To maintain a healthy lawn, you should keep thatch to a minimum through dethatching. Dethatching involves slicing through the grass and getting rid of dense thatch to free the grass for better growth. It can be done alongside other lawn maintenance activities too.

You do not need to overseed after dethatching, but it is recommended if your lawn has bare patches. After dethatching and aerating, your soil will loosen enough to allow the seed for germination. Water, oxygen and other nutrients will also easily be absorbed to support new growth.

Do I Need to Overseed After Dethatching

Yes, you should aerate your lawn before overseeding. It is likely that the layer of thatch you just removed had blocked water and made the soil compact. At the same time, there is likely to be little space between the remaining grass to allow the seeds, water, and nutrients to seep through.

Aerating involves using a special machine with sharp tines that punch small holes into the soil to loosen it. It is normally done when the soil has become too compacted and blocks water and other vital nutrients from getting to the soil.

Compacted soil will also prevent grass shoots from breaking out thus preventing new growth even with frequent watering. By aerating, you will also make it easier to overseed as the new seed and fertilizer will have enough space to settle into the soil and germinate.

Can I Overseed Without Dethatching?

It wouldn’t be practical to overseed without dethatching first unless there is no thatch to remove in the first place due to sparse coverage. The decision to overseed with or without dethatching and aerating first comes down to the condition of your lawn.

It is not a good idea to overseed if the thatch is more than half an inch thick because the seed will not reach the soil to germinate. Thatch usually occupies the space between the base of existing grass and the soil. Overseeding if the layer is too thick therefore means that your seed has no way of settling into the soil. At the same time, fertilizer and water will not also get through the thick layer of thatch.

If, however, you have a thin layer of thatch on your lawn, then you can follow these steps to prepare your lawn for overseeding:

  1. Mow very low than normal and make sure you rake the grass clippings away
  2. If the soil is too compacted, you can loosen it with a normal rake or aerator. You could also choose to spread a thin layer of soil over the freshly mowed lawn.
  3. Water the freshly mowed and de-compacted lawn for at least a day or two.
  4. Apply fertilizer and spread your seed. Choose grass seed that is of the same type as what you have on your lawn for the best results and uniformity.
  5. Keep on watering and adding fertilizer over the next several weeks to help the new grass germinate.

Note: Choose the right time of year to overseed so that your seed can germinate and grow healthy. In most cases, the growing season starts in the late fall and early spring for most grass varieties. You can seek advice from a professional if unsure about the time of year and how to go about choosing the seed and fertilizer when overseeding. Overseeding can rejuvenate an otherwise, old or dying lawn and give it a new lease of life.

Why Overseed After Dethatching?

Under what circumstances or conditions or circumstances should you overseed after dethatching?

To Increase Grass Density

If you were not comfortable with the density of the grass on your lawn even before dethatching, then overseeding immediately after loosening the soil and creating space for seed is a great option. This way you will have more grass germinating on your lawn as the growing season advances.

Too much thatch left unattended for long periods kills young grass leading to grass thinning. In this case, you may want to replenish the lawn with new grass immediately after dethatching. Make sure you plant the same grass as what you already have on the lawn if you are overseeding over old grass for uniformity.

To Clear Dry or Empty Patches

It’s not uncommon to find empty or dry patches on a lawn that has been left unattended for too long and needed to be dethatched. If this is the case, then you may want to overseed over the dry patches after dethatching just to make sure the new grass grows at the same time soon after for a better-looking lawn.

Replacing Aged/Thinned Grass

Yes, grass does indeed, get old and need to be replanted at some point especially if not properly maintained through regular mowing and aeration. If you notice that you don’t have much grass left after dethatching, then it might be a good idea to plant new grass by overseeding after you are done dethatching.

To Correct Dethatching Flaws

Sometimes you or the person you hired to dethatch may set the machine to the wrong frequency and slicing depth thus destroying your grass. Don’t worry, you can correct this by overseeding immediately after dethatching. If you hired a professional, you could even have them offer a discount for this additional service or bear the costs.

To Restore A Neglected/Dead Lawn

Dethatching, then aerating, and overseeding is the formula when it comes to restoring a neglected or dead lawn. A neglected or dead lawn will have a thick layer of thatch and compacted soil with little to no healthy grass to speak of. We are talking about a lawn that has not been mowed or watered for more than two years.

Start by removing the thick layer of thatch so that the aerator can reach the soil and loosen it. You will probably have little to no healthy grass left after this and should therefore overseed. Follow with frequent watering and mulching or spraying fertilizer and you will have a beautiful lawn in a month or so.

Is Aeration Necessary Before Overseeding?

You can choose to aerate or not to aerate your lawn depending on the condition of your lawn and the type of soil you have. Aeration before overseeding is only required in the following conditions:

Aerate First If You Have Dense Grass

Dense grass will not allow the new seed and fertilizer to reach the soil for germination and growth. By aerating, you will give the seed enough space to settle into the soil. Some species of grass tend to grow dense and packed together, therefore, requiring aeration before overseeding. For instance, centipede grass grows horizontally across the soil forming a dense turf.

Aerate First If You Have Compacted Soil

It is normal for lawn soil to compact over time as it remains covered by thatch and grass and does not take in much water. This is especially a problem you might experience If you have thick clay soil in your yard. You will need to aerate first so that the soil is loose enough for the seed and fertilizer to settle in. As mentioned earlier, you can also spread a thin layer of enriched soil on top of the grass before overseeding.

Aerate First If You Just Dethatched

Chances are that the soil below removed thatch has poor water and nutrient concentration. In this case, dethatching should be followed by aeration, watering, and soil improvement using fertilizer before overseeding for the best results.

Is Aeration Necessary Before Overseeding aeration of the lawn

How Can I Tell If I Need to Dethatch?

There are several ways to tell if you need to dethatch your lawn. In most cases, you can tell just by looking at your lawn that there is too much thatch and dead plant material. Here are some of the ways to tell if you need to dethatch:

Dense Dead Plant Material on Your Lawn

If there is a lot of dead plant material beneath or across the surface of your lawn, then it means you may have a thatch problem. You can rake the dead plant material with a normal rake if it’s lying on the surface. However, dead plant material below healthy grass cover requires a power rake or dethatching machine.

Thick Thatch Layer Beneath the Grass

Thatch is essentially a mixture of old or mature grass, dead plants, and other foreign materials lying beneath healthy grass. Over time, the thatch will accumulate and become problematic if it is over an inch thick. You can dig out a section of your grass and see if the thatch layer is above the safe thickness to be certain if you need to dethatch.

Waterlogging/Poor Drainage

Too much thatch acts as a solid barrier beneath grass preventing water from being absorbed into the soil. Over longer periods, the thatch will also cause the soil to become compact and cause water logging or poor drainage in the rainy seasons or after irrigation. This is a sign that you need to dethatch your lawn.

Insects and Pests

An increase in insects and pests hiding inside your lawn is a sign that your grass has grown too tall or has too much thatch that needs to be removed. A thick thatch layer below the surface has the ideal temperatures and conditions for pests and insects such as mosquitoes to breed and hide.

FAQ’s

Most lawn care, gardening, and landscaping companies offer overseeding service. Make sure the company you choose has listed overseeding as one of the services they offer. They should have good ratings and reviews from previous clients for the same service.

Hydroseeding can work better if you are planting a new lawn as opposed to planting over existing grass. The hydroseed slurry will cover existing grass which may not be ideal. The term overseeding means spreading seed over an existing lawn to rejuvenate it.

You will know that you need to overseed if the grass on your lawn has thinned out or dry. You can also overseed to get rid of ugly dead patches on sections of your lawn.

In most places, overseeding should be done in the early stages of spring or late fall when soil conditions and weather is ideal for germination and growth.

Timothy Munene
Author: Timothy Munene - Timothy is a freelance writer and an online entrepreneur.