The mowing season is the period when grass actively grows and requires regular cutting. This duration is highly variable, depending on environmental conditions and the specific type of grass. Mowing seasons can range significantly, from as few as 20 weeks in colder regions to nearly year-round maintenance in tropical climates. Understanding the biological triggers that govern grass growth helps determine the length of your local mowing season.
The Primary Environmental Drivers of Grass Growth
Grass growth is fundamentally controlled by three main environmental factors: temperature, moisture, and sunlight. Temperature is the most influential trigger, as turfgrass varieties are categorized into two major groups based on their optimal temperature range. Cool-season grasses, such as Kentucky Bluegrass and Fescue, thrive in cooler temperatures, with peak growth occurring between 60 and 75 degrees Fahrenheit. Warm-season grasses, like Bermuda and St. Augustine, are more efficient in heat and sunlight, with ideal growth temperatures between 80 and 95 degrees Fahrenheit.
The difference in their biology dictates when each type of grass will begin and cease its growth cycle. If temperatures exceed their ideal range, or drop too low, the grass enters a state of dormancy to conserve energy. For cool-season grasses, growth slows significantly when temperatures consistently rise above 80 degrees or fall below 50 degrees Fahrenheit. Warm-season varieties stop growing when air temperatures drop consistently below 50 to 55 degrees Fahrenheit, signaling the end of their active season.
Determining When the Mowing Season Begins
The start of the mowing season is signaled by soil temperature, not air temperature. Soil temperature directly influences root activity and nutrient absorption, which must occur before measurable blade growth can begin. For cool-season grasses, growth begins when the soil temperature, measured at a depth of a few inches, reaches a consistent 50 to 55 degrees Fahrenheit.
This soil warming generally happens several weeks after the first signs of spring air temperatures. Warm-season grasses require a higher heat threshold before they emerge from dormancy. Their active growth phase starts when the soil temperature consistently reaches about 65 degrees Fahrenheit. The first mow should occur once the grass shows consistent growth, typically a week or two after the soil temperature target is met. This initial cut removes dead winter growth and promotes healthy, dense turf.
Calculating the Total Duration and Identifying the End
The total duration of the mowing season spans from the first consistent growth in spring to the onset of winter dormancy in the fall. Identifying the end requires observing a decline in both air and soil temperatures. The most significant signal is when the grass growth rate slows, which happens when the air temperature consistently drops below 50 degrees Fahrenheit for several days.
This cooling trend cues the grass to begin storing energy in its roots in preparation for the winter dormant period. For most regions, the season concludes following the first hard frost (air temperature drop below 32 degrees Fahrenheit). Once the grass stops growing vertically, mowing is no longer necessary. The total duration for a typical homeowner averages between 25 and 30 weeks per year, but this figure is heavily weighted by location.
Regional Differences in Mowing Season Length
The geographic location is the final determinant of the overall mowing season length, translating the biological triggers into practical timeframes.
Northern Climates
In Northern Climates, which primarily feature cool-season grasses, the season is the shortest. It often lasts approximately 20 to 25 weeks, typically running from late April or early May through late October.
The Transition Zone
The Transition Zone, a band across the central U.S. where both cool-season and warm-season grasses can be grown, experiences a significantly longer season. Homeowners might see an active mowing period lasting 30 to 40 weeks, starting in March and sometimes extending into December. This extended season is due to the area’s tendency to have two peak growth periods, one in the spring and another in the fall, with a mid-summer slowdown.
The Deep South
In the Deep South, where warm-season grasses are dominant and winters are mild, the mowing season is the longest. Maintenance is often required for 40 to 52 weeks of the year. While growth slows in the winter months, the period of true dormancy is short or nonexistent in the warmest southern areas.