My Worm Bin Smells Like Poop – Help!

Question from Melissa:

Here’s a question for you. My indoor worm farm REALLY stinks. I’m fairly new to this, and happy to say the worms are thriving. Is there a way to prevent the “poop” odor that is almost unbearable when I add food? I’ve started wearing gloves when I add food to prevent the odor from staying on my hands. Otherwise it’s an earthy smell which we’re fine with.

Hi Melissa,

The good news is that it’s relatively easy to remedy a smelly bin, and to help prevent it from happening again. Here are some important questions for you to consider:

1) How much food is currently in the bin?
2) What particular kinds of food are in the bin?
3) How much air flow does the bin have?
4) How wet are the contents of the bin?
5) How much bulky, absorbent bedding is in the bin?

Let’s look at each of these in more detail….

Quantity of Food

Overfeeding and/or lack of food optimization is a very common reason for a bin starting to smell. Worms are actually fantastic “odor eaters”, thanks to all the fragmenting, mixing, and aerating they do – along with the bio-filtration abilities present in their castings.

BUT…they can only process so much waste in a given time period.

Part of the problem stems from these crazy “rules of thumb” relating to worm consumption rates that have been circulating around for years now. eg. “worms can eat twice their weight in food per day”. While there are certainly cases where this can be true (even higher rates than that) – this is absolutely the worst thing to use as a guideline when you are just getting started!

My recommendation is always to err on the side of caution, and “let the worms be your guide” – that is to say, only feed based on how quickly the worms are processing the food materials. As alluded to a minute ago, how well you “optimize” your foods can have a major impact on these processing rates (as can a wide range of other variables, such as temperature, air flow, water content of the food etc).

When you chop up wastes really well (especially, if you freeze and thaw them ahead of time) you really help the decomposer microbes gain a foothold, which in turn helps the worms. Mixing your foods with some form of “living material“, can accelerate the process even more.

Different Kinds of Food

Different food materials have different potential for creating foul odors. As a general rule of thumb, I recommend aiming to mix your foods as much as possible, rather than adding large quantities of one particular kind of food (although, this is certainly not a big deal once you get a bit more experience under your belt).

Certain foods – such as members of the broccoli family (eg. kale, cabbage, cauliflower) contain stinky odor compounds that can be released as the material decomposes. So you need to be a bit more careful when adding these (again – optimization, and mixing with other materials should help to limit issues).

One summer I left bins full of broccoli (from local restaurant) sitting outside in the heat for many days. It might as well have been dead fish guts in those bins.

(Thankfully, “necessity is the mother of invention”, and this led me to create my very first vermicomposting trench!)

Starchy wastes like bread, rice and pasta – have the tendency to congeal if you add a lot at once. This can create an anaerobic environment – and even stimulate a fermentation process, which can certainly create some funky odors (and drunk worms). Again, limiting the amount you add at once, mixing with other wastes (etc etc) can definitely help you to avoid issues.

Air Flow

Air flow is hugely important for helping to alleviate odor issues. What’s funny (and ironic) is that a lot of people want to keep their systems as closed up as possible so they DON’T have any bad smells floating around their house – yet it’s the fact that they are tightly closing up the system that often creates most of the issues!

Remember, anaerobic conditions lead to bad smells – not to mention a slow, poor quality vermicomposting process and eventually unhealthy worms! When to provide the system with LOTS of air flow, it’s amazing how many issues (including smell) disappear. In my recent post about “too much bedding”, I shared some images of the type of holes I tend to cut in the lids and sides of my plastic bins these days. Here they are again:

Using open systems – as scary as it might seem – is an even better strategy!

Moisture Content

Almost invariably, when a worm bin starts to smell really bad it means the moisture content is getting too high. Excess moisture obviously impedes air flow (and water can, at best, only hold a fraction of the amount of oxygen that air does), so swampy conditions go hand in hand with anaerobic conditions.

One of the best ways to best ways to “fix” a swampy worm bin is to add lots of…

Bulky, Absorbent Bedding

Materials like shredded cardboard and shredded newsprint can be hugely beneficial in most types of vermicomposting systems – but especially so in any form of plastic, enclosed bin. They can wick up excess moisture, while also allowing more air to circulate. They also create a great habitat structure for the worms.

In your case, I would recommend removing any excess food material you have (and start cutting back on your feeding if the worms don’t seem to be processing the food fast enough), mixing in a lot more bedding (and keeping a thick layer of it over top), and taking steps to improve the air flow in the bin.

If you do have access to any sort of “living material“, mixing some in should also help to remedy the existing odor situation almost immediately.

Hope this helps!

**For Even More Worm Fun, Sign Up for the RWC E-mail List!**
Previous Post

Deep Mulch Vermigardening

Next Post

Rotten Hay Vermicomposting


    • Melissa
    • July 15, 2015

    Thanks! This is very helpful. I’ve already taken care of the airflow (due to a previous issue of escaping worms I added a large hole with wire mesh to my bin). From this post I can tell I need to add living material, and I also need to add a bin underneath for moisture control as well as more bedding. Very helpful! I appreciate the advice.

  1. I’ve been reading that you can dig trenches next to your vegetable beds, and line them with mulch, newspapers, kitchen scraps, the same things that you would put in the worm bins. Then you can add the red worms to these trenches, and they will thrive well, while nourishing the garden.

    If this is true, what happens in the winter. Will the worms freeze if left outside in the trenches? I live in NE Pa.

    Thank you

    • Bentley
    • July 17, 2015

    Melissa – glad it was helpful! Hope things get turned around for you asap.

    Joann – You certainly can. Vermicomposting trenches are something I’ve written about extensively. Here is a post that provides a good summary:

    The beauty of trenches/pits etc is that they make it SO MUCH easier to keep composting worms alive during the winter. Just as regular earthworms stay alive thanks to the insulation protection provided by the soil, so to do composting worms in in-ground systems. I live in southern Ontario – so I would imagine you and I would have a similar winter. I’ve had great success keeping Red Worms alive over winter even in low lying beds with some insulation materials over top, so actual trenches are definitely effective.

    • Arlene Montemarano
    • July 18, 2015

    Fascinated by this article. I use the Worm Inn, and the fabric allows so much air that I am able to add nearly unlimited food waste from two households. But my worms, though numerous, are not as fat as those I had when I vermicomposted in plastic bins. So I thought I would add some LM, precisely the material that remains in the screen after harvesting. But this material always has a lot of worms in it, and I wonder if it is a good thing to mix the LM with the worms in it with the fresh food waste. I have always liked to keep them separate initially, and just let them wander over when they feel like it. I hate to remove all the worms and make the process take longer than it does now. Thanks, Bentley.

    • Nat Scholl
    • August 4, 2015

    Great page, very helpful. I myself use the “worm inn”, and it fascinates me just how fast these little wigglers can grow. The quantity of worms that my rig produces is far greater than any other setup I have used. And its not just that, no, its the quality as well. My inn produces the biggest, juiciest, and tastiest worms that I have ever harvested. I must say, they truly are scrumptious and the inn has has changed my life!

    • Bentley
    • August 7, 2015

    Arlene – sounds like you are doing well with your Worm Inn. Wow!
    Assuming the food waste you are adding is already “worm friendly” (ie not anaerobic etc) it shouldn’t be a prob mixing in living material containing worms. They can always just move away if it’s not to their liking. A stinking, foul waste on the other hand could indeed harm or kill any worms mixed in with it.

    Nat – Uhhmm…”juiciest, tastiest”? “…scrumptious”? LOL
    You may have the distinction of being the first Worm Inn owner to use it as a food growing system.

    • Mani Raj
    • August 17, 2015

    I recently started red worm farm as very small scale in house. I kept some food waste, and with mixing with newspaper. But there is some flies and some red ants coming inside even I covered the bin. How to I remove these small flies and ants.

Leave a Reply

Your email address will not be published.

Get Your Free Vermicomposting Guide!

* Join the Red Worm Composting E-Mail List Today *