When we started our War on Grass™ about a decade ago (I guess the battle began when we officially took ownership of our home) I wasn't entirely sure of the best way to kill the grass. But as we keep taking bigger chunks of turf lawn out to replace them with native plants and pocket prairies, I've learned how to be much more efficient than our initial efforts of using a shovel to dig out sod. Enter the magic of sheet mulching.
For the bigger areas of grass removal, a sod cutter was a lifesaver. I would typically rent the sod cutter for a few days at a time, and many local as well as big box hardware stores have them available. Renting a sod cutter allowed me to make a really even curvy path around the house and to do so as soon as the itch hit me to make a creeping thyme path. For adding our conversation pit and raised beds, the sod cutter made the process relatively quick (weeks instead of months) compared to digging all of the sod out with shovels.
Here's a giant area of useless lawn that doesn't even know it's about to be brutally murdered with a sod cutter.
Poof! The sod has been dug out and replaced with gravel. But uhh, that took a lot of sod cutting time as well as the cost of the rental. And then the weeks of shoveling after to get the remaining chunks of lawn we couldn't get during our short rental period with the sod cutter. Not great!
For most of the yard, and likely for projects going forward, sheet mulching, also known as lasagna gardening, has been way less time-consuming and far less expensive. Efficiency! Less expensive! Adding nutrients back into the soil while subtracting the back pain of digging!
What is Sheet Mulching/Lasagna Gardening?
I generally see the term sheet mulching more often, but as far as I have read, sheet mulching and lasagna gardening are interchangeable. Most simply, sheet mulching is using cardboard to smother all of the weeds and grass and then covering the cardboard with organic material to transform your gross grass into nutrient-rich soil for more productive projects.
We've been collecting cardboard for the past six months with the intention of killing a few more big chunks of turf lawn. (And unfortunately smothering a prairie that included native coreopsis, purple coneflowers and black-eyed Susans in the right-of-way due to a neighbor anonymously complaining to the city about "noxious weeds" that had gotten too tall. No emoji can capture the power of my eye roll, but alas.)
Goodbye, my pocket prairie love. Sadly you will be sheet mulched away due to an anonymous turf lawn-loving neighbor's apparent complaint to the city about your height.
What Do I Need to Sheet Mulch?
First, collect plenty of cardboard. Remove any packaging tape and staples since the layer of cardboard will break down to create your new kickass soil.
Second, organic material. And uhh, that's pretty much it! Organic material is more or less anything that can be broken down naturally. Leaves! Newspaper! Twigs! Sheet mulcher's choice.
Here are some of the organic materials we used to fill up our raised beds before we added compost and soils. We used grass clippings, pine cones, branches and clippings (that had no seeds,) cardboard boxes and pine needles. Anything that will break down naturally should work well on top of your cardboard while sheet mulching.
Here's how we tackled a chunk of land outside of our raised beds in the spring of 2022.
Lay Down Your Cardboard
First, we carefully laid down and overlapped all of our cardboard late winter of 2022. We had a huge, muddy mess around our raised beds from where tomatoes, tomatillos and pumpkins absolutely dominated in the fall of 2021, which means that our cardboard was immediately wet enough to lay flat. If your spot is really dry, you may want to moisten the cardboard so it doesn't blow away and to start the process of decomposition. I wanted to smother all tomato and tomatillo seeds to create a new path around the beds. We extended the cardboard out to the other native plant beds with the goal of adding a little sunflower meadow to hide the potential shame of another tomato takeover from passersby. We did our best to cover everything since the goal of the cardboard is to prevent weeds/grass/unwanted tomato plants to pop up amid the newly created bed.
Oops! All tomatoes in the fall of 2021. And pumpkins. And tomatillos. Maybe need to do a little harsher pruning in the future.
Monster mess in late winter 2022 where the tomatoes had taken over the year prior. No worries, we'll sheet mulch it to smother the grass and tomato seeds.
Sheet mulching step 1: Lay down the cardboard and cover as much as you can to prevent weeds, grass and tomatoes from popping up in your new bed. Be sure to remove all packing tape, staples and any other items attached to the cardboard that you don't want going into your new kickass soil.
Cover Your Cardboard with Organic Materials
Second, we topped everything with leaves collected from around our yard. I do what I can to leave as many leaves as possible for our pollinator and insect pals who are sleeping over the winter, so we usually have more than enough matted up leaves in the spring for projects like this.
Sheet mulching step 2: Cover your cardboard with organic matter. If you leave the leaves instead of raking them throughout the fall and winter, you might have lovely piles ready to go as we typically do.
Cover Your Layer of Organic Materials with Soil and Compost
Third, we added a nice, thick layer of soil mixed with compost that had been cooking in our giant wire composter waiting for its time to shine.
And that's it! A few months after we laid everything down, I transplanted dozens of sunflowers to create a little sunflower meadow next to our new path made of natural gray sandstone and natural gravel.
Sheet mulching step 3: Add your compost and organic soil. For this project we had a whole bunch of old sod that had been cooking for years in our large wire compost bins along with other brown materials, so it worked perfectly to spread that over our cardboard as our final layer.
Our new path is surrounding the raised beds next to the freshly sheet mulched area. The goal is for the path to cut down on tomato plants escaping the beds to help keep them in control. (shakes fist at tomatoes)
Sunflower meadow growing proudly over our new bed thanks to a few healthy layers of sheet mulching with cardboard, leaves and healthy soil.
When is the Best Time to Sheet Mulch?
Any time you're ready to murder some grass is a good time to sheet mulch in my book. It does take a few months for the cardboard to break down, so if you're hoping to plant in the spring it likely makes the most sense to start the process in the fall.
We're now in the middle of winter 2022, and I'm about to lay down another round of cardboard for sheet mulching. I was hoping to time the process around the weather for a window when the ground is frozen so that the right-of-way sheet mulching wouldn't turn into a muddy mess for anyone walking through. Alas, with a temperature change of literally 70 degrees Fahrenheit in Ohio over the past week, I don't think there's a safe bet of when the ground may actually stay frozen this year. (Seriously. In one week we were at -8 degrees and then 68 degrees. YIKES.) I'll likely work on a round of sheet mulching soon and put down some low-growing native seeds so that when people trample around the area they'll push the seeds down into the organic, muddy mess.