When to Reseed Your Lawn

Patchy Lawn

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We all have observed that one home in the neighborhood with a lawn that consistently looks like rich, green carpet. How do they do it? Chances are your neighbor happens to have ideal soil and growing conditions. But, even in the best environment, a turfgrass lawn is an ongoing project that requires consistent maintenance. Knowing the best times of year to reseed can make a difference.

Your growing zone and the type of turfgrass that makes up your lawn determine when to reseed with good results. Summertime high temperatures and humidity, potential drought, and increased traffic all are damaging to turfgrasses. A number of diseases as well as insect activity cause unsightly brown and dead spots and open these areas up to encroaching weeds. To a lesser extent, freezing temperatures can damage and kill off grass that has not established a strong root system and this results in the same dead spots in the lawn.

The standard for a good looking lawn is uniformity in texture, color, height, and density, so reseeding areas of thin or bare turf is an important and necessary task for lawn maintenance. Reseeding is an investment of time and money so you want to choose the right time for the best chance of success.

Signs That You Need to Reseed Your Lawn

The first step before reseeding is to determine what is causing the decline of your lawn and take steps to correct the problem beforehand. When proper treatment is applied, the turf will often repair itself by fall. If bare, brown and weedy spots persist, reseeding will eventually improve the health and look of the lawn.

Tip

Reseeding is often referred to as overseeding. Both refer to sowing grass seed in an existing lawn to thicken the lawn or repair bare spots. However, if your turf is more than 50 percent weeds and bare spots, it may be necessary to start from scratch and redo the entire lawn.

Insect Damage

  • White grubs feed on root systems depriving individual blades of grass of moisture. Large dead patches up to 20 feet in diameter appear in late August to November.
  • Chinch bugs suck the moisture from grasses leaving scattered patches of yellow or brown across the lawn.
  • Billbugs lay eggs within the stems of cool season grasses. Larvae feed in the stems and on the plant crown leaving sawdust-like frass. Damage appears as scattered yellow patches.
  • Sod webworms are moths that lay eggs in the lawn. Larvae feed on the blades at night leaving small ragged brown spots that appear grazed or cut.

Turf Diseases

  • Brown patch affects mostly cool season grasses and occurs during hot weather. Look for circular dead or brown spots a few inches to several feet in diameter. When wet, the blades may appear covered with cobwebs.
  • Summer patch appears as small (2 to 6 inches) scattered light green patches and is prevalent along walkways and driveways. The patches fade to tan and then to a light straw color.
  • Dry spot manifests as patches of brown or dying grass 2 to 4 inches in diameter. It continues to spread in a circular pattern.
  • Necrotic ring spot shows up as circular or donut-shaped rings that spread through spores and can overtake a lawn.

Encroaching Weeds

The best approach for controlling weedy growth is to plant the right turfgrass for your area and to establish a regular maintenance schedule. However, a few weeds almost always manage to creep in. Make a note of the following types to determine if they can be controlled without damaging grass or if you first need to eliminate the problem and reseed.

  • Broadleaf weeds include dandelion, plantain, chickweed, ground, ivy, henbit, white clover, spurge and knotweed.
  • Grassy weeds can be annual or perennial. Crabgrass and foxtail die off in the fall but perennial weeds, which include tall fescue clumps, nimblewill and bermudagrass, should be eliminated and affected areas reseeded.

Why You Should Reseed Your Lawn

Weeds are opportunistic. They often grow rapidly and spread seed easily. When a turfgrass lawn develops thin, brown, discolored or bare patches, weeds will move in unless new grass is grown to fill in the area.

Weeds compete with grass for moisture and nutrients and must first be eliminated before reseeding. It is important to identify the underlying cause killing the grass and apply the correct treatment before attempting to regrow grass in the affected areas.

Combination Lawns

Warm season grasses practical for southern lawns can die off or turn brown during the cooler weather months. To keep it green year round, you can seed cool season grasses in the fall.

Shade Lawns

Shaded areas can be a particular challenge. Although specialized seed is available the success rate remains variable. If you manage to get turfgrass to grow, it will likely be thin, so mow high and infrequently. Alternative ideas for those difficult areas under trees or on the north side of your home include the following:

  1. Apply an attractive layer of natural mulch and plant shade loving plants or ground covers.
  2. Grow a moss lawn. Moss will grow naturally in cool, shaded areas and can be developed into a uniform, green ground cover.

Best Times to Reseed Your Lawn

For best results, reseed your lawn when temperature and moisture levels are optimal and weed competition is low.

  • Reseed grasses when temperatures begin to moderate. The ideal temperature for germination is between 50 and 60 degrees Fahrenheit. For most growing zones, this includes early spring from mid-February to mid-April and late summer from mid-August to the end of September.
  • Adequate moisture in the soil is important for germination and and root development. Spring and early fall usually bring ample rainfall, however if drought conditions persist into September, it's better to wait until later in fall to reseed.
  • When crabgrass is an ongoing problem, wait until it dies back in late summer before reseeding. This helps identify bare areas that need attention.
Article Sources
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  1. https://hort.extension.wisc.edu/2021/09/15/over-seeding-lawn-in-autumn/

  2. https://extension.uga.edu/programs-services/landscape-pest-management/pests-turfgrass/sod-webworms.html

  3. https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/diseases/fungal-spots/necrotic-ringspot.aspx