Overseeding – the one activity we do a lot in the fall to fill in the bare spots and choke out weeds. The standard procedure usually starts with aerating and probably dethatching, but when you don’t want to do these, how do you overseed a lawn without aerating?
To overseed a lawn without aerating, start by mowing it lower than 2 inches and follow it up with raking to remove debris and loosen up the topsoil. Spread the grass seed and then rake over it gently. Fertilize with a starter fertilizer and then water the lawn lightly until the grass grows to a good mowing height.
Recommended Fertilizer: Use the Lawnify Lawn Starter Fertilizer Box
Do you need to aerate before overseeding?
It is not a must that you aerate your lawn before overseeding. However, since aeration loosens up compacted soil, improving the supply of oxygen, and provides nutrients and minerals to the new grass seed, it will improve germination and growth rates and help the grass grow thicker faster.
New grass will grow healthy and dense if the roots develop properly. It is important to make sure the soil is loose enough so that after germination, the roots can grow deeper for better water and nutrient access.
This is why aeration is important especially in lawns with soils that compact easily, such as clay soil. If you have this type of soil, it would be a great idea to aerate first before overseeding.
Can you just sprinkle grass seed on the lawn?
It is possible to just sprinkle grass seed on your lawn and leave it but the germination rate may be low because of the reduced contact between the seed and soil. This is true for lawns with a lot of debris and thatch. You can rake the bare spots before sprinkling grass seed to improve the germination rate.
If you’re overseeding a lawn that has a lot of mulch or grass clippings left behind every time you mow, you may want to rake the dead patches of grass off the areas and spread grass seed over visible soil.
Add top soil to prevent birds from eating the grass seeds and allow them to germinate properly.
How to Overseed a Lawn Without Aerating
Overseeding is a great way of making your lawn grow thick and full. It is even a much better remedy if your lawn has bare spots due to damage from pests such as grubs and chinch bugs. But to get rid of the insects first, use a systemic insecticide labeled to treat them before overseeding so that they don’t eat the new grass as well.
Lawn diseases, drought, and even mole damage can leave you with the need to overseed.
But don’t get it twisted – a lawn growing on sandy soil may not need much aerating as much as a turf on clay soil would. So, consider checking for compaction first.
That said, here’s how to overseed your lawn without aerating first:
1. Mow the lawn lower than 2 inches
The first thing to do when overseeding without aerating is to mow the grass. Cut the grass lower than you usually do. The rule of thumb here is to mow lower than 2 inches, preferably as low as 1-1/2 inches.
- Mowing short before overseeding prevents weeds and established grass from competing with new seedlings.
- It also allows sunlight to reach the soil for the much needed warmth for germination.
- Mowing also prevents grass seed wastage (seeds may lodge in the tall grass).
Pro tip: For this type of mowing, ensure that you use a grass catcher to bag the clippings. You don’t want to mulch the lawn because it will prevent grass seed from being in contact with soil for proper germination.
Depending on the turfgrass you have, you may want to cut the grass much lower than that. This is true for dense and tall grasses such as Bermuda grass which can form a very dense canopy.
The reason for mowing low is to make sure as much of the grass seed as possible gets into contact with soil. In addition, mowing low makes sure the grass gets enough sunlight for growth soon after germination.
Some grass types such as Bermuda grass require full sunlight all day for optimal growth. Therefore, do not be afraid to mow low just before overseeding, but be careful not to scalp the lawn.
2. Rake to remove thatch and loosen soil
Germination can be poor in lawns with a thick layer of thatch. That is why it is important to power rake instead of aerating just before overseeding. Power rake the lawn to remove the tight layer of roots, stems, and rhizomes that build on the surface.
Dethatching is better for overseeding compared to aerating the lawn too many times.
According to the University of Nebraska Cooperative Extension, “It is important to have less than 1/4 inch of thatch when overseeding. If thatch is 3/4 inch or more…,” you may need to power-rake it before you reseed.
To provide an excellent seed germination environment when overseeding without aerating, the soil must be exposed. Hard raking to remove thatch after mowing low will help loosen up the topsoil, making it great for grass seed to germinate upon. Loose topsoil also draws water easily to keep the seed moist for germination.
Pro tip: Power raking damages a lawn to some extent. Ensure that you power rake early in the season to leave enough time for your grass to recover for the rest of the season.
3. Spread the grass seed
The next step is to spread the grass seed over the prepared turf following the label recommendations. Spreading rates vary with the variety of grass you are overseeding with.
You can use a drop spreader or a broadcast spreader to overseed as both will get you great coverage. However, how much seed you want to put down will depend on how thick or thin your lawn is.
If you want to make your lawn thick faster, you may want to spread much more seed almost as if you were establishing a new lawn. Otherwise, you should follow the label recommendations especially for overseeding even though you’re doing it without aeration.
Here are great tips for overseeding your lawn without aerating:
- Make sure there’s good good seed-to-soil contact.
- For the best coverage, spread the seed in opposite directions using a drop spreader.
- Seed at the label’s recommended rate.
- If you don’t have a good spreader, mix your seed with sand and spread it with your hand especially if your lawn is small.
Here’s a guideline on the standard grass seed rate for cool season and warm season grasses:
Avoid adding sand or top soil after overseeding your lawn. Topdressing is not recommended after overseeding because it buries the seed deep leading to poor germination.
4. Rake gently over the overseeded area
After putting down the grass seed, gently rake over the soil to help the seeds settle in. This will prevent the seeds being eaten by birds and also being washed away as soon as you start watering the area.
Be careful not to overdo this step because you can end up crowding the grass seed in one area and leaving the rest of the lawn without any seed. I would recommend you rake toward all directions as opposed to one direction.
5. Fertilize the overseeded area
It is best to fertilize with a fertilizer with adequate phosphorus to help with root development when the grass germinates. Most good starter fertilizers are 10-10-10 N-P-K formulations such as the Lawnify New Lawn Starter Box.
Avoid using weed and feed fertilizers when planting grass seed because some of the pre-emergent herbicides found in such products can inhibit germination or root development of the new grass seeds.
In most cases, you’ll need to apply 1 lb of nitrogen per 1000 square feet when overseeding even without aerating. However, always check the fertilizer label and follow the application instructions.
6. Water the lawn
Water lightly to prevent eroding the seeds away from the overseeded area. Keep the soil moist and not too wet and maintain it at that especially if you did lay down some compost before overseeding. Some compost can be too hot for newly germinated plants and that is why watering adequately is important.
Water two times a day to maintain great moisture levels for better germination. This method is preferred to one session of heavy watering which can wash away the grass seed.
When watering, you want to avoid water puddles because they can damage the overseeded areas. I prefer using an oscillating sprinkler for even watering without eroding the soil.
It might take about 2-3 weeks before all the grass seed germinates. During this time, maintain good soil moisture levels to ensure you get maximum germination rates from the grass you put down.
How Long to Wait Before Mowing an Overseeded Lawn
After overseeding your lawn, you should wait long enough before you start mowing again to prevent causing stress on the newly germinated grass. Since you’ve been watering the lawn a lot, you’ll end up tearing up the new grass easily if you mow too soon before the roots take hold.
Also, mowing when the grass is wet due to the heavy watering can easily cause lawn diseases such as fungus or brown patch disease and derail the growth of your overseeded lawn.
When to mow after overseeding will depend on the grass type. If it is perennial ryegrass, you might want to mow after 10-14 days because this variety of turfgrass grows a lot faster than most other species.
You might want to wait a little longer (probably 20 days or so) if you overseeded with bluegrass because this grass establishes and grows slowly to reach the recommended height for mowing.
While you wait before the grass seed establishes, you can cut the grass to allow the seeds access to sunlight. However, as soon as you see the seeds start to come up, stop mowing and allow them time to grow to a good height.
Sources and references
- University of Nebraska Cooperative Extension, County of Lancaster: Overseeding Cool-Season Lawns
- Colorado State University Extension: Renovating the Home Lawn – 7.241
Hi, Alex Kuritz here. Growing up I remember that my family had one of the best lawns in the neighborhood. Richly green and lush. I did a lot as I grew up in terms of caring and tending for not only my family’s lawn but also my neighbors. I can say I have years of experience, and I am here to share it with you.