The practice of lasagna mulching — also called sheet composting — has borrowed language from housekeeping to describe a kind of slow gardening. I’m partial to the Italian flavor of the first title. In the long run, lasagna mulching makes vegetables taste better because it amends and creates nutritious soil. Indeed, lasagna mulching makes a new and better bed for anything we plant. It’s an excellent method for starting a new garden bed on a lawn. You’ll hear it called “sheet composting” because it’s a form of cold composting. It gets rave reviews because it caters to what all gardeners like to do best: watching and waiting as plants grow and thrive. Only in this case, we’re first watching soil grow and waiting a few months to add seeds or plants to a newly-rich earth. If you’re in a hurry, lasagna mulching is probably not for you; but the benefits of starting a bed for vegetables or ornamentals with this method usually outweigh the inconvenience of delays. Fall is a great time to start sheet composting for a new bed, since it will probably be ready by spring planting time, though you can start any time of year.
The fancy definition says lasagna mulching is a cold composting method used around the world for generations in order to convert green and brown organic material into vegetable or ornamental beds. It improves soil and recycles waste. The basic components are nitrogen (N), carbon (C), oxygen (O) and water (H2O) — all proportioned to break down organic matter into good soil. Oregon State U.Ext.Gardening Techniques.
Benefits. The advantage to the gardener is that cold composting requires less work and expertise than “hot” composting. Although termed “mulching,” it’s unlike mulching intended to conserve moisture around a plant because it actually creates a new bed in a place we plan to use later for growing something, in a few months to a year. The process will suffocate grass and most weeds, so you can start a new bed without digging. We can size our new bed as small or large as we have materials and space. It’s cheap, requiring few tools and minimal labor. Most of the materials are stuff we need to get rid of anyway and would rather avoid sending to the landfill. The real payoff is the advantage to the garden itself. The end product is better soil; better texture that is friable, meaning right size particles that retain water and cohere without packing. It’s a better substance filled with more of the living organisms (fungi and bacteria) that attract worms to “work” the ground so that it can become almost no-till. It’s a better way to amend the red clay of Piedmont Virginia. It will have fewer weeds and more of the trace minerals not easily obtainable in commercial fertilizers. One teaspoon of good quality soil contains more living organisms than the number of people living on earth today! Soil Health Nuggets/USDA.
The Recipe: As with any composting, the basic recipe is 2/3 brown material (carbon) and 1/3 green material (nitrogen) mixed with enough water so that the whole mess is like a squeezed-out sponge. Too much water makes a soggy, smelly mess. Too little water dries out the pile and stops decomposition. Part of the wonder of lasagna mulching is that proportions for cold composing don’t have to be exact. Indeed, some experts recommend using equal proportions of brown and green material. Of course, if you’re trying to make a hot composting bed, that would require a more exacting mixture, using the 2/3 to 1/3 formula. The finer your pieces of brown and green material, the more surface area they will have to decompose more quickly and completely. But unless you have the means and time to chop things up into small pieces and carefully water, just relax and let nature do most of the work.
The Steps to Success:
Lasagna mulching requires months to finish and a considerable amount of material. Therefore, you will want to estimate in advance how much of these materials you can scrounge for free or buy over the months it takes to complete the composting process. Your raw materials will be:
- green matter (grass clippings, weeds without seeds), kitchen scraps (except no meat or grease), peat moss, worm castings, and manure (except no pet waste);
- brown matter (coffee grounds, spoiled hay, tea bags, nut shells, hair, newspaper and cardboard, wood chips, sawdust, and a few wood ashes); and
Remember that some coffee shops will save their coffee grounds for gardeners; many people are happy to give away cardboard or newspapers; and some barns will give away manure. Fresh manure composts better than the bagged manure sold in stores. Fall is an easy time to collect leaves, which you can break down by running over them with a mower, an especially easy process if you have a mower that bags the clippings. Grass (N) and dead leaves (C) mown and bagged together make a great start for this project. Never use walnut wood chips or sawdust from treated lumber. Diseased vegetable vines, especially from tomatoes, or leaves and hay sprayed with herbicide are not appropriate fodder for lasagna mulching.
1. Outline the space for the new bed. The final product will be at least one to three feet high, so you may want to contain the bed with large rocks or a wood frame.
2. Begin by scalping the ground with a mower by setting the blade very low to cut whatever is growing right at the ground. You may want to dig up long roots. Being lazy, I’m taking my time by covering the space with black plastic to cook live plants to death over summer so I can plant in fall. See photo where I have just started a bed. Know that some roots are deep enough to sprout anyway (e.g., dandelion, wire grass) and some seeds can lie dormant for years.
3. The first layer will be brown carbon material. Four to six layers of newspaper or a single piece of corrugated cardboard (thank you, home delivery). Plastic tape is best removed. Wet this layer thoroughly.
4. The next layer will be green nitrogen material (grass clippings, kitchen scraps, etc.).
5. The third layer is brown, trying to add a little more than twice as much brown as the amount of green in the second layer. This gives roughly 2/3 brown carbon to 1/3 green nitrogen. Proportions need not be exact since this is cold composting.
6. Next layer is green.
7. Continue to alternate layers, roughly in these proportions, until the pile is about 18 inches to 3 feet high, sprinkling water whenever the pile begins to dry out.
8. Your last layer should be brown carbon material, which you may cover with chips, burlap or an old cotton sheet to keep it together, especially in windy weather.
Finishing. When the bed is about a foot or so high, there are several options to consider. Plan on three to six months as the minimum time to wait before planting. The higher you build your lasagna bed, the longer it will take for you to build and for the bed to build good soil. Turning the material every so often hastens the process of breaking down the raw components into the final product. If you need to plant immediately, you can add a few inches of topsoil over the bed for seed or for setting out seedlings. Over time, the newly planted garden bed will sink; and you will have to water regularly any plantings on top since the lasagna layers underneath dry out more quickly. If you can stand the wait, simply water the lasagna mulching bed from time to time until the material settles and the new soil crumbles easily in your hand. Then, remove any stems or twigs that failed to disappear and fill your new bed with stuff that grows better than ever. Some gardeners find the lasagna bed takes a year or more to reach peak performance.
Rest easy, knowing you have partnered with a natural process to make a better earth.
“Sheet mulching — aka lasagna composting — builds soil, saves time,” Oregon State U.Ext.Gardening Techniques
Lasagna Gardening: A New Layering System for Bountiful Gardens: No Digging, No Tilling, No Weeding, No Kidding! ( Patricia Lanza, Rodale Press, 1998)
“Sheet Composting,” Univ.Nebraska Ext. Lansing County
“Lasagna Gardening,” Clemson Univ.Coop.Ext. Clemson Home & Garden Info.Center
“Lasagna Gardening,” Univ.Cal./CalaverasCountyMasterGardeners
“No Dig Garden Beds,” Univ.of Fla./lawn-and-garden/no-dig-garden-beds/
“Backyard Composting,” Va.Coop.Ext./HORT-49-PDF
“Gardening Tips: Lasagna Compost,” Marin Master Gardeners, Univ.Cal.Agr.&Nat.Resources, ucanr.edu/sites/MarinMG/?story=662