Summer left your lawn looking pretty rough. All that heat and all those hours spent enjoying it took a toll. And cooler temperatures on the horizon aren’t likely to do your lawn any favors.

So how do you help it recover and prepare it for the colder weather ahead?

It’s simple. Overseed your lawn with fescue.

“It’s a rejuvenation of the lawn,” says Tom Good, Horticulture Assistant with the Kansas State University Extension office in Johnson County.

You do it, he says, when the lawn is weak after long, hot, dry summers wreak havoc on your grass. Adding the cool-season fescue, which grows its best in the cool temperatures of fall and spring, breathes new life into that tired lawn.

Make a Plan

The first step is knowing what you’re starting with, says a guide from the University of Maryland Extension. So get your soil tested.  Apply fertilizer, lime or other soil amendments based on the results from that soil test, which should be sufficient for six to eight weeks.

After the soil is ready, it’s time to choose the right type of seed, the guide says.

Seed choice is paramount. This is a good time to check with your local extension agent and see which fescue cultivars are likely to thrive in your home lawn.

Late summer and early fall bring cooler temperatures and the most favorable climatic conditions for cool-season grasses such as fescues, says the University of Tennessee Extension.

That’s the opposite from warm-season grasses, which do better in warmer temperatures, like St. Augustine or Bermudagrass.  When they’re not growing, they’re in dormancy.

What grows best where depends on your climate, but a large swath of the country is in the transition zone, where the weather doesn’t particularly suit either type.

In the transition zone, home lawns tend to rely on cool-season grasses such as Kentucky bluegrass, ryegrass or a mixture.

In Kansas and other parts of the Midwest, overseeding is extremely common, Good says. Right along the line between cool-season grasses and warm-season grasses, Kansas likely sees more lawn renovation in the fall than anywhere in the country, he says.

“It’s on the hotline,” he says. “It’s a question we get all the time.”

Fescue grass grows best in well-drained soils at air temperatures between 60 and 75 degrees Fahrenheit, and comes in a number of different cultivars:

  • Tall fescue is adapted to a wide range of soil and climatic conditions. It has a medium to coarse texture and tolerates higher temperatures, drought and wear. It’s good for full sun or lightly shaded areas.
  • Fine fescue is an umbrella term for other strains, like chewings, hard and red fescues, the Tennessee guide explains. They get the name from their narrower leaf blades. Fine fescues do well in the shade and drought, but not warm temperatures.
Red fescue
Red fescue grass likes moist soil, especially when it is getting established. It does well in transition zone areas. Credit: Matt Lavin, CC2.0

Start Off on the Right Seed

Not using high-quality seed is one of the top mistakes Good sees when homeowners overseed in the fall.

“It costs more, but believe me, you’re going to like the results a lot more,” he says.

For fescue blends in particular, he says to look at the weed or crop percentage in the seed. You want it to be zero.

“People will go with cheap seed and they have all these weeds come up,” Good says.

The North Carolina Cooperative Extension lays out some guidelines for picking the right grass seed. All the information is on the seed bag:

  • Names of grass cultivars – these should be listed on the seed bag label. Make sure they’re right for your lawn and climate
  • Germination percentage – higher rates mean more seeds successfully take root and grow. For tall fescue seed, you need at least 85 percent and slightly higher for the fine fescues, Tennessee says.
  • Percentage of weed seeds – choose very low weed seed levels, ideally less than 0.25 percent. You want to plant grass, not weeds.
  • Sell-by date – fresher seed mixtures generally have higher germination rates. Choose seeds packaged for this year or next.

With high-quality fescue grass seed in hand, it’s time to move on to preparing the lawn.

Prep the Overseeding Site

Mow the existing lawn short, says the Nebraska Extension. Cut to about 1.5 inches before overseeding, so the new seedlings can compete with the existing grass and weeds.

A short cut also helps sunlight reach new seedlings and prevents seeds from getting stuck in the vegetation. Unlike most occasions, when mulching grass clippings is good for your lawn, bag the clippings for this mow so they don’t interfere.

Thatch also impedes growth from new seed, so it’s next on the to-do list.

Nebraska says it’s important to have less than a quarter-inch of thatch when overseeding.

If you have a thicker layer of thatch than that, use a power rake, aerator or another tool to dethatch your lawn. The North Carolina Extension recommends aerating to reduce soil compaction and help increase soil to seed contact. Holes left when you aerate also capture seeds and hold moisture, leading tall fescue seedlings to come up in tufts from the core aeration holes.

Good recommends a verticutter, which cuts vertical slits into the soil.

“One of the most important things, when you’re overseeding a lawn, is getting soil contact with the seed,” he says.

A verticutter, or vertical mower, makes sure the seed comes into contact with the soil once you spread it.

Some homeowners will also apply topsoil as a topdressing when overseeding. It provides some germination, but “using existing soil and verticutting is a much better method,” Good says.

When Time Is Right, Apply Starter Fertilizer

You want to wait until the soil temperature falls to 50 degrees to 65 degrees Fahrenheit to get the best germination from your fescue seeds. That generally equates to days when air temperature consistently hits 60 to 75 degrees.

Next up is a starter fertilizer.

The Kansas State University Extension says this is the only product other than seeds needed for seeding a lawn.

Don’t be scared to fertilize at seeding, because those young seedlings will need the added push to quickly start germinating and establishing. The existing grass will get a boost, too.

Plant Your Seeds

Your yard is ready. The soil is open, fertilized and moist. The temperature is right. The perfect seed blend is in hand. It’s time for the real work: applying that seed to your lawn.

Use a rotary or drop-type grass seeder rather than applying by hand, says the Nebraska Extension. Be sure your spreader is set properly to make sure it’s applying the correct amount of seed.

Check the bag your seed mix came in to double-check those seed germination rates.

Overseeding requires about half the normal seeding rate, or the rate that would be used on bare soil, including totally bare spots in your lawn. For tall fescue, the normal rate is generally 6 to 8 pounds of seed per 1,000 square feet on bare soil. Cut that in half for overseeding and you get 3 to 4 pounds per 1,000 square feet.

Water everything in and keep the seedbed consistently moist to ensure rapid germination.

It’s a fine line. Good says it’s likely the most common mistake homeowners make when overseeding.

“People either water too much, which smothers the seed, or they don’t water enough so it doesn’t come out,” he says.

Begin with frequent, light irrigation and progress to deeper, more infrequent watering as the seedlings and their root system become established.

This is where you may need mulch. Michigan State says spreading a light mulch of hay will retain soil moisture and keep seedlings from drying out. The recommended rate is one bale of hay per 1,000 square feet, but be careful. Too much mulch cover will smother the seedlings.

Care for the Young Grass

Once that new fescue lawn comes up, you’ve got to keep it up. And it’s going to take some special lawn care practices.

Prepare to nurse your new lawn for about two months, says the Maryland guide.

It also recommends keeping foot traffic off young seedlings for at least a month, as they’re easily injured.

Keep weeds out, too. All that tilling, fertilizing and watering that goes along with establishing new grass from seed also helps establish weeds. Early on, it’s best to pull those weeds by hand.

The control of annual grass weeds such as crabgrass can be a challenge too, the guide says. Broadleaf herbicides should not be applied until the lawn has grown sufficiently to be mowed three times.

Mow the Right Way

Which brings us to the next point: mowing. It may be scary to get out there and mow a young lawn, but it’s a vital part of establishment. Proper mowing height is crucial. Sufficient grass height allows the turf to mature before winter sets in and minimizes encroachment from weeds.

The N.C. extension cites studies showing a 3.5-inch mowing height provides the best growing conditions, minimizes diseases and holds off weeds.

But to help turfgrass like fescue establish, the extension says, let it first reach 4.5 inches and mow it back down to 3 inches the first time you mow.

Allow those clippings to fall into the turf, where they’ll return nutrients to the soil. That alone can reduce the need for fertilizer by as much as 30-percent.

Once you’ve mowed that fall season lawn a few times, the next step is celebrating. You’ve got a newly rejuvenated tall fescue lawn that will tolerate incoming cooler temperatures and stay thick and green longer.

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