Lawns: How to Reseed
How to kill off the old grass and seed a healthy new lawn
IntroductionIf your lawn is weedy or your grass is in poor shape, establish a healthy new lawn by starting over. Follow all our steps for success.
- Broom rake
- Garden rake
- lawn mower
- power tiller
- sod roller
- Black plastic or herbicide
- Grass seed
- Lawn starter fertilizer
- Seed accelerator
- Soil conditioners
Create a healthy lawn by starting over
Let’s get this straight right from the get-go: A healthy lawn doesn’t get taken over by weeds. So if it looks like you’re raising weeds instead of grass, that’s a sign of a more serious problem. And that may mean killing off the grass and starting over. It’s a big reseeding lawn project that’ll take several weekends and may cost you up to 25¢ per sq. ft. for equipment rentals, soil conditioners and seed. If you’re willing to spend more, you can lay sod instead of planting seed, but don’t skip the soil testing and remediation steps. Here’s how to balance your soil’s pH level properly.
Are you ready for a fresh start? Just follow our guide for how to plant grass seed on an existing lawn and you’ll be the happiest gnomeowner on your block.
Evaluate Your Lawn
Going “nuclear” shouldn’t be your first option. Instead, start with spot applications of weed killer, dethatching and core aeration. Hydroseeding is another option to try and boost your lawn. But if you still see more than 60 percent weeds at the start of the next growing season, your lawn is too far gone to save. Your best option is to nuke it and replant.
Project step-by-step (12)
Planting New Grass: Get a soil analysis
Collect samples for a soil test
Plunge your spade about 6 in. deep and pull out a plug of soil. Then slice off a section of the plug (top to bottom). Remove the grass and rocks and mix all the samples together. Don't even think about replanting until you get the results of a soil analysis (cost is usually less than $20). Contact a local extension service or search the Internet for a soil-testing lab near you. Select three different locations around your lawn and collect samples. Mix them together and scoop into a container. Note on the lab form that you'll be planting new grass and whether you bag the clippings when you mow or return them to the lawn. In a couple of weeks, you'll get a report with recommendations about which fertilizers or soil treatments to add.
Planting New Grass: Kill everything
Preparing Lawn for Seeding: Kill the grass with plastic
Lay the poly film over the lawn and secure it with rocks or stakes to begin the reseeding lawn process.
Preparing Lawn for Seeding...Or kill it with herbicide
Cover nearby plants with a tarp. Choose a calm day and hold the spray head close to the grass to prevent overspray. You can kill the grass with chemicals like Roundup or Killzall. But if you hate the idea of using chemicals and have a large area, rent a sod cutter to remove the lawn surface. Or kill the grass by blocking out its sunlight with black poly film (4-mil or thicker; about $100 for a 28-ft. x 100-ft. roll). Remove the poly when the grass is dry and brown (two to three weeks or longer, depending on the weather).
Planting New Grass: Remove the dead stuff
Preparing Lawn for Seeding: Rake off the dead grass
Rip up all the dead grass and weeds with a rigid tine rake and lots of muscle as part of the reseeding lawn job. Now comes the upper body workout: Rake up the dead grass and weeds before you amend the soil. Yup, it's got to be done for this reseeding lawn project.
Planting New Grass: Improve the soil
Preparing Lawn for Seeding: Till in the soil conditioners
Spread the conditioners across the entire lawn. Then till them into the soil to a depth of about 5 in. Don't think you can fix bad soil just by adding a few inches of black soil on top of the old. Instead, rent a tiller (about $45 per day) to till in the soil conditioners recommended by the soil analysis.
“Adding good-quality black topsoil over bad soil is like putting chocolate frosting on a stale cake—it doesn't fix the underlying problem.” — Bob Mugaas, Turf Expert
Planting New Grass: Smooth the soil
Preparing Lawn for Seeding: Rake the soil
Level and smooth the soil with a broom rake. Then drag the rake (tines up) to create "furrows" for this reseeding lawns job. Grass seed needs smooth and level ground to get the best germination. And it needs good seed-to-soil contact. So first remove all rocks and debris, then smooth the soil with a rake.
Planting New Grass: Add a starter fertilizer
Preparing Lawn for Seeding: Jump-start the seed
Spread lawn starter fertilizer into the furrows with a spreader. Don't overdo it. A starter fertilizer gives grass seed the nutrients it needs to germinate and grow quickly. Consult with a local nursery to find the best starter fertilizer for the seed you select. Follow the instructions on the bag for the proper spread rate for a new lawn and apply the fertilizer.
Planting New Grass: Pick seed to match your site
Consult with the grass expert at a garden center to select a seed that matches your site conditions, lawn care preferences and budget. Ask about the newer low-maintenance and drought-resistant varieties. Purchase grass seed by the bag or in bulk, by the pound. But buy just what you need. Don't apply the leftover seed—extra seed actually reduces the germination rate.
Planting New Grass: Prepare the seed
Preparing Lawn for Seeding: Mix the seed
Pour the seed and fertilizer into a plastic bucket and mix it thoroughly. To avoid applying too much seed, mix the seed (4:1 ratio) with a fertilizer/ bulking agent (Milorganite is one brand; about $38 for a 32-lb. bag).
When to Plant
There are good and bad times of year for starting a project like this. In cold climates, plant new grass seed in early spring as the lawns are just coming out of winter (early to mid-April) or late summer from about mid-august to mid-September. In warm-weather climates, plant in late spring/early summer. if you're not sure, contact your local extension service to get planting advice from a turf expert. Learn the best time to reseed your lawn for where you live.
Planting New Grass: Spread the seed
Preparing Lawn for Seeding: Cover the seed
Turn the broom rake upside down and drag it side-to-side over the furrows until only 10 to 15 percent of the seed remains uncovered.
Preparing Lawn for Seeding: Compact the soil
Fill a sod roller halfway with water and roll the seed to pack the soil and seed mixture.
Preparing Lawn for Seeding: Compact the soil
Fill a sod roller halfway with water and roll the seed to pack the soil and seed mixture. Load the seed into a spreader and apply it for the reseeding lawn work. Make sure it doesn't fly into nearby gardens. Rake to cover the furrows as shown. Then compact the soil with a sod roller (rent one for about $20 per day) to get good seed-to-soil contact.
Planting New Grass: Add mulch or grass seed accelerator
Spread the seed accelerator
Set the spreader to the widest setting and walk quickly to get a light application of the pellets.
Close-up of seed accelerator
This accelerator absorbs moisture and slowly releases it. Cover the soil with compost mulch to retain water during germination. Or apply a “grass seed accelerator” (one brand is GreenView, greenviewfertilizer.com; about $22 for 30 lbs., which covers 600 sq. ft.). The accelerator absorbs more moisture than either mulch or hay and then slowly releases it. It also degrades naturally, eliminating cleanup.
Planting New Grass: Water, but not too much
Place an impact sprinkler in the corner of the lawn and set it to spray in a quarter arc. Then move it to the other corners. Water the new lawn generously right after the mulch application, but stop as soon as you see puddles forming. Then keep the soil moist to a depth of 4 to 6 in. for best germination. Keep watering regularly as the seedlings appear and grow. Gradually reduce the watering over a six-week period. Then switch to your normal watering routine. How long it takes for the grass seed to grow varies.
“Most people overwater new seed. Just keep the soil damp for the best germination.”
Bob Mugaas, Turf Expert
Planting New Grass: Cut the grass with TLC
Make the first cut
Mow the new lawn once it reaches a height of 3 in. Use a newly sharpened blade—it's healthiest for the grass. Cut just 1/2 in. per mowing. Set the cutting height to 2-1/2 in. Use a new or sharpened blade to make sharp, clean slicing cuts. Avoid using a dull blade—it rips the grass, setting up the conditions for disease.
Note: Find out how to sharpen a lawn mower blade. Search for “sharpen blade.”
Meet Our Grass Guru
Bob Mugaas is an Extension Educator in Horticulture with the University of Minnesota Extension. Bob has authored or co-authored more than 200 articles on various topics related to turf grass management.
Required Tools for this how to plant grass seed on existing lawn project
Have the necessary tools for this DIY reseeding lawn project lined up before you start—you’ll save time and frustration. You'll also need a shovel, power tiller, spreader, sod roller, sprinkler and lawn mower.