How and When to Reseed or Overseed Your Lawn

Maintain a healthy lawn by reseeding at the right time of year and with the right type of grass, depending on the region in which you live.

Grass seed is divided into two broad categories: cold-weather region and warm-weather region. Cold weather regions, or northern regions, are subject to deep freezes and heavy snowfall throughout the winter months. In warm weather regions, or the south and southwest, extreme summer heat and temperate winters prevail.

Reseeding, or over-seeding makes your lawn more resistant to disease, pests, and drought conditions. The region in which you live determines the best time of year to reseed your lawn, and which types of grass you use for your lawn throughout the year.

Before adding seed to your lawn, however, you need to prepare the area.

Preparation

Kill any weeds in the lawn, making sure you remove the roots. Mow the lawn to approximately 1-inch in height; either trap the grass clippings and dispose of them or rake them up after mowing.

Use a metal tine rake to remove the loose thatch (dead grass and weed debris) lying on the surface of the soil. Removing the loose thatch exposes the soil surface so the seed is better able to germinate.

Use an aerator to loosen the soil surface, and then add fertilizer to the soil, following the manufacturer’s instructions.

Northern Regions

Commonly, September is the optimal month for reseeding your lawn if you live in a northern region. It’s necessary, though, to reseed several weeks before the first frost.

Learn the average date of the first frost in your area, and plan to reseed approximately eight weeks before that date. A rule of thumb is when daytime temperatures average between 70 and 75 degrees Fahrenheit and nighttime temperatures don’t dip below 50 degrees, it’s time to reseed the lawn.

According to the University of Idaho Extension Service, Kentucky bluegrass is the most commonly used grass in the United States, and it’s primarily used in the northern regions. A hardy perennial, Kentucky bluegrass is resistant to pests and drought, but it is slow to germinate.

Add a small amount, of perennial ryegrass to the Kentucky bluegrass seed; approximately 15-to-25 percent of the mix should be ryegrass. The ryegrass germinates more quickly and provides shelter for the newly emerging Kentucky bluegrass.

Another option for northern regions is fescue grass. Use either a mix of fescue and ryegrass or Kentucky bluegrass and fescue. Fescue adds density and is resistant to drought and pests, as well as disease, and may be used in combination with both Kentucky bluegrass and ryegrass.

Southern Regions

Lawns are a year-round element in landscapes throughout the southern regions. Bermuda grass is commonly used because of its high resistance to drought, a frequent problem in the southwestern regions of the United States. A Bermuda grass lawn requires less water and stands up to the high temperatures in southern and southwestern states.

When temperatures drop, though, Bermuda grass goes dormant, leaving the lawn looking brown and bare.

Reseed with a quality ryegrass seed to replace the summer Bermuda grass lawn anytime from mid-September to late October, when daytime temperatures average below 80 degrees but do not drop below 60 degrees.

Ryegrass cannot tolerate the extreme heat in the south and southwest regions and dies back in late spring and early summer. Meanwhile, the dormant Bermuda grass re-emerges when the temperatures warm.

For a healthier and denser summer lawn, you can over-seed with Bermuda grass as the ryegrass dies back. The best month to reseed the Bermuda lawn is from early March to mid-April.

How to Apply Grass Seed

Use a lawn spreader to apply the seed to your prepared lawn; a spreader ensures the seed is distributed evenly throughout the area. Add a portion of the seed to the spreader, taking care not to overfill the dispenser.

Walk in rows, back and forth, lengthwise and then in the cross direction or width-wise, filling the spreader as needed. Walk the perimeter with the lawn spreader when you’ve covered the lawn in both directions.

Use a rake to gently work the seed into the soil. Do not “rake up,” but rather rake across the soil surface in short, back and forth strokes. Add a thin layer of quality topsoil to aid the seeds in germinating.

Water the lawn daily for one week, keeping the soil moist but not wet. Gradually reduce watering to one to two times a week as the seed germinates and the lawn becomes established.