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Composting Worm Feeding Guide: Best and Worst Foods


What are the best foods to feed composting worms? What are the worst foods? People who compost with worms face these questions every day. Fortunately, Uncle Jim’s Worm Farm has this Worm Feeding Guide! Vermicomposting is easy if you know the right foods to feed the worms — and the foods to avoid.

Qualities of Ideal Foods for Worms

Composting worms are hungry for your kitchen left-overs, garden waste, and coffee grounds!

The best foods for worms come from plants. This includes grains, fruits, vegetables, and beans. Plant matter is filled with nutrients and vitamins that worms need. Their excrement, called “humus,” contains digested nutrients and earth-friendly bacteria. Humus makes an ideal fertilizer for growing new plants.

Worms do not have teeth. Their little mouths take in the food. Therefore, they can digest food faster if it is:

  • Soft
  • Cut into small pieces, with a knife or food processor
  • Somewhat moist
  • Buried in the bin – just below the surface for Red composting worms

Qualities of Bad Foods for Worms

Certain foods are not good for worms.

Acidic foods upset the pH in the bin. Worm bins need a neutral pH to stay healthy. If the bin becomes too acidic, there will be a bad odor, and the worms’ healthy could be compromised. Do not add citrus peels, pulp, or juice (orange, lemon, lime). Also, pineapple is too high in acid. Large amounts of tomatoes, tomato sauce, and tomato juice are not good. Very small quantities of these foods will not make a difference.

Salty foods like olives should be soaked in water for a day before feeding. Discard the water.

Do not put toxic items in the worm bin. Worms are living creatures and they could die. Sawdust from pressure-treated wood is toxic. So are plants heavily treated with pesticides and herbicides. Carbon paper and carbonless paper are off the menu. So is office paper, because it is bleached white. Color ink from newspaper is not ideal — shredded newspaper with black ink is best.

Grass clippings from treated lawns are toxic. Additionally, green grass clippings generate too much heat as they break down. These high temperatures can kill your worms.

Fertilizers and other chemical compounds might be suitable for soil. However, they are too strong to add to a worm bin. They contain chemical salts that cause harm to the worms.

Use your common sense when evaluating foods for the bin. Would you eat food that contained toxic chemicals? No. Then don’t feed them to your worms.

How Animal Products and Greasy Foods Ruin the Composter

You should never add meat, animal products, dairy products, or greasy, oily foods to the worm bin. The oils, meat, and milk become rancid as they decompose. Rotting oils cause a powerful and unpleasant odor. Additionally, various vermin will be attracted to the smell. Raccoons — or worse — might start knocking over the bin to feed. Find another way to dispose of leftovers like this.

Another brilliant plan that can backfire is putting animal feces in the vermicomposting bin. Rabbit droppings can be composted under the right conditions. Manure from cattle and other herbivorous farm animals can contain too much salt and urea. They will be too hot for the worm bin. Let the manure “mature” outdoors in the elements for a year. Composting dog and cat feces are utterly out-of-the-question. These pets are omnivorous or carnivorous. Their feces contain parasites, viruses, and toxins.

Diseased plants and animals should never go into the compost bin. Temperatures are not high enough to kill pathogens or seeds. The problem might come back the next growing season.

Items that Won’t Break Down

Some items will take a long time, or eternity, to break down in a worm bin.

  • Fruit pits
  • Avocado pits
  • Contaminants such as plastic toys, shredded window envelopes from mail, etc.

Pick these items out and discard.

How to Scrape a Plate

Dinner is over, but there is still food on a plate. When scraping leftovers from plates, discard meat, dairy products, and bones. Foods drenched in oils, oily sauces, and vinegar dressings should be rinsed or discarded. Citrus and pineapple can go in the trash. Small amounts of tomato are fine. The rest can go in the compost collection pail and later, in the worm bin.

Are members of your household having trouble remembering what goes in the compost bin? Post a reminder next to the collection pail. When in doubt, leave it out.

Composting with worms is good for the environment. The result is superb finished compost, which you can add to the soil for future growing. Feeding your worms the right kinds of foods helps make your composting bin a success. At Uncle Jim’s Worm Farm, we provide superb composting worms (Red worms for composting; Super Reds for putting directly in the garden), composters, and composting knowledge.

15 comments on “Composting Worm Feeding Guide: Best and Worst Foods

    • James Shaw says:

      Hi Joe! Is the bin moist? The moistness in the soil ensures that the worms are not dehydrated. Which type of worms are you using? The Red Composting worms are a much smaller worm than the European Night Crawlers. The Red’s get to be about 1-3 inches long and as thick as cooked spaghetti. Also, adding soy to the worms diet will make them more plump. Hope this helps!

      Reply
    • James Shaw says:

      Hi Patrick! Is the bin moist? The moistness in the soil ensures that the worms are not dehydrated. Which type of worms are you using? The Red Composting worms are a much smaller worm than the European Night Crawlers. The Red’s get to be about 1-3 inches long and as thick as cooked spaghetti. Also, adding soy to the worms diet will make them more plump. Hope this helps!

      Reply
  • Filomena Verniero says:

    I made grape pops for the summer and had a lot left over. It contains fruit and sugars. I was going to feed it to my worms, but, it began to ferment. Is this still ok for them, or will I have drunk worms?

    Reply
  • When i feed my cats,wet food from a reputable brand,they tend to eat most of the juice parts and leave more solids behind. Was wondering if i could add this to the worm farm?

    Reply
  • Linda Johnson Ahlgrim says:

    I use avocado pits by first cutting them in half, them into smaller pieces and then grinding them. The worms love crushed avocado pits.

    Reply
  • Josh kelly says:

    Sugar should be fuel for the bacertia which the worms would eat i add sugar abd left over alcohol mash to my bin but it could just be the quanity and size of my bin that allows it to break down because i add alot of these items that are included on the list of things not to add. Plus i also have reds and European which are larger

    Reply
  • Will worms eat my already past the hot stage compost? I compost leaves crop residue and chicken manure in a hot trench. Can I then use the “finished” compost for the worm bedding? The compost is usually dark brown but you can still tell what plants were there. I assume I should mix lime while composting to get the PH down before giving it to the worms.

    Reply
    • Hello Tony;

      If you mix this finished product with some peat moss and check the pH before adding the worms, it should not harm the worms and will be a food source for them.

      Uncle Jim’s

      Reply

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