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.
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.
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.
The 2019 Vermicomposter's Starter Guide
Your roadmap to a successful beginning in vermicomposting.