Vermicomposting 101: What Do Composting Worms Like to Eat?

Just the idea of getting composting worms to recycle our household waste into awesome fertilizer is pretty exciting, but once you actually start doing it, it’s wise to consider what worms actually like to eat. As a general rule, composting worms will eat any non-meat, non-dairy organic material, but there are some foods that they seem to enjoy more than others, namely:

Curcurbits

Composting worms will absolutely destroy members of the cucurbitaceae plant family like pumpkins, squash, cantaloupe, honeydew, watermelon, etc.

These fruits break down very quickly and lack the sinewy nature of plants like broccoli, so worms are quick to move in on them.

Spent Coffee Grounds

Some folks express concern over high acidity, but this is only true of unused grounds or the coffee itself in liquid form.  The coffee grounds themselves are pH neutral. But they are also sterile immediately after being drenched with scalding water, so I find it takes a few weeks before the worms really move in on them.

I also find that coffee grounds can dry a bin out, so keep an eye on moisture if you’re adding quite a bit of them. Oh yeah….toss the filters in too!

Banana Peels

I like to lay banana peels flat on the surface of the worm bin (with the skin facing up) and come back a few days later and turn the peel over to find a cluster of worms beneath.  This is also fun to do with cantaloupe!

Apple Cores

Another common fruit whose waste is perfect for the worm bin!  Yeah, yeah, I know the seeds don’t break down, but those can be sifted out later.  Apple cores break down quickly, so they’ll be gone in no time!

Manures

These are slightly more advanced because they can be harder to procure than regular food waste, but popular manures come from cattle, rabbits, and horses. Some folks use pig manure, but it is so liquidy and harder to handle that it’s probably not worth your time.

As a general rule, you will want to precompost most manures as introducing them to your bin, especially a closed system like a Rubbermaid bin, will result in overheating and a toxic environment for your worms.

I love horse manure as I find it is the least maintenance-intensive; I can put the worms in a mixture of aged and semi-fresh horse manure and pretty much leave them alone. And the carbon-to-nitrogen ratio also allows it to be a serve as a bedding as well as a food, so I don’t find the need to add fresh bedding every time I feed.

Vegetable Waste

Yeah, yeah, this is a pretty huge category, but your worms will take to pretty much any veggie waste you create during meal preparation.  Carrot peelings, potato skins, broccoli and cauliflower stalks, lettuce, kale, even onion peels (in limited quantities) are perfect for the worm bin.  Veggie waste like this isn’t prone to overheating your bin either, so this is another low-maintenance food.

Some More Tips On What (and How) to Feed Your Worms

  • One of the most frequently asked questions, especially for new vermicomposters, is “Can I put (insert whatever substance) in my worm bin?  The answer is pretty much always “yes, depending on the size of your bin and the amount you plan to feed them.”  Toxicity is always a matter of dosage and while introducing battery acid or, more benignly, peanut butter to your worm bin wouldn’t be helpful, it doesn’t have to spell doom for your worms either. (The above answer does not apply for anyone who wants to sell their worm castings.)
  • Do you need to blend/grind/puree your food before you feed it to the worms? No, you don’t neeeeeed to do this, but the worms will consume an apple run through a food processor much faster than they will consume an unprepared core.
  • Consider freezing organic waste to speed the breakdown and ultimate consumption by the worms. Most fruits and vegetables are 80-90% water and freezing the foods causes this water to expand (as it becomes ice) and rupture the cell walls.
  • While I don’t think it’s necessary to add bedding each time I feed, it should always be top of mind. Feeding without adding bedding can lead to an overwet, overheating, and over-acidic bin. Remember: You can easily have too little bedding. You can almost never have too much bedding.  

If you’re new to vermicomposting, check out my Guide to Getting Started with Vermicomposting.

If you’re not new to vermicomposting and vermiculture and you’re interested in how to ethically make money in this growing industry, I highly recommend the Worm Farming Alliance, run by my friend, Bentley Christie. Get access to some of the smartest worm heads around!

The 2017 Guide to Getting Started with Vermicomposting

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Start on the right foot with the ultimate how-to for the beginning vermicomposter. Get it now.

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