Scalp the lawn in late October by lowering the mower blades to the lowest setting that leaves the grass about 1 inch high. It is important that the permanent grass is not damaged or cut so short that it cannot store enough nutrients to restart growth in the spring. Do not scalp St. Augustine grass; it will not recover in the spring.
Rake the lawn to remove thatch that has built up over the summer. When the lawn is over-seeded, the rye seeds must have easy access to the soil.
Rent an aerifying machine at an equipment rental store. Follow the directions for how to use it properly, or employ an independent contractor to aerify the lawn.
Stop watering the permanent grass 10 days before over-seeding the lawn with rye grass.
Use a push fertilizer/seed spreader or manual hand spreader to over-seed the lawn with an annual rye grass that fits your needs, available at the garden center, by following the application directions on the package. Rye seed for a winter lawn is generally applied at a rate of 10 to 12 lbs. of seed per 1,000 square feet.
Fertilize the rye grass with a complete fertilizer such as 18-6-12 at 5 lbs. per 1,000 square feet.
Water the rye grass lightly, until the soil is moist to a depth of 1 inch, two times daily until the seed begins to germinate and grow.
Begin watering once weekly to a soil depth of 10 inches by applying 3/4 inch of water during each watering session. Use a long screwdriver to test the moisture depth by pushing it into the soil as far as it will go in easily. Water the grass until the screwdriver penetrates to a depth of 10-inches. Over-watering rye grass will cause it to rot.
Prepare the permanent lawn as usual with a sustained-release nitrogen winter fertilizer and a pre-emergent weed control.
Stop watering the rye grass in late April, and allow it to die out so the permanent lawn can come in later in the spring.