The final mow of the season is a significant step in preparing a lawn for winter, transitioning the grass into a state of dormancy that protects it from cold damage. Timing this cut correctly ensures the turf has stored enough energy to survive freezing temperatures and re-emerge healthy when spring arrives. This preparation involves observing environmental cues, executing the proper cut, applying necessary nutrients, and storing equipment safely.
Determining the Final Mowing Date
Mowing should cease when the turf enters its final slowdown, which is primarily dictated by consistent temperature drops rather than a specific calendar date. For cool-season grasses like Kentucky bluegrass or fescue, this typically occurs when average daytime temperatures remain below 50°F (10°C).
Warm-season grasses, such as Bermuda or Zoysia, slow their growth earlier, often when air temperatures consistently dip below 60°F. Continuing to mow during this period of minimal growth risks unnecessary stress on the grass blades. The goal is to perform the final cut just before the first hard frost. This prevents the grass from being too long under snow cover but avoids stressing the plant as it shuts down. The window for the last mow opens once the grass stops producing noticeable clippings over a week.
The Critical Final Cut Height
The final cut height requires adjustment to maximize winter survival and health. Leaving the grass too long causes the blades to mat down under snow, creating a moist environment ideal for fungal diseases like snow mold. Conversely, cutting the turf too short—or scalping it—removes too much photosynthetic surface needed to store energy and exposes the grass crown and roots to cold damage.
For most turf varieties, the ideal height for the final mow is between 2 and 2.5 inches. This height prevents matting but is long enough to insulate the crown where the plant stores energy reserves for spring. Cool-season grasses usually mean setting the mower about half an inch lower than the summer cut to reduce disease pressure. Warm-season grasses, which are more susceptible to cold damage, may benefit from being kept at their regular height or slightly taller for insulation.
Essential Post-Mowing Winter Preparation
Immediately following the final cut, the focus shifts to fortifying the root system and clearing the lawn surface. This late-season feeding step involves applying a specific type of product known as a “winterizer” fertilizer. This blend is formulated with a higher ratio of potassium (K) relative to nitrogen (N).
The potassium component strengthens the grass plant’s cell walls, improving its resilience to cold, drought, and disease. The nitrogen is typically slow-release and helps the grass store essential carbohydrates in its root system and rhizomes. This nutrient storage is used for survival over the winter and provides the energy for a faster, healthier green-up in the following spring. Applying this fertilizer after the grass stops growing above ground, but before the ground freezes, allows the roots to continue absorbing and storing these nutrients.
Clearing all debris from the lawn surface is another necessary step to prevent disease and damage. A thick layer of fallen leaves left on the grass will block sunlight and trap excessive moisture, which can smother the turf and promote the growth of snow mold and other pathogens. Leaves should be thoroughly raked or mulched with a mower, ensuring the grass blades remain visible to allow for air circulation. Removing this organic debris prevents the creation of a habitat for rodents like voles, which can cause significant damage to turf while feeding under snow cover.
Preparing Equipment for Storage
Once the final cut is complete, properly preparing the mower for storage ensures its longevity and reliable performance next spring. Fuel left in the tank over the winter can degrade, leading to gum and varnish deposits that clog the carburetor and fuel lines. To prevent this, either run the engine until the fuel tank is completely empty, or add a fuel stabilizer to a full tank and run the engine for a few minutes to circulate the treated fuel.
The mowing deck should be thoroughly cleaned of all caked-on grass and debris, as this organic material holds moisture and can cause rust and corrosion. For combustion engines, it is highly recommended to change the oil while the engine is still warm, as old oil contains contaminants that can damage internal components during extended storage. Finally, for safety, always disconnect the spark plug wire to prevent accidental starting while the mower is being cleaned or stored.