Plant your ryegrass seed in the fall when daytime temperatures come to remain below 70 degrees Fahrenheit and overnight temperatures remain above 50 F.
Dethatch or verticut the lawn surface to provide a way for the ryegrass seed to make contact with the soil and make a level and lush carpet of grass. Rake up all of the thatch that comes to the surface, composting or discarding it.
Mow the lawn very low without scalping it. The lowest mowing height will vary based on the variety of warm season grass you presently have planted. Use a catcher to collect all of the cuttings and compost or discard them.
Cast 10 lb. of annual ryegrass seed for every 1,000 square feet or 5 to 15 lb. of perennial ryegrass for every 1,000 square feet. More seed will result in a more lush lawn, but do not exceed these amounts. Walk over the seedbed in one direction to cast half of the seed and then turn 90 degrees and cast the second half over the same area to create an even carpet of seed.
Brush the seed down towards the soil using a broom and a gentle raking motion.
Water the seed in well so that the surrounding soil becomes wet but not so waterlogged that the soil or seed is displaced.
Keep the soil evenly very moist to wet with twice or thrice daily light watering sessions through the germination, which should occur in five to 10 days and until small green shoots start to emerge.