Many people ask about how to separate worms from the castings in their worm farm. This is a very important skill for worm farmers and it is important to share with you.
In order to effectively separate worms, it is important first to understand their instincts. Compost worms are brilliantly wired to cope with their surroundings and we can use this to our advantage.
Firstly, they are naturally attracted to moist, high food areas of the worm bin. Worms will naturally cluster near the last place they were fed. A professional worm farmer with 15 years’ experience observed that baby worms will naturally congregate near the top of the compost pile while mature worms can be found underneath it. Therefore, an easy way to collect a few worms (and some castings) for a new bin, is to peel off the layer of food and grab a handful of worms from underneath.
A more scientific method is to Stop feeding the worm farm. Instead put soft food scraps like banana peels and celery in a mesh bag (e.g. onion bag). Place this on top of the compost in the worm farm. Once the food in the tray runs out, the worms will move into the mesh bag looking for food. You can then lift the bag out, worms and all.
Worms also gravitate towards smooth or hard surfaces. During winter rains, we have found dozens of worms clinging to the carpet on top of the worm windrow. We could simply roll back the carpet and brush the worms into the container for removal.
Similarly, worms also love cardboard or paper. Corrugated, laminated cardboard allows worms to crawl into the channels and breed. The cardboard and paper also provides a hard surface and a backup worm food. Next time you check your worm farm, put a layer of torn pieces of paper and cardboard on top of the bedding. You will be surprised at how many compost worms are underneath it the next time you visit. Check out this video to learn more about feeding your worms cardboard and paper.
The most scientific method for those who want clean worms is to sort the worms using their hatred of light (heliophobia). Worms will normally move away from light as they know it will dry out their bodies. That is why you may see plenty of worms when you first open your worm farm, but many of them disappear within two or three minutes.
When sorting worms using the light separation method, follow these steps:-
- Tip the remainder of your worm farm tray on a flat surface (e.g., table) under bright light.
- Leave the pile alone for 10 minutes or so as the worms will migrate down, away from the light.
- Remove the castings until you start seeing worms then leave them to migrate further down for another 10 minutes.
- Repeat the process a few times until you see a large clean pile of worms clumped together at the bottom.
- Quickly package them up or move them into your next worm farm or compost bin. It is critically important not to let them dry out or get stressed. If you need to keep them “clean” on a temporary basis, put them in an insulated container with some bedding like straw, leaves or sawdust.
Check out this video to watch a worm farmer using this method.
Another sorting method commonly used by worm farmers is sifting. This relies on the worms’ size compared with the bedding material and worm castings around them. Commercial worm farms use large rotating trommel screens to sift the castings and collect the worms at the end. You can see an example here. You can make your own rotating trommel by following the instructions in this video.
