Sheet mulching (a.k.a. Lasagna Layering) is a technique for building new planting areas through composting in place. It uses gathered materials, microscopic organisms and time to create rich furtile soil. Fall is a great time to sheet mulch because you can use the winter to allow the breakdown of the materials and have a new spot to plant in the spring.
Sheet mulching doesn’t require any weeding or tilling first. The mulching process kills back weeds and keeps the soil ecology undisturbed. You’ll find the biggest job involved with in-situ mulching is gathering the materials. It’s a good idea to have all the materials you need on hand, and then just go for it.
The balance of Carbon to Nitrogen in a good sheet mulch is around 30:1. So you want to put down thick layers of carbon based materials (C or browns) and thin layers of nitrogen rich materials (K or greens). It doesn’t have to be exact, but keep in mind thick brown, thin green.
Here are some materials that work great for sheet mulching:
For the base of the pile use cardboard (tape and staples removed), newsprint (not the color ink ad pages), old rugs, carpet, or cloth (all non-synthetic fabrics). Basically you want anything that is going to be impenetrable to the weeds until it first kills them. Then it will break down allowing the seeds or plants roots you plant to access the soil below.
spoiled alfalfa hay
wood chips (often free from power line crews)
leaves (think of all the bags people just throw out). Oak leaves are especially good.
Food scraps. Make sure not to use meat, but veggies are great. Find a cannery or a place that sells juices. They often have buckets of carrot, beet, and orange peels and pulp, plus all kinds of good other stuff.
Stable manure/Chicken manure/Cow patties/Goat Poo
Fresh Grass clippings/old grass clippings
Bark or Sawdust from a saw mill
Well aged compost or garden soil. This will give your sheet mulch a microorganism jump start and help break it down faster.
Soil amendments if necessary, though a good balanced sheet mulch shouldn’t require any.
If the grass or weeds are really high to begin with, as in an unmowed pasture, you can cut the new bed area back with a scythe, weed eater, lawn mower, or manual weed wacker. This can be a nice compost layer underneath the cardboard barrier. Alternatively you can leave the grasses tall and just smash them down with the cardboard (obviously this won’t work with newspaper).
One thing that mulch/compost needs most to break down well is moisture. Make sure the ground that you are planning on building the mulch up on top of is well moistened to begin with.
Once you have your spot picked out and have watered it and gotten all the big stuff cut down, you are ready to start laying down the first layer– cardboard, newsprint, or fabric. A great place to find BIG pieces of cardboard is the hardware store cardboard dumpster or a place that sells refrigerators, furniture, and other large appliances.
After laying down the weed barrier you can start layering your materials right on top. These “sheets” will make up the new soil once broken down. Any combination of the above materials listed should work well. Just remember to use more carbon than nitrogen at this point and between each layer give it all a good soaking with the hose. On the very top/last layer use a material that is weed seed free, such as straw, leaves or sawdust.
The final product should be about 1-2 foot tall. That’s a big pile! If you start gathering stuff now, in a short time you will be ready to go.
Let your new bed sit and mellow for the winter. The worms will move in, and by spring you will be able to plant some seeds. If you plan on using the bed for vegetables consider plants that are not heavy feeders for at least the first year, go with legumes. It also could be wise to plant a cover crop the first year to give the sheet mulch more time to break down. By year two or three the spot will be primo.
This article was written by Emma O’Connell, Founder of Pick-A-Pepper.com–Fresh Local Food at Your Fingertips!
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