Monitor the weather, which dictates the rate of growth for the grass. The conditions for growth vary, but generally if the temperature is above 41 degrees Fahrenheit or 5 degrees Celsius, the grass will be growing enough that it needs regular cutting. Below 41 degrees, you can expect a 50 percent reduction in the metabolic growth rate of grass for every drop in temperature of 1 degree Celsius, or about half a degree Fahrenheit.
Avoid cutting the grass when the ground is wet. Similarly, you should not cut grass when the ground is frozen. In both cases, the mower may damage the ground and the grass because of the moisture combined with the cold temperatures. Wait for the ground to dry before cutting bent grass in winter.
Cut the grass short prior to winter, and maintain that short length. About 25 to 40 millimeters is a good length, though this may vary, depending on your specific needs. If you are maintaining a bent grass putting green, for instance, you may need to maintain a different length. Definitely avoid letting the grass grow excessively long, however.