Moldy Bread as Worm Food

Questions from Nicole:

Hi. I have an indoor worm bin in my apartment. Can I feed my worms
bread that has gotten moldy? Will the mold harm the worms? Would it
make the bin too smelly? Thanks, Nicole.

Hi Nicole,

The short answer is YES, you can certainly use moldy bread – BUT it’s important that we explore this “moldy” topic in greater depth.

Fungal growth in a worm bin – and moldy food in general – is not necessarily a “bad” thing, but it IS something you might want to keep in check (assuming you are not actually trying to grow mushrooms in your worm bin – another topic of discussion altogether!). Fungi play an important role in the breakdown process, but if you allow them to grow to the “fruiting” stage, you can end up with clouds of spores billowing out of your bin every time you open the lid. For anyone with mold allergies (or with someone else in the house who has them) – and especially with certain kinds of mold – this is definitely not a good thing.

That said, it is typically not difficult to keep fungal growth in check, so there is no need to worry. The key is to break up the mycelium – gentle mixing with a small hand rake should do the trick – before the fruiting bodies develop. Getting back to your original question – just generally, when you break up moldy materials and mix them up with plenty of other (non-moldy) materials, it should help to suppress further growth and spore release. You can take things a step further by adding a lot more bedding and/or living material, such as well aged horse manure, so that all of the moldy stuff ends up basically buried.

It’s important to point out that the size of the worm population and the amount (and type) of food wastes being added can have a major impact on mold growth. When you are aging the system prior to adding worms, for example, this tends to be a very common time for fungi to seemingly take over the bin. But once everything is mixed up (especially with the additional steps recommended above) and the worms have been added, it’s very unlikely you’ll end up with much more in the way of obvious growth – especially if you are burying your waste materials and feeding in moderation (both recommended). The worms should keep any additional fungal growth in check.

Hope this helps!

P.S. All these recommendations should also help to ensure that the bin does not get smelly as well!

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    • tom
    • August 23, 2014

    I mix my moldy bread with wet food scraps and blend it with coffee bread by it self takes to long.

    • tom
    • August 23, 2014

    coffee also seams to help with the smell and worms love it I get about 40 gal. per week.

    • Patti Martinez
    • June 30, 2021

    Hi thanks for the info about mold bread
    And I would like to known do I add paper or towels all the time I feed my worms
    Thanks Patti

    • Bentley
    • September 1, 2021

    Hi Patti – paper towels (assuming that is what you mean by “towels”) that haven’t been used with harsh cleaners etc should be ok. Shredded newsprint and shredded cardboard tend to be better bedding materials. I also tend to use a lot of “scrunched” scrap paper in my systems and that seem to work well.

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