter hardiness.

Application best practices

Use a calibrated spreader and follow label rates. Fill the spreader off the lawn (on pavement) to avoid accidental spills that cause burn. Water in the fertilizer if the product label directs you to do so.

Do not apply before heavy rain, which can cause runoff and waste product. Sweep granular material off driveways and sidewalks back onto the grass.

Environmental and safety notes

Overfertilizing wastes money and can harm water quality. Follow label rates, observe local fertilizer ordinances, and choose low-phosphorus products unless a soil test indicates a deficiency. Keep children and pets off treated areas until the product has been watered in or as the label specifies.

Fertilizing consistently, based on soil tests and grass type, is the most reliable route to a thicker, healthier lawn.