· by Michael Blair, Nashville's Lawn Care
Tall fescue, which is most of the lawn in Middle Tennessee, does its best growing in exactly the weeks when people stop mowing. Cool nights and warm soil in October are ideal for it. The mistake is not mowing too late; it is stopping too early, leaving long grass to mat down under leaves and wet weather.
Grass grows until the soil cools
Fescue slows and finally stops when soil temperature drops into the mid-forties and stays there. In Nashville that usually happens well after Thanksgiving, and in a mild year it can be December. Until then it is still growing, just more slowly each week.
Bermuda and zoysia are different. They go dormant with the first hard frost and turn straw colored, and once that happens there is nothing to cut. If your lawn is warm-season grass, the last mow is whenever it stops growing, and it will tell you plainly.
Height for the final cuts
Through summer, fescue wants to be cut tall, three and a half to four inches, so it shades its own roots. In fall you bring that down gradually, a notch at a time over the last few mows, finishing somewhere around two and a half to three inches.
The reason is what happens under snow, wet leaves or just a long wet stretch. Grass left long lies over on itself and mats, and matted fescue is where snow mold and other fungal problems start. Shorter grass stands up, dries out and comes through winter cleaner. Do not scalp it though; taking more than a third of the blade at once stresses the plant at a time it is trying to store energy.
Voles, leaves and the mat
Voles tunnel under long grass and leaf cover all winter, and the runways they leave show up in March as bare lines through the lawn. A lawn cut shorter and kept clear of leaves gives them nowhere to hide from hawks and owls.
Leaves are the other half of it. A light scattering can be mulched in with the mower and is good for the soil. A thick layer, which any lot with mature oaks or maples produces, smothers the grass underneath and has to come off. Mowing over a heavy leaf layer just makes a wet mat of smaller pieces.
- Lower the deck a notch at a time over the last three or four cuts
- Mulch light leaf fall in; remove heavy layers
- Keep mowing as long as the grass is putting on growth
- Do the final cut when the grass has clearly stopped
Putting the mower away properly
Fuel left in a mower over winter is the reason it will not start in March. Either run the tank dry or add stabilizer and run the engine long enough to get treated fuel through the carburetor. Change the oil, clean the deck underside and sharpen or replace the blade so it is ready for the first spring cut.
A ragged spring cut from a dull blade tears grass rather than cutting it, and torn blade tips brown off and open the plant to disease. Doing the blade in December means the first cut in March is a clean one.