You should stop cutting grass when it has largely stopped growing for the season, which is typically when temperatures consistently fall below about 6-10°C (43-50°F) and before the first hard frost. This timing usually occurs in late October to early November in many regions, though it varies depending on local climate. The last mowing should be about a week before the first frost to prepare the lawn for winter. Cutting grass shorter before winter helps prevent it from matting down under snow, reducing fungal disease risk and helping the lawn recover better in spring. After the last cut, it is important to keep the lawn clear of leaves and debris to avoid smothering the grass over winter. To summarize key points:

• Stop mowing when grass growth slows/stops, usually around late October or early November.
• Ideal cutting heights vary by grass type but generally lower the blade for the last cut.
• Cease mowing prior to the first frost to give grass time to prepare for dormancy.
• Keep the lawn clear of debris during winter to promote healthy regrowth next spring.