How Much Should I Feed My Worms?

The question of how much to feed your composting worms can vex the beginning vermicomposter, and if you’re in an area like I am that features both hot and cold weather, then that amount can vary wildly.

So if I were you, I would get out of the mindset of trying to looking for a one-size-fits-all number.

For example, if you’re under the assumption that worms eat 50% of their own weight each day and you mindlessly feed your 10lbs of worms 5lbs of food waste each day, you might find that you’re grossly overfeeding them.

Overfeeding = worms escaping your bin!

You may also find that you’ll soon have zero lbs of worms to feed because they’ve escaped the hot, stinky mess, you’ve made of their home. You might also inflict protein poisoning and/or kill them by overfeeding them, especially in a small, closed system.

This isn’t to say that your worms won’t eat that much. Some folks will claim that their worms will eat up to 50% of their own weight each day.

I’m not the one to doubt them.

But it’s better to start slowly. For your first feeding, be conservative and try 10% of your known worm weight and observe your worm bin daily to see how the worms are dealing with what you fed them. Even if worms can eat 50% of their own weight, I ‘ll bet you dollars to doughnuts the worms aren’t going to completely finish off that 10% in 24 hours.

And the reason is pretty simple.

Worms are eating more than what you feed them.

Say what?

We tend to think of worm “food” as the nitrogen-rich “green” material like food waste. While this isn’t incorrect, worms are also eating the “brown” material we consider to be bedding, which is decomposing, albeit at a slower rate than food waste or whatever you are feeding them.

This is why I love aged horse manure for my worm beds. Its carbon-to-nitrogen ratio is fairly high and it is considered a bedding by most vermicomposters, but the worms love to eat it, meaning I could go many days, even several weeks without feeding my worms if there is horse manure present.

The cool part is that the worms are excellent self-regulators. If they lack food, or other conditions in your bin aren’t quite optimal (but not awful), the worms will eat and process your waste more slowly, reproduce more slowly, and the mass of the individual worms will most likely shrink as well.

And this is exactly what happens when I actually go weeks without feeding my worms or when it’s wintertime and the temperature in my worm beds gets down to 50F.

In other words, there are some benign, not-so-awful downsides to underfeeding your worms.

But there’s only bad stuff that can arise from overfeeding them.

6 thoughts on “How Much Should I Feed My Worms?

  1. i get confused. if the worms eat the bedding! then why do we feed them! if food is always present and eating it they poo adding to the bulk of the bin. so the bin get fuller and fuller. so dose the contents of the bin have to be full with possibly uneaten bedding (cuz they have been eating food) to harvest any casting.
    all so. at what depth do we start our new bedding at ? all ways eager to learn.
    Thank you.

    1. Hi Helen,
      In a nutshell, the worms eat microbes which are growing on decaying food and bedding. But bedding decays too slowly to provide a really good food source for the worms, so you still want to feed them.

      As for adding bedding, you should consider adding some bedding periodically, but it’s not necessary EVERY TIME you add food.

      As for depth, the worms really only work the top 6-12 inches of your bin, so when you get a depth of 18 inches or so in a mature bin, you’ve probably got enough at the bottom to harvest. That’s the hard part about using a Rubbermaid bin for vermicomposting. You need to disturb the whole bed in order to harvest castings.


      1. Thank you. it makes more sense now. i had looked for an answer to that question but i think google got fed up with me and i got nowhere.
        as a newbie it is good to have some where and some one that we can ask this type of question.
        onwards and upwards with my learning and hope to raise and grow on loads of happy worms.
        i do however have one more question.
        why is it so hard to get worms or cocoons sent / shipped to Spain?
        i was told by one company that spain dose not allow them into the country. on searching the internet about this i come up with what is and is not allowed into countries and the only thing “one chapter” that was about spain was no shipment of and weapon or parts even if accompanied with paperwork.
        so no mention of worms. cocoons. or soil.

        1. Hi Hazel,
          I think most countries have fairly strict restrictions on shipping anything considered livestock across the border. I take it there are very few composting worm suppliers in Spain?

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