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How to Kill Grass Under Deck?

How to Kill Grass Under Deck?

Do you have a deck in your backyard? If so, you may have noticed that there is some grass growing underneath it. This can be a real pain to deal with, as the grass can quickly take over and make your deck look ugly. In this article, we will provide you with a full guide on how to kill the grass under your deck. We will cover everything from common questions to the best methods for getting the job done. So read on and learn how to get rid of that pesky grass!

Why Does Grass Grow Under Decking

One of the most annoying aspects of having a deck is that grass and other types of weeds tend to grow underneath the boards. Whether you’re dealing with an established lawn or just some occasional sprouts, it can be difficult to get rid of these pesky plants.

So why does grass grow under your deck in the first place? Grass can easily grow under decking as it is a typically shady area, providing protection from the sun and wind. Additionally, when rainwater drips between the planks of your deck, it combines with trapped dirt and debris to form an ideal environment for grass seed to take root and flourish. Yes, the combination of ample sunlight and plenty of water makes this area perfect for grass and weeds to grow. This problem can become especially bothersome if you don’t have a clear pathway or easy access to the underside of your deck.

Another factor is that when a deck is installed, there may be excess dirt or soil left behind in the area underneath which creates a perfect seedbed for grass to grow. Also, if you have any trees nearby then bird droppings can fall onto the area below your deck and provide fertilizer for grass growth.

So, while it may be annoying to find grass growing under your deck, you can take comfort in knowing that there is usually a logical reason behind it! If you want to stop this from happening then make sure to ensure that your deck is properly sealed off with waterproof sealant, keep the area below clear of dirt and debris and repair any cracks or holes that appear.

Getting rid of the existing grass before laying down your decking planks can also help to prevent further growth. If you do decide to go down this route then make sure that the grass is completely dead before installing your deck boards! This prevents any remaining roots from regrowing and taking hold under the planks.

Now that you know why grass tends to grow underneath your deck, let’s look at some of the best ways to get rid of it for good. With some simple maintenance you should be able to keep grass from growing underneath your deck. [1]

Why Does Grass Grow Under Decking

How to Get Rid of Grass Under Deck

However what should you do if you have an existing grass problem under your deck? Let’s get into the details of how to properly kill grass under deck. Luckily, there are several methods for killing grass and weeds, so you should have no problem finding one that works for your situation.

Place a weed control fabric

Weed control fabric, also known as ground cover cloth or landscape fabric, is a product used to prevent weeds from growing in your garden beds. This type of material is made out of plastic and is designed to be laid down over the soil before growing any plants. It blocks sunlight from reaching the weed seeds that are in the soil, so they don’t have a chance to germinate and grow. Weed control fabric can be beneficial when it comes to killing grass under deck because it prevents new grass seedlings from sprouting up in between cracks or crevices in your deck boards or under railings.

It is important to note that weed control fabric does not work like a herbicide, which would kill existing weeds and grass. Weed control fabric is designed to prevent new weeds and grass from sprouting up in the first place, so it won’t do much good for existing plants. But if you lay down weed control fabric before planting your lawn or garden beds, it should give you better results in the long run by preventing any new weeds or grass from taking root.

When laying down weed control fabric be sure to use enough staples along the edges of each sheet to ensure that it does not shift when you water your lawn or garden beds.

Use mulching

Another of the most popular methods for killing grass is to use mulching. Mulching involves placing a thick layer of material over the affected area which blocks out sunlight and suffocates any plants that are growing there.

You can find mulch in many forms, from wood chips to gravel, so you should have no problem finding something suitable for your deck. Make sure to spread it out evenly and then wet it down thoroughly with a garden hose or sprinkler. This will help to make sure that the mulch stays in place and can do its job properly.

Use mulching

Use a weed killer

The easiest and most widely used methods for killing grass and weeds is to use a weed killer. Weed killers or herbicides come in various forms and can be purchased at most garden centers or online.

When using a weed killer, make sure that you read the instructions carefully before applying it as different products have different application methods. Also note that many types of weed killers are toxic to animals and humans so you should take extra care when using them near your house or yard!

Once you’ve applied the product, allow it to sit according to the instructions on the label before removing any dead plants with a rake or shovel. It’s best to pick a herbicide specifically for the type of grass under your deck. For example, if you have a lawn-type grass under your deck, choose a weed killer designed to kill that type of grass.

Perform regular inspections

Another key way to ensure that grass and weeds don’t take root and grow under your deck is to perform regular inspections. Take a walk around the area at least once a week and look for any signs of new growth. If you spot any, it’s important to act quickly as this will give you the best chance of preventing them from getting established.

At every inspection, make sure to also check all cracks, crevices, and edges of the deck boards or railings for any signs of new growth. If you do find some growing in those areas, use a small hand trowel or garden weeder to dig them out by their roots before they have a chance to spread further. [1], [2], [3]

Perform regular inspections


Why is there weeds under my deck?

Weeds naturally grow and thrive in dark, moist environments. Unfortunately, these conditions create a perfect environment for weeds to thrive under your deck, especially if there is soil or mulch present. Over time the weed seeds can be moved around by animals or wind, allowing them to take root and spread. In some cases, the weeds may have been intentionally planted near the deck as part of landscaping efforts.

Regardless of how they arrived, it’s important to remove any grass and weeds before they become too established or begin spreading further into your yard. Otherwise you could end up with an unsightly mess that will require more work to control.

How do I stop weeds under my deck?

The safest way to stop weeds from growing under your deck is to use a combination of mulch and ground covers. Mulch blocks sunlight from reaching the soil, preventing weed seeds from germinating. Ground covers act as barriers to weeds and are an effective way to prevent them from sprouting up in the future.

If there is already established vegetation under your deck that you’d like to remove, you can use a specialized herbicide designed for this purpose. When using any kind of chemical product it is important to read and follow all instructions on the label carefully and take extra precautions when applying the product. Wear protective clothing such as gloves, long-sleeved shirts, and eye protection while handling herbicides or spot treating with chemical products.

We don’t recommend you mix mulch and herbicides together however, as they can be hazardous if used together improperly.

How do I stop weeds under my deck?

How do you get rid of weeds on decking quick?

The quickest and most effective way to get rid of weeds on decking is to apply an herbicide that specifically targets grassy and broad-leafed weeds. For best results, make sure to choose an herbicide labeled for use on decks.

Start by brushing away any loose debris from the surface of the decking before applying the herbicide. This will allow the product to penetrate deeper into the soil and be more effective against pesky weeds.

Once you have applied the herbicide, it’s important to wait several days after application before walking or playing on the deck. This will help ensure that all of the product has had time to do its job and kill any weeds.

Can I spray vinegar under my deck?

Yes, you can spray vinegar under your deck to reduce the growth of grass and weeds. Vinegar is a natural non-toxic weed killer that can be used in hard to reach areas such as under decks, or on patios or driveways. When sprayed, the vinegar will kill any vegetation it comes into contact with and inhibit new growth for several weeks. Make sure you are not spraying near any plants that you want to keep alive as they may also die from contact with the vinegar.

What do you put under decking to stop weeds?

The best way to prevent weeds from growing in the area underneath your deck is to lay down a weed barrier fabric. This type of fabric is designed specifically to block out light and restrict the growth of plants, which helps to stop weeds from emerging. It also acts as a moisture barrier, trapping water and preventing it from reaching the soil where it can foster weed growth.

Before laying down your weed control fabric, be sure to remove as much of any existing vegetation and weeds. You should also make sure that the ground beneath your deck is level by adding or removing soil as needed. Secure it in place using landscaping staples and then cover it with a layer of gravel, bark chips or other material. This will help keep the fabric in place and provide an attractive finish.

Once you have your weed barrier in place, be sure to check it regularly for any signs of weeds beginning to emerge. If you notice any sprouts coming through, take care of them right away to stop them from taking root and spreading under your deck.

Useful Video: How to Kill Grass Under Deck?


You want your deck to look as sharp and inviting as possible, and unfortunately grass growing under it can be a hindrance to achieving that look. Thankfully, with the right methods and tools you can get rid of the pesky grass for good.

While chemical-based solutions are often more effective, organic methods such as smothering or using vinegar methods may be preferable to some homeowners due to their environmental friendliness. Whichever approach you choose though, keep in mind that killing off existing weeds is only part of the battle — ongoing maintenance will be necessary to prevent new ones from popping up in the future.

Regular inspections of your deck should be done, paying particular attention to any signs of new grass growth. Applying a layer of mulch or groundcover can also help prevent the re-growth of weeds and grass under your deck.

If your backyard has an area under your deck that’s overrun with weeds, don’t fret — follow our guide above and you should have no problem getting rid of it and keeping your deck looking sharp. Good luck!


  1. https://www.texastreetrimmers.com/prevent-grass-from-growing-under-deck/
  2. https://peppershomeandgarden.com/what-can-i-put-under-my-deck-to-prevent-weeds/
  3. https://knight-fencing.co.uk/stop-weeds-coming-decking/