SHOULD YOU OVER-SEED YOUR LAWN IN WINTER?
Rye grass is a cool season grass that can be seeded over the top of the permanent, warm season lawn. When temperatures cool down and the warm season grass stops growing and goes dormant, over-seeding creates a green lawn year-round.
The benefit to over seeding with rye grass is that your lawn stays pretty green all throughout the winter. However, there is no benefit and even some detriment to the permanent grass by doing this.
Since the rye grass is actively growing, it needs to be watered and fertilized through the winter, exactly what you should NOT do with the warm season grass underneath it. Studies have shown that repeated application of rye seed on top of warm season grasses year after year causes decline in the permanent grass.
If you are in specific need of winter curb appeal such as putting your house on the market, over seeding with rye would be a good idea. On the other hand, doing it every year just to have a green lawn in winter will increase need for lawn maintenance and decline in the long run.