Cool-Season and Warm-Season Grasses
Turf grass species are categorized as either cool-season or warm-season types. Cool-season grasses grow vigorously during the relatively cool, wet weather of spring and fall. They are not, in general, tolerant of heat, and they usually go dormant during the hottest, driest part of summer. Warm-season grasses grow well in summer heat, but they are not tolerant of cold temperatures. They go dormant and often turn yellow during winter, and they may not survive in areas with harsh winters. Because of these characteristics, cool-season grasses are best suited to the northern United States, and warm-season grasses perform better in the southern states.
Virginia is located in a transition zone between the climates in which cool-season grasses do well and those in which warm-season grasses are the best choice. The climate of southeastern Virginia falls into U.S. Department of Agriculture plant hardiness zones 7 through 8a while the northwestern part of the state falls into USDA zones 5 through 6. Consequently, both warm- and cool-season grasses may struggle in the state, and the best choice of grass species for your lawn depends on where in Virginia you live.
Among cool-season grasses, tall fescue (Festuca arundinacea) is well-adapted to use in most parts of Virginia. It is hardy in USDA zones 2 through 7, and it has deeper roots than other cool-season grasses, which helps it tolerate heat and drought in the warm parts of the state. Kentucky bluegrass (Poa pratensis), which is also hardy in USDA zones 2 through 7, does well in northern Virginia, the Shenandoah Valley and the hilly, southwestern parts.
Warm-season grasses are, in general, best used in the Tidewater region, although zoysiagrass (Zoysia spp.), which is hardy in USDA zones 6 through 9, may perform well in the cooler parts of the state as well. Centipedegrass (Eremochloa ophiuroides) is hardy in only USDA zones 7 through 8 and should be planted in only the Tidewater region.
Cool-Season Planting Time
The best time to plant cool-season grass seed is in late summer or early fall, when temperatures are cooler and rains are more frequent than in previous months. In northern and western Virginia, the ideal planting window is between mid-August and mid-September, and in eastern and southern Virginia, the best planting time is between the beginning of September and the middle of October.
Planting cool-season grass seed in spring is not recommended because it subjects young seedlings to drought and heat stress, as well as competition from summer-germinating weeds.
Warm-Season Planting Time
The best time to plant warm-season grass seed in all parts of the state is in late spring or early summer, typically between the middle of May and the end of June.