Mulching is mulching, right? Well, not quite. Sheet mulching is an easy, natural method of getting rid of grass and weeds by layering different mulches to block sunlight. It takes patience and some sweat, but it’s an inexpensive, eco-friendly alternative to aggressive tilling and sod-cutting.
Let’s walk through what sheet mulching is and how to sheet mulch your lawn in nine simple steps (no linens required!).
- What does ‘sheet mulching’ mean?
- When to sheet mulch
- Where to sheet mulch
- What you need to sheet mulch
- How to sheet mulch, step by step
- Benefits of sheet mulching
- Disadvantages of sheet mulching
- FAQ about sheet mulching
- Giving your lawn a comfort blanket
What does ‘sheet mulching’ mean?
Don’t rush out and buy a silk blanket for your lawn. Despite the name, sheet mulching (AKA sheet composting) doesn’t involve any bed sets. It’s a permaculture technique of smothering grass and weeds by layering paper, cardboard, and other organic materials over a portion of your lawn that you want to change.
Sheet mulching is a way to build nutrient-dense topsoil from the ground up. Layers of mulch block sunlight from reaching existing plants and seeds, and they improve soil quality while they’re at it.
Sheet mulching is a popular option for homeowners who want to replace their old, thirsty grass with a fresh garden or drought-friendly xeriscape.
When to sheet mulch
While you can sheet mulch at any time of year, it’s ideal to sheet mulch in fall. This gives plants the entire winter to decompose, so you can spring into spring with a fresh planting area filled with nutrient-rich material. If you sheet mulch in October, your garden should be ready for planting in April.
Alternatively, you can sheet mulch in middle to late spring when weeds like crabgrass are becoming a menace.
It generally takes five to six months for sheet mulching to work its magic, but depending on your mulch type and height, it could take as long as a year. It’s a long wait, but the result is a weed-free area that’s ready for long-term planting success.
Where to sheet mulch
Sheet mulching is especially useful for areas with persistent weed problems that need a full makeover. However, it also can be performed on a generally weed-free zone that needs healthier soil for the plants you want to grow.
Framed, raised beds and new garden beds benefit from good sheet mulching. If you prepare them in the fall, they’ll be ready to give plants a nutrient-rich home in spring.
Sheet mulching is the first step to getting rid of your old lawn, or a portion of it, and replacing it with something more sustainable (like a rock garden or rain garden).
For homeowners in California and the Southwest, sheet mulching holds financial appeal: Local governments have begun offering rebates and financial incentives for those who replace their green lawns with xeriscapes.
What you need to sheet mulch
- Biodegradable weed barrier (newspaper, cardboard, or both)
- Lawn mower
- Soil test
- Compost or manure
- Brown mulch like straw, pine needles, or shredded bark
- Spading fork
- Garden knife (optional)
- Small plants (optional)
Pro Tip: Mulching on a budget? Your local recycling center is a great resource for free cardboard boxes, and you can ask your neighbors to save newspapers for you.
How to sheet mulch, step by step
Sheet mulching means you’ll add layer upon layer of different mulches: First a light layer of green or brown mulch, then cardboard or newspaper, then compost, then a brown mulch. It’s like cooking a delicious lawn lasagna (hence its nickname, lasagna gardening). Follow these 10 simple steps to get your lawn cooking.
1. Test your soil
Test your soil to see what soil amendments and fertilizers it needs, so you can give your new growing area a healthy start. Call your local cooperative extension office for information about soil labs near you.
2. Mow low
Mow the area you want to sheet mulch on the lowest mower setting. For healthy grass, this is something you do not want to do. But here, the goal is to stop your grass from growing, so you want to scalp it. Don’t remove fresh grass clippings: They’ll serve as natural mulch.
Pro Tip: Flag or mark sprinkler heads before you mow to prevent accidental damage.
3. Weed it out
Some heavy-duty weeds (like blackberry, oxalis, thistle, and bindweed) won’t respond to sheet mulching, so you’ll need to remove them individually, either manually or with a shovel. Clear out any twigs or rocks so your soil surface has strong contact with the mulch.
4. Open the soil
If your soil is compacted, now is the time to gently aerate to give it an oxygen boost. Push your spading fork into the ground and rock back and forth to loosen the soil and create holes for nutrients to enter. Dealing with poor soil? Sprinkle rock dust (pulverized silicate rock rich in calcium, magnesium, potassium, and phosphorus) over your area for a quick nutrient lift.
If you’re planning to plant bigger plants (in 5-gallon or larger containers), this is your moment. You won’t want to dig through a thick layer of mulch to plant them later on.
Pro Tip: Turning your soil may seem like the perfect way to help your lawn, but resist the urge to flip it. Tilling or turning your soil with a shovel will disrupt the soil ecosystem.
5. Add a thin layer of mulch
Before blanketing your area with newspaper or cardboard, spread a thin, 1-inch layer of compost, cottonseed meal, shredded leaves, or straw. This first layer of organic mulch will attract earthworms and other beneficial insects that help aerate the soil.
Use your rake to gently even out the mulch.
6. Water thoroughly
Soak this layer and the ground beneath it with water to start the decomposition process.
7. Spread newspaper or cardboard
Spread layers of newspaper or cardboard over your area, overlapping the edges by 6 to 10 inches so that no sunlight makes its way to the ground underneath. Wet the newspaper or cardboard with water using a sprinkler or hose. Water sets the weed barrier in place and speeds up the decomposition process.
- If you’re using newspaper, it should be 8 to 10 sheets thick (about a quarter of an inch).
- If you’re using cardboard, it should be one to three layers thick to prevent holes from forming.
Holes allow light to penetrate to the soil surface, which encourages weed growth. Remember, this layer is all about smothering weeds and grass so they won’t grow again.
If you’ve planted larger plants, keep their root areas free from newspaper and cardboard so they can get nutrients from the air and soil surface.
Pro Tip: Remove tape from cardboard, staples from magazines, and glossy pages from newspaper ads before you lay them out. They often aren’t biodegradable and can harm your plants.
8. Add compost
Using a wheelbarrow and a shovel, cover your weed barrier layer with a 2- to 3-inch layer of compost or manure. Spread it evenly across the top of the cardboard or newspapers. This nitrogen-rich “green layer” is the secret ingredient to fast decomposition and healthier soil.
Pro Tip: Don’t want to pay for compost at a garden center? You can easily make your own compost at home with table scraps and lawn waste.
9. Spread brown mulch
Now that your compost is in place, spread a 3- to 4-inch layer of organic material like wood chips, pine needles, sawdust, or shredded bark. This is the carbon-rich “brown layer” that feeds beneficial microbes, acts as a soil insulator, and prevents compaction. Spray the layer with water to settle it.
If you stop here, your newspaper, compost, and mulch layer will stand 7 to 9 inches tall. However, you don’t have to brush off your knees just yet. If you want a higher garden bed, you can repeat the layering process and build a sheet mulch bed up to 3 feet tall.
Just note that the more mulch you have, the longer it will take to decompose. If you want a nicely decomposed, weed-free area in five months, you won’t want a 30-inch layer of mulch.
Pro Tip: Make sure there are no sneaky weed seeds in your mulch. Straw often contains extraneous weed seeds, so use high-quality straw from a trusted provider.
10. Wait and water
Water the sheet mulched area with about an inch of water weekly. Your sheet mulched area is ready for planting when the layers have decomposed to the point that you cannot distinguish the old lawn from the mulch: It all looks like one fresh, fertile space. Remember, this typically occurs five to six months after mulching.
Once your area is ready, pull the mulch back, cut through the cardboard, and dig your plants deep into the soil to ensure that roots make contact with the ground.
Can’t wait? If you want some visual appeal as your weeds and grass decompose, spread 2 to 3 inches of compost on top of your brown mulch and add small plants to your area. Use a gardening knife to cut small holes in the layer of cardboard or newspaper and insert plants. Voila!
Benefits of sheet mulching
✓ Easy way to expand a garden
✓ Sustainable and eco-friendly
✓ Can be done in a large or small space
✓ Uses readily available materials
✓ Natural way to recycle
✓ No heavy-duty equipment needed
✓ Naturally prevents weeds: No herbicides required
✓ Improves soil quality and builds organic matter
✓ Increases soil moisture and water retention
✓ Excellent for establishing a xeriscape
Disadvantages of sheet mulching
✗ Requires patience and planning
✗ A more involved process than cutting sod
✗ Takes months to decompose
✗ Some weeds still emerge and require hand weeding
✗ May need to be repeated in weed-prone patches
FAQ about sheet mulching
Yes, a 3-inch layer of mulch will generally decompose in a year, so it’s a good idea to add mulch yearly to continuously prevent weeds. Break up compacted mulch before applying fresh mulch, and be careful not to mulch directly around tree and shrub roots.
Some weeds will make a comeback as birds fly over your lawn and squirrels plant seeds and nuts. Weed by hand or apply an organic herbicide as weeds rear their heads. You also can reapply cardboard and compost over areas with a particular weed infestation.
Don’t worry, it’s completely harmless. Yellow fungus (also known as the delightfully-named “dog vomit”) looks like a neon sponge from outer space, but it’s really just a natural part of the decomposition process. It won’t hurt your plants or your pets.
Compost and mulch are usually measured in cubic yards, and the amount of compost and mulch you need depends on the size of your area.
Calculate the volume of compost you need by multiplying the area (in square feet) by your desired depth (in fractions of a foot), and then dividing by 27.
Let’s say the area of your space is 250 square feet, and you want your compost to be 3 inches deep.
Convert your desired depth of 3 inches to feet.
–3 inches / 12 inches =0.25 feet
–You want your compost to be 0.25 feet deep.
Multiply your area in square feet by your desired depth in feet to find the cubic feet of compost needed.
–Area in square feet x Desired depth in feet = Cubic feet of compost needed
–250 square feet x 0.25 square feet =62.5 cubic feet of compost needed
–You’ll need 62.5 cubic feet of compost to fill your area.
There are 27 cubic feet in a cubic yard, so to convert, divide by 27.
–Cubic feet of compost needed / 27 cubic feet per cubic yard=Cubic yards of compost needed
–62.5 cubic feet of compost / 27 cubic feet per cubic yard=2.31 cubic yards
–You’ll need 2.31 cubic yards of compost.
Repeat this calculation to find the amount of mulch you’ll need. If you want a 3-inch-deep layer of mulch, you’ll need the same amount of mulch as compost.
Unlike silk sheets, sheet mulching can be completely free if you use your own compost and get free mulch from an arborist or tree recycling center. However, if you don’t have your own compost or if you want to spring for higher-quality mulch, you’re looking at a total cost of about $200 to $250 for a 250-square-foot area.
Mulch ranges from $20 to $60 per cubic yard, and compost costs $30 to $50 per cubic yard. Newspapers and cardboard can be purchased or collected on your own to lower the cost.
Giving your lawn a comfort blanket
Sheet mulching may not involve cotton or flannel, but it’s the perfect blanket for your weedy spaces. Plus, it’ll protect the planet: Every acre of turf that is sheet mulched keeps 85 tons of sod out of landfills and prevents the use of 10 pounds of herbicide.
If you’d rather read the newspaper than spread it over your lawn, call a local lawn care pro to vanquish your weeds while you relax and get some shut-eye on your real sheets.
Main Photo Credit: Ryan | Flickr | CC BY-ND 2.0