By: Anne Baley
Starting a garden from scratch can involve a lot of backbreaking labor, especially if the soil underneath the weeds is made of clay or sand. Traditional gardeners dig out the existing plants and weeds, till the soil, and amend it, then put in plants for landscaping or food growing. There’s a smarter way to do this, and it’s called sheet composting or sheet mulching.
What is sheet mulching? Keep reading to learn more about sheet mulch gardening.
What is Sheet Mulching?
Sheet mulching involves the layering of organic materials, similar to lasagna gardening. Different layers of ingredients are placed on the ground in layers, much like building lasagna in a pan. The layers turn the existing weeds into compost and add nutrients and soil amendments to the dirt underneath, while allowing a first year’s planting to start your garden. Save time and effort by using sheet mulching when converting a grassy space into a new garden bed.
How to Use Sheet Mulching in the Garden
The key to sheet mulching is building up the layers to create a complete compost heap in one flat space. Accomplish this by layering materials with different chemicals to offer, such as nitrogen or potassium. Start the process by removing as much of the old grass as possible. Mow the yard at the closest setting and remove the clippings, unless you have a mulching setting on your mower.
Top the grass with a 2-inch (5 cm.) layer of compost. Add the compost until you no longer see any grass blades. On top of the compost, layer the grass clippings and more green waste to a depth of 2 inches (5 cm.). Water well until the entire bed is soaked.
Cover the green clippings with a layer of newspaper or cardboard. If using newspaper, make it about eight sheets thick and overlap the sheets so that the paper completely covers the entire garden bed. Sprinkle water on the newspaper or cardboard to help keep it in place.
Cover the paper with a 3-inch (7.5 cm.) layer of compost. Cover this with a 2 to 3 inch (5-7.5 cm.) layer of wood chips, sawdust, chopped tree prunings, or other other organic mulch.
Nestle larger plants or smaller seedlings in the mulch. The roots will grow down through the mulch and grow well in the compost below, while the compost and clippings underneath the paper will break down the grass and weeds, turning the entire plot into a well-drained, moisture-retaining bed.
That’s it. Quick and easy, sheet mulch gardening is a great way to grow gardens organically and is a common method applied to permaculture gardens.
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Which Sheet Mulching Materials AreSuitable For A 'No Dig' Garden?
The technique of sheet mulching is used in 'no dig' or 'no till' gardening. You can choose from a wide variety of sheet mulching materials according to personal preference and availability.
The important thing is to combine them in roughly the right proportions.
Think of your no dig bed as a long thin compost heap and use approximately the same combination of 'brown', or dry, materials and 'green', or fresh ones as when making compost.
Brown materials are drier than greens. They contain more carbon and break down slowly. Green materials, on the other hand, are moist, nitrogen-rich and decompose quickly.
A ratio of three brown to one green is about right - but you don't have to worry about being too precise.
Many of the materials you can use can be had for free, or at least for very little money. So check out the lists below and look around your neighbourhood for likely sources.
Organic gardeners all know that the key to healthy, vigorous plants is in the soil. Compost maximizes the bio-diversity of soil organisms, which in turn transforms still more organic materials to accessible nutrients for your plants.
Decomposition takes time, so it’s best to sheet compost an area in fall.
Sheet composting, or sheet mulching, is a passive method of composting, and it is done on the site that you wish to enrich. There is a minimum amount of labor required, and the results take time but, as in nature, compost happens – and you will be rewarded with beautiful soil and bountiful harvests!
Sheet Mulching Photo: Kristen Wernick
Sheet composting can be used to create new and fertile gardening sites. Land previously given over to a lawn, or groundcovers, such as, ivy or vinca, or perhaps just assorted weeds, can be reclaimed, with time, by layering materials that will decompose in place.
Before beginning CNPS strongly urges you to test your soil for composition, minerals, and legacy issues (past owners’ soil treatments). Soil tests should assist you in making informed decisions about soil amendments.
When to start
Decomposition takes time, so it’s best to sheet compost an area months in advance. Materials will be decomposed enough to plant in the area the next season by the next year you will not be able to recognize any of the original materials. Given time the layers of paper and organic materials will have smothered the roots of plants previously growing on the site, and decomposed into wonderfully rich and fertile soil.
Quantities listed here will convert an area of fifty square feet. To create fertile soils for California native plants, you will need:
- A 2 to 3 foot stack of newspapers,
- about 300 sq. ft of corrugated cardboard boxes,
- about 1/4 to 1/2 cubic yard of finished all-green compost (compost without animal manures)
- and approximately 5 to 7 cubic yards of bulk organic matter.
This list is meant only to serve as an example if possible recycle what you have on hand, or free materials that can be had for the asking. Neighbors will often save newspapers if you ask for them appliance stores are a good source of cardboard. Cotton fabrics can take the place of some of the paper coffee companies will sometimes give away burlap sacks, and you could also recycle old cotton sheets, towels or clothing.
Lawn clippings, leaves and shredded plant trimmings can be accumulated by your gardeners straw bales are available cheaply if they become wet, and chipper bark is often dumped free of charge by the tree companies. Be sure to ask the tree company what kind of trees make up the chipper bark avoid Eucalyptus, California Bay and Walnut. These trees contain chemical compounds that inhibit plant growth the chipped bark is fine for use on pathways, but not in planting areas. Materials can also be purchased. Corrugated cardboard in large, wide rolls a loosely woven burlap fabric made for landscape purposes, and finished all-green compost.
Water the area well before you plan to start the process. Plants growing on the site will need to be cut to the ground. Don’t remove the cut vegetation the greens will be food for the decomposers. Roots of most weedy plants can be left in the ground, but woody stumps or pieces should be removed. A dryed-out lawn can be left in place sheet mulch right over it.
This is a great opportunity to amend your soil, and increase its fertility with an array of micronutrients. Acid soils can be sprinkled with lime alkaline soils will be improved with a little gypsum or sulfur. Bonemeal and rock phosphate will supply phosphorus, which is essential for root formation, early growth and good seed formation. Kelp meal, greensand, or rock dust all add trace minerals.
If the area is compacted, or you are dealing with clay, take the time to open it up just a bit before you start to mulch. Simply push a fork or spade into the ground and rock it back and forth to open up holes in the ground. Turning disrupts the soil ecology so that is a bit of hard work that is best avoided! One of the very best amendments to apply is rock dust simply sprinkle it liberally over the area.
Apply a thin layer of nitrogen rich materials this can be fresh grass clippings, finished compost, blood or cottonseed meal. This layer will attract the earthworms, burrowing beetles and other invertebrates which will help loosen the soil.
Cover the area with about one quarter inch thick layers of newspaper. Avoid using the glossy pages from the paper, and remove the staples and tape from the cardboard. Overlap the edges by three to four inches, and wet everything down as you work. The purpose of the paper is to create a light blocking layer that will smother the weeds an added benefit is that the worms also love the darkness and moisture that the paper creates.
Add another layer of finished compost or green materials on top of the newspaper, always wetting materials as you build the sheet mulch. All-green compost can be applied in layers up to several inches thick if you’re recycling grass clippings, be sure to spread them out thinly.
Add a layer of cardboard on top of the compost or any other green material. Be sure to remove all the tape, metal staples, or plastic, if you are working with recycled cardboard pieces. Also be sure to overlap the edges liberally, and wet everything down as you work.
Now you are ready to add the carbon-rich mulching materials in a layer up to six inches deep. This can be fresh or spoiled straw (avoid hay, which often contains seeds), stable sweepings (as long as there’s not a lot of manure included), chipped yard waste, deciduous leaves (not live oak leaves), or pine needles or the chipped bark and leaves available from many tree trimmers.
Tip: Sheet mulching can be built up to a depth of a foot or more the top layer should be all one type of material (either straw or chipper mulch) for a tidy and uniform look that you can live with for several months.
Water the sheet mulched area about once a week if the rainy season does not materialize, or if you are not sheet mulching during the rainy season.
Everyone who gardens can compost your plants, and our environment will benefit from it. Organic materials are returned to the earth, building rich and fertile topsoil that retains moisture, warmth, and oxygen. Such healthy soil is the underlying support of the entire web of life, and a resource center for healthy plants.
Starting Seeds in Pellets
|Sheet Compost Slideshow|
This method often utilizes both hot and cold composting systems depending how much and how often material is added to the row. However over time it doesn't matter and the result will still be a rich fertile growing medium for your plants. No need to be in a rush it will be ready when its ready and not before.
For more in the slideshow series go to the Slideshow Library
While it is not necessary it often helps to speed up the process by covering the whole area with black plastic once the last material has been added. This will keep the decomposition process going longer into the colder winter months and regulate the moisture better.
Depending on the materials used and climate, your composting efforts will be well decomposed within 6-9 months from the time you have added the final layer. When the compost is finished dig it directly into the garden area it was composted and plant your crop in the rich organic soil.
Each time we turn the soil, we disrupt billions of bacteria, fungi, insects, worms, and other animals living in the first few inches of earth. The unlucky ones are sliced by the shovel or flipped to the surface where they dry out in the sun and die. Others end up in compacted areas where they die because air and water aren’t able to move through the soil.
The rest of the soil ecosystem has to find balance again. Insects and worms rebuild “homes.” Bacteria reestablish colonies. Fungi regrow mycelial networks.
As if the thought of all that digging and tilling wasn’t discouraging enough!
Sheet Mulching vs Lasanga Gardening
What’s the difference between lasagna gardening and sheet mulching? Here’s a quick look at the similarities and differences.
Let’s start with the similarities. In both, you layer 8+ inches of organic material (such as leaves, grass clippings, manure, wood chips or kitchen waste) on top of the ground. Both can be created on top of existing turf or chopped down weeds. Both include a weed barrier layer near the bottom. The layers decompose and leave behind rich soil.
The term lasagna gardening, coined by Patricia Lanza, describes the layering of organic material in the garden similar to the layers of pasta, meat, and sauce in lasagna. Her recipe includes peat moss as a key ingredient and newspaper as the weed barrier. You can read more about the origin of Lanza’s lasagna gardening here.
Sheet mulching is a term used to describe a thick pile organic matter over a “sheet” that could be overlapping newspapers, cardboard, clothing or carpet. It’s a method taught and used often in permaculture.
Rather than a specific recipe, sheet mulching is a set of loose guidelines. You can use pretty much any type of organic matter, and permaculture teaches us to choose based on what’s available on-site or locally. Sheet mulching calls for at least 8 inches of mulch, echoing the advice of charismatic thick-mulch advocate Ruth Stout.
Whatever you want to call it, and whichever method you want to practice, the results are fantastic soil for your future gardens! If you’d like to try out soil building through layers of mulch, check out our step-by-step sheet mulching tutorial to get started.