Im not going to lie, i'm a strong advocate of sheet mulching, also known as the lasagna method. Throughout the years working here at Roots of Change Garden i've sheet mulched every area at least twice over. Its a great method to build up soil in a possibly contaminated urban environment as well as using organic resources readily available for free instead of spending the whole budget on buying soil. We also have a lot of thick clay topsoil in our area which is not bad, but not great for plants due to its poor ability to retain water and to allow roots to move freely through it. Even slightly increasing the organic matter of soil can dramatically increase the water holding capacity of that area, which is a major necessity in our region. Sheet mulching is basically horizontal composting over large area. A simple google search will reveal many different debates over the perfect things to add into which layer but the general concepts is to layer various thicknesses of Carbon based materials (Browns) with Nitrous material (Greens), so don't feel tied down to one specific way. My method is always following these guidelines but applying which ever materials I can get access to at that time.
Here is my most often used example:
And here is what I mean when we say browns and greens:
So the method of applying these layers is quite simple:
Step 1) Cut grass and weeds and low as you can to the ground surface (at this point you can also apply a black plastic tarp over the area for several weeks to completely kill the roots system of the grasses and weed seeds, but its not necessary)
Step 2) Add any soil amendments, like blood meal or bone meal, or fresh raw (un-composted) manure or fresh raw kitchen scraps. Disclaimer: Fresh manure or kitchen scraps need to be as close to the bottom layer as possible to allow them the time to fully compost before plant roots access them(
Step 3) Add water. It is important to add water in each layer because the microbs, bacteria, and fungi that were hoping to bring into the system thrives best in moist environments.
Step 4) Lay down the cardboard/paper. The most important part of this step is to make sure each seam on all four sides of the cardboard is overlapping 6 inches - 1 foot. This is because this layer acts as your biodegradable weed barrier that smoothers and seals away sunlight. depending on time and preference you can also remove any staples or tape you find because these will not decompose, easiest way is to wet the cardboard to remove the tap or tear out the whole corner or edge that contains the staples. For these reasons its best to find cardboard that is as large of sheets as possible with as little tape or staples as possible. I always go straight to the furniture and mattress outlet store's dumpsters to find these massive sheets! Don't forget to add water to this layer! Water can help wet the cardboard and make it lay flat to the ground and lay down the seams tighter as the next layers get added on top.
Step 5) Add a thick carbon, brown layer. This layer is thicker than the other layers because composting works best with more carbon based material than nitrogen based material. My most used carbon layer is dried leaves or wood mulch. In the urban environment and age of grassy front lawns, allows the ability to drive around and collect the paper or plastic bagged up leaves from the season right on the sidewalk. The best bags are leaves that have been shredded already, bagged in paper bags (use the paper in the cardboard layer below), or don't contain a lot of grasses or trash. If you' re familiar with hugelkultur (adding wood), you can add this between step 4 and 5.
Add water to get the break down process going!
Step 6) Add already composted compost. Were talking about compost that is broken down and starting to look like soil. This compost is like your match to the whole bon-fire. This layer introduces the existing microbs, bacteria, and fungi that has already been at work composting, and adds them right into your new bedding.
Step 7) Optional: you can add one more additional layer of "Garden soil mix." Often, these mixes already contain levels of compost in them and do have their own collection of microbs, bacteria, and fungi, but often these mixes also have some level of sand that is helpful for drainage and grit for the worms to digest. These two last top layers of compost and soil allow you to plant directly in the area as the sub-layers start to break down throughout the season adding nutrients and the "living soil" aspect.
Step 8) Add top dressing fine mulch. If you are not planning to sow seeds directly in the top layer then you can add mulch on top to cap off the whole system. Whether you are adding transplants now or later you can still add mulch now. Mulch is key in our drought like region because it helps retain the water that is in the soil as well as protect harsh heat and light from getting down into the layers with the microbs, bacteria, and fungi. They don't like the sun at all and we want them to thrive, because they are the most important part of this system.
*** If you are just planning on making a pathway / walkway, or even trying to get rid of grass while increasing the water holding capacity of the soil without planning to plant into it any time in the next season, then just follow steps 1-5. Often the most simplest way is to cut the grass, lay down cardboard, overlapping well, and adding a thick layer of mulch (2-5 inches thick).
*** Mulch is free from the city here:
The Bitters Brush Recycling Center (northeast)1800 Wurzbach Parkway, 78216Nelson Gardens Brush Recycling Center (southwest)8963 Nelson Road, 78252
more info here: https://www.rootsofchangecoop.org/single-post/2017/02/07/Free-Mulch-provided-from-the-city