As we’re deep into late summer, our lawn’s weak spots are on full display. Our turf has had an intense season of active growth and exposure to seasonal extremes. With high heat, moisture fluctuations, potential disease issues, and wear and tear, it’s no wonder we may face patchy coverage. 

Fortunately, early fall is the prime time to plant grass seed in bare spots. Filling patchy grass is an easy landscape fix to refresh the look of the yard. It brings a quick boost in curb appeal to span the next seasons.

Seeding Basics

Existing turf benefits from careful overseeding.

When it comes to planting grass seed in bare spots to increase lush, leafy blades, you can overseed the whole lawn or focus only on those bare spots. Targeting the worn areas makes site preparation easy, requiring only a little work before seeding to make a lasting impact. Choosing the right type of grass and sowing at the best time for your growing area creates a foundation for robust growth.

If you have a few thinning patches, planting grass seed is a streamlined process to make it thicker. Overseeding is adding a layer of seed to existing grass. 

When to Sow

Timing sowing before frost gives grass a solid start.

The best time of year to plant grass seed in bare spots is late summer and fall, with spring as the next top contender. The mild air and soil temperatures, coupled with regular seasonal moisture, support healthy roots and blades. Skip sowing in the high heat of summer to avoid seedling stress and weed competition.

In zones 7 and warmer, plant warm-season grasses through September, avoiding hot and dry spells. These selections rely on warm conditions and adequate moisture to germinate. Ideal soil temperatures are between 65 and 70°F (18-21°C).

In zones 6 and cooler, sow cool-season selections in mid-August through mid-October. These need cool air and soil temperatures with regular moisture to germinate, with an optimal soil temperature range of 50-60°F (10-16°C). Gauge your first anticipated frost date, and sow grass seed to fill in bare spots at least 45 days before.

In addition to optimal temperatures, there are also better conditions to sow in. Opt for non-windy and non-rainy times of day for easy scattering with seeds staying in place.

Choose the Right Grass

Site conditions determine which types grow successfully.

Turfgrass broadly falls into two main types that grow better according to warm and cool climate conditions. Warm-season grasses grow in zones 7 and above and include Bermuda, St. Augustine, centipede, and zoysia. Cool-season grasses grow in zones 6 and colder, with Kentucky bluegrass, perennial ryegrass, and tall and fine fescues as common species.

Choose a seed for your site based on your current grass type for a match. If your site conditions have changed (like more shade from a mature tree canopy), choose the seed based on sun exposure, your growing zone, and uses, like foot traffic.

Prep the Patch

Light raking prepares spots for new healthy growth.

Clearing and smoothing are site preparations that ensure the best soil contact for the seeds. If you’re overseeding a large area like the entire lawn, mow it to two inches high to spread an even seed layer. 

For sowing grass seed in bare spots, lightly rake thatch or browned material. Clear away any sticks, rocks, or other surface impediments. Dig with a spade or shovel to lift grasses, weeds, and roots. Turn the soil a few inches deep, if feasible, to loosen it. If your bare patch is also a low point or could use filling after weeding, add a layer of topsoil or compost and turn it in with the existing soil.

Smooth the Surface

Leveling the area makes maintenance much easier later.

The last steps before seeding are to rake the spot and pat it to make it smooth. Use a hard garden rake to remove clumps or clods and even out high and low spots to create a relatively even surface. A smooth area maximizes coverage and germination, improves drainage, promotes even growth, and eases maintenance without hidden ruts or mounds.

Scatter the Seeds

Spread carefully for even coverage across the area.

Scattering grass seed to fill bare spots is easy and doesn’t take much material. Scatter by hand or, for larger areas, use a drop spreader. Broadcast the seeds to achieve about 50% coverage (half seed, half exposed soil). Scattering extra seed is tempting, but too much leads to overcrowding and potential diseases.

Lightly tamp the seeds by walking across the patch. Or, add an extra fine layer of sand or topsoil to secure the seeds in place. Grass seed only needs planting at ⅛ to ¼ inch deep. Securing the seeds promotes surface contact for moisture absorption and rooting, while still allowing ample access to sunlight.

Optionally, mulch lightly with clean, weed-free straw for extra seed security. A light layer decomposes as seedlings grow and disappears with the first mowing. If you can’t source weed-free straw, skip this step.

Watering Protocol

Keep new growth consistently moist until blades reach height.

Seeds and seedlings need regular moisture from daily watering to thrive. Sometimes, they need it two or three times daily during hot, windy conditions or dry spells. Aim to keep the area moist, but not soaked and oversaturated.

Water lightly to moisten the soil surface, avoiding excess runoff. Seedlings usually appear in two to four weeks, but germination depends on the variety. Continue daily watering until blades are two inches tall. Reduce watering frequency while increasing the run time. Watering slightly longer allows for consistent, deep watering to promote more extensive roots. 

Mowing

Keep mowing height around three inches for health.

Stay off of newly seeded areas for two weeks or longer. When blades reach four inches high, it’s time to mow. For healthy growth, mow grass to three inches (with a minimum of two inches).

As growth slows for the season, the mowing frequency should taper off to every other week or two until dormancy. Avoid mowing on wet days (which can create ruts) or frosty mornings (which can cause damaged blades to die back).

During the active growing season, turf benefits from a regular maintenance schedule, including fertilizing, for a lush, grassy space.