How to Prevent Weeds in Concrete Cracks

Learn how you can kill pesky weeds and prevent new ones from coming back in their place.

The sight of weeds sprouting up through the gaps in your concrete can be infuriating – especially when you waged war on them just a few days before.

Not only a simple blemish to your curb appeal, weeds can also damage your concrete. As they grow up through the cracks and their roots take hold, they can break down your slabs little by little.

But to get rid of these unwelcome guests, you can kill weeds as they come up, or prevent them from happening in the first place. 

A-1 Concrete Leveling provides concrete caulking services that have helped countless customers maintain weed-free concrete. But as a trusted nationwide concrete care company with over 30 years of experience, we aim to educate you about all the options you have.

In order to do just that, we’ve created this article that will walk you through how to kill weeds in concrete cracks and how to prevent them in the first place.

How to Kill Weeds in Concrete Cracks

Before preventing new weeds from sprouting, you first have to kill the ones that are already there. Here are some of the ways you can go about killing weeds in concrete joints and cracks:

• Vinegar

A mixture of white household vinegar, salt, and dish soap can be sprayed onto weeds to kill them. You may need to spray the weeds multiple days in a row to get the full effect. Horticultural vinegar is a higher-strength alternative that can speed up this process.

The vinegar solution won’t be able to distinguish between good and bad plants, so be sure to only spray weeds. 

• Rock Salt

Sprinkling rock salt directly on the soil where the roots of the weeds are, or spraying the soil with a mixture of rock salt and water can kill the weeds (and any neighboring plants). 

It’s important to note that the salt can break down concrete over time, so this method does come with risk when used on concrete expansion joints or cracks.

• Boiling Water 

Pouring boiling water over weeds is inexpensive, easy, and natural. The high temperature can kill the roots of the weeds, but it can be tricky and time-consuming if you have a lot of ground to cover.

• Pulling Them

Pulling out the weeds and as much of their roots as possible can be one of the easiest and most effective ways to get rid of them. 

This is easier to do when the soil is wet, and tools such as a soil knife, cape cod weeder, or v-notch weeder can help you out.

• Propane Torch

Buring the weeds with a propane torch can scorch and kill them, but this can be a fire hazard if there is dry grass nearby.

• Store-Bought Weed Killer

There are plenty of chemical weed killer options at big box stores. If you go this route, be sure to choose the proper herbicide for the weeds you have.

How to Prevent Weeds in Concrete Cracks

You can kill weeds as much as you like, but new weeds will end up growing back in their place if you don’t keep it from happening. 

Here’s how you can prevent weeds from growing in concrete expansion joints and cracks:

• Seal the Gaps and Cracks

Use a flexible concrete caulk to block weeds from growing up through expansion joints, cracks, and other gaps. The caulk sticks to the concrete and doesn’t leave any room for weeds to grow. 

Be sure to remove all weeds and soil to create sufficient space for the caulk. A power washer might be a good option to clean out the cracks, but be sure to allow it to fully dry before caulking.

Avoid using mortar or concrete patches, as they will eventually crack or break down as the concrete naturally expands and contracts, opening up space for new weeds to grow.

• Pull Weeds Before They Go to Seed

Remove weeds as soon as you see them sprouting, as waiting until they produce seeds will allow them to spread quickly to other areas around your property and concrete.

• Use Chemical Herbicides

Chemical weed killers found at big box stores also often double as prevention from new weed growth for multiple months after application.

• Clean Landscaping Tools

Seeds from persistent weeds can attach to garden tools and be transported to other areas, so wipe them down after use and before storage to limit the spread of weeds.

Your Next Steps

Now that you know what it takes to kill and prevent weeds from coming back, you’re ready to get to work protecting your concrete. 

Taking preventative measures is crucial to ensuring weeds don’t grow back up through your concrete cracks, and sealing up those gaps can be one of the most effective ways to do that.

Here at A-1 Concrete Leveling, we offer concrete caulking services, but we also have a DIY guide on how to caulk driveway cracks if you’d like to try it out for yourself. 

Not keen on caulking your concrete yourself? Click the link below to schedule a free onsite cost estimate for your concrete caulking needs: