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.
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 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!
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!