There are two times of the year that is best for overseeding a lawn, spring and fall. Overseeding can renovate an existing lawn to grow off-season grass. This is to keep the lawn green when the primary turf is dormant. Lawn renovation in the spring is the best time for lawn overseeding. Overseeding in the fall is normally done in warmer, southern climates to ensure green grass during the winter, while the warm season grasses are dormant.
Regardless when overseeding over existing grass, these tips will help many lawn projects be successful and is the first step to preventing grub worm problems.
Preparing your Lawn for Overseeding
Mow the grass as short as a mower will cut. Almost scalp the grass.
Aerate the lawn. Aeration will improve oxygenation, which will help new grass seed grow faster and more robust.
Top-dress the yard with a compost/topsoil blend. This will help incorporate organic matter into the lawn, improving soil structure, which will, in turn, improve grass germination and long term health.
Water the grass thoroughly-giving it at least one inch of water a day after top-dressing. This will put water into the soil so that as the grass seed starts to germinate, it has the necessary moisture to do well.
How to Achieve Even Coverage of Seed
Once the yard is prepared for an overseeding project, use these techniques to achieve even coverage of the lawn with the grass seed.
Calibrate a spreader. Do this to set the spreader drop rate according to a normal walking stride. How fast the stride will influence the coverage. All spreaders will have instructions for doing this.
Then, fill the spreader with half of the seed and spread the seed evenly walking in one direction.
Next, fill the spreader with the other half of the seed and overseed walking perpendicular to the previous direction. Whether overlaping each row slightly depends on whether if a drop spreader or a broadcast spreader is being used (With drop spreaders, do not overlap-but do precisely line up with your row. Broadcast spreaders require overlapping the throw patter by about 1/3 on the next pass).
To keep the seed coverage even, top-dress the grass seed with a light compost mix. Just barely cover the seed (This is more of a dusting of material). It will help keep moisture near the seeds and help increase capillary action of the soil.
Follow-up Care after Overseeding a Lawn
Once successfully completed lawn overseeding, care for it properly to ensure that it thrives. Here are the best ways to ensure good germination rates and healthy growth of a lawn overseeding project.
Protect the lawn from foot traffic from people and animals.
Water the lawn gently several times a day. Let the seed just barely dry between watering.
Once the grass seed has germinated well, switch the watering schedule to deeper and less frequent watering.