Is Overseeding Your Lawn Every Year Worth It? What to Know Before You Start

One of the best ways to keep your lawn looking thick and lush is overseeding, the process of spreading new grass seed over your existing turf. But how often should you overseed, and when is the best time to do so? The answer depends on your lawn’s condition, climate, and the type of grass you grow. This guide explains what you need to know about how often to overseed to keep your lawn looking its best.

Why to Overseed Your Lawn

Overseeding is done for different reasons, depending on the climate where you live. Overseeding lawns in northern regions helps create thick, carpet-like turf during the growing season. In areas with warmer winters, overseeding keeps lawns looking green year-round.

Warmer Regions

Homeowners in the South and Southwest—regions where winter temperatures rarely fall below freezing—overseed in fall to keep their lawns looking green through winter when the existing grass goes dormant. A cool-season grass seed is planted in the existing warm-season lawn. This seed will germinate and quickly green up the lawn in late fall when the warm season grass turns brown and goes dormant. Expect the overseeded grass to actively grow through winter, requiring mowing and occasional watering. 

When spring hits and temperatures rise to 80°F and beyond, the warm season grass will begin growing again. The newly flourishing warm season grass will overtake the cool season grass. The cool-season grass will die out completely.

Cooler Regions

If stressors such as lots of foot traffic, extended drought, and construction have left your once-thick lawn thin and patchy, overseeding is a relatively simple solution. Overseeding adds to the existing grass, filling in gaps and reinvigorating the lawn’s appearance. Unlike overseeding in a warm region where a different type of grass is used, overseeding in a northern region involves using the same type of grass as the existing lawn.

How Often to Overseed

To achieve your goal of a thick, green lawn, should you overseed every year or is that a waste of time and money? Here's how to decide how often to overseed your lawn, depending on your region.

Warmer Regions

Lawns in the South and Southwest can be overseeded annually. Without overseeding, these warm-season lawns go dormant and turn brown for a few months in winter before greening up again in spring. Overseeding is a must for a green winter lawn, but it isn’t necessary for the existing turf to thrive. Without overseeding, a warm-season lawn will simply enter dormancy in late fall and then begin regrowing in spring. 

Cooler Regions

In northern regions, overseed lawns when they show signs of wear and tear, when the turf looks thin and patchy. This might be as frequent as every two years or so on lawns that see heavy use. If poor drainage, disease, or lack of nutrients is causing turf to thin, first address these issues before overseeding for the best outcome.

When to Overseed

Wait until the heat of summer passes to overseed in both northern and southern regions. Moderate soil temperatures and more regular soil moisture in late summer and fall make for excellent germination conditions for cool-season grass.

Warmer Regions

Let temperatures in fall determine the best time to overseed. These cues will indicate cooling soil temperatures: night temperatures consistently in the 50s and the average midday temperature is in the 70s. After several days of cool nights and daytime highs in the 70s, the soil will be adequately cool to overseed. This timing generally corresponds to about 4 weeks before the first killing frost date, if frost is common in your area.

Cooler Regions

Overseed in late summer or early fall. The warm soil conditions will spur grass seed to germinate quickly. Aim to overseed at least 4 weeks before the first killing frost in your region to give grass seed time to get established.

Tips for Overseeding Success

Use quality seed. Overseed your lawn with a grass type that is recommended for your area. Consult your local garden center or Extension Office. In southern regions, annual ryegrass is the most popular type of grass for overseeding. Kentucky bluegrass is common in northern regions.

Ensure seed-to-soil contact. Just before overseeding, reduce the mowing height of the existing grass by 25 percent. Let the clippings fall onto the grass; they will contribute to the seedbed for the new seed. Use a core aerator before spreading seeds to boost soil contact. Dense southern lawns might require vertical mowing or light dethatching before overseeding.

Water smart. After overseeding, irrigate 3 to 4 times a day for the first 7 to 10 days or until the seed germinates. Continue watering, never allowing the seedlings to dry out. Gradually reduce watering to about once a week after the seedlings are established.

Wait to mow. Begin mowing overseeded grass when it is about 3 inches tall. For a good, clean cut, be sure the mower blades are sharp and mow when the lawn is thoroughly dry.

Time it right. You can get all the other factors right—quality seed, good seed-to-soil contact, timely watering, regular mowing—but if you don’t get seed down at the right time, the whole project is lost. Right timing is essential.