Composting worms make food scraps break down quickly, but some foods can hurt them. Vermicomposting with worms is increasingly popular with people who want to reduce trash, produce free fertilizer, and save resources. Therefore, vermicomposting fans have a vested interest in keeping their Red Worms or European Night Crawlers healthy. Worms can break down a wide variety of organic materials, with a few exceptions. Uncle Jim’s Worm Farm explains which foods can hurt composting worms.
In a Tight Space
In the wild, worms will wiggle to a suitable food source. They have an entire smorgasbord outdoors.
A composting bin is a tight space. We set up this habitat for them. The worm bin has the walls and sides, the drainage holes, the lid, and the bedding. Whatever food scraps we put in there become part of their little environment. They are at our mercy, and they are almost like pets. Thus, responsible worm owners will be picky about what goes into the bin.
No Fats or Oils
Humans need fats and oils to survive. Nearly everyone gets fats from vegetable oil, sauces, butter or margarine. Many of us consume animal products, which are often rich.
However, in the confines of a worm bin, fats and oils go rancid. On exposure to air, oils oxidize and smell terrible! They may also attract unwanted pests.
Dairy products such as milk, cheese, and yogurt should never go into a worm bin. Even non-fat varieties are bad for composting worms.
Therefore, dispose of meat, bones, gristle, and dairy products in the trash. Rinse oily dressing off left-over salad. Food doused with oily sauces or butter may not be salvageable. Better to throw out greasy left-overs than risk your worm bin’s health.
An acidic environment is unhealthy for worms. Anything you add to the bin becomes part of their environment. Thus, avoid adding acidic foods. One or two spoilt tomatoes a week will not cause much damage. But a steady diet of acidic matter, or an entire bag of orange peels, could alter the pH of your worm bin. Worms like a neutral pH of 7. Common acidic foods are the flesh and peels of oranges, lemons, and limes; pineapples; raw onions; and tomatoes.
Limited Processed Foods
Foods that come in a package and have more than one ingredient have been processed. Many households rely on processed foods for convenience and a long shelf life. On the other hand, processed foods often have added sugar, salt, and hydrogenated oils. You can tell by reading the ingredients.
The additives make the food take longer to break down on the shelf. They also make foods more difficult to digest.
Worms will break down the food faster when it’s easy to digest. Limit the number of processed foods you add to the worm bin. Certain fast food restaurants fill their food with oils, sugar, preservatives, and salt to add shelf life, increase efficiency, and keep food looking attractive. Be selective about which restaurants you patronize. And be selective about how much processed food you give your worms!
Eating more whole foods, such as fresh fruits and vegetables, is good for you and your worms.
Hot peppers are spicy because they contain capsaicin. Capsaicin causes a sensation of pain in our mouths. Do not add hot peppers to your worm bin. Also, throw out spicy foods. The effects on your worms might not be pretty!
Shredded corrugated cardboard and black newsprint are approved for vermicomposting. See our article about cardboard and worms. An occasional handful of these items will not harm the worms. They also make great bedding when you start a worm bin.
White office paper is bleached, and this is unhealthy for the worms. Colored inks are also not recommended. Windowed envelopes contain plastic, which will never break down. Coated paper will not work.
A very small amount of grass clippings is OK, but too much will over-heat the bin. The clippings should not come from a lawn treated with pesticides or herbicides.
The Obvious: Non-Foods
We shouldn’t have to say this, but the worms cannot eat non-foods. You might be surprised at the stories we have heard over the years. Soap, plastic toys, teeth, pet droppings (except rabbits), most food packaging, thick white paper napkins and coated paper plates, and general household trash are very bad ideas. Large avocado pits will not break down anytime soon. Use your common sense. Pull out anything that does not belong.
Help your household remember what is compostable. Post a sign at the collection site.
We also offer finished compost, made by our worms at our farm in rural Pennsylvania.