How to Reseed a Lawn

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 project that’ll take several weekends and may cost you around 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.

Are you ready for a fresh start? Just follow our guide 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. 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.

Note: Find out how to dethatch and aerate for greener, healthier grass, here.

Don’t even think about replanting until you get the results of a soil analysis. 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. 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, mix all the samples together and scoop the soil 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.

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) secured with rocks or stakes. Remove the poly when the grass is dry and brown (two to three weeks or longer, depending on the weather).

Now comes the upper body workout: Rake up the dead grass and weeds with a rigid tine rake before you amend the soil. Yup, it’s got to be done.

Don’t think you can fix bad soil just by adding a few inches of black soil on top of the old. Instead, spread the conditioners, recommended by the soil analysis, across the entire lawn. Then rent a tiller and till them into the soil to a depth of about 5 in.

‘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

Grass seed needs smooth and level ground to get the best germination. And it needs good seed-to-soil . So first remove all rocks and debris, then level and smooth the soil with a broom rake. Then drag the rake (tines up) to create ‘furrows.’

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 spread the fertilizer into the furrows. Don’t overdo it.

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.

To avoid applying too much seed, pour the seed and fertilizer/bulking agent (Milorganite is one brand), in a 4:1 ratio, in a plastic bucket and mix it thoroughly.

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, your local extension service to get planting advice from a turf expert.

Load the seed into a spreader and apply it. Make sure it doesn’t fly into nearby gardens. 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. To get good seed-to-soil , compact the soil with a rented sod roller filled halfway with water.

Note: Learn how to use a spreader to fertilizer and reseed your lawn, here.

Cover the soil with compost mulch to retain water during germination. Or apply a ‘grass seed accelerator’ (one brand is GreenView, greenviewfertilizer.com). Set the spreader to the widest setting and walk quickly to get a light application of the pellets. The accelerator absorbs more moisture than either mulch or hay and then slowly releases it. It also degrades naturally, eliminating cleanup.

Water the new lawn generously right after the mulch application, but stop as soon as you see puddles forming. One way to get even watering is to 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. Keep the soil moist to a depth of 4 to 6 in. for best germination. Water regularly as the seedlings appear and grow. Gradually reduce the watering over a six-week period. Then switch to your normal watering routine.

‘Most people overwater new seed. Just keep the soil damp for the best germination.’

Bob Mugaas, Turf Expert

Mow the new lawn once it reaches a height of 3 in. Use a newly sharpened blade?it’s healthiest for the grass because it’ll make sharp, clean-slicing cuts. Cut just 1/2 in. per mowing. Always 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, here.

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.