Smelly, overly-moist worm bins are a common problem. Luckily, it's also a fairly easy issue to overcome. Too much moisture in a worm bin is caused by one of three things:
- Too many foods with high moisture content.
- Too much water added to the bedding.
- Too little fresh bedding added.
Too Many Moist Foods
To cure the problem of too many moist foods in your bin, there's a two-step process to getting your bin back to normal. First, stop adding foods with high moisture content. These include melons, cucumbers, tomatoes, and berries. You can add them again once your bin gets back to normal, but try to do so in moderation. The second part of the cure is to add some fresh, dry bedding to your bin.
In most cases, people use shredded newspaper for bedding. Simply pull aside some of the wet contents of the bin and add a layer or two of dry bedding. It will absorb some of the moisture. Be sure to add some near the bottom of the bin, as this is inevitably where most of the moisture has collected.
Adding Too Much Water
So many of us worry about our worms drying out, and the result can be that we are overzealous with the spritzer bottle. The remedy for this is simple: simply stop watering for a while, and add some fresh dry bedding as described above. When it's time to start watering again, do so only after digging into the bin a bit and feeling to see if the contents are really that dry. Often the top layer will be a little dry, but everything under that is fairly moist. By mixing the contents of your worm bin every once in a while, you can maintain a fairly even moisture content without spritzing. If you are finding that the contents are dry, add a few high moisture content foods, or add some fresh moistened bedding. That should even things out very well.
Not Enough Fresh Bedding
The final issue is possibly the easiest one to fix. Once a worm bin has been going a while, the bedding will inevitably start to disappear. This is a good sign; the worms and microorganisms in the bin are doing their job. However, the bedding also acts kind of like a sponge in your worm bin, soaking up extra moisture and preventing a wet mess from sitting in the bottom of the bin. Once the bedding breaks down, the excess water has nowhere to go. To remedy this, simply add a few layers of fresh, slightly moist (or dry, if the bin is very wet) bedding material.
A moist worm bin can be a stinky mess, and result in drowning death of your worm herd. By paying attention, and taking the appropriate action when you need to, you can avoid this worm bin mishap.
Composting with Worms. Oregon State Extension