Summer is in full swing, which means it’s time to show off some beautiful summer gardens! Oakland Local met up with City Slicker Farms’ Backyard Garden Mentor and farm assistant, Joseph Davis, to talk about one of gardening’s most important ingredients: compost.

What is compost?

Compost is essentially decomposed organic matter made from things in your kitchen — food scraps, tea bags, paper — that can add important nutrients to your garden soil.

Why it’s important

  • The natural cycle: In the process of consuming food, some things we eat end up as waste products, but compost allows those waste products to turn into something that can be put back into the soil.
  • “It’s a great way to bring in the microorganisms: the microscopic critters that actually do the work that makes things happen,” Joseph said.
  • It’s economical: If you make your own, you don’t have to spend any money to buy it!
  • You’re diverting things from the waste stream: “Throwing an apple into the garbage can and then putting it into the landfill is kind of a waste of that apple. If you throw an apple into your compost or at least into your green bin, it can be reused and turned into something that you can use for your garden.”

What to remember

Your compost needs a balance of “brown” and “green” ingredients: brown is carbon, green is nitrogen.

Green ingredients are things such as food scraps: essentially any of your vegetables and fruits. Peelings from potatoes, the ends of carrots, and produce that got a little bit rotten in the refrigerator all counts as green.

Brown ingredients are things such as newspaper, dried leaves, tea bags, coffee grounds, and horse manure. Woody things like branches and twigs can work, but they take a lot longer to break down, so get them it in as small of pieces as possible.

What not to put in your compost

Glossy papers or leaves that are waxy. Some leaves work better than others. For example, leaves from magnolia trees are very waxy and don’t break down fast enough for composting.

Why a balance of green and brown?

It has to do with the bacteria: the microorganisms that break down the matter. If the ratio of nitrogen is too high, what you’ll end up with is anaerobic activity, which can cause the rotting smell of food. Ideal compost should smell like the earth.

You won’t get the best kind of usable compost if the nitrogen ratio is too high or low. If the nitrogen ratio is too low, you’ll just have a big pile of leaves, which will just take too long to compost because of insufficient nitrogen to feed the microorganisms to break everything down. You need a carbon-nitrogen balance somewhere between 30 to 1 and 15 to 1. Most people just measure it visually.

How big should your compost be?

It is recommended that a compost pile be at least 3 feet by 3 feet by 3 feet.

Keep animals away

Make sure your compost is contained so rodents and other animals like possums and raccoons don’t get into it.

If you live in an apartment or somewhere limited in outside space, stick to worm composting

If you don’t have your own little yard where you can gather greens and browns, then you’re better off doing worm composting. This is actually easier for most households since it doesn’t require as much space.

You can get a box that has some way to drain — or purchase a worm bin — and put some red wiggler worms in there along with your food scraps and paper. The worms will eat up the ingredients and leave behind worm castings, which is digested matter that’s nutrient-rich for plants. You can then use the compost for your indoor and outdoor plants.


This is how you can tell if the compost is kicking in correctly. With a long thermometer (for a three foot pile, a thermometer that’s a foot and a half is ideal) you can check the core of your compost pile. It should be hot: above 130 degrees.

One last tip

If you want your compost to move faster, don’t be scared to twist, turn and shake it!

For those interested in learning more, visit Joseph onsite at the City Slicker Farms farm at Union Plaza on Thursdays and Saturdays.

One Response

  1. rayon

    Coffee grounds are high in nitrogen, and count as a green – although they look brown.


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