When winter approaches, the rigorous mowing schedule of summer must change, shifting from regular maintenance to an “as-needed” approach. The colder months introduce a period of slow growth or complete dormancy for turfgrass, fundamentally altering how often a lawn needs attention. Determining a proper winter mowing routine requires understanding the specific conditions that trigger or halt growth. This seasonal shift requires adjusting both the frequency of cuts and the height of the mower blade to protect the grass until spring returns.
Identifying When Mowing is Necessary
The need to mow the lawn in winter depends entirely on the type of grass and local temperatures. Grass enters dormancy, or suspended growth, as a natural defense against cold weather. For cool-season grasses, such as Fescue and Kentucky Bluegrass, growth slows significantly below 50 degrees Fahrenheit and ceases when soil temperatures drop into the low 40s.
Warm-season varieties, including Bermuda and Zoysia, are more sensitive to cold. They typically enter a full dormant state, turning brown, when soil temperatures drop below 55 degrees Fahrenheit. In regions with hard, freezing winters, the lawn will likely be completely dormant or snow-covered, requiring no mowing. However, in transitional or mild climates, grass may continue to grow slowly, requiring occasional cuts. Never attempt to mow the lawn if there is frost on the blades, as this can cause irreparable damage.
Determining the Ideal Winter Mowing Frequency
Winter mowing frequency is dictated by the actual growth rate of the grass, not a fixed calendar schedule. For lawns in mild climates that are still growing slowly, a general rule is to mow every three to six weeks. This interval depends on the turf type (cool- or warm-season) and the amount of sunlight and moisture received. Cool-season grasses may need trimming during warm spells, while warm-season grasses usually remain fully dormant.
The absolute rule governing cutting is the “one-third rule,” which states that you should never remove more than one-third of the grass blade’s total height in a single mowing session. During the winter, even slow growth can lead to grass exceeding this limit if left unattended for too long. Adhering to this principle minimizes stress on the plant, which is already working to survive the cold, and helps conserve its energy reserves.
The Importance of Cutting Height
Setting the proper cutting height is a delicate balance in winter. Cutting too short exposes the plant’s crown to cold damage and stresses the root system. Conversely, leaving the grass too long can lead to matting under snow and create an environment susceptible to winter turf diseases, such as snow mold.
For cool-season grasses, the ideal final winter height generally falls between 2 and 2.5 inches. This range is short enough to deter disease but long enough to protect the roots.
Warm-season grasses have a different winter requirement since they go dormant. Experts recommend maintaining their standard height or raising the blade by about a half-inch in the fall. This slightly taller height provides better insulation for the crown and roots during the dormant period, helping the turf survive the cold and protecting against winterkill.
Seasonal Transition and Final Mows
The winter mowing period is bracketed by important transition cuts in late fall and early spring. The final cut before the grass enters deep dormancy sets the lawn up for a healthy winter. This last mow is typically performed at the lower end of the recommended winter height, often around 2 to 2.5 inches for cool-season varieties, which minimizes the risk of fungal diseases.
It is beneficial to gradually reduce the mowing height over a few sessions in the fall rather than making one drastic cut, which minimizes shock to the plant. When spring arrives and temperatures warm, the first mow should occur when the grass shows clear signs of active growth. At this point, the blade height can be raised back to the standard, taller height for the growing season, promoting deeper root development and overall turf health.