Fall is the time to prepare your tall fescue lawn for winter by strengthening its roots and eliminating any damaging elements, such as insects and weeds. You'll need to treat your tall fescue lawn differently in the months leading up to winter than during summer. Your tall fescue lawn will have different needs and problems to attend to during the fall. You can take some simple steps to keep your tall fescue healthy in the fall and prepare it for the dormant season so that you'll have a beautiful lawn the following spring.
Water your tall fescue lawn once each week in the absence of rainfall to deliver about 1 to 1 1/4 inches of water, moistening the soil to a depth of about 5 inches. If you have sandier soil, water once every three days, delivering 1/2 inch of water each time.
Feed your tall fescue lawn with a turf-grade fertilizer once in mid-September and once in November. Apply a 12-4-8 or 16-4-8 NPK (Nitrogen-Phosphorous-Potassium) fertilizer at a rate of 1 pound of nitrogen per 1,000 square feet of lawn.
Mow your tall fescue lawn to keep it at 2 1/2 to 3 inches high between September and November. During the fall, allow the grass clippings to remain on the lawn to feed the tall fescue.
Aerate your tall fescue lawn in the fall, especially if you have heavy foot traffic on the grass. Water your lawn the day before you aerate it to soften the soil. Make two perpendicular passes with a lawn aerator over the entire lawn and break up the plugs.
You can rent a lawn aerator at most garden stores, but be sure to use an aerator that lifts up and removes soil plugs.
Treat your tall fescue lawn in the fall for any broadleaf weeds. Spray your lawn with a broadleaf weed herbicide, but be sure to follow the directions on the label carefully.
Watch for grubs in your lawn in the fall, because autumn is an ideal time to treat tall fescue for white grub infestations. In September or October, apply an approved insecticide for white grubs according to the label's directions after watering the lawn thoroughly.