Overseeding a lawn is a project that should be undertaken every four years to keep the lawn dense and healthy. On old, neglected lawns, rather than ripping them out, sometimes renovation is called for and overseeding is one method used to accomplish this. Overseeding a lawn with Zoysia is challenging. Zoysia seed needs lots of sunshine to germinate and the shade cast by existing grasses prevents the sun from reaching the seed. To be successful, mow regularly to allow the zoysia seedlings to receive sunlight and avoid being crowded. Overseed with Zoysia in June.
Mow the lawn as close as possible.
Rake the existing lawn to remove any dead grass or other debris.
Mix the grass seed, at a rate of 1 lb. per 1,000 square feet of planting area, and 6-2-2- fertilizer, at the rate suggested on the fertilizer package, and pour the mix into the broadcast spreader.
Sow half the seed mixture in strips, in a north to south direction. Sow the remaining half in strips, going east to west.
Rake the area lightly, using the back side of the rake. This will move the seed through the existing grass, onto the soil.
Water the lawn as you normally do and keep it moist by watering every day until the Zoysia seed germinates. This may take as long as three weeks. On particularly warm or windy days you may need to water more than once a day.