Here’s a good article on lawn care by the BH&G Garden Editors for Better Homes & Gardens.
Take advantage of cool fall weather to fertilize, control weeds, and improve the health and appearance of your yard. A little work now will pave the way for a lush, green carpet when temperatures warm up again in spring.
Adjust Your Mowing Height
If you raised the height of your lawn mower in summer to reduce heat stress to your lawn, return the mower deck to its normal mowing height (about 3 inches tall is best for most grasses) in fall. Cutting your lawn slightly shorter in autumn helps prevent the grass from matting down under leaves and snow. Avoid cutting the grass too short, however. Tightly clipped turf has fewer roots and allows weeds to get a foothold.
If a summer drought persists into autumn, consider watering your turf deeply a couple of times before freezing weather sets in. A couple of deep soaks, moistening the soil several inches, before the soil freezes helps the lawn transition to winter. Frequently the fall weather pattern will change and nature will provide the moisture for you. If you have to water, do so in the morning when the winds are lighter, limiting evaporation.
Fall is the best time to fertilize your lawn if you live in the North. Cool-season grasses, such as bluegrass, fescue, and ryegrass, respond well to feeding in early September and again in late fall (late October or November). It helps them green up earlier and look better in spring.
Avoid fertilizing dormant warm-season grasses in the South unless they have been over seeded with winter ryegrass.
Creating a healthy, lush lawn is the best way to choke out weeds, instead of relying solely on chemical herbicides. Focus on mowing at the proper height, aerating as needed, and adding fertilizer to provide essential nutrients. Smaller weeds usually will get shaded out when your lawn is in top shape. For larger weeds, break out your weeding tools and pull up these pesky plants, roots and all. If you must use a spray, follow all label instructions carefully and target just the weeds you want to kill rather than treating your entire lawn.
Repair Dead Patches
Early fall is an ideal time to reseed dead or thin patches in cool-season lawns. If you seed in autumn, you’ll have fewer weeds to deal with next year. And the seedlings will become established before stressful hot weather conditions arrive. A mulch product embedded with seed and fertilizer is a convenient way to fill the gaps. Be sure to prepare the soil bed with a rake before seeding and encourage quick germination by watering new seed regularly for a couple of weeks after application.
Fall is a good time to start a new cool-season lawn or patch existing turf with sod. Moderate temperatures and abundant moisture get sod off to a quick start. High-quality sod will be thick, dense, and weed-free. It’s a convenient way to get an instant solution to bare spots. If conditions turn dry, be prepared to water new sod daily.
Check For Thatch
Thatch is a layer of dead organic matter near the soil surface. A thick layer of thatch can lead to disease and insect problems as well as damage from drought and cold weather. Thatch may develop when you overfertilize your lawn or water too frequently. Check for thatch by turning over a small area of turf with a spade. One inch of thatch or less is not a problem. If there’s more than that, your lawn will benefit from removing some thatch.
Remove Excess Thatch
Dethatching involves cutting through the thatch layer and ripping out the debris. Power rakes or vertical mowers are effective tools for this and can be rented from hardware stores and rental agencies. Use a hand rake to remove the thatch from the lawn after it has been pulled out by one of these machines. Compost the removed thatch.
Test Garden Tip: Power raking and vertical mowing can damage centipedegrass, St. Augustinegrass, and others that spread by surface runners. Use a machine that has knives correctly spaced for these grasses.
Aeration also reduces thatch, improves drainage, and loosens soil. Core aerators are the preferred type of aerators. They remove plugs of soil, or cores, breaking up thatch and improving soil structure. The cores are left on top of the turf and slowly break up depending on rain, mowing, and traffic on the turf. Aerate cool-season grasses in early fall and warm-season grasses in spring.
Apply A Top Dressing
Topdressing means applying a thin layer of soil or compost to your existing turf. The process improves growing conditions by reducing thatch, increasing the amount of organic matter in the soil, smoothing bumps in the lawn, and lessening the need for fertilizer. Spread a ¼- to ½-inch layer of high-quality soil over the entire lawn, but especially in problem areas where grass is thinning. Be sure to dethatch or aerate before you apply a topdressing. Then work the topdressing into the soil by raking it in.
Remove Fallen Leaves
Remove fallen leaves by raking them or mulching them with a mower before they mat down and smother your grass. A mulching mower works well to shred small amounts of leaves and returns the shredded organic matter to the soil, much like topdressing. Stay on top of mulching fallen leaves by running over the lawn with a mulching mower every couple of days in late fall. When many leaves are present, rake them off the lawn and compost them.
Drain Irrigation Lines
Completely drain your lawn’s irrigation system before freezing weather arrives. You can empty the system with compressed air or use drain valves. For best results, shut off the water to the system and drain each zone separately. Also drain the main supply line from the house. If you use an air compressor, don’t exceed 50 psi of air pressure.