Composting 101
Learn how to make a compost pile that creates the optimal conditions for decomposition.
Building a Compost Pile
There are two main ways to make compost: cold compost (minimum effort) and hot compost (maximum effort).
Cold Black Gold
Nearly every expert I talked with admitted (sometimes sheepishly) that they do this type of composting in their own back yards because it’s easy. Here’s how to make cold compost: Mix together yard wastes, such as grass clippings, leaves, and weeds, place them in a pile, and wait 6 to 24 months for the microorganisms, earthworms, and insects to break down the material. Add new materials to the top of the pile. You can reduce the waiting period by occasionally turning the pile and monitoring and adjusting the pile’s moisture level. The compost will be ready when the original ingredients are unrecognizable. Generally, compost on the bottom of the pile “finishes” first. You may not want to include woody material, because it breaks down too slowly.
Pros: Takes little effort to build and maintain; can be built over time.
Cons: Takes up to 2 years to produce finished compost; doesn’t kill pathogens and weed seeds; undecomposed pieces may need to be screened out.
Some Like It Hot
Hot, or fast, composting takes more work and the right combination of ingredients, but you can get high-quality compost in under 2 months. Here’s how: Wait until you have enough material to create compost critical mass (27 cubic feet), which is the minimum volume for a pile to hold heat. Then mix one part green matter with two parts brown matter. Bury any vegetative food scraps in the center to avoid attracting animals. Check to make sure the mixture has the ideal moisture level. Continue adding mixed greens and browns and checking the moisture until you’ve built a pile that is 3 feet by 3 feet by 3 feet, or 5 feet wide at the base and 3 feet wide at the top. The microorganisms will immediately start decomposing, and their bodies will release heat. The pile will insulate the heat, and the temperature of the pile’s interior will reach 120°F to 150°F. Turn the pile weekly and regulate moisture levels. After about a month, the hot phase will be done, and the pile will finish decomposing at temperatures between 80°F and 110°F. The compost will be ready to use when it no longer heats and all of the original ingredients are unrecognizable.
Pros: Produces high-quality compost within 2 months (and sometimes as soon as a few weeks); can kill weed seeds and pathogens. (Organic Gardening does not recommend adding weed seeds or manures that contain human pathogens to compost—hot or cold—because uniform heating is difficult to achieve in home compost piles.)
Cons: Time-consuming; requires careful management of moisture, air, and C/N ratio.
Compost Yeas and Nays
Browns
Greens
What not to compost
Learn how to make a compost pile that creates the optimal conditions for decomposition.
Building a Compost Pile
There are two main ways to make compost: cold compost (minimum effort) and hot compost (maximum effort).
Cold Black Gold
Nearly every expert I talked with admitted (sometimes sheepishly) that they do this type of composting in their own back yards because it’s easy. Here’s how to make cold compost: Mix together yard wastes, such as grass clippings, leaves, and weeds, place them in a pile, and wait 6 to 24 months for the microorganisms, earthworms, and insects to break down the material. Add new materials to the top of the pile. You can reduce the waiting period by occasionally turning the pile and monitoring and adjusting the pile’s moisture level. The compost will be ready when the original ingredients are unrecognizable. Generally, compost on the bottom of the pile “finishes” first. You may not want to include woody material, because it breaks down too slowly.
Pros: Takes little effort to build and maintain; can be built over time.
Cons: Takes up to 2 years to produce finished compost; doesn’t kill pathogens and weed seeds; undecomposed pieces may need to be screened out.
Some Like It Hot
Hot, or fast, composting takes more work and the right combination of ingredients, but you can get high-quality compost in under 2 months. Here’s how: Wait until you have enough material to create compost critical mass (27 cubic feet), which is the minimum volume for a pile to hold heat. Then mix one part green matter with two parts brown matter. Bury any vegetative food scraps in the center to avoid attracting animals. Check to make sure the mixture has the ideal moisture level. Continue adding mixed greens and browns and checking the moisture until you’ve built a pile that is 3 feet by 3 feet by 3 feet, or 5 feet wide at the base and 3 feet wide at the top. The microorganisms will immediately start decomposing, and their bodies will release heat. The pile will insulate the heat, and the temperature of the pile’s interior will reach 120°F to 150°F. Turn the pile weekly and regulate moisture levels. After about a month, the hot phase will be done, and the pile will finish decomposing at temperatures between 80°F and 110°F. The compost will be ready to use when it no longer heats and all of the original ingredients are unrecognizable.
Pros: Produces high-quality compost within 2 months (and sometimes as soon as a few weeks); can kill weed seeds and pathogens. (Organic Gardening does not recommend adding weed seeds or manures that contain human pathogens to compost—hot or cold—because uniform heating is difficult to achieve in home compost piles.)
Cons: Time-consuming; requires careful management of moisture, air, and C/N ratio.
Compost Yeas and Nays
Browns
- Dry plant matter; dead leaves, stalks, twigs, and grass.
- Sawdust (not sawdust from plywood or treated wood)
- Straw or hay
- Wood chips
- Shredded newspaper or cardboard (not corrugated)
- Pine needles
- Paper towels
- Wood ashes
- Wine corks
Greens
- Uncooked fruit & vegetable scraps
- Manure
- Washed eggshells
- Weeds that have not gone to seed
- Coffee grounds and teabags
- Hair
- Fresh grass clipping, leaves & plant matter
- Seaweed
What not to compost
- Meat or fish
- Diseased plants
- Cooked food
- Perennial weeds
- Fat or oil
- Weeds that have gone to seed
- Dog or cat feces