How to Stop Weeds from Growing Under Your Deck

Decks are becoming increasingly popular amongst homeowners as they allow you to create an outdoor space to socialize with friends and families. Many people consider their decking to be an extension of their living space.

The problem with decking is that weeds can grow underneath, and in some cases, will even grow up between the boards. If you don’t take steps to stop weeds from growing, they may damage your decking or become unsightly. Weeds can also become a breeding ground for insects and animals. Whether you’re thinking of having new decking installed or are maintaining your existing decking, there are many ways to stop weeds from growing. Let’s look at how to prevent weeds from growing under decking.

Stop Weeds From Growing Under Deck

If weeds are becoming a problem under your decking, there are several things you can do. Here are some of the best ways to stop weeds growing before you build your deck, as well as if you already have decking in place.

Use Landscape Fabric

Stop Weeds from Growing Under Deck

The best way to stop weeds growing is to lay a landscape fabric before the decking is built. This will create a water-permeable barrier that will prevent weeds from growing. The material stops sunlight from reaching the weeds and seeds, which means they will be unable to grow. Laying fabric stops even the toughest and most stubborn weeds from growing.

You can make the area under your decking look more attractive by spreading some gravel over the landscaping fabric. Make sure that you lay landscape fabric first, don’t cut corners, and use only gravel as weed can sometimes grow through gravel.

It’s best to use between three and four inches of gravel, as this will help keep the area free of weeds. Gravel helps to protect your landscape fabric from animals who may be walking over the area. It also helps to increase the lifespan of the landscape fabric and weighs it down.

Don’t Use Plastic Sheeting

Some people suggest using plastic sheeting under decking, but this isn’t a good idea. Landscape fabric is best as it allows rainwater to pass through and soak away. If you use plastic sheeting, water will start to collect in puddles. You don’t want to end up with stagnant water under your decking, as this will smell and create a breeding ground for insect pests such as mosquitoes.

You should also avoid using mulch as this can cause fungal growth as it will get damp. The wood chips can also start to rot and smell bad. It’s best to use gravel to protect and hold down your landscaping fabric. An alternative would be a synthetic mulch made from recycled tires.

Using Weed Killers Under Your Decking

Remove Weeds from Deck With Pesticides

If you already have decking and you don’t want to take it apart to add landscape fabric and gravel, you can use a weed killer under your decking. There are a few different types of weed killer that can be used under the decking. One of the most popular is long-lasting weed killers; these only need to be applied once a year and will kill existing weeds.

Alternatively, you can use a pre-emergent weed killer in the early spring. It’s best to use these types of products in late March or early April, as they stop weed seeds from germinating.

Pre-emergent doesn’t kill mature weeds, so you’ll need to apply the product early so that weeds don’t start to grow under your deck.

Natural Weed Killers

Killing Weeds around Decking

If you’re looking for a more environmentally friendly solution, there are a few natural products on the market. Choose a product that contains corn gluten meal (CGM). This is a natural pre-emergent herbicide that can be applied in the early spring and will stop weed seeds from germinating. These products dry out weeds and their seeds and kill them. You’ll need to use CGM annually.

You can also try making your own herbicide using a mixture of horticultural vinegar and dish soap. This can be sprayed on mature weeds to kill them. Alternatively, pour boiling water on weeds to scorch the leaves and kill seeds and roots.


The best way to stop weeds from growing under your deck is to lay landscape fabric topped with three or four inches of gravel underneath your decking. This creates a barrier to stop weeds from growing.

You can also use various weed killers, pre-emergent herbicides, or natural solutions to get rid of weeds.