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Composting Kitchen Surpluses: Eggshells, Coffee Grounds, and Orange Peels

oranges coffee grounds and eggshells for compostingAt Uncle Jim’s Worm Farm, we get questions about how to compost three common kitchen scraps: eggshells, coffee grounds, and orange peels. These are all popular foods and beverages. On average, we consume approximately 1 egg and 2 cups of coffee per day. That’s a lot of scraps! Fortunately, composting worms can take the burden off landfills and incinerators. These and many other kitchen scraps can be turned into free fertilizer by composting them with worms.

Composting can be successful at any scale. Single apartment dwellers, large families, restaurants, coffee shops and even institutions can compost unwanted organic materials. If you don’t already have a composting program, browse our website and order red worms from Uncle Jim’s Worm Farm. We also carry small-scale composters that can be used indoors or out.

How to Compost Egg Shells

Eggs are highly nutritious and perfectly packed in oval shells. The shells are made mostly from calcium, and they are inedible. However, composting worms need a little grit. Their digestive systems love small pieces of eggshells. Eggshells also reduce acidity in the worm bin. A lower pH is good for composting bins, because it reduces odors and helps prevent toxic conditions for the worms.

Your kitchen likely produces far more eggshells than your worms need. You will end up throwing out most of your eggshells. They are more a “treat”. Every once in a while, rinse some eggshells and remove the inner lining. Let them dry. When you have several dozen, crush them using a rolling pin or mortar and pestle. Sprinkle them on top of your compost bedding and gently mix. For a few weeks, you will see tiny flecks of eggshells in the bin. Soon enough, they won’t be noticeable anymore. Then, you can add some more.

Composting Coffee Grounds

When you have finished forcing hot water through ground coffee beans, you have two products: delicious coffee and waste coffee grounds. Some k-cups have coffee grounds in them. The used coffee grounds are organic material, so they can be composted.
However, be careful! If you put too much dry coffee grounds in your worm bin, the dryness could hurt the worms’ skin. They need moisture to stay healthy. The bedding should have the consistency of a wrung-out sponge. Wait until the grounds are cool. If they are dry, add a little water when putting them in the worm bin.

Coffee is acidic, and so are coffee grounds. This can throw off the pH in the worm bin and create problems. Therefore, mixing crushed eggshells with coffee grounds will help neutralize the acid.

If you run a coffee shop or restaurant, experiment to find the right mix of coffee grounds and crushed eggshells. Also use other organic material to balance out the abundant coffee grounds.

Oranges and Composting

This popular citrus fruit is eaten straight, added to recipes and squeezed for juice. Their perfect sphere packages are a tempting addition to the compost bin. They are organic material, right? However, if you have employed composting worms to break down the garbage, worms won’t like oranges. Oranges are highly acidic and can harm the worms. They throw off the pH balance in the bin, which can cause noxious odors and even worm die-off.

Your bin can probably handle orange peels, pulp and flesh in small quantities. In general, though, citrus fruit is bad news for worm bins. Best to toss these leftovers in the trash.

Uncle Jim has been raising worms for more than 30 years. Thus, we are experts on composting with worms. Take a look around and you will find plenty of composting knowledge, live worms, composters and accessories. We are active on social media, so please subscribe. You can get special offers and composting tips by signing up for our email list.

2 comments on “Composting Kitchen Surpluses: Eggshells, Coffee Grounds, and Orange Peels

  • Filomena Verniero says:

    I am looking forward to taking care of my new “babies”. Is diatomaceous earth and black Mucuna Pruriens powder, also known as Cowhage, an Ayurvedic herb, OK to add to my worm farm?

    Reply
  • Susie Adams says:

    In Some areas of the country it is not advantageous to add egg shells because there is too much calcium in the soil. I’ve lived in Salt Lake City and Tucson and both recommend no egg shells. The answer to composting and pH is make sue you add more carbon (brown)than green,

    Reply

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