Lawn grass types are divided into cool-season and warm-season species.
The cool-season grasses grow best in the northern parts of the United States. The intensity of summer heat and drought stress will limit how far south they can grow.
Warm-season grasses flourish in the
heat of the South. Their northern boundaries are dictated by intensity
and duration of winters.
The area sandwiched between the northern and southern growing zones is known as the Transition zone.
Both warm and cool season species can be grown in this region.
However, no turfgrass species is perfectly adapted. Seasons with
environmental extremes will cause the most carefully selected variety to
struggle or even die.
Cool-season species grow well in cool temperatures - between 60° to 75° F
is optimal. A typical growing season starts with a flush of growth in
the spring, then slowed (sometimes to dormancy) in the summer, followed
by another flush of growth in the fall.
These lawn grasses need to be watered during hot, dry periods or they will go dormant and can be injured or even die. Many cool-season species will retain a green color during the winter.
The best cool-season lawn grasses:
Perennial ryegrasses are mainly used in seed blends as a nurse grass, because of its quick germination rate, and for overseeding warm-season species.
is another common cool season species - used mainly on golf course
greens and tees. It can make a real nice lawn but is very high
maintenance. In some areas, bentgrass can be an invasive weed that is
dificult to control.
Warm-season species are adapted to the southern and south western
regions and sub-tropical to tropical climates. They are slow to green
up in the spring, thrive during the warmer temperatures - 80° to 90° F
degrees - then go dormant and turn brown when the weather gets cold.
Some lawns can be overseeded with a cool-season species in early fall to maintain a green color through the winter. Overseeding also protects dormant grasses from extreme cold temperatures and traffic.
Popular warm-season grass types:
Year-round weather conditions are less than ideal for both types of grasses, making this area the most difficult to grow a beautiful, environmentally friendly lawn. The winters can be too cold for many warm-season species and the summers too hot and dry for many cool-season species.
Tall fescue is the most common and best adapted transition grass type in the eastern transition zone. Kentucky bluegrass,
bermudagrass and zoysiagrass can be used on certain sites. Buffalograss
is a good choice for unirrigated lawns in western semiarid regions.