Recycling organic debris for composting and improving soil doesn’t have to be a chore! If hot composting is not for you, try one of these easy cold composting methods. They are considered “cold” because little or no heat reaction occurs as the material decomposes.
Each has advantages and disadvantages but the end result is the same: improved garden soil and less organic waste in landfills.
Sheet mulch composting
Sometimes called “lasagna gardening,” sheet mulch composting involves making alternate layers of green (nitrogen) material and brown (carbon) material.
You can use this method to easily create a new planting bed or to prepare an existing garden bed for planting. When done over existing lawns, it kills the grass and uses the available nitrogen and organic matter in the sod for the new planting bed. It is a great way to encourage the growth of micro- and macro-organisms in the soil.
How to prepare a sheet mulched bed:
- Layer 3 to 4 sheets of black-and-white newspaper over the area to be mulched. Be sure to overlap the edges of the paper so no light reaches the grass. Sheets of cardboard may be used as well. Wet the paper or cardboard with water.
- Make the first layer with a green source such as manure, coffee grounds, vegetable food scraps or fresh grass clippings, or a combination of two or more green materials.
- Add a layer of brown material such as leaves, straw, shredded paper, dryer lint, etc. on top of the green with about the same thickness. Sawdust may be used but has a much higher percentage of carbon, so use thinner layers.
- Add another green layer on top of the brown.
- Cover with a brown layer. This keeps the nitrogen from escaping and reduces pests such as flies.
- Continue building the bed until it is about 12 inches tall. You can build it all at once or over time as materials are available. Always end with a brown layer. One final option is to cover the finished pile with moistened burlap bags. This helps to keep the bed neat and increases microbial activity in the soil as the compost decomposes.
If you finish your sheet mulch in the fall, the new garden bed will be ready for planting in the spring. Once decomposition is complete, you may dig down through the layers to plant. You may choose to turn over the new bed, but it isn’t necessary.
To plant young seedlings in the freshly created bed, make a hole twice the size of the root mass of your plant start, fill the hole with compost and set in your seedling. Do not allow the stem of the plant to come into contact with the fresh, decaying organic material.
To plant seeds in a new sheet mulch bed, screen a 2- to 3-inch layer of compost over the top of the bed and plant your seeds in this. Water normally. You may continue to add to a planted sheet mulched bed, always leaving 2 to 3 inches of space around the stems of existing plants.
Sheet mulch composting is a great way to easily make new garden beds, create borders or add to existing borders.
In-situ (in-place) composting
In-situ composting simply involves burying organic material directly into garden soil.
Bury the material at least 12 inches deep to discourage dogs, cats or other small animals from digging it up. Rotate the composting site to avoid over-concentration of material in one spot.
One option is to cover the site with black plastic as the material decays. Slugs and snails will be attracted to the decaying material and will cling to the underside of the plastic. Lift the plastic and destroy or remove them. This is an effective method for reducing slug and snail populations prior to planting.
Trench composting makes use of the walk space in between garden beds.
How to prepare a compost trench:
- Dig a trench 12 to 18 inches deep by 12 to 18 inches wide (or your path width) and pile the soil on top of a garden bed next to the trench.
- In the fall, pack the trench solidly with leaves, straw or chopped garden debris up to the surface level of the garden bed.
- In the spring, turn the decomposed material in the trench onto the top of the garden beds and use the trench as a pathway during the growing season.
- Repeat the process each year.
You may plant directly into the composted material.
To avoid walking in mud in the spring, spread more straw or a layer of bark mulch in the trench.