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Is your lawn looking a little the worse for wear this spring? Thin, brown, bare spots, and too many weeds? If so, it’s time to overseed.

What is Overseeding?

Very simply, overseeding is the practice of spreading grass seed over an existing lawn. Overseeding is done to replace worn-out grass with new, healthy grass. For warm-season grasses, this is done in the spring, and for cool-season grasses fall is the best time. Cool-season grasses can also be successfully overseeded in the spring if done early enough to give seedlings the time to mature before the summer heat.

Warm-Season Grasses

Warm-season grasses are mainly found in the southern United States and should be planted in the spring so they can grow during the hot summer months. They prefer temperatures between 80 and 95°F. and are ideal for areas with water restrictions because they require just a fraction of the water needed by cool-season grasses. In colder temperatures, warm-season grasses go dormant and turn brown.

Warm-season grasses popular in the Central Texas and Austin areas include Bermuda grass, buffalo grass, St. Augustine grass, centipede grass, and zoysia grass.

Some warm-season grasses, such as Bermuda, buffalo, St. Augustine, and zoysia can also be found in north Texas.

Cool-Season Grasses

Cool-season grasses are the dominant type in the northern United States.

They should be planted in the fall and spring, and they grow best in temperature ranges between 60 and 75°F. In the summer heat, cool-season grasses can go dormant and turn brown if water is scarce.

Cool-season grasses popular in Texas include Kentucky bluegrass, ryegrass, tall fescue, and Texas bluegrass.

Correct Existing Lawn Problems First

If you suspect lawn problems beyond normal thinning, test your soil and make corrections before overseeding. Use the test recommendations to amend the soil and repair any bare spots.

How to Overseed Your Lawn

Plan Weed Control

If you want to apply weed control and prevention products on your lawn first, check the packaging guidelines for waiting times before overseeding. With some pre-emergent herbicides, you’ll have to wait months and will need to plan accordingly.

Mow the Lawn

Mow the lawn shorter than usual and bag the clippings.

Check Thatch Buildup

Check the amount of thatch buildup on the lawn. Thatch is the layer of dead grass and organic material on top of the soil. A certain amount is normal and beneficial but having more than 1/2 inch is harmful to your lawn’s health. Too much thatch can also interfere with overseeding because grass seeds need contact with the soil to germinate.

If the thatch layer is about 1/2-inch-thick, and it’s pretty easy to push your finger through, then aerating the lawn should be enough to break it up. 

However, if the layer of thatch is really thick, and tough to get your finger through, you’ll have to dethatch your lawn. Dethatch using a dethatching rake, a bow rake, or a rental power dethatcher. Remove the loosened thatch from the lawn.

Aerate the Soil

Next, aerate the soil. Aerating breaks up compacted soil, as well as thinner thatch layers, and helps water, air, and nutrients reach grass roots so they can grow deeper. It also allows the seeds to settle into the soil, giving them a good start.

Both manual and power aerators are available. Covering a large area with a manual aerator (which you can buy) will take a while, so renting a power aerator might be your better choice.

Flag any obstacles on your lawn, such as sprinkler heads, and underground lines, to avoid damaging them.

Aeration is easier when the soil is moist from a previous day’s irrigation or rainfall. If the soil is too dry, the aerator tubes can’t penetrate as deeply. If the soil is overly wet, wait a few days to prevent the aerator tubes from getting clogged with wet soil.

With aeration, you want to end up with holes spaced about 3 to 4 inches apart, so go over the lawn a couple of times in different directions. The soil cores left on the lawn’s surface will break down naturally after a few weeks.

Choose the Right Seed

Overseed with exactly the same seed type as your existing lawn. Mixing two grass types might fill out your lawn, but it will result in different colors and textures and may not be the result you were hoping for.

More importantly, the two grass types might have widely incompatible watering, fertilizing, and sunlight requirements, as well as heat and cold tolerances. They’ll compete with each other, with only one type doing well.

Spread the Grass Seed

Use broadcast rotary or drop spreaders for large lawns, and handheld spreaders for small lawns to apply the grass seed. Check the grass seed package for the recommended application rate and spreader setting.

After sowing the seed, go over the lawn lightly with a rake to help the seed settle in.

Water Thoroughly

Never let the seeds completely dry out. You may have to water several times a day until the seedlings are about 2 inches high. Follow the grass manufacturer’s instructions for fertilizing and mowing. Make sure any fertilizer is appropriate for new grass.

Overseeding with Water Restrictions

Water restrictions pose a problem for overseeding. However, some homeowners have done it successfully by sowing the seed the day before their designated irrigation watering day. On the sowing day they use a hose-end sprinkler, and the following day they run their irrigation system.

The seed was slower to germinate, but the homeowners were pleased with the result.

The pros at South Austin Irrigation do not perform overseeding services, but are happy to provide many different irrigation systems repair services.  Call us at (512) 534-7449 for fast and reliable service.