When the worst of the summer heat subsides, you're poised to roll up your sleeves and do some fall lawn care. However, the regimen right for your situation will vary based on whether your lawn is composed of warm-season or cool-season turf grass. If you are unsure which type your lawn is made of, take a sample to your local county extension.
Cool-season turf grasses are called such because they thrive in the cool weather usually associated with spring and autumn. Examples of cool-season turf grasses include rye grass, the fescues (both "fine" and "tall" kinds), Kentucky blue grass, and bent grass. By contrast, warm-season turf grasses grow most actively when the weather is warm, which is why they are the preferred grass types of southern U.S. state. Examples include Bermuda grass, Saint Augustine grass, zoysia grass, and buffalo grass.
If your lawn is not performing well, have your soil tested. Corrections made in the fall will help promote a lusher lawn in the spring. If the soil test shows a need to reduce acidity, apply lime now. If alkalinity needs to be reduced, apply sulfur.
Weeds continue to plague both cool- and warm-season grasses in the fall, so apply a weed-control product. Avoid newly seeded areas of cool-season grasses, and use targeted spot treatments on tougher weeds.
Dethatching the Yard
If you have cool-season grasses, dethatch your lawn by raking or with a piece of equipment known as a dethatcher or power mower. When thatch, a layer of organic matter, builds up to e more than half an inch thick, it can prohibit movement of water and nutrients. For bad cases of soil compaction, you may have to employ the technique known as core aeration. This creates openings in the soil, allowing air, water, and nutrients in.
Warm-season grasses should not be dethatched or aerated in the fall. Instead, save that task for spring or early summer, when the grass is activity growing.
Watering the Grasses
Don't think that because the temperatures outside are no longer consistently high, you can totally forget about watering in the autumn. Fall lawn care for cool-season grasses includes ensuring that lawns receive enough water in the autumn to carry them through the long winter. Overall, you won't need to water nearly as much as in summer, but during hot, dry spells in autumn, remember to provide sufficient water.
Warm-season grasses only need to be watered for as long as the lawn is growing. When it stop growing, the grass can rely on rainfall for its watering needs. However, if you overseed for winter color, they you need to maintain a regular water schedule.
Fertilizing the Lawn
Cool-season grasses also need to be fertilized. Apply 1 pound of nitrogen per 1,000 square feet of lawn, or purchase a product that has a low, middle number for NPK; for example, Scotts' "WinterGuard" Turf Builder has an NPK of 32-0-10.
Avoid fertilizing lawns composed of warm-season turf grasses in autumn, as it undergoes a hardening-off process during this time of year to prepare it for winter. Fertilizing warm-season grasses in the fall may interfere with that hardening-off process.
Overseeding the Grass
By overseeding with annual winter ryegrass (Lolium multiflorum), homeowners whose lawns are composed of warm-season grasses can enjoy a green carpet during the winter, instead of having to look at a brown lawn. When you buy the seed, be sure to ask for the annual, not the perennial. Annual winter ryegrass will die back when summer's heat returns, turning over the lawn once again to the warm season grasses. This exit is a timely one. The problem with the perennial winter ryegrass is that it doesn't go away, competing with your warm season grasses for sunlight, water, and nutrients.
Lawns composed of cool-season grasses can also profit from overseeding. But in this case, the motivation behind overseeding lawns is not winter cosmetics, but to fix bare patches―with an eye to next year's lawn.
Mowing the Lawn
If you have warm-season turf grasses, increase the lawn mower height by a half-inch. Cool-season grasses do not need an adjustment on mowing height.
According to Robert E. Kozlowski at the Cornell University Cooperative Extension, mowing your lawn with a lawn mower set at a proper height can save you from having to rake or bag your lawn clippings. Mow when your grass is dry and 3 to 3 1/2 inches tall. Never cut it shorter than 2 to 2 1/2 inches or remove more than one-third of the leaf surface at any one mowing. Valuable nutrients in the grass clippings can do your lawn some good when left right where they lie after mowing―as long as their bulk is kept to a minimum.
Employing Kozlowski's lawn care tip will entail more frequent mowing, but the result will be a healthier law that's fed by nutrients that you would otherwise be hauling away. A mulching lawn mower will help with this task, as you do not need to be quite so careful about the height at which you cut your grass because the clippings are shredded up more finely.
Continue to mow the lawn until the grass stops growing, a date that will be determined by the weather.
Both warm- and cool-season grasses benefit from leaf management, as mats of fallen leaves can harm the health of the lawn. Mow and mulch smaller quantities of leaves, or rake, bag, or compost the leaves if there's larger amount.