Your Complete Guide to Overseeding a Lawn

If your neighbor's thick, lush lawn has you green with envy, it might be time to perform some routine maintenance on your own landscape. While there are plenty of yard upkeep tasks you should keep on your checklist, one of the most important is overseeding—the process of dispersing seeds throughout your lawn to encourage new growth (if you want to grow a new lawn or fill in a completely bare area, this is called seeding).

This is a maintenance step you should practice whether you're planting new grass or patching up an existing area. The process is simple, but there's a few things to keep in mind before starting, like when to seed and the type to use.

Figure Out Your Grass Type

Before getting started, it's important to understand your grass type, which will determine the best time to seed and the type of seed to use.

Warm-Season Turf

If your grass turns brown in the winter, then you likely have warm-season turf. Common varieties include Bermuda, Zoysia, Centipede, or St. Augustine—all of which respond more favorably to sodding or sprigging opposed to seeding, says Marc Mayer, the regional technical manager at TruGreen.

Cool Season-Turf

However, if you reside anywhere throughout the Midwest or Northeast, where grass remains somewhat green through the winter months, then you're dealing with cool-season iterations, such as Kentucky Bluegrass, Tall Fescue, or Ryegrass.

The Best Time to Overseed Your Lawn

Once you know the type of grass you have, you can more easily determine the best time to apply your seed. Cool-season grasses, which can survive moisture and temperature extremes, are best planted in spring or early fall; they're mostly used in the North. Warm season grasses should be planted in early summer when the soil has warmed up; it's no surprise that they do best in warm weather locales, like the South.

The Right Type of Seed for Your Lawn

For the seed to flourish, it must be a good match with your local growing conditions—there are types of seed dedicated to cool and warm season turf. Additionally, you should consider the amount of sunlight, shade, and wind the area gets, as well as foot traffic and water availability.

Prepare Your Soil

As is the case with many yard or gardening projects, you'll need to ensure your soil is in good condition in order to help what's growing in it thrive.

Do a Soil Test

If the soil is too acidic or alkaline, which is measured on a pH scale, grass will have a tough time growing. Have a sample of your soil tested at a local extension service. Ideally, your soil will have a pH between 6.0 and 7.5.

Break Up Soil

You want the soil to be in as good a condition as possible so that the seeds will germinate, so remove any large rocks, roots, or debris that you see with a sharp shovel; remove any existing grass with a sod cutter. Turn soil with a rotary tiller to break up compacted clumps. Soil should consist of pea-sized particles for best results. Use a rake to gently even out the surface.

How to Overseed Your Lawn

Laying down the grass seed is most commonly done by overseeding—the process of adding new grass seed to existing turf. "Many grass types lose density over time and require periodic overseeding," says Marc Mayer, the regional technical manager at TruGreen.

Prepare Your Lawn

Once you've determined your seed type, it's time to prepare your lawn for germination. First, inspect your lawn for clumps of dead grass material, also known as thatch, as this will help ensure good contact of seed with soil.

Next, mow your grass to the shortest height your mower will allow, bag the clippings, and then rake your lawn to remove any leftover debris and loosen the top layer of soil. Then apply your seed.

Apply the Seed

The process of overseeding is relatively straightforward. Kurt Morrell, the A.P. farm associate vice president for landscape operations at the New York Botanical Garden, says it's typically accomplished with a seeding machine that a homeowner can rent from local garden centers. "If it is not possible to use an over-seeding machine, it is always best to prepare a proper seedbed and cover the seed with soil by raking the seed in," Morrell says. "Cover with salt hay, which does not include weed seeds."

Water Generously

According to Mayer, watering is one of the most important aspects of successful overseeding. After applying seed, a heavy watering is in order, after which a daily watering should be performed until seeds germinate, which can take up to two weeks.

Once germination has occurred, continue to water thoroughly every few days. "Once the grass seed germinates, do not let the top half inch of soil become dry otherwise the turf plant could be killed," says Morrell. Mayer adds that it's also important to avoid heavy activity, such as mowing, on the delicate area.

Overseed Annually

Luckily, overseeding isn't something you need to do daily, weekly, or monthly like some other yard maintenance tasks—just once per year will do the trick. "Annual overseeding is recommended to thicken lawns and make them more attractive, but also to introduce improved varieties of grass that are hardier, less prone to insects and diseases, and more drought tolerant," says Mayer.