The grass cutting season is not a fixed date on the calendar but a period dictated by the biological response of turfgrass to rising temperatures. The mowing cycle begins when the grass exits winter dormancy and starts active vertical growth, and it concludes when colder weather forces it back into a rest state. Understanding these temperature thresholds and growth cycles is essential for maintaining a healthy, dense lawn. Proper timing ensures the grass blades can maximize photosynthesis, develop strong root systems, and resist disease and weed invasion.
Defining the Start of the Mowing Season
The initial cut of the year is determined primarily by soil temperature, which governs the biological activity within the grass plant’s root system. Cool-season grasses, such as Kentucky bluegrass and fescues, typically begin growth when soil temperatures reach a sustained 40 to 45 degrees Fahrenheit. Warm-season grasses, including Bermuda and Zoysia, require much higher temperatures to break dormancy, usually starting when soil temperatures consistently rise to between 60 and 65 degrees Fahrenheit. Regardless of the grass type, the practical trigger for the first cut is when the blades are visibly tall enough to warrant mowing. Making the first cut too early, before the grass is actively growing, can cause unnecessary stress on the emerging plant.
Mowing Frequency During Peak Growth
Once the season is underway, the frequency of mowing must be adjusted according to the rate of growth, which fluctuates based on water availability and temperature. The fundamental principle for routine maintenance is the “one-third rule”: never remove more than one-third of the grass blade’s height in a single mowing. This rule ensures enough leaf surface remains for efficient photosynthesis and prevents the plant from diverting stored energy away from root development. During the peak growing seasons of spring and early summer, grass growth accelerates, often requiring mowing every four to seven days to stay within the one-third limit. Conversely, during periods of summer heat or drought, growth slows dramatically, and the mowing frequency can be reduced to every two weeks or less.
Timing the Final Cut of the Year
The end of the cutting season is signaled by the cooling of temperatures, which causes the grass to slow its growth and prepare for winter dormancy. Most grass types stop growing once soil temperatures consistently drop below 50 degrees Fahrenheit. The final cut should be timed just before the first hard frost is expected in your region. This last mow is important for winter health, requiring the grass to be at a slightly shorter height than the summer maintenance level, typically around 2 to 2.5 inches. Cutting the grass to this lower height ensures the blades stand upright, reducing moisture retention and preventing matting under snow, which encourages fungal diseases like snow mold.