Does Mulch Kill Grass? Will Grass Grow Through Mulch?

Share on:

When it comes to mulching on soil we fall into two different conditions. One is if you want to lay mulch over a soil where you don’t want anything present like you do in case of playground areas and the second case is when you want lush greenary and lay mulch to even help that greenery and plants grow more.

So when you are clearing out your soil that would be the garden or flower bed. Or you wont be clearing out anything and that would be your lawn where grass is growing.

In both conditions, you either want the soil clear or soil loaded with green parts. The green parts I am referring here is grass.

Sometimes people need to get the rid of grass and need mulches to do that and sometimes people want to keep that grass and let their lawn or yard look green as hell.

Thats what I have broke down in this article. You will have a clear idea on how can you use mulch to kill your grass and on the opposite side how can you use mulch to keep your grass growing lush green.

Does Mulch Kill Grass or Not? Both Cases Are Possible

does mulch kill grass, picture showing mulch use to kill grass

There are some frequently asked questions:

Will mulch kill the grass?

Will Grass Grow Through Mulch?

Does Mulch Help Grass Grow?

To address these questions, we must first grasp the concept of mulch that kills the grass and the one that help grass grow.

Mulch is a layer applied to the lawn for the purpose of increasing its effectiveness and health.

Mulch comes in a variety of types, including organic and inorganic mulch which is laid over grass.

So it leaves us to two scenarios:

If you use organic mulch, then grass will grow under mulch and if you use inorganic mulch, it will kill the grass.

How Grass Grow When The Mulch Is Organic?

Organic mulch is obtained from plants and aids in grass development.

Organic mulches are solely used in lawns and yards where you want your area to be lush green.

Organic mulch contains tremendous amount of nutrients that help the grass grow. Grass consumes those nutrients along with water and sunlight and do photosnythsis to prepare it own food and start growing at a good rate.

Side by side the major benefit organic mulch comes with is that, you don’t need to remove it from soil as it decomposes and adds nutrients to soil which is very beneficial.

Leaves and grass mulching is the mulching technique that helps your grass grow in your lawn or yard. Becasue the mulch you produce through grass and leaves is itself organic type.

Major nutrients that organic mulches contains are:

Elements in MulchEffect It Has on Grass Growth
NitrogenBuilding blocks of grass proteins and enzymes which mean it directly affects growth.
PhosphorousIt is vital for all grass for harvesting the sun’s energy and convert it into growth and reproduction.
PotassiumIt is associated with the movement of water, nutrients and carbohydrates in grass tissue.

As a result, grass begin to grow. Mulch, in this way, supplies nutrients that aid in the growth of grass.

Good Mulches That Helps Grass Grow

Down below are the mulches that decomposes over time into the soil and make soil rich with nutrients in other words they help grass grow very much:

1. Leaf Mulch

Dried leaf is an organic resource which helps the grass grow.

2. Manure and Dead Plant Material

Manure means animals debris from poltary farm. And dead plant material means dead leaves, trees shrubs and grass itself. If you spread it over grass it will surely help grass grow. From composition, manure contains beneficial microorganisms and promotes more growth of micorogranicsms in the soil which is very beneficial to the roots of grass and help them grow.

3. Pine Needle Mulch

3 inch thick layer of pine needle mulch help grass grow.

4. Straw Mulch

Straw mulch is best where there is grass and also some shrubs. You can spread it around and rest of ground will be covered with grass. So overall look would be great.

5. Coffee Chafe Mulch

It also let grass grow.

6. Buckwheat Hulls Mulch

It also let grass grow.

7. Peanut Hulls Mulch

It also let grass grow.

8. Cocoa Hulls Mulch

It also let grass grow.

The above mulches help grass grow, also keep in mind that you must keep the mulch thickness below 2 inches or grass will never grow.

How Grass Does Not Grow When the Mulch Is Inorganic?

Inorganic mulch is used to kill or remove grass. You may add or replace your deteriorating mulch to keep grass from growing.

Inrganic mulches also brings tremendous benefits to your soil like:

Inorganic mulches prevents soil erosion, promotes water retentions, inhibits evaporation, keep precipitation water in soil, make ground healthy for your pets and children, make soil look attractive with their mulch color and many more.

Among many techniques sheet mulching is the one that I used the most, I have also mentioned other mulches that you can use are mentioned below.

mulch prevents sunlight, air, and moisture from reaching the soil. As a result, the grass is deprived of nutrients. Thus, grass growth is halted. Gradually, the grass begins to degrade and eventually dies completely.

Occasionally, inorganic mulch is too thin or does not spread evenly across the surface, allowing air, sunlight, and water to permeate. This creates an environment that helps grass grow.

It is important to mention that inorganic mulch functions as a shield, preventing sunlight, air, and water from penetrating the soil. This inhibits the growth of grass and weeds. But poor mulch spread and human errors cause the grass growth.

So you should always mulch the right way to prevent grass growth when laying mulch.

Mulches That Can Kill Grass

Down below are the mulches that can really help you to kill grass:

1. Sheet Mulching

Sheet mulching is an inorganic mulching technique that is used to kill the grass.

Grass takes nearly 8-10 months to die. This procedure may be performed at any time of year but must encompass three months of seasonal growth.

On positive side, sheet mulching is beneficial on all types of grass and in all types of environments, whether sunny or shady. A cloth or newspaper can be used for sheet mulching.

When laid over grass, sheet

2. Wood Chips

If you ask me “Will grass grow on wood chips” I would say yes. Biologically speaking, wood pieces has carbon in it. When piece start to deteriorate over time, the carbon inside them is ready to bind with the nitrogen in the soil that grass needs to survive. This nitrogen binds with the carbon of wood chips mulch and kills the grass effectively. Placing a thick layer of 4-5 inches will be enough to kill grass and prevent its growth for more than two years.

wood chips packet
3. Bark Mulch

It is another better option to control grass growth. It lasts longer than the woods chips mulch with a mere 3-4 inche thick layer placement on soil. Moreover, it is readily available on local stores. The reason I don’t like it compare to wood mulch is, it is light weight which makes it prone to flow with wind or storm. You may need extra care like netting to hold mulch in place.

bark mulch
4. Newspaper/Paper Pellet Mulch

This mulch is very effective in killing grass. As it doesn’t let the grass to do the gaseous transport to their stomata which helps them to prepare food via photosynthesis. I mean that’s the most important thing that any living thing will need. You can also called it sheet mulching. Usage of sheet mulching is shown in the video below:

5. Plastic Mulch

Plastic mulch alternatelviy called as weeds barrier as also a best mulch type that you should use to control grass growth. These mulch are basically a polymer material that lasts 3 to 4 years longer than normal mulches.

plastic mulch
6. Rubber Mulch

Rubber mulch is a good grass killer but the major cons it come with is that it is not environment friendly.

rubber mulch
7. Rock Mulch

Rock is a solid thing that’s why it wont let grass grow under it as it inhibits gaseous and solar light trapsonportation to grass, resulting in eventual death of grass. Rock mulch can lasts more than 5 years. Once thing that you need to be careful about using rock mulch is that, place it in a way that now void spaces a left in between rocks as there will be a chance that grass may comes out from these voids or holes. A perfectly laid rock mulch is shown below:

rock mulch laid perfectly

Final Conclusion to the question “Does Mulching Help Grass Grow Or Not”

To conclude, organic mulches like leaves and grass mulch help grass grow. Where inorganic mulch once spread on grass kills the grass plus given the right conditions, poor mulching, and a favorable environment, grass can grow through inorganic mulch because it gets favourable environment, sunlight and nutrients to grow. However, if you do proper mulching grass cannot grow under the inorganic mulch.

Do I Need to Remove Grass Before Mulching?

The short answer is YES! if you have planned to kill the grass and don’t what it anywhere in the area where you are mulching.

Mulching is a cheap way of controlling weeds and creating a healthy and clean look to your grass.

For this reason, it is necessary to eliminate grass before mulching. It assists mulch to perform its function effectively.

If the grass is removed properly, the mulch will remain in its place and prevent weeds to grow. You can forego grass removal if it is less than 3 inches high.

How to Keep Grass From Growing Under Mulch?

It is vital to prevent grass growth beneath the mulch. Mulch mostly inhibits the growth of grass and weeds.

Grass grows in certain circumstances. It may impair the mulch’s effectiveness, necessitating the need to prevent grass from growing beneath the mulch. To do this, we can use different methods as listed below:

1. Use of Cardboard or Newspaper

Use of Cardboard or Newspaper to keep grass from growing under mulch

The most effective among them is the use of cardboard or newspaper.

It is an effective and inexpensive method of controlling grass growth. Mulch is created by spreading cardboard or newspaper over the soil’s surface.

This way, grass will naturally degrade and a continuous barrier will be built, preventing the growth of weeds and grass.

Cardboard/newspaper acts as mulch.

By mulching them, a thick double layer is generated that blocks both water and sunlight. Eventually, grass will cease to grow beneath the mulch.

For keeping grass from growing via cardboard mulching, the following materials are required.

Materials Required

  • Newspaper
  • Cardboard
  • Tool for weed pulling
  • Mulch
  • Lawn mower

The following steps should be followed:

Procedure

  1. Mow the grass in the section of lawn where you want to inhibit it. You’ll be using newspaper to cover the space, and the paper will lay better over short grass. If your grass is less than 3 inches in length, you can skip this step.
  2. Remove dandelions and oxalis, which are persistent weeds. Perennial weeds are undesired plants that sprout from the same root year after year. These are robust plants that have the ability to recover once the mulch has degraded.
  3. Overlay the area with heavy layers of newspaper or cardboard covers. At least ten sheets of newspaper should be used to create the newspaper layers. Overlap the borders by 4 inches to create a more effective barrier against grass.
  4. Using water, dampen the newspaper or cardboard.
  5. Distribute the mulch evenly over the newspaper or cardboard. You would like the mulch to be at least four inches thick, preferably six inches, to completely block out light and air. Take care not to rip or displace the cardboard or newspaper. Once the mulch has been laid, re-water the area for compaction of the mulch.
  6. At least three months should pass before planting in the area. This allows the mulch to accomplish its job of killing the grass and the newspaper or cardboard to decompose. During this time period, you should only water the mulch if strong gusts threaten to sweep it away.

2. Use of Chemical Spray/Vinegar

Use of chemical spray/vinegar to kill grass under mulch

Grass and weeds can be sprayed with a herbicide to keep them from growing beneath the mulch.

Additionally, vinegar can be sprayed on invading grass. Because vinegar is completely natural, it is affordable and safe to use. It can be used in combination with dish soap. This way, it will have a thick consistency and will adhere to grass and weeds.

This is an effective but not permanent method of eliminating grass and weeds.

3. Defined Edges

defining edges to prevent grass from growing under mulch

If you have mulched your flowerbed, be sure to edge it. What’s the point of this?

You can prevent grass and weed roots from getting underneath your mulch by edging, particularly by forming a deep edge.

It can be defined by a stone and can prove to be a physical barrier for grass growth.

4. Solarizing Method

You can kill grass and weeds with the sun. It takes six hours of sun a day for six weeks in the summer to kill the grass and weeds. The sun kills the grass and weeds but it doesn’t hurt the earthworms. You can use solarizing to kill weeds and grass before you plant new plants.

It kills the weeds and grass down to a depth of 4 to 12 inches.

It kills weeds, harmful soil microbes, and seeds. It doesn’t hurt beneficial microbes or earthworms.

This method works best on fescue, ryegrass, and bluegrass, with partial success on Bermuda grass.

Pros and Cons of Mulching

Pros
  • It prevents lawn form sun damage
  • It reduces weeds growth
  • It retains moisture of soil
  • It acts as fertilizer
  • It provides nutrients to your lawn
  • It prevents soil erosion
  • It balances the temperature of soil
  • It saves your time and money
Cons
  • It can limit growth by preventing sun light
  • It can create hidden space for lawn insects

Advantages of Mulching

Without any doubt, mulching is really helpful for the health of your lawn.

Organic mulch is produced when we cut the grass of our lawn with the help of a lawnmower. Then this grass is chopped into smaller ones.

Forthwith, it is spread over the grass and acts as a fertilizer.

It helps in soil fertility, balancing soil temperature, conservation of moisture etc.

In short, mulching is beneficial to your lawn in all aspects but mulching appropriately is the only condition.

Disadvantages of Mulching Grass

If mulching is not done properly, it can damage your lawn in various ways.

In a similar manner, if a thick layer of mulch is formed over grass, it can be a constant hidden place for harmful insects and pests.

Likewise, it can cause suffocation for grass by over mulching.

Some mulching materials can absorb nitrogen from the soil, so use nitrogen-rich fertilizer (alfalfa and soybean meal) for mulching.

Mulching Grass vs Bagging

There are a few queries people usually ask me

  • Should I mulch or bag?
  • Should I use mulching or bagging blades?
  • Is mulching better or bagging?

Let me give you simple answers here below:

In past, lawn owners preferred to bag the leaves instead of mulching. They had concerns regarding the health of their lawn.

But now, it has been proven that mulching is safe and healthy for your lawn compared to bagging.

It provides nutrients to your lawn. Naturally, leaves and grass mulch can fulfil 30% of the Nitrogen needs of your lawn.

Of we compare mulching and bagging we can simply say that instead of bagging, mulching is beneficial for yourself, for your lawn and also for your environment.

Mulching saves your time and money. You do not need to buy fertilizers for your lawn. So this way, it is beneficial for you.

It makes your lawn healthy by removing weeds, adding nutrients, avoiding soil erosion etc. It proves that mulching is good for your lawn.

It prevents the waste of chemical fertilizers especially nitrates that are harmful to our environment. So mulching is far better for the environment.

Does Mulching Grass Spread Weeds?

That’s another hot question comes you may come across while mulching. Let me simplify it for you.

It is a common myth that mulching grass spreads weeds, which is not true.

Mulching protects your lawn from weed growth instead of spreading it. To repeat, mulching appropriately is the only condition that will not promote weed growth.

If you spray your lawn regularly and treat it with care, there is no chance left for weed growth.

Frequently Asked Questions

What happens if you put mulch over grass?

There are two things that can happen if you put mulch over grass. If mulch is a barrier like plastic mulch, it will kill grass. If a mulch is a growth promotor like grass clippings or leaves then it will help grass grow.

Do you need to remove grass before mulching?

If you are planing to have a cleared soil where you don’t want anything to grow, then yes you should remove grass before mulching. As mulching will be more effective side by side preventing the soil erosion.

When is the best time to put mulch over grass?

Mulching in Mid of spring is the best time for your grass.

Does grass grow under mulch?

Grass doesn’t grow under mulch if mulch is the best type like rock, rubber or plastic mulch.

Does mulch thickness matters when you lay grass on it?

Yes, If you are using organic mulch and mulch thickness is less than 2 inch it will help grass grow and if it is more than 2 inch it will kill the grass. if you are using inorganic mulch, thickness doesn’t matter, it will always kill the grass.

What kind of mulch kills grass?

Mulch like wood, bark, plastic, rubber, or rock mulch kills grass effectively.

Will mulch stop grass from growing?

Yes, if you are using wood, bark, plastic, rubber, or rock mulch, it will grass underneath for sure.

Will mulch choke out grass?

Yes, mulch doesn’t let grass breathe and doesn’t let sunlight to reach the grass and cause its eventauuly death as grass cannot prepare its own food via photosynthesis due to the mulch barrier on top of it.

Will grass grow on wood chips?

No, if you put a layer of 4 inch thickness on top of grass it will not let grass grow. As wood chips has carbon in it which bind with nitrgen in the surrounding area. Nitrogen is something that grass needs the most. But wood chips make it unavailable and cause eventual death.

Do pine needles kill grass?

Yes, Pine needles can kill grass. Due to their acidic nature they can kill grass if you keep its thickness to 8 inch when laying it over grass.

Does mulch kill weeds?

Yes mulch does kill weeds and also any vegetation that comes underneath it. The best mulches to kill weeds are rubber mulch, plastic mulch, and premium weed barrier sheets.


Summary of Whole Article

Mulching is way much better than bagging, mulching your grass with a mulching mower and spreading it over the grass again make your grass healthy. Inorganic or thick layering of organic mulching does kill grass if you are using the right mulch like wood, bark, plastic, rubber, or rock mulch. The main concept behind killing grass is to not let is do gaseous transport and catch sunlight. Which eventually leads to its death. As it doesn’t have anything to do photosynthesis to prepare their own food. If You are using other mulches like straw mulch, grass will not get killed. Though, if you are using organic mulch with a thickness less than 2 inches, grass will surely grow.


Photo of author

Jack

After doing my master’s in agriculture, I went on with this field for more than 15 years because I love working in green. I have experienced using modern machinery and techniques that can help farmers and landscapers to achieve something great. My goal will be to deliver you the best reviews and information to make the right decision.

Leave a Comment