planting grass seed in the fall is the best time to plant cool-season grasses or over-seed warm-season grass with perennial rye grass. planting grass seed. If north of the transitional zone of the U.S., the best time to plant grass seed will be between August 25th and October 5th. If located in the warmer south and over-seeding, grass seed is best established when planted between September 20th and October 25th.
Soil quality and preparation are important steps in planting a new lawn. Begin by removing the existing vegetation. If planting a new lawn in a large area where there are lots of weeds, spray them with a non-selective herbicide like Round-Up to save hours of physical labor. If over-seeding, you're obviously will not want to kill your base grass with a herbicide application but what you can do is mow down your warm-season grass as low as you can. This along with verti-cutting and power raking, will reduce thatch and improve good seed contact to the soil.
At this point you will want to add the necessary fertilizer and any soil amendments that the ground may need. What and how much you need to apply can be determined by taking a representative soil sample and sending it off for analysis. Your local university extension office should be equipped to analyze and interpret your soil sample. You want to uniformly incorporate the grass fertilizer and soil amendments into the top 2 to 3 inches of top soil. The best way to achieve good incorporation is by using a good roto-tiller. For over-seeding projects, add 5 lbs per 1,000 square feet of a 16-20-0 analysis fertilizer two weeks after planting.
For a new lawn, you then want to level the soil as best as possible. The new soil needs to settle naturally, or you can speed up the process by adding more water. If water is added, wait for the soil to dry and then pull out any weeds that germinate. Then rake the soil so it has small groves in it. At this point you soil is now ready for planting grass seed.
For both a new lawn and over-seeding, apply 1/2 of grass seed in one direction on the soil using a spreader. Then put the other 1/2 of the seed in the other direction. Lightly rake the seed in and then roll the soil lightly with a roller. To achieve good seed to soil contact and maintain good soil moisture, top dress the grass seed with a thin layer of mulch or compost. This is not necessary but will improve grass seed germination, especially if under pressure from hot weather or drying winds blowing across the soil surface.
If sod is installed, repeat the same steps from above and make sure the soil is firm enough that the grass sod will not sink in after it is walked on. After sod is installed, roll it with a roller in two directions and water it twice a day until it roots. When grass sod can no longer be picked up by grasping it with your hand, it is rooted.