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Can Cardboard Kill Grass? Transform Your Garden in 2-4 Months

ByHelen Webster Published on

Ever tried to kill grass with cardboard? It sounds like a DIY hack that’s too good to be true, right?

Using cardboard to wage war on unwanted grass might seem like an odd choice at first glance. But hey, if you can order pizza and get a gardening tool at the same time, why not?

I’ve tested this method myself, and it’s like hitting the snooze button on your lawn’s growth. It’s simple, effective, and surprisingly satisfying.

Using Cardboard as a Grass Killer

I’ve found that using cardboard to kill grass is an eco-friendly method that anyone can do with minimal fuss.

caardboard in grass

The Process of Smothering Grass

The key to using cardboard as a grass killer lies in its ability to smother and deprive the grass of sunlight and air, effectively killing it over time.

Here’s how I do it: I lay down sheets of cardboard directly on top of the grassy area I’m targeting. It’s key to overlap the edges by at least 6 inches to prevent grass and weeds from sneaking through the gaps.

After laying the cardboard, I soak it thoroughly with water to help it conform to the ground’s shape and prevent it from blowing away.

Next, I cover the wet cardboard with a generous layer of organic material, such as compost, bark, or mulch. I usually go for about 4 inches but more can be beneficial, depending on the tenacity of the grass and weeds in the area.

This layer does double duty; it weighs down the cardboard and begins the process of enriching the soil below for future planting.

Selecting the Right Type of Cardboard

Not all cardboard is created equal when it comes to killing grass. I’ve learned to use large, flat pieces of cardboard like those from appliance or furniture boxes.

These work best because they cover more area and usually don’t have as much ink or tape on them.

It’s important to remove any staples, plastic coatings, or tape from the cardboard as these materials won’t break down in the soil and can be harmful to the environment.

Gathering Necessary Materials

Besides cardboard, gathering the right materials upfront makes the job smoother and ensures you don’t have to pause midway through your project. Here’s my checklist:

  • A sufficient quantity of cardboard to cover the target area, with extra for overlapping.
  • A hose or watering can to wet the cardboard.
  • Organic mulch, compost, or bark for covering the cardboard.
  • A pair of gloves to protect your hands.

I find that having these materials on hand allows me to focus on the task at hand, ensuring that the cardboard stays in place and begins the grass-killing process effectively.

From my experience, this method not only kills grass and weeds but also improves soil health, making it a win-win for starting a garden.

Step-by-Step Guide to Killing Grass With Cardboard

box in grass

Identifying and Preparing the Target Area

Picking the right spot is key. You need a vision. What’s this space gonna look like when you’re done?

Are we talking a veggie paradise, a flower haven, or maybe a mix? Once you’ve got that pictured, it’s time to prep.

Clear out any large rocks, sticks, and other debris that could poke through your cardboard. This isn’t just about making the space look tidy; it’s about ensuring that the cardboard layer has full contact with the grass you’re aiming to say goodbye to.

Mow the grass down low to ensure the cardboard can lay as flat and close to the soil as possible. Wetting the area lightly can make the grass more pliable and the cardboard easier to shape around the terrain.

Laying the Cardboard Properly

For the main event: laying down the cardboard. This isn’t about just throwing down some pieces haphazardly. You’ll want to overlap the edges of the cardboard by at least 6 inches.

This overlap is the secret sauce that prevents any stubborn blades of grass or particularly ambitious weeds from making their grand escape.

I like to use large, flat pieces, avoiding anything with glossy finishes or heavy inks – we’re going for eco-friendly and effective here.

Make sure the cardboard covers the target area completely, and don’t skimp on coverage. Those grass and weed seeds are just waiting for a sliver of sunlight to stage their comeback.

Securing the Cardboard in Place

This step can be the make or break – literally, if the cardboard decides to take flight on a windy day. After laying down the cardboard, soak it thoroughly with water.

This not only weighs it down but also jumpstarts the decomposition process. Then, cover the cardboard with a generous layer of organic mulch. I’m talking about a good 4 inches or so.

The mulch keeps the cardboard in place, helps retain moisture, and, as it breaks down, feeds the soil underneath. Plus, it gives the area an instantly neater appearance, which can be a nice bonus if you’re trying to keep things looking tidy during the transition.

In my experience, this method is a game-changer for anyone looking to transform their lawn into something more useful and environmentally friendly.

How Long Does It Take?

From my experience, the timeframe isn’t overnight but it’s surprisingly quick for such a simple, environmentally friendly method.

Typically, the cardboard begins to suppress and kill the grass underneath within a few weeks.

However, the total time to complete grass death and decomposition can vary, depending on factors like climate, the thickness of the cardboard, and how wet the cardboard stays.

Generally, I find that a period of 2 to 4 months is a good benchmark for expecting to see significant results.

If you’re aiming for quicker decomposition, ensuring the cardboard remains moist is key. Sprinkling water over the mulch regularly can speed up the process.

Also, the warmer and more humid the weather, the faster the cardboard and grass underneath will break down. For those in cooler climates, patience is necessary, as the cardboard will take longer to decompose.

Remember, the breaking down of cardboard doesn’t just eliminate the grass—it’s a transformational period where the cardboard and the disappearing grass underneath become nutrient-rich compost for your future garden.

It’s a cycle of renewal that preps your soil beautifully for native or climate-appropriate plants. By the time the cardboard has disintegrated, the soil beneath is more fertile, aerated, and ready for planting.

In essence, while it takes a bit of time, the benefits of using cardboard to kill grass extend beyond just removal. It enhances soil health, making it an excellent kickoff for your garden revamp.