Home Composting

When organic materials such as leaves, twigs, grass clippings, and food scraps break down aerobically (with oxygen), they turn into compost. Farmers and gardeners often refer to compost as "black gold" because it is a nutrient-rich soil amendment that can help plant growth. Compost improves water retention and aeration in soil while also providing carbon, nitrogen, phosphorus, and other elements.

In addition to being good for the soil, composting is good for the environment because it reduces the amount of organic material going to landfill. Organic materials decompose anaerobically (without oxygen) in landfills and produce methane (CH4), a powerful greenhouse gas 25 times more potent than carbon dioxide (CO2). To learn more about climate change and greenhouse gases, visit the EPA's website.

Backyard Composting

To get started, buy a compost bin from a home improvement store or garden store. You can also make your own using scrap wood and chicken wire, or drill holes around the sides of an old garbage container. Depending on the kind of composting that is best for you, there are many styles of bin available. Once you have a bin, choose a good location where the bin is conveniently accessible, close to a water source, and has good drainage. If you're like most households, you'll be adding new material to the pile every day - don't build the pile so far away that you're discouraged from walking over on a rainy evening!

Single pile passive systems require little to no turning and produce a continuous supply of compost throughout the year. Organic material is deposited on top in layers, and the composting process happens by itself. The downside to this system is that the composting takes a lot longer, and the finished compost can be a little trickier to retrieve. Although you can certainly build a free-standing pile, it is recommended the material be enclosed or contained to keep pests out.

Three-bin active systems produce compost very quickly, but they require more space and are a little more labor intensive. The material requires periodic turning using a pitchfork or shovel to distribute oxygen and microorganisms to speed decomposition. Once things get going, one bin usually contains finished compost, one bin contains compost that is resting or "curing", and one bin is receiving fresh material.

Tumbler systems are easy to use and keep pests out. They are enclosed cylindrical containers with handle to spin the entire thing, which eliminates the need for a shovel or pitchfork. However, these bins are usually more expensive, and this style of composting limits the amount of compost you can produce because the container becomes harder to turn the more material is added. It also requires that you stop adding new material until the older material inside can finish composting.

Backyard composting bins
Fruit and vegetable scraps and peelingsMeat, bones, or shells (these can go in your green curbside bin)
Pasta, grains, rice, and breadCooking oil, grease, or liquid waste
EggshellsHuman or animal waste
Coffee grounds and filtersPaper plates, bowls, or cups with plastic coatings/linings
Tea bags (paper sachets only)
Cans, bottles, glass, plastic, or paper (these belong in your blue recycling cart)
Paper towels and napkins (no cleaning wipes or baby wipes)
Batteries, paint, motor oil, or other household hazardous wastes
Pizza delivery boxes (no frozen pizza boxes)
Sudden Oak Death infested material
Paper egg cartons
Poison oak, cactus, palm fronds, pampas grass, or bamboo
Grass clippings, leaves, and other landscape prunings
Weed seed heads
Plastic bags or utensils (including those labeled "compostable" or biodegradable")

* Note: If you have grass clippings and don't want to use them in a compost pile you can leave them on the lawn to decompose. This practice of grasscycling saves time and money while also helping the environment!

backyard composting materials

To make the best compost, mix a variety of carbon-rich materials with nitrogen-rich materials. Dry leaves, hay, and newspaper are considered "browns" that are carbon-rich, while damp and wet vegetable peelings, grass clippings, and coffee grounds are considered "greens" that are nitrogen-rich. Aim for a ratio of 2 parts "browns" with 1 part "greens". Keep in mind that the smaller the material, the more surface area exists for microorganisms to occupy, and the faster things will decompose. Chop up kale stems and apple cores before throwing them into the pile!

Water will need to be added on occasion, but this is something you can eyeball. If you squeeze the maturing compost in your hand, it should not be dripping, but it also should not crumble apart. If the material is too wet, water will force out the oxygen and turn the pile anaerobic, creating unpleasant odors. If the material is too dry, bacterial activity slows down and may become dormant. Don't worry, things don't have to be exact, and you'll get the feel of it in no time.


Help for the home gardener

Ask an expert! Ask a Sonoma County Master Gardener (707) 565-2608 or email mgsonoma@ucdavis.edu. Master Gardener volunteers are trained and certified by the University of California, Cooperative Extension. Workshops and seminars are given regularly at various libraries.

Worm composting

Worm composting or vermicomposting is the practice of using worms to make compost. The word vermi is the Latin word for worm, and worms like to feed on slowly decomposing organic materials (e.g., vegetable scraps). The end product, called castings, is full of beneficial microbes and nutrients, and makes a great plant fertilizer.

For worms and worm bins, contact:

Compost Club
(707) 922-5778

Mass Wiggle
(415) 425-4592

Sonoma Valley Worm Farm
(707) 996-8561