Would You Like A Cheap, Easy Way To Harvest Worm Castings?

A beginning vermicomposter with a finished batch of worm compost is like the dog who finally catches up to the car it’s been chasing. They both ask themselves “now what the heck do I do with this?”

While producing a lively, microbially active bin chock full of wigglers is a source of pride, this success is met with new challenge: how best to harvest the castings?

Update: I have released a more comprehensive blog post about how to harvest castings and I ask a simple question: Do you need to harvest your worm castings at all? Read it here.

Unless you’re wealthy, lucky, or sophisticated enough to be blessed with a flow-through reactor designed to make harvesting a breeze (or you’ve sprung for Worm Inn Mega) you’re going to need a way to periodically remove your castings from your worm bin that doesn’t break the bank (or your back).

Now there’s a general rule when hiring contractors that when it comes to speed, quality, and a cheap price, you can pick two, but you’re not going to get all three.

The same holds true for worm harvesters and equipment for separating castings from the worms and substrate. Large, trommel-style worm harvesters are expensive, and if you’re going to attempt to build one yourself, you need some serious engineering chops.

But you’re going to separate your worms from their poop in no time. On the other end of the cost scale, the low-tech light harvesting method will still help you harvest castings or worms, but it can be painfully slow and tedious.

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CompleteMy mission at the Urban Worm Company is to make worm composting as simple as possible. So I’d like to offer an inexpensive solution to harvest castings and safely return as many of your worms as possible back to your bin. This Urban Worm Castings Harvester is a small-scale solution constructed almost exclusively from PVC pipe, with a little help from a threaded rod, simple hardware, and a cylindrical metal mesh office waste basket to serve as the rotating trommel.

My initial testing has produced finely screened worm castings with little distress to the worm population. And best of all, it can be built for under $50 dollars with parts and materials purchased from any large hardware store. While this particular design is not well-suited to harvesting worms, it could be adapted for that purpose with a more sophisticated trommel setup.

Please check out the video below of the Urban Worm Harvester in action!

[youtube https://www.youtube.com/watch?v=H7MDwblpMVY?feature=oembed?&feature=youtu.be&w=1165&h=874]

The concept is simple.

The PVC provides the frame upon which the waste basket spins around the threaded rod which serves as the axis. The castings fall into a container (in this example a mortar mixing bin) or on to a tarp placed beneath the frame.

The angle at which the waste basket rotates is easily changed by sliding the 1/2-in PVC support bar to the desired height. The more full the basket, the higher the angle you’ll need to keep the contents from falling out the open end.

The trommel may be spun by hand but I prefer to use an electric drill with a bit driver and a socket to rotate it. I would imagine there are some gear heads out there may be able to fashion an even more automated motorized rotation system.

I am really excited about this harvester’s applicability for the home composter. The castings are as finely screened as any worm castings I’ve seen thanks to the tight metal mesh of the makeshift trommel, which is probably as fine as 1/8-in landscape cloth. But the benefit of highly-filtered castings comes at the cost of a limited throughput.

You aren’t going to work through a cubic yard of moist vermicompost in a reasonable time. To get around this, you could find a waste basket with a larger mesh or you could fashion your own mesh cylinder using landscape cloth as seen in many home harvesters.

giveawaydarkIf you’re cramped for space and have a small-scale vermicomposting system, this may be a good solution for you. When disassembled, all parts can fit inside the trommel for easy storage and it can be reassembled in less than 5 minutes.

I am offering the plans for the Urban Worm Casting Harvester free of charge. I’m psyched to hear what you think.

Harvester Plans

If you have finished castings and need a way to harvest them, let me send you free plans for a harvester.

Sweet! Now check your email to confirm your subscription and get your plans immediately.

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12 thoughts on “Would You Like A Cheap, Easy Way To Harvest Worm Castings?

  1. Thanks for the great idea. To give back a little bit, here is what I am doing.
    The body of the trommel is the Staples basket like tours.
    I am using a 1/2 ” piece of PVC for the axle
    To create the spiders (the spokes) I am using 1/4″ x 12″ pieces of all-thread. These are placed through the basked and through holes in the PVC axle- the Up-down spoke is placed about 1″ from the side-side spoke.
    I already have a 1 1/4″ frame I use for an elevated bed (1 1/4 PVC pipe & 1-1/4 in. Furniture Grade PVC 3-Way Elbow in White
    Here’s the good part!
    I am using SNAP SADDLES for the bearings.
    The bearings are made by (1 1/4 snap saddle-1/2″ nipple-1/2″ snap saddle
    If this sounds confusing, go to Home Depot and search for these parts…you’ll see how it comes together.
    Thanks again for the great idea. Hope you try it & post the pic here.

  2. Thanks for the great idea Barry! The axle part is probably the least “elegant” part of this contraption. I will definitely check out the snap saddles at the hardware store. It seems I’m there every day!

  3. I love the idea, and I can’t wait to try it out!
    I bought all the materials, but I realized that #1, I got the wrong adapter piece. There is a male adapter, and a female. I got the female… don’t ask me why! Lol! I’m not by any means a plumber, and I don’t know the least thing about PVC, except it makes cool marshmellow guns. 😀
    #2, I hadn’t the slightest idea what a “1×1/2 inch Tee” was, so I bought two 1 inchers, and one 1/2 inch. Now that I looked at your pictures closely, I see exactly what I was supposed to get. (Ok, maybe I’m a little blonde)

    So, if I may make some suggestions, would it be too much to take a pictures of the pieces?
    And maybe specify that it needs a male adapter.
    Thanks for sharing how to make it!
    Kate

  4. Hi Kate! I did think of taking pictures of all pieces – and maybe I should have – but I was just trying to keep the file size as small as possible. Maybe some pics of the easy-to-confuse parts?
    But thank you for the feedback. I didn’t realize there were slip and thread male adapters! I will adjust the directions.
    Once it’s together, I would love to hear how it works for you! Like any casting separator, it will work better with drier vermicompost.
    Thanks again,
    Steve

  5. Ohhhh, I just realized the adapter you were talking about. Yes, I kind of left you with a 50/50 chance there didn’t I? 🙂

  6. Hi,

    Hope you are well.

    I have tried constructing the worm separator as you have instructed to NO joy. I was wandering if I will be able to buy from you a completed constructed model.

    If the answer is yes, please send me how much it will be. I am in the United Kingdom.

  7. Brian,
    Firstly, thanks for joining the e-mail list!
    Secondly, I am wondering if maybe there was some difficulty going from standard to metric with joining the parts together?
    Was there a specific issue that I can help address? Feel free to either respond to the comment or e-mail me at [email protected]

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