There are several reasons why you might want to separate your composting worms from their bedding. Perhaps it is time to harvest the finished compost. Or maybe something has gone REALLY wrong in the bin, and you need to start your bin over again. Uncle Jim’s Worm Farm offers several techniques for separating your worms from most of their bedding.
If your worms have been munching on scraps for more than a few months, there should be plenty of “black gold” (worm castings) in the bin. Worm castings are an all-natural, nutrient-rich fertilizer for the garden and houseplants. They are also filled with friendly microbes that are good for the soil.
Once in a while, a worm bin has an intractable problem. If it is sopping wet, you can try blotting up puddles, opening the drainage holes, and adding dry bedding (such as peat moss, shredded newspaper or coconut coir). If your worm bin smells bad, you can remove offending scraps, mitigate the pH, take out mold and mildew, and avoid over-feeding. Sometimes an ant colony turns an outdoor bin into a nursery and if removing the lid doesn’t discourage them, it might be time to cut your losses. Worms might be trying to escape en masse. If you try to fix it, and it can’t be fixed, it’s time to start over.
Attract Worms with Food
If time is on your side, the most natural way to make worms assemble together is with food. This technique is easiest if you use a tray-based composter, such as the Worm Factory 360 or Can-O-Worms composter. Feed only in the top tray. Most of the worms in the lower trays will climb up to get the food. If there are still too many worms in the lower trays, dig around and see if there is undigested food scraps in the lower trays. If so, remove them or move them to the top tray. When the worms have mostly vacated the lower trays, dump the trays out and use the completed compost in your garden. If your bin is spoilt and you need to start over, you will need to also sort the worms (see below).
If you have a simple composting bin, such as the Worm Ranch or a bin made from a tote, focus on feeding the composting worms in just one corner of the bin for a couple of weeks or more. The worms will figure out that to get food, they have to go to that spot. To get the worms in a convenient bag, just put bedding and food in a mesh onion bag or burlap sack and bury it; after a few weeks, dig it out and you have a bag of worms. The rest of the bin should have fewer worms. You can take away the worm castings from the other parts of the bin, leaving the highest concentration of worms in the bin. You may elect to add more bedding at this point.
If you have an over-population of worms, the food technique might not work well. There still might be worms mixed in with the majority of the worm castings. You’ll have to decide whether to try a different separation method, or just keep some worms in the fertilizer. Releasing them into the garden, mixed in with the fertilizer, gives these worms a chance at a new life. They are not ideal for the garden, but they won’t do your garden any harm. (Super Reds/European Night Crawlers are bigger and better for the garden.)
Sort the Worms from Compost Using Piles
You can separate composting red worms from the compost or bedding by using their natural aversion to light. Here is a shortcut for sorting the worms using mounds:
- Start by picking a spot indoors or out that has good lighting, but not too much direct sun.
- Dump the contents of your composting bin onto a tarp.
- Shape the bedding/compost/worm mixture into a bunch of mounds. You can form a peak on top to form cones.
- Let the mounds sit for a few minutes. The worms will dig down deeper into the mounds.
- Brush off the material on the top of the mounds. This is your completed compost (if you are harvesting worm castings) or the old bedding that needs to be discarded or used as compost (if you are starting over again). Set aside.
- Repeat steps 4 and 5 until piles of worms remains. It’s OK if there is still some material mixed in with them.
- Put fresh, slightly moist bedding in the worm bin, and place the worms on top. Shining a light of them will encourage them to dig down.
Whether you want to use dark, rich organic fertilizer in your garden or start over with a fresh worm bin, separating composting worms isn’t too difficult. The resulting compost can be screened to remove debris, then dug into the garden, used to make starts, or turned into compost tea.