Hardiness zones 4 through 6 have average annual low temperatures of between -30 and 0 degrees F. This climate region includes the northern contiguous United States and extends as far south as the central plains. Lawn grass species in this climate must be hardy enough to withstand extreme seasonal changes and are predominately cool season grasses.
Kentucky Bluegrass is native to Europe but commonly found throughout the United States. This cool-season grass requires full sunlight, regular watering and semi-annual fertilizer applications. Kentucky Bluegrass is sensitive to hot, dry conditions and will become dormant during periods of drought.
Tall Fescue turfgrass is a cool season grass popular in home lawns and athletic fields due to its high tolerance for pedestrian foot traffic. Tall Fescue grass has a dense, coarse texture and deep root system that enable the plant to grow during periods of drought. Like other cool season grasses, Tall Fescue remains green and grows for 7 to 9 months and becomes dormant during the winter.
Fine Fescue grass is a cool season grass with thin, fine blades that have the unique ability to grow in dry, shady lawn environments. Unlike Tall Fescue, Fine Fescue turfgrass has a poor tolerance for pedestrian foot traffic and tends to grow in bunches that can lack aesthetic appeal. Fine Fescue grass is commonly found in the cold, windy, dry climates of the northernmost United States and southern regions of Canada.
Perennial Ryegrass is a cool season grass that prefers cool, moist environments with less extreme temperature fluctuations in summer and winter. Perennial Ryegrass is faster growing than other cool season grasses and is often mixed with both warm and cool season grasses to enhance lawn appearance in early spring. Perennial Ryegrass is shade tolerant but sensitive to moist, moderate temperatures.