How to Top-Dress and Overseed Lawns

Adjust the cutting height on your mower to its lowest setting, and mow your lawn twice; once lengthwise and once crosswise. This will allow the new seed to penetrate to the soil instead of sitting on top of the grass.

Aerate your lawn with a mechanical aerator. If you don't own a machine, you can rent one. An aerator opens the lawn by removing plugs of soil, which improves oxygenation and penetration of organic nutrients, and promotes strong root growth. Go over the lawn once without overlapping the passes.

Spread a half-inch layer of quality top-dressing over the lawn. Fill any obvious dips and hollows, and smooth the surface with the back of a wide leaf rake. This adds organic matter and nutrients to the soil and improves seed germination.

Prepare your soil for overseeding by watering the lawn thoroughly with a full inch of water a day before you apply new seed. Allow at least 12 hours for the water to soak into the ground.

Calibrate the drop rate of your seed spreader by following the instructions that came with the device. This is especially important if you are using a drop spreader instead of a broadcast spreader. With a drop spreader, each row must be lined up precisely without overlapping; with a broadcast spreader you must overlap each line by about a foot to ensure full coverage.

Scatter a light layer of organic compost mix over the lawn after the overseeding. Add just enough compost to cover the new seed. This will help retain moisture and promote germination.

Drive wooden stakes into all four corners of the lawn, and cordon off the area with bright-colored construction tape. Keep the tape in place for the first week to 10 days to prevent foot traffic. If you have a large dog, keep the animal away from the lawn during this period to allow unhindered germination.

Water the lawn lightly two or three times a day during the first week or two. After new growth starts, revert to a regular watering schedule. Water daily during hot weather. Water three to four times a week until your lawn is fully established.