Whether gardener, wildlife enthusiast or concerned citizen, it makes practical sense to compost.
- Compost is a soil conditioner that aerates your soil and improves moisture retention. Any type of soil benefits, regardless of clay or sand content.
- Compost is an organic fertilizer that is easy and safe to apply. Over-application of man-made fertilizers can produce environments which become “toxic” to plant growth. That won’t happen with compost.
Composting is a natural process of recycling organic matter. It reduces landfill waste and associated costs and creates a valuable resource.
What is compost?
Compost is humus, the earthy end-product of the decomposition of organic matter. Composting emulates this process, which occurs at a slower pace in nature.
How does it work?
To work with your composter and not against it, it is vital to understand a few basics about the process. Large chewing insects begin breaking down the organic material. The smaller chewing insects handle finer matter while the microorganisms (bacteria and fungus) complete the process of creating humus. Working together, these organisms are what drives composting. Like all living creatures, they require food, air, water and warmth to survive.
Their food is a mixture of “brown” matter (high in carbon) and “green” matter (high in nitrogen). Each type of organic material has its own carbon-nitrogen ratio. Green material (like waste produce, fresh plant and grass clippings, green weeds) is generally available year-round. Brown matter (like dry grass and fall leaves) is abundant in the fall, but can be made more accessible during the summer months by storing it in piles.
For efficient decomposition, the carbon-nitrogen ratio of the material in your composter should be between 25 and 30 to 1. This guide emphasizes the need for regular additions of high-carbon material throughout the composting process to maintain as high a carbon-nitrogen ratio as possible.
How do I compost?
- A sunny location is best but shade will work, though at a slower rate.
- Use a large enough container, minimum 3 feet by 3 feet by 3 feet (27 cubic feet or about 1 cubic metre).
- Contact with the soil surface is crucial so that organisms have access to their food.
- Add no more than a 3-inch layer of any particular material at any one time.
- Build with alternating layers of “green” and “brown” matter.
- Use sufficient material to maintain organism populations and levels of heat and moisture.
- Ensure that the pile remains moist, but not wet.
- Keep the pile aerated (e.g. turn with a fork once a week).
- Adding a few cupfuls of composted manure will speed up the process.
What to add
- Soft plant material from your garden including weeds
- Waste food scraps of plant origin
- Egg shells, tea bags, coffee grounds, bread
- Dryer lint, hair clippings, feathers
- Newsprint, cotton or wool scraps
- Grass clippings, leaves
- Wood ash
What NOT to add
- Meat, fish or milk products unless you want to attract “problem” wildlife
- Diseased plant material or plants that have gone to seed
- Pet litter or excrement
- Pesticides on grass or plants
And don’t let the pile dry out!
- Closed container with lid and air holes
- Open wood frame structure
- Mesh framework, most suitable for full season composting (e.g., fall leaves, sod)
- Rotating container, into which garden soil must be introduced
- In-ground pit, with cover which can include meat scraps
- Worm composter (indoor, year-round)
Get to know your composter
Composting is far from being an exact science. Observe and experiment with your composter. Incorporate new knowledge into a system that will work for you — and don’t give up. There is so much more to be gained from composting, than compost. It’s educational, economical and nature will thank you for your efforts.
Recommended readings and resources
- Bradley, Fern Marshall and Ellis, Barbara W. 1997. All-New Encyclopedia of Organic Gardening. Rodale Press, Pennsylvania.
- Campbell, Stu. 1990. Let it Rot! The Gardeners’ Guide to Composting. Storey Publishing, Vermont.
- Cullen, Mark, and Johnson, Lorraine. 1992. The Real Dirt — The Complete Guide to Backyard, Balcony and Apartment Composting. Penguin Books, Markham.
- Harris, Marjorie. 1991. Ecological Gardening. Random House, Toronto.
- Composting Council of Canada.
Editor’s note: Since this how to sheet was created, the City of Ottawa started a “green bin” program. Compostables, including many items not recommended for backyard bins, are now collected weekly by the city. See What goes in your green bin.