Fall lawn care for cool-season grass

September is the most important time to fertilize cool-season grasses such as tall fescue, bluegrass and ryegrass. It's also the time to seed a new lawn and to overseed thin spots. If you live outside the cool-season belt, your county extension office has the calendar for your grass.

What you need

• A spreader and lawn fertilizer
• A core aerator, rented, or a lawn service to run one
• Grass seed matched to the lawn, and a slit seeder for an established lawn
• A mulching mower

Steps

1. 1

   Fertilize in early fall

   Apply about 1 pound of nitrogen per 1,000 square feet, following the rate on the bag. If the lawn gets only one feeding a year, make it this one.

   45 min

2. 2

   Aerate a few days after rain

   Run the core aerator while the soil is still slightly damp, and only where the lawn needs it. Leave the soil cores on the lawn to break down over the next few weeks.

   90 min

3. 3

   Overseed the thin spots

   A slit seeder set to the seed's rate works well on an established lawn. Keep a patched area moist until the seed sprouts, and keep watering while the young grass grows.

   60 min

4. 4

   Mulch the clippings and leaves

   Bagging them takes nutrients away from the soil, so mow them back into the lawn. Don't let leaves pack down and smother the grass.

   30 min

5. 5

   Keep mowing until growth stops

   Mow at the usual height for your grass until it stops growing. Fall heights run from about 1 to 3.5 inches, with tall fescue the highest. Make sure the lawn goes into winter with moist soil, not wet.

   30 min

6. 6

   Check the lawn in late fall

   When the leaves are mulched in with grass showing through, the soil cores are breaking down and new grass fills the thin spots, the fall work is done.

   5 min

Weeds

Fall is a good time to kill broadleaf weeds, and late September is the best time for a broadleaf herbicide. A systemic herbicide applied then is more likely to kill the whole plant, roots included. Read and follow the label on any product you use.

Late in the season

Once cool days slow the grass's growth, a moderate feeding helps the roots grow and the turf thicken. Some lawns get an optional late "winterizer" feeding, about a week after the final mowing.

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