Will Grass Grow Through Mulch? (All You Need to Know)

You may have heard of mulch but you may not know exactly what it is. Mulch is a covering that is placed in the garden to help improve soil health and strength. There are pros and cons to mulch, but overall the benefits of mulch outweigh the disadvantages by a long shot.

Mulch is available in organic materials such as wood chips or pine straw, and you can even get inorganic mulch like rubber nuggets.

Finally you are jumping into a project and you are using mulch for the first time. You are probably thinking how does this mulch stuff prevent grass and weeds from growing through? Don’t worry, let’s get into the answers.

Will Grass Grow Through Mulch?

Mulch acts as a barrier to sunshine, air, as well as water penetration too. Of course, when mulch is placed correctly all it will stop grass growing through as well as weeds.

Mulch is used to inhibit the growth of weeds and grass. Periodically, though, grass may emerge on the top and start growing. Grass growth is influenced by a number of factors:

  • Mulch might be too thin or not scattered uniformly all across the top, enabling air and water to get through.
  • Proper preparation was not completed before mulching, enabling grass to quickly and easily continue growing.
  • Suitable growing atmosphere: good soil, organic matter, proper drainage, and regular water. 

Grass and weeds can start to grow as a result of such factors. Mulch can actually provide the nutrients which helps in the growth development of grass and weeds.

It is obvious that grass can definitely grow and thrive through mulch under the correct conditions, with weak mulching and a suitable growing atmosphere.

Grass will not be able to grow beneath mulch if it is properly mulched.

RELATED: Will Grass Grow Through Sand? (All You Need to Know)

Can Mulch Prevent Grass From Growing?

Absolutely. Mulch is a very smart way to stop grass and weeds from growing and millions of homeowners use it for that very purpose.

Taking the proper steps to correctly lay mulch is the best way to have a successful grass free mulch garden. Follow the tips below to prevent grass growth though mulch.

If there is a lot of mulch in your yard, for whatever reason, and you are looking to grow grass, you may want to get rid of the mulch that is there to ensure the proper growth and nutrients and elements of grass.

Simply rake it up, dispose of it correctly, and get started on growing a nice lawn!

How to Prevent Grass From Growing Through Mulch?

There are many ways to prevent grass from growing through mulch.

1. Lay Landscaping Fabric

Landscaping Fabric to prevent grass growing through mulch

One of the most common approaches to prevent grass and weeds under mulch is to use landscaping fabric. 

There are different types of landscaping fabric materials, such as polyester, polypropylene, linen, and so on. No matter the material, these are designed to allow water to flow between the fabric while preventing anything from growing through them.

Whenever I lay mulch I have used a landscaping fabric sheet, cut it to size, cut areas for plants, and I was able to prevent unwanted plant growth such as grass and weeds. 

Can Grass is Grow Through Landscape Fabric?

Grass cannot grow or germinate when landscape fabric is placed. If you have grass growing through the landscape fabric area this means the fabric has been compromised one way or another.

If grass is growing where you have landscape material here are possible reasons why:

  • there’s a whole or tear in the fabric allowing growth through it
  • your landscape fabric is rotting from organic breakdown (some organic mulches and topsoil’s can eventually breakdown certain landscaping fabrics)
  • An animal, rodent, or insect has eaten/ripped the fabric allowing growth

It’s not the end of the world if this happens. You can apply a herbicide to kill the unwanted growth and then apply a new piece of fabric to cover the area back up.

2. Spray with Vinegar or Pre-Emergent Herbicide

Spray with Vinegar or Pre-Emergent Herbicide prevent grass in mulch

You can also spray the soil, grass, or weeds with vinegar. A mix of vinegar, salt, and dish soap makes for a great organic herbicide that will kill grass and weeds growing through your mulch.

Or you can choose a pre-emergent herbicide, this is a chemical option that is toxic to plants and will kill/prevent grass growth and weed growth. Be careful as it can damage plants you want to grow in your garden. 

3. Edge the Mulch Garden

Landscaping edging prevent grass growth and weeds spreading into mulch beds

Edge the areas around your mulched flower beds to prevent grass and weeds from growing through it.

Proper edging techniques can help prevent the spread of grass growing into your garden. Furthermore, edging helps prevent weed seeds from ending up inside your garden beds.

Edging will also keep your mulch in place, meaning it will keep its thickness preventing growth from underneath.

Some great types of edging are: 

  • Edging Stones
  • Plastic Edging
  • Wooden Landscape Edging
  • Metal Edging
  • Composite Edging
  • Concrete Edging

4. Lay a Thick Layer of Mulch

Lay a Thick Layer of Mulch to prevent grass growth and weeds

Mulch can hold off on all growth if it is laid in thick amounts. It must be thick enough and dense enough to act as a smothering shield to the soil underneath.

For mulch to act as a smothering shield to prevent grass and weeds growing, it must be 2.5 to 3 inches thick.

Not all mulch is thick and strong enough to prevent growth and that’s why other options above are recommended first.

Grass can grow through mulch if it has the ideal conditions it needs. With good sunlight, water, and rich soil, mulch may not be able to prevent such growth underneath. 

Having a good thick layer of mulch in addition to the other options above ensures no grass or weeds will grow up through.

How to Kill Grass and Weeds Under Mulch?

There is no single answer, there are a few ways to kill grass and weeds under mulch. 

  1. Pull and dig up any grass and weeds
  2. Smother with plastic, cardboard, or newspaper
  3. Use a Herbicide and Spray on Growth area

You can grab high-concentration vinegars (like I mentioned above), mix some salt and a teaspoon of dish soap into a gallon of vinegar and spray it on the areas to kill. 

This is a simple organic grass and week killer option to use on growth under mulch beds.

Can I Mulch my Current Lawn to Kill the Grass?

If you are trying to kill your lawn you may want to read our detailed article here.

Mulching a lawn to kill it is not an efficient way to kill grass. There are much easier processes (and less messy) that will kill your lawn. The best option is to cover the grass somehow so it dies off in a few weeks. You can cover with a tarp, cardboard, or a plastic cover. 

If you want a mulch lawn without the grass under it you can follow these steps: 

  1. Kill grass by smothering it with cardboard or tarps (2 weeks)
  2. Recycle/compost dead grass
  3. Spray pre-emergent herbicide to ensure to grass or weeds grow
  4. Cover yard with a durable landscaping fabric
  5. Lay mulch of your choice

Final Thoughts

Now we have a good understanding of how grass and weeds can still grow under mulch under certain conditions. Following the most recommended prevention tips will help keep unwanted grass from growing through your mulch beds.

Grass and weeds can both be prevented from growing under mulch and also killed if they happen to show up. 

If you have any questions regarding mulch and grass please ask me in the comment section below! 

Check our our related mulch articles: 

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