When Is the Best Time of Year to Fertilize Grass in the Midwest?

Warm- and Cool-Season Grasses

• Lawn grass comes in two types: warm weather and cool weather. The Midwest is a transitional zone where both types of grasses are found in lawns. As the names imply, each grass experiences its greatest growth in the weather best suited for it. This affects the type of fertilization program that a homeowner will use. Zoysia and Bermuda grass are two frequently used warm-season grasses while Kentucky bluegrass, ryegrass, and fescue are cool-season grasses.

Warm-Weather Grass Fertilization

• Fertilize warm-season grasses in the spring and summer. These grasses do much of their growing during the summer and need the extra boost. Two pounds of nitrogen per 1,000 square feet is an appropriate amount to put down on established lawns. Too much fertilizer risks burning the grass -- or destroying its roots. Fertilizer can also run off and pollute the water table.

Cool-Weather Grass Fertilization

• Cool-weather grasses benefit from a light application of fertilizer in the spring and summer, but their best time to receive a major fertilization is during the late summer and early fall. The spring fertilization should come as the plants slow down their early growth. The fall fertilization amount should be about 1 to 1-1/2 lbs. of nitrogen per 1,000 square feet. In late October lightly fertilize again with a fast-acting fertilizer to prepare the roots for winter.

Mulching The Grass

• Free fertilization is available for both warm- and cool-season grasses when you cut your lawn. By using a mulching mower instead of bagging the clippings, you allow the nutrients to stay on the lawn and decompose back into the soil. Lawn clippings do not add to the problem of thatch since that is mostly made up of dead and woody rhizomes the plant is sending out for reproduction.