Lawn overseeding cost

Seeding a lawn costs $0.10 to $0.30 per square foot for seed and starter fertilizer spread on prepared ground. Overseeding a lawn that is only thin is usually cheaper than that, because it is sold as an add-on to a core aeration visit rather than by the foot.

What decides whether the money is well spent is not the seed. It is timing: seed put down in the right few weeks for your grass type comes up and survives the next summer, and the same seed a month late mostly feeds birds.

What it costs

The per-foot seeding rate is how crews price seed on bare or badly thinned ground, where the soil is raked or slit open first. On a lawn that still has decent cover, overseeding rides along with the aeration visit: the aeration figure covers about 5,000 square feet, and seed at the same visit adds roughly half again.

Overseeding, hydroseed or sod

These are three answers to three different lawns, and the per-foot prices only matter once you know which lawn you have.

Overseeding puts new seed into an existing lawn without killing it. It suits grass that is thin, tired or patchy, where at least half the ground is still covered with the grass you want. The old turf shelters the new seedlings, so there is no bare soil to wash away.

Hydroseeding, at $0.10 to $0.25 a square foot, sprays seed, mulch and fertilizer onto bare, prepared soil. It is for starting a lawn, not thickening one; sprayed over existing grass, the slurry sits on the thatch. The hydroseeding guide covers when it beats dry seed.

Sod, at $1.00 to $2.50 a square foot laid, replaces the lawn outright. It makes sense when the existing lawn is mostly weeds or the wrong grass, when the ground needs regrading anyway, or when you need a finished surface in weeks. The sod installation guide covers the preparation.

A quick way to choose: stand over the lawn and look straight down. If you can see soil between most blades but the grass that is there is the grass you want, overseed. If you see mostly weeds, clover or a different coarse grass, overseeding only grows more of what is already winning.

Timing by grass type

Seed needs warm soil to germinate and a few months of mild weather to root before the season turns against it. That window is different in the North and the South.

Cool-season lawns, meaning tall fescue, Kentucky bluegrass, perennial ryegrass and fine fescue across most of the northern two thirds of the country: late summer to early fall is the best window, roughly mid-August to late September depending on latitude. The soil is still warm, nights are cooler, and most annual weeds are winding down. Spring overseeding works, but the seedlings meet their first summer with shallow roots, and spring crabgrass control and new seed do not mix.

Warm-season lawns, meaning Bermuda, zoysia, centipede and St. Augustine across the South: late spring to early summer, once the soil has warmed and the existing grass has fully greened. Seeding these grasses in fall is a waste, because the seedlings go dormant before they establish.

Two warm-season details matter for the quote:

St. Augustine is generally not grown from seed. It is patched with sod or plugs, so a quote to overseed it is a quote to look at twice.

Winter overseeding is a different job. In parts of the South, dormant Bermuda is overseeded in fall with perennial ryegrass purely for a green winter lawn. It is cosmetic, it has to be repeated every year, and the ryegrass competes with the Bermuda as it wakes up in spring.

The aeration guide uses the same seasons, which is why the two jobs are booked together.

Why aeration comes first

Seed that sits on top of the lawn germinates poorly. It dries out between waterings, washes into low spots and is eaten. What every good overseeding method has in common is getting seed into contact with soil.

Core aeration pulls plugs and leaves thousands of small holes. Seed spread straight afterward falls into the holes and into the crumbled soil from the plugs, which is the cheapest way to get good contact across a whole lawn.

Slit seeding uses a machine with vertical blades that cut shallow grooves and drop seed into them. It gives better contact than aeration alone and is the usual choice for heavily thinned lawns. It is often priced per square foot, closer to the seeding rate.

Dethatching first is worth it only where thatch is thick. A spongy layer over about half an inch keeps seed off the soil whatever else is done.

Before any of it, mow lower than usual and bag the clippings so seed can reach the ground. Afterward, a starter fertilizer helps, and the fall feeding round covered in the lawn fertilization guide is what carries new seedlings into winter.

Watering: the part most overseeding fails on

New seed needs the top half inch of soil kept moist, not soaked, until it germinates. That usually means light watering once to three times a day for two to three weeks, depending on heat and wind. Perennial ryegrass comes up in about a week, tall fescue in one to two, and Kentucky bluegrass can take three or more, so a mixed seed comes up in stages.

Once most of the seed is up, water less often and more deeply to drive roots down. Mow when the new grass reaches a normal mowing height, with a sharp blade.

Without a sprinkler system or a lot of patience, this is where the money goes to waste. If the lawn cannot be watered for three weeks, delay the job.

A worked example: a thin lawn of 5,000 square feet

A cool-season lawn of about 5,000 square feet in a northern suburb. Most of it is thin rather than bare, with about 1,200 square feet of bare and weedy patches under a play set and along a path. The owners compare repairing it in September with starting over.

Repairing it:

• Core aeration of the whole lawn: $100 to $250
• Seeding the bare and thinnest areas: 1,200 sq ft × $0.10 to $0.30 per sq ft = $120 to $360
• Fall fertilizer round: $50 to $120
• Total: $270 to $730

Starting over with sod:

• Stripping the old lawn: 5,000 sq ft × $0.30 to $1.00 per sq ft = $1,500 to $5,000
• Sod supplied and laid: 5,000 sq ft × $1.00 to $2.50 per sq ft = $5,000 to $12,500
• Total: $6,500 to $17,500

The repair costs a small fraction of the replacement and keeps the grass that is already growing. The catch is time: the overseeded lawn looks patchy for a month and does not fill in fully until the following spring, where the sod is usable in a few weeks. If the lawn is mostly weeds rather than thin grass, the second list is the honest one.

Frequently asked questions

How much does it cost to overseed a lawn?

On a lawn of about 5,000 square feet, overseeding is usually sold with core aeration at $100 to $250 plus roughly half again for the seed. Bare or heavily thinned areas seeded by the foot run $0.10 to $0.30 a square foot.

Is it better to overseed or lay new sod?

Overseed when the lawn is thin but the grass is the kind you want. Sod when the lawn is mostly weeds or the wrong grass, when the ground needs regrading, or when you cannot wait a season for it to thicken.

Can you overseed a lawn without aerating it first?

You can, but much of the seed will not reach the soil. On a lawn with thin cover and loose soil, raking hard after mowing short can be enough. On compacted or thatchy ground, aerating or slit seeding first is what makes the seed worth buying.

Can you overseed a St. Augustine lawn?

Not in the usual sense. St. Augustine is not generally sold as seed, so thin areas are repaired with sod or plugs, and fixing the shade, watering or pest problem that thinned it comes first.

Related guides

• Lawn aeration cost — the visit overseeding usually rides along with
• Hydroseeding cost — for bare ground rather than a thin lawn
• Sod installation cost — when it is time to start over
• Lawn care cost — where overseeding sits in a year of service
• Lawn fertilization cost — the fall round new seed needs