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Reader Question: Stinky Worm Bin?

By October 31, 2011

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I received this email from Vicki:

"Hi Colleen. I've had my worm bin for a little over two months, and for the last week or so it has started to smell rotten. I keep reading about how worm bins don't stink, but mine definitely does! What can I do to get rid of the smell?"

Thanks for the question, Vicki. I think that in the zeal to sell people on vermicomposting, many writers overstate the simplicity of worm bins. Worm bins that are being properly maintained don't stink. But the key phrase there is "properly maintained." And if you're new at worm herding, figuring out how to create the optimal conditions in your bin can be rather hit or miss.

There are a few things that can cause a worm bin to be smelly. Most commonly, the cause is too much moisture. This can be caused by adding too much water to the bedding, but is more often caused by adding too much "wet" food at once. Melon, squash, cucumbers, tomatoes -- all of these are very moist foods that can cause an excess moisture problem. Luckily, it's pretty easy to fix a wet worm bin.

Other issues could be that you've added too many smelly foods, such as onions or garlic. If that's the case, remove as many of those as you can, and hold off from adding any more of them for a while. Also, be sure to avoid adding meat or dairy, as the spoilage of these foods will definitely make your worm bin smelly.

I hope this helps! A smelly worm bin is annoying, but it's pretty easy to remedy, and you'll be back to a sweet-smelling bin in no time.

More About Vermicomposting:
How to Set Up a Worm Bin
Worm Bin Problems: Worms Trying to Escape
Best and Worst Foods for Your Worm Bin

Latest Articles on About Organic Gardening:


November 8, 2010 at 7:07 pm

Agree with you about the smell of a worm bin. It can be, as you describe, hit or miss and some smells are natural and to be expected when things are decomposing. It isn’t like worms are deodorizers or odor neutralizers.

November 13, 2010 at 12:44 pm
(2) Chris says:

My bin before was too wet. It didn’t smell bad, but I had a hard time harvesting vermicompost because everything kinda clumped together.

Something that really helped is a variation of adding new dry bedding. Instead of adding fresh shredded newspaper, I just added a layer of a whole newspaper on top. The following day, I removed it and added a new whole newspaper. I just alternated those two. This way, I didn’t really add anything permanent to the system. It really helped my bin. Try it!

November 18, 2010 at 2:46 pm
(3) doccat5 says:

The smell comes from overfeeding your worms. Cut way back on the amount you are offering until they can “catch up”. You won’t hurt the worms, they’ll be fine. Notice if you have an very “wet” bin, that also contributes to odor problems. If so, simply, adjust your lid so more air can circulate in the bin. And do add more dry material to the bin. I use shredded black and white newspaper for mine. Mix it in throughly. The paper will help absorb extra moisture and redistribute the food sources.
We have 4 bins and are going to add another 2 shortly.
We’re still working on harvesting the castings, we’ve found if we do this outside in a partially shady area, we have had the most success. We use a big flashlight over the top and the worms dive for cover, making scrapping off the top layer of castings much easier and it goes a lot faster as well.

November 21, 2010 at 2:26 pm
(4) organicgardening says:

Some odor could definitely be coming from food, but the worst (and most common) odors are the result of anaerobic conditions in the bin, which is more often than not due to too much moisture. Adding dry bedding and not adding overly moist foods (such as melon, tomatoes, etc) for a while will take care of it.

November 8, 2011 at 6:47 am
(5) doccat5 says:

Everything Colleen said in the above article is correct. You are probably overfeeding as well. Add more dry materials to your bin to help absorb the extra moisture and back off on the feeding for a couple of weeks. We’ve discovered we sometimes have to “crack” the lid on the tubs to help aerated and increase moisture evaporation, especially if it’s humid. Don’t give up, it’s well worth the effort. Worms are such marvelous little creatures and their waste is a gardener’s best friend!! It is truly Black Gold!!

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