Sheet mulching is a dig-free approach to soil prep hailing from the school of permaculture, where natural processes in the garden are favored over gardener manipulation and intervention.

Photo: Greg Luke Smith

The term mulch is nothing new to the experienced gardener. Used loosely, it refers to any top layer of decaying organic matter—whether it be bark, hay or grass clippings—and most good gardeners use it as a protective layer around plant bases to suppress weeds and encourage water retention in the soil.

In a forest, mulch happens in layers as leaves, twigs and branches pile on top of each other. Much like a compost pile, the deepest layer of materials is in the most mature state of decomposition, and is overflowing with microbial and insect life, providing ideal conditions for new plant growth. No one comes in with a shovel or a rototiller to toss the materials around, yet life goes on.

In a bare backyard with few trees to shower mulching material and continue the cycle of healthy soil, sheet mulching aims to mimic this natural process. You’ll have to gather materials and some sweat is still involved, but, if executed properly, an entire garden bed can be prepped in a day. It's ideal for anyone with a troublesome back, and can be done anytime of the year. The following is just one of the many and varied sheet-mulching methods to choose from.

Step One: Don’t weed, and don’t dig.

Photo: Greg Luke Smith

Contrary to conventional gardening wisdom, which calls for the occasional turning of soil, permaculturists argue that such disturbances are, in fact, a source of unnecessary stress for the minimal ecosystem found in your typical backyard. They also lead to drainage problems when the soil underneath the tilled area is left compact and hard. Plants have a hard time penetrating this layer, creating a container gardening affect with growth and drainage issues. Meanwhile, any existing insect and microbial life is disturbed, leading to a setback in the ecosystem.

Also, unless the area contains an invasive and detrimental plant, the existing vegetation, dandelions and all, is valuable green manure. Though it is tempting, weed-pulling robs the soil of the few nutrients it has. Instead, mark off the mulching area with boards or garden fence and run over it with a mower or scythe—or simply grab a friend and trample the area!

Step Two: Apply Nitrogen

Photo: Greg Luke Smith

Though sheet mulching aims to mimic nature, it also caters to gardeners who’d rather not wait months on end for the goods to surface, which is why step two calls for a nitrogen rich starter as the first layer. I used a bagged steer manure from the local nursery, but enriched compost or worm castings will also do the trick. Apply roughly 25 pounds per 50 square feet, or somewhere between two and four inches thick, and water thoroughly. Or, do as I did and sheet mulch in the rain—unintentional on my part, but you never know in Seattle.

Step Three: Suppress Weed Growth

Photo: Greg Luke Smith

This is the step that let’s the gardener get away without weeding. On top of the nitrogen layer, lay down an organic, breathable weed barrier to kill existing weeds and block light that would lead to germination of new weeds. Newspaper, cardboard, natural rug and even old blue jeans are all acceptable materials for the barrier, which rots away in a few short months, feeding the soil as it does. For its local abundance, I used cardboard (two sheets thick), leaving no gaps where weeds, or light, could peek through. It helps to let your chosen material soak in the rain before laying it down, but if that’s not possible in your region, give the material a good soak with the hose once it’s in place.

Step Four: Pile on the Compost

Photo: Greg Luke Smith

Use a fully-finished compost for this layer to ensure that no weed seeds end up on the top end of the weed barrier, and spread it evenly till it’s at least three inches thick. If you have them, you can also add fallen leaves and grass clippings here, as long as you can ensure they are weed-free.

Step Five: The Top Dressing

Like the forest floor, the top layer of the sheet mulch should contain fresh plant parts, such as bark, leaves, wood chips and branches—materials that might as well have just fallen from trees and plants above. Not only will this layer help retain moisture in the soil, but as it slowly decomposes, it will continue to add nutrients. Most recipes call for three inches or more of this top layer.

Photo: Greg Luke Smith

And that’s it! All that’s left is to fill the space with favorable plants and to replenish the top layer periodically. The more crowded the garden, the less opportunity for weeds to peek through once the weed barrier has decomposed, so seed liberally. The proof is in the yield. My long neglected backyard is now happily growing carrots, scallions, green peppers, orange bell peppers, four kinds of tomatoes, kohlrabi, corn, beets, sunflowers, cucumbers, zucchini, summer squash, fennel, beans, peas, lettuce, broccoli, cauliflower and kale—all without lifting a shovel, and only occasionally pulling a weed. A gardener could get used to this.