Centipede, a warm season grass, is planted from the upper south and mid-west to Southern areas.  This seasonal grasses is best planted in the late spring / early summer of each year.  Early summer is considered by turf experts to be the best planting date because summer temperatures and rainfall allow for faster germination and rapid establishment of the grass.

Centipede generally should NOT be planted later than around August in the Fall (later than 90 days before first expected frost / freeze).  The reason is that there is a danger in if the seeds germinate the plants may not reach enough maturity before winter dormancy occurs to survive a winter.  ---

DORMANT SEEDING:
Some people do what is called winter "dormant seeding" .. In this method they wait until after cool weather arrives and there is no danger of the temperatures returning above 60-65 degrees.  They then plant the seeds and expect that the seeds will lie dormant in the soil until warm temperatures return in the spring.  Germination then occurs in the Spring after soil temperatures rise above 65 degrees.

 

While this procedure does work in some cases, it is much more risky than waiting until spring to plant your seeds.  Seeds lying in the soil over the winter run the risk of premature germination during a warm snap and then death upon return of cold weather.  They also could experience rot if there was an extended period of wet weather.  Thus it is a gamble to plant this way, but one that is sometimes done simply because a person may not want to wait till spring to plant.  

In general planting ryegrass with the centipede in the fall, increases the risk to the centipede seeds & seedlings becoming establishing in the spring.  Any grass that is already growing in a lawn area such as a ryegrass is competition to the little seedlings when they start germination --- which means that some seedlings will not survive the competition from the ryegrass (or weeds) once they germinate.