Will Grass Or Weed Grow Through Mulch? – How To Stop Them?

Mulch is a very valuable tool for gardeners. It can provide a lot of control to suppress the grass and weeds in the garden. A mulch layer in your flower beds and other areas of your garden can discourage unwanted plants from growing. At least this is how it’s supposed to work, but sometimes grass and weeds can appear through the mulch.

Yes, grass and weeds can grow through mulch. As mulch cannot fully block the air and sunlight and can have some gaps which can give way to the grass or the weed to permeate. Grass and weed seeds can also germinate in mulch if they receive sufficient sunlight and moisture and can establish roots in mulch.

So, what do you do if you see grass or weeds growing in your garden? Let’s talk in detail about how you can protect your garden.

Will Grass Or Weed Grow Through Mulch? - How To Stop Them?

What is Mulch?

Mulch is any material that is used to spread or lay over the surface of the soil as protection or covering. Mulch is used to retain moisture in the soil and suppress the grass and weeds in the garden. It also helps in keeping the soil cool in summer or prevents frost heaving in winter. 

Two kinds of mulch are used – Organic mulch and Inorganic mulch. 

  • Organic mulch includes formerly living materials that are now dead such as shredded bark, sawdust, woodchips, chopped leaves, straw, grass clippings, pine needles, and newspaper. 

Organic mulch will decompose in the soil slowly adding nutrients and structure to the soil. The drier and woodier the mulch is, the more time it will take to decompose into the soil and the fewer nutrients it will add to the soil. 

It is also very crucial to know the origin of organic mulch you are going to spread in your garden as it can contain harmful chemicals or weed seeds which can cause some serious problems in your garden.

  • Inorganic mulch includes black plastic, landscape fiber, and stone/gravel. Synthetic or inorganic mulch is good in holding moisture and blocking the weeds and grass in the garden but they don’t add any nutrients or structure to the soil and will not decompose and require you to replace them when they have openings or when they are not able to suppress weeds and grass.

How is Mulch beneficial for your garden?

Spreading mulch in your garden can be very beneficial for the soil as mulch is an organic matter which can decompose in the soil and can provide essential nutrients and other stuff which can make the soil rich. 

Mulch is also good in retaining moisture which helps the plants to grow faster without facing any dry conditions and it also helps with the drainage of the soil. Mulch also helps the soil by retaining the temperature of the soil as it can keep the soil cool in summer and protect from frost in the winter. 

Can grass or weed grow through mulch?

Grass and weeds need air, moisture, and sunlight to grow, and if they can get all of these then they can grow very easily. Mulch is used to suppress the weed and grass by blocking the sunlight and air from getting to the plant.

But sometimes the mulch is too thin or has gaps that can give way to air and sunlight and the weeds or grass can grow through it. The mulch itself is very good for plants to grow and establish roots if they can get sunlight, air, and moisture.

Sometimes when you buy mulch, it can contain unwanted plants or seeds of weeds which can germinate in your garden. So what should you do to protect your garden bed from unwanted grass and weeds? 

How to prevent grass and weed from growing through mulch?

If you are seeing grass and weeds growing through the mulch in your garden bed then the mulch may be too thin to suppress the plants. There are several ways to prevent or reduce grass and weeds in your mulched garden beds: 

  • Newspaper or cardboard – Newspaper and cardboard are very good at retaining moisture. But with moisture, they don’t have gaps and can block the sunlight fully getting to the soil or the grass and weeds. To use as a mulch take two to four sheets of newspaper or a single sheet of cardboard. Cover the sheets with one to three inches of organic mulch which will keep the sheets in place and ensure that this will at least last throughout a growing season. 

You also don’t need to remove the old layer of mulch to put the sheets. Just put the sheets on top and cover it with mulch. This will make the layer more dense and hard for the grass or weeds to grow through it.

  • Black plastic sheet – The black plastic sheet also works like a cardboard sheet and blocks sunlight fully to get through and suppresses the grass and weeds, but it can’t hold moisture and will not be able to decompose in the soil. You need to remove the plastic sheet if it rips up from someplace and gives way to unwanted plants. 

You also won’t be able to get to the soil if you need to fertilize it. Plastic also gets very hot in the summer and it can also kill all the good things in the soil. The plastic sheets can also block drainage and can create puddles around the garden.

  • Landscaping fabric – Landscaping fabric also works as a plastic sheet or cardboard and blocks the sunlight fully suppressing all the unwanted plants from growing in the garden. But unlike plastic sheets, it is porous and has good drainage which is good for the soil and keeps all the organic matter alive in the soil while retaining moisture. Just put the landscaping fabric on top of the soil and put a one to three-inch layer of mulch on top to keep the fabric in place similar to the newspaper and cardboard sheet. 
  • Spray with vinegar – An organic way to kill grass and weeds in the garden is to spray it with vinegar as vinegar is very good at killing the plants. Mix one cup of vinegar in one gallon of water and one tablespoon of liquid soap to make the solution stick to the plant. Spray this solution on the unwanted plants very easily without any harmful effect on the garden. Keep in mind that this solution can kill any plant coming in contact so don’t spray it in the plants that you want to keep in the garden.
  • Pull out weeds and grass – The last resort if you are seeing some grass or weeds plants growing through, is to pull them out so that you don’t have any seeds left behind by these plants to grow in the future and put some thick layer of mulch or sheet over that particular area. This will be a quick and easy way to prevent the grass from growing through the mulch.

There are some chemical ways to eliminate the weeds and grass from the soil and prevent them from growing in the future. But they can be harmful to your garden and can also damage other plants. So going organic with one of the processes mentioned above can be very effective and easy in eliminating and preventing the grass or weeds from the soil.

Do you need to remove grass before mulching?

No, you don’t need to remove grass before mulching the soil if the grass is not very long. The grass will die off when you block the sunlight and air and will not be able to grow further. It will decompose in the soil and provide back all the nutrients into the soil. 

Hope you find all the answers and know, how to protect your garden from unwanted grass or weeds. Get Set Gardening!