Citrus Vermicomposting

Citrus fruit wastes tend to be among those considered less-than-ideal for vermicomposting. They are highly acidic and the rinds contains volatile oils (and are slow to break down in general), so even a mellow vermicomposter like myself tends to treat them with caution.

That being said, I DO like to push the envelope every now and again (wink wink), so when I started noticing a lot of juiced lemons showing up in the coffee grounds I regularly pick up (from a local coffee shop), I thought it might be fun to set up some sort of citrus vermicomposting experiment.

If you’ve been following the blog closely this spring you’ll know that I’ve settled in to a pretty consistent multi-pronged waste optimization strategy for preparing my waste materials, involving a freeze/thaw, chopping, and then mixing with “living materials”. I decided to take the same approach in this case as well.

A couple of days ago I removed a small garbage bag of lemon halves that had been sitting in my chest freezer for more than a week. I let them thaw outside for about 24 hours before cutting them up with heavy duty scissors and mixing them with some “living material” collected from the edge of one of my outdoor worm beds.

The lemons were pretty badly infested with fruit flies by the time I started chopping them up, so I definitely won’t be doing any indoor experimenting with this particular batch. I’ve decided instead to add the mix to my raspberry garden worm bed (something I’ll write more about at some point) at the back of my yard. I did want to make things a little more interesting, though, so I created two different batches of the lemon mix, one with rock dust mixed in, and one without any. I’m curious to see if buffering the acidity does anything to aid with the break down process (render it more “worm friendly” etc).

I will keep the material nice and moist (so as to make sure that moisture content isn’t a limiting factor), and keep a close eye on the two treatment zones over the next few weeks to see what happens.

Stay tuned!

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    • Laura
    • June 13, 2012

    Or you could Bokashi the citrus first. I add the occosional lemon peel (after the 2 week ferment) to my worm bin and they move in after a couple of days and demolish them.

    • John Duffy
    • June 13, 2012

    I’m looking forward to the outcome of this experiment.

    • Deb
    • June 13, 2012

    I put a half lemon that had been in the fridge a couple months in my bin. I put it to the side, just in case. Every time I checked, the red wigglers were all over the inside of the peel. Also put fresh squeezed lime peels in another bin. Without the fruit, it’s not nearly as popular.

    • Jeff Cummings
    • June 20, 2012

    Neat idea, I was wondering about this too, because the Worms Eat My Garbage book says the Limonene in the Essential Oil of the peels is toxic to the worms.

    However, I think the limonene is non-toxic to the worms, but is an anti-bacterial essential oil constituent. This would kill the worms food, wouldn’t it?? Imagine being covered and your house saturated with a substance that would kill your food, or make it poison. That would not be good.

    I did think that perhaps letting the peels compost or rot first, the mold being the first thing that would attack them, would first allow the mold or fungi to eat the limonene and make it inert, and render the energy bio-available to bacteria after that…?

    What do you think? Hope your experiment works also, as I am an avid juicer, and always have lots of fruit peels, and rarely feed them to my small worm bin, as I don’t want to kill their food…or them.


    Jeff C

    • Al
    • July 14, 2012


    I just wanted to hear how things are progressing with your
    “Citrus Vermicomposting” experiment?

    I noticed one of the comments suggested that the peels/”waste” citrus
    be bokashied first. I bokashi many things before they go into my worm
    bin. Including citrus. But (and this is an inadvertent “other topic”) I
    often run into the problem of overheating as the bokashi gets to a point that the worms feel comfortable to move into it.

    Anyway, would really like to hear how things are progressing with your
    “Citrus Vermicomposting” experiment.


    • Bentley
    • July 14, 2012

    Thanks for the nudge, Al.
    As it turns out, I will need to do this one again – but this time with one of my indoor bins. I guess the good news is that the citrus waste was readily processed in my outdoor beds – but it was tough to actually monitor it or do any sort of comparison.

    Will definitely come up with a better way to test this out.

    • shara
    • November 12, 2013

    what is the answer i need it for a research paper and no one else has eny thing like it because i think the citrus in lemons kill composting worms

    • Bentley
    • November 17, 2013

    Shara – there is no single definitive answer. Citrus is definitely a material you need to be careful with, but in moderation (ie NOT like I did in this particular experiment – haha) it should be fine – especially in systems where the worms have plenty of room to spread out in, and when there is some buffering capacity of the habitat.

    • Dani
    • April 7, 2014

    Hi! It’s been a while since your last comment, so I hope you’re still reading this… I have a TON of citrus peels and occasional moldy fruit (lots of tangerine trees), as well as loads of wood ash. I’m trying to figure out some way to combine them and neutralize the acidity/alkalinity, and also to minimize the limonene contribution so my worms can deal with the citrus. Do you think letting them sit in a separate bin to mold and break down for a while before adding them to the worm bin would help? What was the end result of your citrus experiments, or is there another post I can read following up on this? Thanks!

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