Traditional Composting

Why should we compost? 1) uncovered ground leads to lost nutrients so compost enables soil to retain nutrients needed for healthy plant growth and rich soils 2) pH in San Diego is alkaline because we do not receive enough rain so compost helps to balance this out 3) avoid toxic stuff – store bought compost can contain sewer sludge, and sludge can contain heavy metals from improperly disposed meds, etc 4) saves landfill space and GHG emissions.

What should go in a compost pile? Carbon rich materials also known as “browns” (dried leaves, shredded newspaper, hay, pine needles, saw dust) and nitrogen rich material also known as “greens” (coffee, fresh grass clippings, vegetable/fruit scraps) with an ideal ratio of 30:1 C:N

What should the ratio of “browns” to “greens” be? An ideal ratio of 30:1 would maximize the compost process. A good way to think about this ratio is remember that your “greens” should be buried in your “browns.” This will also avoid pests and odor.

What can I do if I don’t have enough browns? For residents with limited yard space, finding enough browns for your pile can be quite tricky. Try shredding newspaper and mixing it in your pile.

What shouldn’t go in a compost pile? Meat, fat, grease, diary, bones, animal feces, weed with seeds, diseased plants, ice plant, cacti, palms, invasive root systems.

What is the difference between traditional and commercial composting? Traditional composting can range from passive heap to hot pile, decomposes faster with the help of carbon. Commercial sites can compost feces because they get temperatures high enough to burn off bad microbes.

What is making my compost smell? When the C:N ratio is off, this can create some funky smell coming from your compost pile. The likely culprit is having too much nitrogen in the pile, meaning there is too much “greens.” This can be offset by adding dried leaves, cardboard, shredded newspaper, hay, pine needles, saw dust.

What can I do about ants in my pile? If your compost pile is attracting ants, that is an indicator that your compost is too dry.

What can I do about a dry compost pile? Moisture assists in composting but most native plans in San Diego contain little water and they are hard to compost. Try wet newspaper strips or spraying your compost bin with a squirt bottle until the pile feels like a wrung out sponge.

Is it safe to add eggshells? YES, eggshells add calcium to the compost pile. Eggshells can also be added directly soil and help keep snails away. It is best to dry them for a couple days so the eggshells are easier to crush in the soil.

What is a batch pile and how is it different from a “As I go” pile? A batch pile is a composting method of adding materials until your compost bin is full; piles are generally smaller to increase the harvest time and this is considered the quickest method to harvest which can take 4 to 6 months. A “As I go” pile is a composting method of continuously adding materials to your compost bin, this is a slower method of composting and it can take from 8 months to 1 year to harvest.

To learn more about traditional compost basics click HERE


What is vermicomposting? Organic material is broken down through the use of worms and it requires more food scraps and less yard waste which is ideal for apartments and small family homes and it offers a more convenient smaller scale version of composting compared to traditional composting.

How do I start vermicomposting?  A one square foot bin space is needed for each pound of food scraps generated per week so residents can build or buy a bin. Vermicompost bin require proper bedding to hold moisture and contain air space for the worms. Common bedding choices include: moistened shredded paper, newspaper, corrugated cardboard, napkins, paper towels, or paper egg cartons. The bedding should feel about as moist as a wrung out sponge. Worms also require small grit substances in order to aid in digestion. When you are setting up your bedding, make sure to add a small handful of sandy soil, egg shells broken into small pieces, or bird grit into the bin.

Where can I purchase worms? Worm suppliers can be found on WasteFreeSD by searching “Worms.”

When can I start adding my food scraps? Once the vermicompost bin and bedding is all set add food scraps and bury them in the bedding. Don’t over feed them because the food can smother the worms to death. Your bin should never smell, an odor would likely mean you are over feeding your worms. You can feed them moldy food, the bacteria actually helps give the worms a head start on digesting the food and keep in mind that food scraps are best digested when cut into small pieces. Also avoid adding citrus because it’s naturally antibacterial. Lastly, always give worms a place to go, for example if you give them food they don’t like, they need to be able to move left/right/up/down.

When can I harvest the vermicompost byproduct? The worm castings are the byproduct of vermicompost. If you don’t harvest your castings, the dirt-like end product of your pile, the worms will continue to digest the castings and the nutrient levels will go down subsequently.

How do I care for my worms? Worm bins should never be placed in direct sun. Direct sun exposure can lead to high internal bin temperatures even if the ambient temperature is still within the acceptable range, so providing shade for the bin is highly recommended. Outdoor bins may be insulated with blankets or soil, or brought inside when cold. Worms don’t have lungs, they breathe through their skin so fats and oils will coat their skin and can make it hard for them to breath, so avoid putting fatty or oily foods in your vermicompost bin. Worms don’t like motion, vibration or extreme heat/cold.

Bokashi Composting

What is bokashi composting? Bokashi is a method of pickling your food waste and “storing your greens” for later use in your traditional compost pile.

What is an inoculant? An inoculant is used to pickle the food waste; this inoculant is a combination of anaerobic microbes. Effective Microorganisms are available for sale online (this is a brand name, developed by a professor in Japan) and you can also find online tutorials on making your own inoculant. The inoculant is then added to spent grain (for example, used hops from a local brewery) or paper. Simply add your food wastes to a 5-gal bucket and some inoculated grain/paper as you go along.

What can go in a bokashi compost pile? Bones, fat, milk cheese and both cooked/raw meat can be added to your bokashi compost bin. After you bucket is full, add more inoculated grain/paper on top, close the lid, and in ten days to two weeks your pickled food scraps are ready to be added to your traditional compost bin. Your pickled food waste is a good way to help heat up your traditional compost pile quickly, speeding along the time it takes for your compost to be ready for your garden.

What type of mold should I be concerned about? White mold is a healthy indicator; green, red or brown mold are not a healthy indicator.


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