When to Fertilize Grass After it Has Been Aerated & Over-Seeded

Timing

• The best time to fertilize is immediately after aerating and overseeding the lawn. Use a starter fertilizer as these formulas are high in phosphorous -- an element which may be too deep in the soil for the new grass roots to reach. Although not mandatory, some gardeners apply a liquid fertilizer six weeks after overseeding. The type you hook up to your hose is ideal. Choose a day when the temperatures are forecasted to remain below 80 degrees Fahrenheit, to avoid burning the lawn.

Aerating

• Aerating a lawn accomplishes several things. The most significant for overseeding is that it reduces soil compaction and roughs up the soil so the seeds have something to grab hold of. Core aeration should be done annually, generally in June or July for warm season lawns and in August for cool-season turf. Most of the large home improvement stores rent core aerators.

Overseeding

• For large lawns, use a spreader to disperse the seeds in a checkerboard pattern. For spot seeding, sprinkle the seeds with your hands. Water the grass seeds to keep the soil moist at all times during germination. Once the seeds sprout, you can back off to a more normal watering schedule, where 1 inch of water a week is standard. If you can't be home during the day to keep up with watering the grass seeds, mulch the bed with straw. This also helps protect the seeds from hungry birds.

Fertilizer Application

• A broadcast fertilizer spreader is ideal for laying down the starter fertilizer, but the tool you use ultimately depends upon the size of the overseeded area. If you've done minor overseeding on small spots, spread the fertilizer by hand -- wearing gloves, of course. Use the broadcast spreader on larger areas. Calibrate the spreader to be sure you don't over-fertilize and damage the seeds. Use the rate suggested on the fertilizer label and water the soil to a depth of 6 inches after applying.