Harvesting Worm Castings

When to harvest?

In my bins, the finished worm castings are actually dark brown muddy paste. There are no other visible decomposer insects present, and the worm population also has usually started to decrease in size, imho. This happens usually one or two months after I stop adding more food in the bin. Note that I am talking about non-juiced/ground foods here.

How do I harvest castings?

There is the Scoop-Off-Thin-Surface-Layer-While-The-Worms-Head-Downwards-In-The-Bin-technique.

A handy one, especially for harvesting worms, is the Lure-The-Pink-Wriggly-Workhorses-Into-A-Disposable-Plastic-Box-With-Sum-Fresh-Banana-Peels-tech, this takes 2 or 3 rounds before basically all over 2 week old worms are harvested.

The first one above is ok for small bins. The second one will work with larger ones, but you will need to add more plastic-box-trap-containers if the bin is large.

For big jobs, its best to use a worm harvester made of stainless steel screen. Its basically slightly tilted rotating cylinder made of screen with a ‘solid wall’ end that you gradually dump the bin contents into. The processed caste falls to the collecting box under the harvester, while the worms roll downhill inside the cylinder into the solid-walled ‘collector’.

Is there any way to get everybody out of the castings before they’re harvested?

Yes, in my opinion there is. Food lures! The worms will go after moist white bread or banana peels like a rasta for ganja!!

As worms can use their sense of smell to track down worm-treats, and move actively after foods, using food lures works very well, especially so in a mature bin where fresh food availability is low.

Combined with some kind of simple mechanical trap this works very well, and very few worms will stay behind.

A wormer by the OG name of ‘Aprilfool’ introduced this simple concept:

The method that I use for seperating worm from the bin is something I call worm wrangling. When the bin is about two months old I don’t feed them for a week or two then place a slice of bread on top. In a day there are hundreds of worms under the bread that are easily scooped with a trowel and placed in a new bin. I do this for a week. Then I leave the rest of the worms to finish the food that left in that bin. In about another two months there are few worms and all castings, in that bin.

In a tray system, or a box-in-a-box type of worm bins (where the outer box acts as a leachate-juice tray) one can simply add the food lure in a empty tray and after some days most of the worms will be in that tray, and can be collected. Repeat once or twice and you should have helped almost all hatched worms in the bin to emigrate.

Or one can simply bury some kind of empty container so that its mouth is flush with the worm castings surface and drop a worm treat in the container – since the worms have easy access to a fresh food source they will congregate in the container.

Remember to keep things moist so that worms and their food lures wont dry up.

There are other ways – like you mentioned, drying the vermicaste will motivate the worms to find more hydrated surroundings. I guess one could use citrus peels as a repellent to drive them out.

Of course, getting the cocoons (the worm eggs) out would require hand sorting or a mechanical cocoon separation machine.

I wonder how long the new generation would survive in pure castings. maybe you could let it sit until they die-off.

Well, many worm farming guides and companies say that the worms will eventually die in ‘finished’ worm castings.

I have not seen this happening in ‘finished’ worm castings. Also Mary Appelhoff, ‘The Worm Woman’, US worm movement ‘spokesperson’ says that worms will survive indefinitely in worm castings. I think that well made worm castings will always contain at least few worms, unless separated mechanically or otherwise.

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