Planting several types of grass is common in areas of the U.S. where neither warm nor cool season grasses offer consistent success in establishing a healthy lawn. Generally speaking, this is the case in Virginia, Kentucky, North Carolina, Arkansas, Tennessee and parts of Ohio, the Texas Panhandle, Indiana, northern Alabama, Illinois, northern Georgia, Kansas and Missouri.
Test the pH level of your soil with a commercially available testing kit and also evaluate your yard's sun exposure. Identify transition zone grasses that may thrive in your soil. They include Kentucky bluegrass and perennial rye grass, which do well in pH neutral soils and full sun conditions. Other options are tall fescue and Zoysia grass, which grow in full to partially sunny conditions in slightly acidic soils. With the exception of Kentucky bluegrass, the other varieties do well in high traffic lawns.
Pair compatible grass seeds to make it possible to have a green lawn when warm season grasses brown and fall dormant or cool season grasses die back. Living in a transition zone makes mixed seed lawns an excellent method of hedging your bets against brown or yellowing spots--and subsequently unhealthy looking lawns--when seasons change. Good combinations are Kentucky bluegrass and perennial rye grass, Kentucky bluegrass and fine fescue (cool season grass) or tall fescue and wheat grass.
Weed the lawn area where you intend to plant and rototill it to a depth of about 6 inches. Rake up any rocks or roots. Make sure to also remove any weeds or prior lawn grasses you encounter. Supplement the soil with about 3 inches of compost and mix it under by tilling the area once more. Rake the area until it is level and then water well.
Sow the grass seed with a hand spreader. Sow at the seed manufacturer recommended setting. Cover the area with a quarter inch of top soil and keep it moist by watering frequently but briefly. This prevents runoff---and seeds that wash away in the process---and encourages the germination of the grass seeds.