Peat moss is helpful when overseeding because a top dressing of peat moss protects the grass seed from scavengers. Peat moss also retains water, keeping grass seeds moist and encouraging them to sprout. However, peat moss is acidic and will add acid to your soil, which can be detrimental to long-term grass growth. Not only that, but peat moss use is not sustainable—peat moss is harvested from drained wetlands and does not grow fast enough to replenish what is harvested. Instead of using peat moss, consider a top dressing of compost.
Should You Use Peat Moss When Overseeding?
Peat moss use is a controversial topic. While it provides benefits to new grass seed by keeping it moist and protected, it has its drawbacks. The natural acidity of peat moss and its effect on your soil chemistry should be considered before use. Not only that, but peat moss harvesting represents a danger to the environment.
Pros of Using Peat Moss When Overseeding
Peat moss absorbs water like a sponge and retains moisture for long periods of time. This is a huge benefit when you are overseeding your lawn. Grass seeds must be kept constantly moist in order to sprout. If grass seeds dry out as they germinate, they will die, resulting in a much lower yield from your seeding efforts.
- Peat moss absorbs up to 20 times its dry weight in water. A layer of peat moss over grass seeds keeps the seeds moist and promotes germination.
- A 1/8–1/4 inch thick (3–6 mm) layer of peat moss protects seeds from birds.
- Within weeks, peat moss breaks down into organic matter.
In addition to moisture retention, a thin layer of peat moss spread over your newly seeded lawn protects the grass seed from birds. If grass seed is left uncovered, large quantities of it will be eaten by birds. When you use peat moss as a top dressing, the moss breaks down over the course of a few weeks. This feeds the soil as organic matter. This provides a small number of soil nutrients.
Cons of Using Peat Moss for Overseeding
Peat moss is slightly acidic and releases acids into the soil, so using it for top dressing when overseeding can make your soil less favorable to grass growth long term. However, most peat moss isn’t acidic enough to cause major damage to soil quality. It is important to note that peat moss is very poor in nutrients compared to other overseeding materials, such as compost. Also, unlike compost, peat moss does not contain soil microbes that help feed your lawn.
- Using peat moss can make your soil more acidic, leading to poor grass growth in the long run.
- Peat moss breaks down into a very nutrient-poor fertilizer. There are several natural fertilizers that provide a better boost for grass seedlings.
- There are no helpful soil microbes in peat moss.
- Peat moss harvesting is an unsustainable environmental threat.
The biggest con of using peat moss is the fact that it is harvested using unsustainable, ecosystem-damaging practices. The centuries-old peat moss that is harvested for fertilizer grows extremely slowly, meaning more and more peat bogs have to be drained and harvested. Wetlands known as peat bogs are destroyed in order to feed the peat moss industry. This leads many to avoid using peat moss in their yard and garden.
What are Peat Moss Alternatives for Overseeding?
Instead of peat moss, use compost when overseeding. Compost is created from sustainable fertilizer sources, such as leaves and grass clippings. It can be made organically, without damaging the environment. Even better, it retains moisture to encourage grass seed sprouting, protects seeds from birds, and feeds the soil with a healthy dose of fertilizer and healthy microbes.
- Compost is the ideal substitute for peat moss when overseeding.
- Unlike peat moss, compost is a sustainable resource.
- Compost has better fertilizer properties than peat moss and will not increase soil acidity.
- In most cases, compost is less expensive than peat moss.
Spread 1/8–1/4 inch (3–6 mm) of compost over your lawn, spread your grass seed, then rake the compost to cover the majority of the seeds. This process is just as simple as using peat moss, better for the environment, and get this—compost is cheaper than peat moss.
How to Use Peat Moss When Overseeding
If you decide to use peat moss as a top dressing when overseeding your lawn, the process is very simple. Just follow these steps:
- Mow your yard low, to a height of about 2 inches (5 cm).
- Aerate your lawn using a core aerator.
- Use this broadcast spreader to distribute your grass seed evenly over the yard.
- spread peat moss over the seeded areas in a layer 1/8–1/4 inch (3–6 mm) deep.
- Water immediately after spreading the moss to moisten it.
This process works equally well whether you are using peat moss, compost, or a blend of compost and topsoil.
How Many Square Feet Does a Bag of Peat Moss Cover?
A single 3-cubic-foot bag of peat moss is enough to cover 300 square feet of lawn. Essentially, 1 cubic foot of peat moss will provide top dressing for 100 square feet. When overseeding, most lawn care specialists apply 3–4 bags of peat moss per 1,000 square feet.
- 1 bag containing 3 cubic feet of peat moss is enough to top-dress 300 square feet of lawn.
- Use 3–4 bags of peat moss per 1,000 square feet of seeded lawn.
Keep in mind that peat moss expands once it is removed from the bag. Not only that, but peat moss sponges up water, swelling in size and weight. What may seem like an extremely thin layer of peat moss is usually more than enough. Remember, even a 1/8 inch (3 mm) layer of dry peat moss is enough to cover seeds and provide them with moisture.
Can You Top Dress Soil with Peat Moss When Overseeding?
Peat moss is a traditional soil top dressing for overseeding projects. The reason for this is that that peat moss retains up to 20 times its dry weight in water, providing a constant source of moisture that grass seeds need. This helps your seedlings sprout and survive the initial stages of life. All you need to do to accomplish this is to spread a 1/8–1/4 inch deep layer of peat moss over your lawn after seeding. However, it’s important to keep in mind that compost and compost/topsoil blends are also effective soil top dressings when overseeding and are typically much less expensive than peat moss.