Topping your lawn with fresh seed and mulch, a procedure called overseeding, works best on thin lawns using healthy grass. The newest seed establishes more quickly and grows thicker if you apply the right formula for planting, mulching it using peat and supplying proper care. Overseed warm season grasses in early summer, or cool season grass in autumn or early spring.
Preparing to Seed
A thick thatch layer prevents seeds from reaching the ground to germinate or root. Remove the thatch when the layer is over 1/2-inch heavy with a dethatching rake or a mechanical dethatcher. Aerating using a core aerator after dethatching opens up the ground, which allows air and moisture to reach grass roots while also helping the seeds and peat penetrate the ground for better sprouting and amending. The dirt plugs eliminated during aeration split and dissolve into the soil during future waterings and mowing.
The total amount of seed is based on the type of grass and the area you’re covering. For example, for Bermuda grass (Cynodon dactylon), that grows in U.S. Department of Agriculture plant hardiness zones 7 through 10, apply 1 lb of grass seed for every 1,000 square feet of lawn. Water the ground to moisten it, then broadcast the seed evenly over the lawn using a drop spreader or a handheld rotary spreader.
Covering the seed lightly after sowing aids germination by holding in moisture. Peat moss retains moisture while still allowing air circulation, but you can substitute compost or topsoil if necessary. Fill a peat spreader, which looks like a wire mesh barrel with a handle attached, with peat or compost. Roll the spreader throughout the lawn to apply a thin, even layer of peat in addition to the seeds. The layer should be no longer than 1/4-inch thick. You can pull the back of a rake gently through the lawn to degree and push the peat down beneath the grass blades so it sits directly on top of the seed and soil.
Frequent, light watering ensures the seeds stay moist to germinate quickly. Water immediately after seeding, supplying about 1 inch of water. Continue to water the lawn daily at precisely the same pace, or twice daily during hot weather when the top 3 inches of soil dries out quickly. After the seeds start to sprout, typically within a week, reduce watering to once or twice per week. You can start mowing when the grass is 4 inches high, cutting it no lower than 2- to 3-inches tall. The newly seeded grass is considered completely established after you mow it three or four times.