How to overseed a lawn: mow to 1.5 to 2 inches, open the soil with a core aerator, vertical mower or slit seeder, spread seed evenly, and keep the seedbed moist. Iowa State University Extension says successful overseeding needs good seed-to-soil contact. Do it from mid-August to mid-September for the best result.
Learning how to overseed a lawn takes one afternoon. Getting it right takes timing, the right tool and steady watering. This guide gives the steps, how much seed to use, how to seed without aerating, and when to hand it to a pro.
Wade’s Property Services is a locally owned company in Sherrard, Illinois. If you would rather skip the work, our aeration and overseeding Quad Cities service covers it.
How to Overseed a Lawn: Step by Step
These steps show how to overseed a lawn, following Iowa State University Extension’s page on overseeding a lawn.
- Pick the time. Mid-August through mid-September is the best time to renovate a thin lawn. See our guide on when to overseed lawn areas.
- Mow low. Cut to 1.5 to 2 inches to reduce competition from the old grass.
- Open the soil. Run a core aerator over the lawn 3 or 4 times, until there are 20 to 40 holes per square foot.
- Spread the seed. Use a drop seeder.
- Work it in. Drag the lawn with a piece of chain link fence or a drag mat to break up soil cores and mix the seed into the soil.
- Water and mow. Keep the seedbed moist, and mow often at first.
That is how to overseed a lawn in six moves. Core aerators, vertical mowers and slit seeders can be rented at some garden centers and rental stores, Iowa State notes. Our guide to aerator rental vs hiring a pro covers that choice.
How Much Grass Seed to Overseed
How much grass seed to overseed is the second most asked question after timing. Honest answer: the seed label sets it, and it depends on the species.
Illinois Extension lists suggested rates on its page about planting a new lawn. Those rates, in pounds per 1,000 square feet, are:
- Kentucky bluegrass blend: 1 to 3
- Kentucky bluegrass and perennial ryegrass (80:20): 3 to 4
- Kentucky bluegrass and fine fescue (50:50): 3 to 5
- Tall fescue blend: 6 to 9
Illinois Extension warns that going over the rate can give weak, spindly seedlings and disease. The Iowa State overseeding page does not give a separate overseeding rate, and these tables are written for seeding lawns in general. So how much seed to overseed lawn areas on your property is a label-and-lawn question. Ask your seed seller, or ask any company you hire, which rate they use and why. For species, read Kentucky bluegrass vs tall fescue.
How to Overseed Lawn Areas Without Aerating
Here is how to overseed a lawn when you skip the aerator. A core aerator is not the only tool. Iowa State lists two others.
- Vertical mower. Its knife-like blades slice through thatch and into the top 1/4 to 1/2 inch of soil. One or two passes should be enough. Remove the loose debris, sow the seed with a drop seeder, then go over the lawn again to work the seed in.
- Slit seeder. It cuts small grooves in the soil and places seed in them. Iowa State says it suits large areas.
Illinois Extension adds a plain tip for small sites: drag a leaf rake upside down across the seed for good contact. It also suggests sowing half the seed in one direction and half at right angles, to cover evenly.
Skipping all of these is where overseeding fails. Seed that rests on top of thick grass has poor seed-to-soil contact. That is why we pair aeration with seed.
Overseeding Lawn Tips for Water and the First Mow
How to overseed a lawn well means care after seeding as much as work before it.
Water. Iowa State says to keep the seedbed moist with frequent, light watering, usually at least once a day. For new seedings it says to keep the upper inch of soil moist. Illinois Extension notes the same exception: a newly seeded lawn is the case where the surface needs to stay moist.
First mow. Iowa State says to mow a newly seeded lawn when the grass is 3 inches tall, using a sharp blade, at 2 to 2.5 inches. In the overseeding case, mow often at 1.5 to 2 inches at first, then raise the height gradually to a final 3 inches.
Feeding. About 6 weeks after germination, apply 1 pound of nitrogen per 1,000 square feet.
Sprouting. Most turfgrasses sprout in 2 to 3 weeks if kept moist, Iowa State says. Tall fescue can sprout in five to ten days.
Need this done? Wade’s does aeration and overseeding together for thin and worn lawns. See our lawn aeration and overseeding service and ask for a free quote.
Common Overseeding Lawn Tips: What to Skip
A few things are worth avoiding.
- Pre-emergent herbicides. Iowa State warns that crabgrass preventers and most pre-emergents can kill cool-season grass seed. Use only labeled products.
- Seeding in summer. Iowa State says late May to mid-August is extremely difficult and usually unsuccessful.
- Heavy seed rates. More is not better, as the Illinois warning shows.
- Skipping the water. Dry seedlings die fast.
Our post on overseeding mistakes goes deeper on what goes wrong.
When to Hand It to a Pro
DIY knowledge of how to overseed a lawn works on small lawns with time to water. A pro helps when the lawn is large, the soil is hard, or you cannot water daily. Illinois Extension notes that a homeowner and a company each have a part to play, so ask what is included before you hire. Our guide to choosing a lawn overseeding service lists the questions.
What Homeowners Ask
Searches on this topic repeat a few questions. People ask how to reseed in spring and how long grass takes to grow. They ask when to plant seed in fall, and whether they should aerate before overseeding.
What Our Customers Tell Us
Wade’s has a 5.0 star rating on Google. Public reviews often mention reasonable pricing, a polite and professional crew, and tidy cleanup. We quote each lawn on its own.
Let Wade’s Handle How to Overseed a Lawn
Now you know how to overseed a lawn: timing, soil contact, seed and water. If it feels like a lot, we can do it. Wade’s pairs core aeration with grass seed in Davenport, Bettendorf, Moline, Rock Island and nearby towns. For Moline yards, our lawn care Moline IL page covers the local details.
Read about our aeration and overseeding Quad Cities service, then call (309) 235-9237, Monday to Friday, 7:30 AM to 4:00 PM, for a free quote. You can also request a quote online.
Frequently Asked Questions
How to reseed a lawn in spring?
Seed from early April to mid-May only if you can water often. Iowa State warns of annual weeds and says most pre-emergents kill grass seed. Fall is the easier season. Read our timing guide first.
How long does it take for grass to grow?
Iowa State says most turfgrasses sprout in 2 to 3 weeks when kept moist. Tall fescue can sprout in five to ten days. Keep the top inch of soil damp the whole time.
How much grass seed to overseed a lawn?
Follow the seed label. Illinois Extension lists 1 to 3 pounds per 1,000 square feet for Kentucky bluegrass blends and 6 to 9 for tall fescue blends. Too much seed can cause weak seedlings and disease.
Should I aerate my lawn before overseeding?
Aerating is one good way to get seed to the soil. Iowa State also lists vertical mowers and slit seeders. Without any of these, seed has poor contact with the soil.
When should I plant grass seed in the fall?
Iowa State says mid-August to mid-September, and sowing seed from late August through September. Illinois Extension gives early August to early September for northern Illinois.
Can Wade’s overseed my lawn for me?
Knowing how to overseed a lawn is one thing, and doing it is another. We pair core aeration with grass seed. Call (309) 235-9237, Monday to Friday, 7:30 AM to 4:00 PM, for a free quote.
Sources
- Iowa State University Extension, Overseeding a Lawn
- Iowa State University Extension, Seeding a New Lawn
- Iowa State University Extension, When should I start mowing a newly seeded lawn?
- Illinois Extension, Planting a New Lawn
- Illinois Extension, Choosing Home Lawn Care Services
- Illinois Extension, Watering Your Lawn
