The microorganisms that break down organic material in your soil will happily do the same job in a compost bin. Your role as a composter is to provide the conditions for nature's crew of decomposers—the bacteria, fungi, and bigger creatures such as sow bugs and worms—to go to work. Browns, Greens, Air and Water are the "big four" that will keep every compost pile happy. We have some basic information about making compost below, for more details check out our Tools for Building Healthy Soil guide.

Build or Buy a Compost Bin

The right bin makes composting easier and keeps pests out. Whether you want a simple wire-mesh enclosure for yard trimmings or a rodent-resistant tumbler for food scraps, we have a guide to help you choose — plus step-by-step plans for building your own.

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What to Put in Your Backyard Compost Bin

Deciding what to put in your backyard compost bin is an important part of the process. Maintaining the right balance between "brown" and "green" materials will help your compost pile break down faster and keep it from getting smelly. If you are going to compost food scraps you must use a rodent-proof bin.

Browns

  • Fallen leaves
  • Chopped, woody prunings
  • Pine needles
  • Sawdust from untreated wood
  • Straw

Greens

  • Fruit & vegetable trimmings and rinds
  • Lawn clippings
  • Weeds without seed heads
  • Coffee grounds & filters, paper tea bags
  • Herbivore manures: e.g. goats, horses, chickens

What NOT to Put in Your Bin

These items can attract pests, create odors, or introduce harmful substances into your compost. Put them in your curbside green cart instead — commercial composting facilities can handle what backyard bins can't.

  • Grains, beans, or breads
  • Sawdust from plywood or treated wood
  • Meat, bones, or fish
  • Pet feces (dog, cat, or bird)
  • Diseased plants (in cold piles)
  • Dairy products or grease
  • Large amounts of soiled paper (e.g. pizza boxes)
  • Bio-plastics, even if labeled "compostable"

How to Make Good Compost

This 'recipe' works for mixing food scraps and yard trimmings together, requires a rodent-resistant compost bin and active maintenance to prevent animal nesting and feeding.

Four basic elements or 'ingredients' are necessary for effective composting to happen: browns, greens, air and moisture.

  1. Add yard trimmings to your bin, chopping all materials into pieces 4"-6” or smaller. 'Greens' are moist, fresh material (nitrogen) and 'browns' are dry, woody material (carbon). Add equal parts of greens and browns, with alternate 4" tall layers of each. You can gently mix the layers with a pitchfork.
  2. Wet all material with water as you add. Moisture is critical for effective decomposition.
  3. Food scraps need to be buried and mixed into the center of the pile.
  4. Add to the bin as often as you like but be sure to mix in enough browns to balance your greens, and always top with browns (never dump food and run).
  5. Turn or mix the pile about once a week. Keep all materials in the bin as moist as a wrung-out sponge. 
  6. Harvest rich, brown, finished compost by sifting out coarse, unfinished materials after 3 to 8 months.

How can you tell when compost is done?

  • It will look like soil and smell sweet and earthy.
  • The volume of the pile will shrink by 30-50 percent.
  • The original materials will be unrecognizable, except some woody pieces.

Storing Compost

We recommend “aging” your compost by letting it sit for six months before using. If unfinished compost is added to your soil, the decomposer organisms compete with plants for nitrogen, resulting in stunted plant growth and yellow leaves.

  • Cover with a tarp or keep in a sheltered space to protect from the rain and sun.
  • Remove the tarp periodically to provide air.

Troubleshooting & FAQ

Smelly pile? Not breaking down? Attracting pests? Most composting problems have simple fixes. Our troubleshooting guide covers the most common issues and answers frequently asked questions so you can get your compost back on track.

Troubleshooting & FAQ
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On-Site Composting Assistance

Is your community garden, urban farm, school, or organization looking to start or improve an on-site composting system? StopWaste offers free technical assistance from experienced composters who can visit your site and help you get set up. This service is available to community groups, organizations, businesses, and institutions in Alameda County.
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Additional Resources

Tools for Building Healthy Soil

Learn more about building healthy soil with this guide that provides tips to help you get started in your garden. It covers soil building strategies including composting, sheet mulching and cover cropping.

On-Farm Composting Toolkit

This in-depth guide can answer all of your compost questions. Whether you are an urban farmer, community gardener, or a backyard homesteader, this toolkit supports you in becoming an expert composter. Urban farms and community gardens grow two things: plants and soil. Building healthy soil is fundamental for growing healthy fruits and vegetables and supporting healthy communities. The benefits of building soil extend to farms and gardens that raise animals and grow plants for fiber, and is particularly vital for people who work with urban soils, where the impacts of development may have left

Visit the StopWaste Gardening Channel on YouTube for more videos on composting and gardening.