Dates below are typical for the Midwest and similar climates; shift them a few weeks earlier in the North and later in the South. Warm-season lawns have different needs, covered at the end.
Late August to mid-September
☐ Seed bare spots and overseed thin areas
Iowa State University Extension puts the window for seeding cool-season lawns at about mid-August to mid-September. That gives new grass time to establish before hard frost. See our step-by-step guide to overseeding a thin lawn and use the grass seed calculator to buy the right amount.
☐ Core aerate compacted lawns
Core aeration pulls small plugs of soil out of the lawn so air, water and roots can move down. Iowa State suggests early September, aiming for 20 to 40 holes per square foot, when the soil is moist. The University of Illinois notes that aerators can’t cut hard, dry soil, so aerate a few days after rain. Leave the cores on the lawn to break down. Aerating right before overseeding gives seed great soil contact, and it’s the perfect moment to topdress with a thin layer of compost (about ¼ inch); our compost calculator works it out.
Mid-September
☐ Fertilize
If you fertilize only once a year, this is the time. Iowa State recommends feeding in mid-September with no more than 1 pound of actual nitrogen per 1,000 square feet. Use our lawn fertilizer calculator to convert that into pounds of product for your bag and lawn.
☐ Test your soil and lime if needed
Fall is a convenient time to take a soil test. If it calls for lime, you can apply it whenever the ground isn’t frozen, and freeze-thaw cycles over winter help work it in. Turn the recommendation into bags with the lawn lime calculator.
Late September to early November
☐ Control perennial broadleaf weeds
Dandelions, clover and creeping Charlie are moving sugars down to their roots in fall, so a systemic weed killer applied now travels to the roots too. Iowa State suggests late September to early November. Always follow the label, and don’t use weed killers on newly seeded areas until the new grass has been mowed several times; check the product label for the waiting period.
☐ Keep mowing, and don’t scalp
Keep mowing as long as the grass grows, which in Iowa is often into late October or early November. Never remove more than one-third of the blade at once. Keeping a reasonable height (around 2½ to 3 inches for most cool-season lawns late in the year) lets the grass keep making food for its roots.
☐ Deal with leaves
A thick mat of leaves smothers grass. Thin layers of dry leaves can be shredded with a mulching mower so the pieces fall between grass blades and feed the soil. Heavy layers should be raked or mowed more than once. Leaves raked into planting beds make good winter cover.
☐ Keep watering in dry spells
Fall can be dry. Lawns need about an inch of water a week, especially new seed and sod. Our sprinkler run time calculator turns that into minutes per zone.
Before the ground freezes
- ☐ Do a last mowing, then clean and store the mower.
- ☐ Drain and store hoses, and shut off and winterize irrigation systems.
- ☐ Clean, empty and store the spreader.
If you have a warm-season lawn
Bermuda, zoysia, St. Augustine and centipede are slowing down in fall, not gearing up. Skip fall fertilizing (feed in late spring and summer instead), do major seeding and sodding in late spring to early summer, and keep mowing at your usual height until the grass goes dormant. Fall is still a good time to test soil and control winter weeds.
Sources
- Iowa State University Extension: Late summer and fall lawn care
- University of Illinois Extension: Five fall tips for cool-season lawn care