The type of grass determines when you should plant it. If you want to plant grass in the fall, then pick a type of cool season grass to plant. Planting information is printed on the bag of grass seeds. Cool season grasses should be planted when the air temperature is between 60 and 75 degrees. These temperatures ensure that the soil temperatures are between 50 and 65 degrees. If the soil temperature is not right, then the seed will not germinate or grow.
If you prefer to plant grass in the late spring and early summer, consider a warm season grass. The soil temperature to plant this type of seed is just above 70 degrees. This means that the daytime temperature should be around 80 degrees and the nighttime temperature should be between 65 and 70 degrees. The lowest temperature should be over 55 degrees for the few weeks before planting. If the soil temperature is less than 50 degrees or more than 90 degrees, then the grass seeds will not grow.
Where to plant
The best place to plant either cool or warm season grass seed is in a bed designated for grass only. The soil should not be too loose or too compact and there should be no other plants growing in the bed. This eliminates competition for food, water and light and helps the grass seed grow faster. Planting grass seed in a lawn with other plants gives the new seed more competition and may reduce the amount of plants that live past the seeding stage.
When planting grass in a seed bed or an existing lawn, the seeds should be planted between 3 and 6 mm (1/8 and 1/4 inch) into the soil and then covered with loosely compacted soil. Planting the seeds in the soil instead of spreading them on top of the soil ensures that the seeds retain moisture. Ideally, the seeds should touch as much of the soil as possible. Follow the directions on the grass seed bag about watering the seeds. Water is an essential part of the seed germination period. Too much or too little water will kill the seeds and prevent them from growing.
Most seeds should start growing between five and 30 days after planting. The germination period is listed on your seed bag. If you do not see any grass growing after 30 days, then start over because your grass did not germinate. Your seeds might have been too old (only use seeds for one year after their test date), the soil might not have been the right temperature, birds or other animals might have eaten the seeds, or the seeds might have received too much or too little water. There are many extraneous factors that can keep seeds from germinating.
Here is a list of grasses and the number of days till germination:
Bentgrass 10-15 Bermuda 10-30 Bluegrass 20-30 Buffalo Grass 14-28 Centipede 14-21 Fescues 7-15 Rye Grass 5-10