When the seasons change, knowing when to put the lawn mower away is crucial for maintaining a healthy yard. Mowing at the wrong time in late fall or early winter can inflict lasting physical damage on grass blades and the underlying turf. The decision to stop mowing depends on environmental conditions—specifically air temperature and the presence of frozen moisture—that make cutting harmful to the plant’s cellular structure. Understanding the physiological limits of your lawn ensures it survives the cold months and returns vibrant in the spring.
Defining the Temperature Limit for Grass Health
The air temperature indicates when grass growth slows and the plant enters a protective state called dormancy. Most grass types cease noticeable growth when air temperatures consistently drop into the 50 to 55-degree Fahrenheit range. Cool-season varieties, like fescues and bluegrass, may continue to grow until temperatures fall below roughly 45 degrees Fahrenheit. Once the air temperature falls below this lower limit, the grass is preparing for winter and is no longer actively producing enough new tissue to withstand the mechanical stress of mowing.
Attempting to mow grass that is fully dormant can cause irreversible damage to the blades. When the plant is in this state, the tissue loses much of its natural flexibility and becomes brittle. A dull mower blade can tear or shred the dormant grass blades rather than cleanly slicing them. This physical trauma leaves the grass susceptible to disease and desiccation throughout the winter. Therefore, stop mowing when the daytime air temperature remains below 50 degrees Fahrenheit.
The Dangers of Mowing Frozen or Frosty Turf
The presence of frozen moisture on the grass blades is a concern, even if the air temperature is above 50 degrees. When frost or ice crystals form on the turf, the water inside the grass cells expands. Any pressure applied to these frozen blades, whether from a mower tire or the cutting deck, will cause the ice crystals to rupture the cell walls.
This crushing action causes immediate cellular damage, often visible as dark or bruised tracks left behind the mower. This is a form of freezing injury that destroys the integrity of the plant cells. The resulting damage can persist for months, leaving unsightly brown patches that will not green up until the spring growing season. The absolute rule is to avoid all traffic on the lawn, including mowing, until all visible frost has completely melted away.
Protecting Your Mower in Cold Weather
Cold temperatures create operational challenges for the mechanical components of a lawn mower. Engine oil viscosity is a primary concern, as oil thickens significantly in cold weather. This increased thickness makes the engine harder to turn over, resulting in difficult starting and greater internal wear on engine parts.
Gas and Battery Maintenance
For gas-powered mowers operating in marginal temperatures, using a synthetic oil suited for cold weather helps the engine start more easily. Battery-powered mowers require special attention, as extreme cold can drain their charge and reduce the battery’s lifespan. Remove the battery and store it in a cool, dry place indoors to protect it from freezing temperatures.
Seasonal Storage
If the mower is being stored for the season, draining the fuel or adding a stabilizer is necessary. This prevents the gasoline from breaking down and causing clogs in the fuel system.