If you have an area of land or a lawn with patches and clumps of moss, you may prefer to replace it with grass.

But simply putting down grass seed doesn’t always work.

Can I Put Grass Seed Down Over Moss?

Moss being raked off of grass

Ideally, you should rake the moss away and treat the soil to make it less acidic, and raise the pH before you put down grass seed.

Grass seed usually needs to make contact with soil before it germinates so laying it directly on top of moss may not work.

Also, growing conditions that are ideal for moss are often too wet, acidic, and light-deprived for grass to flourish.

Whether or not the seed will grow depends on the conditions of the environment where the moss was growing.

You can put grass seed down over moss, but whether or not the grass will sprout and survive depends greatly on the conditions of the growth area, including moisture, shade, and soil composition.

Grass and moss are both survivors but they largely thrive in different conditions, so if the environment favors one over the other, one of them might wind up dominating that portion of ground in the end.

If you put grass seed down over moss in an environment that favors moss, the grass may not survive.

But the opposite is also true; if you put grass seed down where there was moss, but it’s in an environment that favors grass, the grass seed has every chance of sprouting and thriving.

Understanding The Different Environments That Moss And Grass Thrive In

To have an idea as to whether the grass will win over moss, It’s important to first understand the differing requirements of moss and grass.

Also Read: Will Grass Grow In Sand?

Ideal Growing Conditions For Moss

Moss is a category of small, non-flowering plants that generally grows on the ground or at the base of trees.

Although moss comes in many varieties, most types have similar requirements for growth and survival.

The three main components necessary for moss growth, generally, are:

  • Moisture.
  • Shade.
  • Acidic soil.

Moss Likes Wet Conditions

It tends to grow in areas with an abundance of water in the soil, or in persistently rainy and damp regions.

It’s common to see moss appear after a flood or heavy rain when the ground is saturated and there are bare patches of ground with no other plants (not the best conditions for grass).

Moss can survive dry periods once it takes root but thrives better in soggy conditions.

It also commonly grows on tree trunks – again, the damper the better.

Although there are moss varieties that can tolerate long periods of direct sunlight, most are typically found in areas that have a lot of shade.

Heavily wooded areas with thick canopies of tall trees blocking the sun are often replete with moss.

In sunnier areas, moss can often be seen growing only on the shady side of tree trunks.

Moss Likes Acidity

It likes to grow in soil with a very high level of acidity (around 5.0 pH – 5.5 pH).

In fact, moss may even grow in areas where it might normally be too sunny for moss simply because the soil has the perfect pH.

Wooded areas where moss thrives tend to have high-pH soils due to dead plant matter on the ground decomposing into acids.

So how do these factors affect grass?

Ideal Growing Conditions For Grass

Grass Doesn’t Like To Be Soggy

Like moss (and most plants), grass needs plenty of water to live.

But where moss loves wet, saturated ground, too much water in the soil can actually suffocate the grass or make it prone to water-borne diseases.

Lawn care tips frequently warn not to “over-water” grass, but moss does not share the same concern.

Grass Needs Sunlight

Similarly, while moss does best when shaded from the sun, grass typically requires at least a couple of hours of sunlight daily.

Grass needs a higher pH in the soil (i.e. more alkaline) than moss does.

A good pH target for growing grass is 6 pH – 7 pH.

How To Put Grass Seed Down Over Moss

Based on these competing conditions it may be possible, with some effort, to tilt the playing field in favor of grass.

Watch For Excess Water

To prevent over-saturated soil that moss loves but which chokes grass, check the area for drainage issues.

There may be a consistent source of excess water that can be diverted away from your desired growth area using small retaining walls or irrigation channels.

Also, be sure you are not over-watering the area.

Check For Adequate Sunlight

Your newly seeded grass will need sun.

With moss already on the ground, there’s likely too much shade.

Look for ways to increase direct sunlight.

If possible, prune back tree branches or clear any other obstructions that are blocking the sun.

Check The pH

A pH testing kit can be obtained from lawn and garden retailers to assess the acidity of the soil.

If the soil pH is more conducive to moss growth, you can apply lime to make the soil more alkaline.

This process must be done carefully, though.

If the pH is made too high then neither the moss nor the grass can survive.

How To Plant Grass On Your Lawn When Moss Is Dominant?

Moss typically begins to take over when the soil is acidic or your lawn is getting too much shade.

Neither of these conditions is ideal for the growth of a lush, healthy lawn.

Grass Needs Light

If there’s nothing you can do about the heavy shade being cast on your lawn (i.e. your lawn is heavily shaded due to surrounding buildings), you might want to consider some grass alternatives, perhaps gravel or paving stones.

While some types of grass can put up with a little shade, you might struggle to find ones that do okay in heavy or total shade.

Most Grasses Prefer Lower pH Levels

You can do a pH test and If the soil is acidic, you can apply some lime, which will make the pH level more favorable for grass and also kill the moss in the process.

In fact, it’s not necessary to apply any chemical to kill the moss.

A good raking will get the job done.

Remove The Moss And Dead Material

The lawn should be thoroughly raked to remove dead moss from the surface.

To germinate, grass seed will need to be in direct contact with the soil and won’t sprout on top of dead moss.

Put Down Grass Seed

At this point, you can overseed.

Tilling shouldn’t be necessary but you might want to use about 3/4 of an inch of quality soil to provide a seedbed and level out the bumps on your lawn.

Once you’ve spread your new grass seedlings, you’ll need to provide them the essential nutrients they’ll need to grow fast.

Water And Fertilize

Apply a starter food/fertilizer of your choice for new grass and lightly water one or two times per day to help keep the soil consistently moist until your new grass seed begins to flourish.

Once your new grass begins flourishing, you can water it deeper and less often to encourage the roots to extend more deeply into the soil.

Final Thoughts

If you’re looking to put grass seed down in dark and damp conditions that favor moss, chances are you’re going to have to improve the soil and environment if you want that grass to grow into a lush lawn.

But as long as the ground is getting enough sunlight in that area, it’s usually not too difficult to treat the soil and improve it enough for grass to flourish.