How Long After Aerating Before Fertilizer?

Aeration Benefits

• Aeration helps your turf grass benefit from fertilizer by improving soil drainage and root growth. If you fertilize right after aeration, water can easily move the nutrients through the soil to the root zone. Improved drainage from aeration also controls thatch, which is a dense layer of undecomposed plant material that accumulates on the soil surface. Thatch prevents water from carrying nutrients to the root zone and promotes fertilizer runoff into streams. Excess fertilizer in streams leads to algae growth, which crowds out other aquatic life.

Warm-Season Grasses

• The best time to aerate and fertilize a warm-season grass lawn is in late spring or summer, when the grass is actively growing. Warm-season grasses include St. Augustine grass (Stenotaphrum secundatum), which thrives in U.S. Department of Agriculture plant hardiness zones 8 through 10, and zoysia grass (Zoysia japonica), which is hardy in USDA zones 5b through 10. Immediately after late spring or early summer aeration, evenly spread 1 pound of actual nitrogen per 1,000 square feet of aerated warm-season lawn. Water thoroughly to wash the nutrients into the soil.

Cool-Season Grasses

• You should aerate and fertilize cool-season lawns in the fall, when the temperatures are cooler and there is less risk of heat stress. Immediately after you aerate the lawn, spread 1 pound of actual nitrogen per 1,000 square feet of lawn. Water the fertilizer into the soil. Cool-season grasses include tall fescue (Festuca arundinacea), which is hardy in USDA zones 4 through 7, and Kentucky bluegrass (Poa pratensis), which grows in USDA zones 2 through 6. Both of these species are invasive in some areas, so you may need a fence or other barrier to control their spread.

Reseeded Lawns

• If you reseed or overseed your lawn immediately after aeration, you should not use a fertilizer that includes weed killer or crabgrass preventer. These products contain herbicides that will prevent desired turf grass seed from germinating. After aeration, a newly seeded lawn benefits from starter fertilizer. For example, you can spread 4 pounds of 9-13-7 starter fertilizer over the soil after aeration and before seeding. Rake the fertilizer into the top 3 to 5 inches of soil. After you spread the grass seed, cover the seed with 1/4 inch of the fertilized soil.