phone icon 01925 943011



How to Keep Grass From Growing Under My Composite Decking

  • Henry A
  • February 16, 2021

One of the worst enemies of decking is the grass beneath them. You may or may not have considered this as a threat before. But when it reaches your patio, you’ll see how much damage it can cause. If you have some uncontrollable weed growth under there, you will need to fix it immediately. If not, you will need to do some extra precautions to prevent it. The question is, how do you keep grass from growing under my composite decking? And why is it such an urgent matter for decking?

Why Is Grass Bad for Decking?

There are many reasons why the grass is not good for decking. One of the main problems is moisture. If the decking is relatively close to the ground, the moisture from the plants can affect the decking. When exposed to moisture, decking will swell, which can be damaging to some types of materials.

Another reason why grass growing under your decking is bad is that it can be a perfect spot for insects. If you have wood, your decking will be more susceptible to insect damage. On top of all of that, a decking with grass can be a breeding ground for moulds and fungi, which will not only stain the decking but can damage it as well.

Of course, you also wouldn’t want a decking with weeds bursting from the ground. It doesn’t look good any way you look at it. Fortunately, there are several ways to deal with it.

How to Keep Grass From Growing

When targeting the weeds underneath your decking, you have a few options that you can do. Here are some of the ways to do so.

Manually Removing the Weeds

While not a long-term solution, you can remove the weeds from the ground. It’s one of the easiest ways to remove and keep the grass from growing. However, it’s only possible if there is a big enough space between the decking and the ground. If you can fit in through the gap, you can do it by hand. Otherwise, you can use a hoe to clear away the weeds. Take note that some weeds may not grow back, but perennials might come back.

Place a Landscaping Fabric and Gravel over the Top

If manually mowing the weeds is ineffective, you can try to dig an inch or two in the target area. Once you’ve done that, cover it with landscaping fabric, tarp, or plastic. The fabric will prevent the growth of weeds. Then, fill the area with gravel or other similar materials to avoid pooling. This step is crucial, especially when installing decking close to the ground. The gravel provides better drainage for the decking and avoids water pooling. Aside from gravel, you can also use mulch, such as wood chips, newspaper, and sand. Using this method is effective since it limits the sunlight and water that the weeds can get, which slows or stops their growth.


If there is no space underneath the decking or there’s no way to reach it through the sides, consider using herbicides instead. For the best results, consider getting herbicides with Glyphosates. It prevents the weeds and plants from producing the essential proteins that they need. You can easily get them from your local stores. Alternatively, you can make your very own natural herbicide. One example is by mixing vinegar, salt, and liquid dish soap. The salt and the acetic acid from the vinegar help to effectively kill the weeds. Reapply herbicide whenever you notice that the weeds are growing back. When using chemicals, make sure you wear the proper protective equipment.

Regularly Keep Watch

Most importantly, always keep checking on the ground. Not all of these solutions are permanent. There is still a slight chance for them to grow back, especially during the spring. For instance, when using mulch or landscaping fabric, check whether they shifted. If you see any weeds or grass growing back underneath the decking, repeat these tips.

Grass can be damaging to your decking. To save you the trouble of decking repairs and replacements, make sure that you keep the grass from growing under the decking.

Manually remove it or use herbicides, or layer the ground with landscaping fabric and gravel or mulch. With these, you won’t need to worry about weed growth for a while.

Previous ArticlePrevious Article

How Do You Remove Mould From Composite Decking?

Next ArticleNext Article

How To Lay Wooden Decking Tiles on Grass

Request a sample