Annual ryegrass is a cool season crop that grows green and lush during the winter months. It is often used as a cover crop in winter gardens to prevent erosion and to provide organic material to the soil as it decays in the spring. It is also used to overseed warm-season grasses. This provides a green cover during the winter, preventing disease to the weakened warm season grass. Ryegrass grows in sun and shade and is resistant to extremely cold temperatures.
Decrease irrigation to the warm-season turf grass as the temperature cools in mid-September. That's a recommendation of Clemson University Extension.
Run a de-thatching power rake through the lawn to expose the soil underneath the warm-season grass and to remove thick thatch, says David M. Kopec of Arizona University. Run a Verti-cutter (a proprietary vertical lawn aerator and dethatcher) over the lawn if thatch is spread throughout the lawn and is thick.
Fill your drop spreader with 10 lbs. of annual ryegrass seed per 1,000 square feet of lawn and sow half of the seed while operating the spreader in passes back and forth across the entire lawn. Then spread the other half in passes that are perpindicular to the direction you spread in the first pass to overlap the seed.
Rake the seed so that it is slightly covered in dirt and below the warm-season grass. Water the lawn two to three times a day, watering slowly to prevent washing away the seed and to keep the soil 1/2 inch depth moist.
Mow the grass once it reaches a height of 1.75 inches down to a height of 1.5 inches and fertilize using a high-phosphate fertilizer such as superphosphate, triple superphosphate, or a complete fertilizer that is 20 percent phosphorous or more by weight.