When can I stop mowing my lawn this fall?

My lawn seems to have stopped growing for the year, but it has been three weeks since I last cut it. Since we are in November now, is it OK to stop mowing for the season?

— Anita Mason, Wheeling

Mowing has a major impact on lawn appearance and health, and it’s difficult to give you a definitive answer without seeing the current condition of your lawn. Many gardeners cut their lawns too short during the growing season, which makes the turf more susceptible to drought stress and invasion by weeds. I maintain my lawn at 3 to 3½ inches during the growing season. It is a good idea, though, to mow the lawn at a shorter height of 2 inches or so for the last time of the season. This will help reduce the chances for snow mold fungus. It is likely that your lawn should be mowed again this fall. It will be best to reduce the height gradually over the last two to three times that you mow for the season if you have been mowing at a height of 3 inches or more. Ideally, you should avoid removing more than a third of the grass’s height when cutting it. Keep mowing as long as the grass continues growing, and stay off the lawn when there is frost present. As the temperatures get colder, most lawns with bluegrass will begin going dormant and take on a greenish-yellow appearance that eventually fades to tan. The lawn will remain dormant until spring when the ground thaws and the weather begins to warm up.

I use a mulching mower for my yard and simply mow over the leaves that fall on the lawn. The mower grinds up the leaves to recycle into the lawn, which is good for the grass and saves a lot of time raking leaves. A sharp mower blade is important to maintain throughout the year and more so in fall when you are also mulching leaves. Check the air filter more often too, as mowing over leaves generates a large amount of dust. You may need to do some raking if you have a very thick layer of leaves on the grass or make a couple of passes over the lawn with the mower to grind the leaves up. The grass should not be heavily or completely covered by leaves or clumps of grass when you are finished for the season. Alter your direction of mowing every couple of times you mow to avoid having the grass being repeatedly pushed in one direction and laying over.

Using a mulching mower in the fall to grind up leaves on the lawn results in a more natural appearance, as the ground-up leaves will be visible. Some gardeners may want a neater appearance to the turf after it is mowed. Most mulching mowers have a setting with the option to bag grass clippings. Switch to using a bag in the fall to achieve a cleaner appearance after mowing. The bagged grass clippings and leaves after mowing are great to add to the compost pile.

For more plant advice, contact the Plant Information Service at the Chicago Botanic Garden at plantinfo@chicagobotanic.org. Tim Johnson is senior director of horticulture at the Chicago Botanic Garden.