Composting is essentially a controlled version of what happens on a forest floor: microorganisms, fungi, and small invertebrates break down dead organic matter and turn it into a dark, crumbly material called compost. That compost is rich in nutrients and organic matter that can improve soil.
Here's how the process works:
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Microbes do the heavy lifting. Bacteria and fungi consume kitchen scraps and yard waste as food. As they digest it, they generate heat, water, and carbon dioxide.
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They need the right ingredients. Successful composting depends on balancing:
- "Greens" (nitrogen-rich materials): fruit and vegetable scraps, coffee grounds, fresh grass clippings.
- "Browns" (carbon-rich materials): dry leaves, shredded cardboard, paper, straw, wood chips.
A rough rule of thumb is about 2–3 parts browns to 1 part greens by volume. Too many greens can make the pile wet and smelly; too many browns can slow decomposition.
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Air is important. Most home composting relies on aerobic (oxygen-loving) microbes. Turning or mixing the pile occasionally adds oxygen, which helps it break down efficiently and reduces odors.
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Moisture matters. A compost pile should feel like a wrung-out sponge—moist but not dripping. If it's too dry, decomposition slows. If it's waterlogged, oxygen is pushed out and unpleasant smells can develop.
What can you compost?
Good additions:
- ✔️ Fruit and vegetable scraps
- ✔️ Coffee grounds and paper filters
- ✔️ Tea leaves and most tea bags (if they're paper, not plastic)
- ✔️ Eggshells (they break down faster if crushed)
- ✔️ Dry leaves
- ✔️ Shredded newspaper or plain cardboard
- ✔️ Untreated plant trimmings
Usually avoid in a backyard compost:
- ❌ Meat, fish, and bones
- ❌ Dairy products
- ❌ Oils and greasy foods
- ❌ Pet waste
- ❌ Diseased plants or invasive weeds
These items can attract pests, create odors, or introduce pathogens.
What happens over time?
As the microbes work:
- The pile often heats up, especially if it's large enough.
- Materials gradually shrink and lose their original appearance.
- After a few months (or longer, depending on conditions), the compost becomes dark, earthy-smelling, and crumbly.
A simple beginner setup
If you're just getting started:
- Keep a small container in your kitchen for food scraps.
- Empty it into a compost bin or pile regularly.
- Add a layer of dry leaves or shredded cardboard each time you add food scraps.
- Mix the pile every week or two if you can.
- Keep it slightly damp.
With a good balance of greens, browns, moisture, and air, composting is surprisingly forgiving. Even if it slows down or gets a bit smelly, adjusting those four factors is usually enough to get it back on track.
