The Cardboard Method For Turning Lawn Into Garden Beds | Empress of Dirt

The cardboard method is one of the easiest ways to convert grass lawn into garden beds. With the cardboard in place, the grass gradually dies off and the cardboard decomposes. Most beds are ready to plant in about 4 to 6 months, although it can take longer.

When you’re ready to plant, our handy soil calculator tool estimates how much soil, mulch, compost, or potting mix you need for your garden beds, raised beds, window boxes, flower pots, and urns.

Want an easy way to create a new garden bed?

If you don’t mind a waiting period, one of the most efficient ways to turn grass lawn into a flower or vegetable bed is to cover it with cardboard and wait.

Depending on the cardboard and conditions, this process may take weeks, or months, or longer—although most seem to be ready in a matter of months.

As the cardboard gradually breaks down and decomposes, any plants or seeds below die off.

The result? Plain soil ready for soil amendments and plants. Home gardeners have used this method for decades.

There are numerous approaches. Some use sheets of cardboard, others use several layers of plain, brown paper or newsprint. Some cover the paper materials in mulch, others hold everything down with metal pegs (“landscape staples”) or rocks.

You may see it called “sheet mulching” or “smothering.”

No matter what, it’s all the same in the end: good-bye grass, hello new garden bed.

Let’s go over some tips for choosing materials and how to get started.

Or jump right to the instructions here.

Contents

Frequently Asked Questions

What is cardboard made from? Will it add nutrients to the soil?

Cardboard, like paper, is fundamentally organic matter, usually made from trees. It’s around 50% carbon with lots of cellulose for microbes to digest.

Cardboard and other papers do not, however, provide other nutrients for the soil.

After creating new beds with cardboard, you will need to replenish the soil by topping it with several inches of soil amendments like compost, leaf mold, or other organic mulches.

The purpose of this technique is simply to get rid of the turf in the easiest way possible.

Is cardboard safe for the garden?

What are the long-term effects? Is it okay for a healthy eco-system?

The answer is: science doesn’t know. Using cardboard to create garden beds has not been studied.

We have the anecdotal evidence of countless gardeners using this method and liking the results, but we have little or no information on the temporary or long-term effects on the soil.

Without specific research to guide us, we have to rely on what we do know about plants, soil science, and pollutants and make the most informed decisions we can.

What’s the best cardboard to use?

There are all sorts of different types of cardboard. Even if most of your boxes come from Amazon you’ll notice that they may not all have the same composition.

Whether it’s corrugated or flat box board or some combination, we want to be sure whatever we use in the garden is just paper-based and nothing else.

Knowing what an environmental issue plastic pollution and microplastics are in our air, soil, and waterways, it seems smart to avoid using any cardboard with a plastic coating or other synthetic bits.

Preparations should include removing any tape, stickers, tags, plastic handles, packing slip pouches, and so on.

Also, remove any staples or other metal wires or pieces or they may come back to bite you later.

We just want plain old cardboard and nothing more.

What about chemicals in the cardboard like bleach or inks?

Again, because the use of cardboards to create garden beds has not been studied, there are no definitive answers.

While cardboard and newsprint are made from trees, there is a lot of processing involved—mechanical, thermal, and chemical. This may include adding various agents like bleach to lighten the color and inks for printing.

In the past, inks were concerning because they contained heavy metals. Today, most are vegetable-based although some heavy metals may be present in full-color inks.

If you have any concerns about heavy metal levels in general, it’s wise to get your soil tested.

It’s also helpful to note that heavy metals occur naturally in soil so it’s not unusual that you will have some present. The question is always whether they might get into our food or bodies at unacceptable levels. If your land was used previously for burying trash or manufacturing, container growing may be a better option. There are free plans for building raised beds here.

The goal is to ensure the soil is food-safe, meaning safe for growing things like fruits, vegetables, nuts, and herbs. Even if you don’t grow these things now, it’s smart to maintain your garden to this standard for future uses.

Because I don’t know what’s in a lot of cardboard, I stick to using plain, brown cardboard without any glossy surfaces or printing.

How many layers of cardboard should I use?

In most instances, one layer of cardboard is sufficient. You want it thick enough to block light and last long enough for the grass to be eradicated, but not so thick that it will take years to break down.

Can I use this method to prepare raised beds?

Yes, the cardboard method works nicely for raised beds. It’s the same steps used for preparing open, in-ground garden beds. Line the bed with plain cardboard, dampen it, add 6-inches (or more) of good quality soil, compost, or other organic mulch. Several months later when the cardboard has rotted and the grass below is gone, it’s planting time.

When is the best time to do this?

You can start this cardboard method any time of year other than when the ground is covered in snow. All you need is grass lawn—mowed down as low as your mower goes, a bunch of plain cardboard sheets, and compost or other soil amendments.

No matter when you start, it will likely take several months for the new garden bed to be ready for planting.

Will roots grow through the cardboard?

It’s possible that any strong roots might grow up through the cardboard, especially those from nearby trees, shrubs, or vines. Some extra resilient weeds may also survive the process and need to be removed with a shovel, getting every last bit of roots out of the ground.

Does cardboard make a good mulch?

Some gardeners have had success using cardboard as a mulch, but it’s not something we’d recommend as a long-term mulch in garden beds.

While cardboard can suppress weeds, it also creates a barrier blocking or reducing how much water, air, and other gases may move freely between the soil and air. This means any plants growing nearby may struggle to get what they need and soil health could be compromised.

Knowing the cardboard method does a good job getting rid of grass, it doesn’t seem like the best idea to place it around plants we do want to grow.

Landscape fabric doesn’t work either—in the long run—because either it’s too flimsy to do the job or so thick it too smothers the soil below. Weeds also like to grow in it. Plus, it’s synthetic which means it has to be removed at some point to avoid polluting the soil.

A better option is to add a few inches of an organic mulch like shredded tree bark to suppress weeds while maintaining soil and plant health.

Can I use wrapping paper instead?

Again, we don’t know. There are countless types of wrapping paper and how they decompose in garden beds or compost piles has not been studied.

If it’s plain, unbleached paper without colorful printing or a glossy surface, like brown kraft paper, it’s probably a good candidate both for the compost pile (shredded) or used several layers thick to create a new garden bed.

Most wrapping paper, however, doesn’t really seem that earth-friendly.

How To Remove Grass Lawn With Cardboard or Newspapers

Unlike “lasagna gardening” where many different layers of organic materials are added, the cardboard method is much simpler. It just uses cardboard with a soil amendment on top and fits in nicely with the no-dig approach to gardening.

Measure

The first step is to measure your new garden bed space and estimate how much coverage you will need. You will need to overlap each cardboard sheet by several inches to ensure no light gets through.

If using newspapers, use at least three layers—the thicker it is, the longer it takes to decompose but the better it will be with persistent weeds.

Prepare Materials

Gather and prepare your cardboard or newspapers.

Flatten boxes.

Remove any tape, staples, labels, stickers, and so on.

Prepare Lawn

Mow lawn as low as possible in the new garden bed area.

Add Cardboard & Mulch

Place cardboard on the freshly mowed grass, overlapping each piece by several inches.

Water cardboard until damp, not drenched.

You can add a top dressing now or later. Adding it now helps hold the cardboard in place for the months to come. Now or later, you’ll need approximately 6-inches of some combination of compost, shredded leaves, or other organic mulches—whatever your outdoor plants will like.

Our soil calculator can tell you how much you need based on the size of your new bed.

Alternately, you can hold cardboard in place with landscape staples or rocks. If you use staples, have a plan for removing them later.

Each week, make sure everything is snug in place. Water the area as needed during dry spells.

Depending on the materials used, amount of rain, and how persistent your grass lawn is, it will take weeks or months for the grass to disappear.

When the cardboard has vanished and the grass is gone, top up the new garden bed with compost (or other soil amendments) as needed and start planting.

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~Melissa the Empress of Dirt ♛