Caring for warm- and cool-season grasses

Here at SoilKit, we know that caring for your lawn isn't one-size-fits-all. It depends on your local climate and weather, the type of grass in your lawn, and the needs of your soil, among other things. This article puts a spotlight on the differences in caring for cool-season vs. warm-season grass. Which one is growing in your yard? Leave a comment and let us know if you learn anything new from the summary and chart below!

Cool-season grasses

Cool-season grasses include Kentucky Bluegrass, Fescues, Bentgrass and Ryegrasses. They are also referred to as northern grasses because they are hardy and well-adapted to cold winter climates. Cool-season grasses grow vigorously in the cool months of fall and spring (60-75º F) while growth slows in the heat of the summer. They require adequate water to beat the heat and stay green all summer. Otherwies, to conserve water resources, these grasses can go dormant and turn brown over the summer before bouncing back to a lush green in the fall. During harsh winter weather, they may go dormant as well due to below-freezing temperatures. In mild climates where the ground doesn't usually freeze, such as the West and the transition zone, cool-season lawns stay green all winter too.

The most important time to fertilize cool-season lawns is in fall and spring to kick off periods of vigorous growth. In regions with harsh winters, you should not fertilize in spring until the grass is "greening up" and has started to grow. In most areas, cool-season grasses are not fertilized in the heat of summer. Summer feeding can damage the turf, promote disease, and contribute to watershed pollution since the grass isn't able to utilze the nutrients. Click here for a lawn care schedule for cool season grasses.

Warm-season grasses

Warm-season grasses include Bermudagrass, St. Augustinegrass, Centipedegrass, Zoysiagrass, Bahiagrass and Carpetgrass. They are often called southern grasses because they grow best in hot summers (80-95º F) and lack the winter hardiness of the cool-season grasses. Although you can't tell by looking at the blades, there's actually a scientific reason that warm-season grasses have an edge in hot, dry conditions: they split the photosythesis process into two steps that ocur in different cells, so the main reaction is sheltered from the elements (this is called C4 photosynthesis, to distinguish it from regular C3 photosynthesis). Depending on location, warm-season grasses grow vigorously from mid to late spring through summer and into early fall. They usually turn brown and go dormant in winter, even if temperatures stay well above freezing.

The most important time to fertilize warm-season lawns is from spring through summer and, in some southernmost areas, into fall. Warm-season lawns should not be fertilized prior to active growth in spring (wait until you have mowed the lawn twice) or late into the fall (stop six weeks prior to the expected first frost). Click here for a lawn care schedule for warm season grasses.

	Cool season grasses	Warm season grasses
Spring🌷	Active growth: fertilize acording to soil test results (wait until after green up)	Start of active growth: wait until you have mowed the lawn twice to apply fertilizer Best time to overseed/install plugs: late spring/early summer
Summer☀️	Slow growth/dormancy: avoid fertilizing under heat stress. Provide adequate water.	Active growth: fertilize acording to soil test results
Fall🍂	Active growth: fertilize acording to soil test results Best time to overseed/install plugs: late summer/early fall	End of active growth: stop applying fertilizer six weeks before expected first frost date
Winter❄️	Dormancy (for regions with below-freezing temperatures) Active growth (for regions with mild weather): fertilize acording to soil test results	Dormancy