Lasagna Gardening: Build Soil and Get Rid of Weeds

Healthy topsoil, or humus, is necessary for growing healthy plants. However, topsoil takes dozens of years to naturally accumulate through the slow decomposition of leaves and other organic material. For people who don´t have the budget to buy those overpriced bags of garden soil sold at hardware stores, lasagna gardening is a quick and efficient way to quickly build the healthy soil you need for your garden. You can build your lasagna garden quickly and efficiently through using readily available, organic materials that are often considered waste by others.

How Top Soil Forms

The acclaimed agrarian writer, poet, and farmer Wendell Berry once admonished humanity in one of his poems to “Put your faith in the two inches of humus, that will build under the trees, every thousand years.”

We don´t often think of the idea of hope in terms of the black soil underneath our feet, but perhaps a necessary sense of humility is urgently needed. Our anthropocentric hubris has led us into believing that we have sufficient technological prowess to control whatever ecological mishaps our excesses may entail. Our industrial lives are lived so quickly and chaotically that we have lost all sense of natural time. Topsoil forms at the rate of a couple of inches per century. We use it up in the short span of just a few harvests. We got around this problem in earlier times by moving farther out onto the frontier, pillaging lands from cultures who had learned to coexist with the natural rhythms of nature and exploit that land until its fertility was also lost.

Topsoil forms from the accumulation of leaves, fallen branches, the dead bodies of insects, and other organic material that is slowly broken down by a community of billions of unseen workers. Healthy topsoil is never a finished product, but rather a continual creation that stems from relationships of mutual benefit from organic material and the microscopic soil life.

Building a Fertile Garden on Top of an Abandoned Parking Lot

Despite the massive loss of topsoil caused by bad land management practices and the encroachment of human disturbances upon healthy ecosystems, there are ways to create the conditions quickly and efficiently to allow for soil to build faster than at the natural pace of the natural world.
One of the guiding principles of permaculture is the idea of “accelerated succession.” This principle considers that through proper observance of the natural processes that allow for overall systemic health, it is possible for humans to intervene in the natural world in ways that allow for a quicker recuperation of the health and resiliency of the ecosystem.

Given enough time, an abandoned parking lot in some downtrodden inner city will eventually return to nature. It may take hundreds, or even thousands, of years for the natural processes to retake control over the urban concrete jungles, but nature will eventually prevail. The concrete will crack, seeds will blow in from some distant forest or be brought on the feet of birds and eventually plants and even trees will begin to appear in those cracks.

As leaves fall from the quick growing pioneer species of trees, our abandoned parking lot will soon be covered in abundant organic matter that will eventually decompose into the beginnings of a healthy top soil.

The problem, of course, is that our human society doesn´t follow the same timeline as the natural world. While Nature may not be in any sort of hurry to fix the abuses of our industrial society, we still need to find ways to sustainably provide our species with the food it needs while not obliterating the overall ecosystemic health of the places where we live. The principle of accelerated succession would have us find ways to mimic the natural processes of soil building, but do so in a way that allows for soil to build up in a swifter and more efficient manner.

What is a Lasagna Garden?

Lasagna gardening, also known as the sheet mulch method, is a way to apply the principle of accelerated succession to the creation of healthy top soil. Not only will the creation of this top soil improve the resilience of the natural world, it will also allow us to reap more abundant yields for our sustenance.

To begin a lasagna garden, it´s usually best to find a healthy supply of cardboard, newspaper, or some sort of other thick, organic-based material. This material will smother out the other weeds or undesirable undergrowth before eventually decomposing. On top of this initial layers, the “sheets” or subsequent tiers of materials are arranged so as to create a gigantic compost pile in place that will break down quickly into a fertile humus. There is no universally agreed-upon recipe for the layers that should make up a lasagna garden as the materials will largely depend on what excess organic material you can find in your region.

A general rule of thumb, however, is to layer “brown” materials, or carbon-rich materials with “green” materials that are high in nitrogen. Brown materials can include dried leaves, hay, straw, wood chips or other residues from your garden and yard. Green materials include fresh grass clippings, kitchen waste, and animal manures. The mixture of carbon and nitrogen materials will begin a composting process.

Here’s a lasagna garden how-to:

– First rough up the soil where you plan to place your garden bed. This can be done with a shovel or spade.
– Next, lay down a double layer of thick cardboard.
– On top of the cardboard, lay a 1-inch thick coating of a high-nitrogen material such as chicken, cow, or horse manure.
– On top of that layer, place 3 inches of straw or shredded leaves.
– Depending on the amount of organic material you have available, continue to layer one-inch stratums of nitrogenous material with 3 inches of carbon-rich material.
– On the top, lay a 1-2-inch-thick mat of compost or decent soil and cover with a thin layer of mulch.
– You can then directly plant seeds or seedlings into the compost layer. As the plants grow, their roots will reach into the decomposing layers of the lasagna garden bed.

After your first growing season, your lasagna bed should have decomposed into a several inch thick bed of rich, fertile soil.

Benefits of a Lasagna Garden

The most obvious benefit of lasagna gardening is that it allows us to create the needed conditions for soil creation in a time frame that suits our human purposes. At the same time, however, a lasagna garden also helps the natural world to regain its resiliency and overall health. Imagine the typical suburban front yard. After years of growing a monoculture of green grass that was managed with extensive chemical applications, the soil underneath that shiny green exterior is most likely compacted and devoid of any sort of soil organisms. A few lasagna garden beds placed throughout the yard would speed up the natural process of soil building.

As certain areas of the soil regained their natural health, the increase in beneficial soil organisms would slowly start to move into other parts of the yard. Earthworms would begin to migrate out of the lasagna garden beds and into the hard, mistreated soil beneath the lawn. Over time, the entire landscape of that abused front yard would gradually begin to revert back to a thriving soil system capable of supporting much more and diverse forms of plant life.

While there are no panaceas to help us “fix” the mess we have made of the world, following the principle of accelerated succession concedes us the opportunity to help the natural world recover more quickly. A few lasagna beds scattered throughout our yard will not only increase the yields of vegetables, fruits, flowers, or other things we grow, but also help to speed up the resurgence of an overall healthier ecosystem.