My family recently purchased 20 acres of raw land in Northeast Missouri on which we are building a food forest and organic gardens. I aim to grow most of my family’s fresh vegetables during the summer months, and to preserve food for the next winter.
The sheet mulch technique mimics the processes of nature: in a healthy forest, a litter layer of fallen leaves, twigs, branches, and decomposing plants creates a moist, weed-free environment that is teeming with microbial life. Similarly, by layering carbon and nitrogen-rich organic materials and allowing them to compost directly in the beds, a sheet mulched garden will enjoy enhanced moisture retention, weed suppression, and over time, improved soil structure. Best of all, sheet mulching creates garden space with no tilling or digging!
Why sheet mulch?
Sheet mulching is relatively inexpensive and can turn an otherwise undesirable area into a garden. If you have a large backyard, imagine turning a corner of your lawn into a space to grow food! For those of us with heavy clay soil, sheet mulching spares the backbreaking work of digging or turning the soil. Sheet mulching is also ideal for weedy areas, as the weeds are cut down and left to decompose in place, and then smothered with layers of organic material. Finally, sheet mulching makes use of what might otherwise be considered home yard waste such as grass clippings, leaves, cardboard, and newspaper, and diverts these materials from landfills into lush, bountiful gardens.
Sheet Mulch Basics
Creating a sheet-mulched garden is very similar to making lasagna – layer, layer, layer. In fact, some people call this method “lasagna gardening.”
It can be done with a wide variety of organic materials, some of which are likely available for free or cheap: straw, hay, leaves, wood chips, saw dust, manure, stable bedding, compost, food scraps, cardboard, newspaper, or grass clippings.
1) Get yourself some big old piles of organic matter!
Sheet mulching uses an incredible amount of organic materials, so plan accordingly.
For our sheet mulch project, my family purchased an enormous straw bale, but we were able to source free topsoil, sawdust, finished compost, and unlimited horse manure from a local university farm.
If you don’t have immediate access to a large amount of materials, you can sheet mulch over time; many years ago, I sheet mulched a new garden space over the course of several months and simply added leaves, food scraps, manure and grass clippings as I acquired them.
2) Prepare the earth.
To begin, first cut down weeds and tall grass in place and leave them to decompose.
If you want to add any soil amendments, such as lime, rock dust, kelp meal, or wood ashes, go ahead and sprinkle them right on top of the cut grass.
Some gardeners will also recommend also opening up the earth a bit by inserting a digging fork and rocking it back and forth before pulling it back out, but quite frankly, I skip this step completely. Finally, spread a thin layer of a high nitrogen material such as manure or grass clippings to accelerate decay of the weeds and grass and to stimulate soil life. Wet this layer thoroughly.
3) Establish a weed barrier.
Next you will lay down materials to smother any emerging weeds. I like to use cardboard or a ½ inch thick layers of newspaper as a base layer, but other acceptable materials include burlap bags, paper sacks, or cotton or wool clothing. Be sure to remove any packing tape or plastic from your cardboard, as these will not decompose.
As you fill your desired garden area with cardboard, overlap the edges by at least six inches to assure that weeds will not find their way through cracks.
Again, wet this layer thoroughly.
4) Layer your organic materials, watering as you go.
It seems that every sheet mulch enthusiast has their own preferred methods of layering organic materials.
I chose to imitate lasagna’s layers of sauce and cheese and alternated three-inch layers of wheat straw with composted horse manure. Continue layering your organic matter until you create a thick layer of materials; my beds are about 12 inches tall.
Remember that your layers of straw, hay, leaves and manure will compost over time and will shrink considerably!
5) Top it off.
If you plan on seeding or planting into your sheet mulch beds right away, make your final layer approximately three inches of finished compost, or compost mixed with soil.
If you are preparing your beds in advance, for instance in the fall, then you can finish with manure. Top off the pile with a weed free layer of straw, sawdust, leaves, or wood chips – something that will hold moisture and prohibit weeds.
6) Plant! Now you are ready to plant directly into your new garden. Simply move aside the finish layer of straw, sawdust or wood chips and plant into the compost layer below. My personal experience has been that root crops may not flourish in a first year sheet mulch bed, but once your pile of straw and manure decomposes into rich, dark soil, and the cardboard or newspaper breaks down, plants with long taproots will penetrate the soil below.
After weeks of hauling and layering materials, my sheet mulch garden is almost complete.
If I reach down deep into the layers, I feel the warmth of decomposition.
Already we have planted onions, arugula, potatoes, corn, and some flowers into the beds.
Next spring, we will have a garden replete with rich soil, earthworms, and microbial life, ready for another year’s bounty.