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David’s Tub Harvesting Method


David Lozowsky’s tub harvester


Quite some time ago I made a video and wrote about my ‘Garbage Bag Harvesting Method‘ for separating worms from mature vermicompost. The idea behind this method was that it was a simple, inexpensive, and passive means of transferring worms to a new bin. Anyone who has gone down on all fours with a tarp and the contents of a mature worm bin to do the “light harvesting method” will know all too well that this is not the most enjoyable way to spend your time (speaking of which – I currently use a modified version of the light harvesting method that I will be writing about soon).

I received an email recently from good vermi-friend (and long-time reader of RWC) David Lozowsky, who shared with me his method for separating worms from vermicompost. His method is based on the same principles as the garbage bag method, but in my opinion is a much better approach. Rather than using a thin film of plastic, David simply uses an empty bin (of the exact same dimensions as his worm bins) with 1/4″ holes drilled in the bottom.

Interestingly enough, David uses the exact same bins as me – Rubbermaid Roughneck totes with the following dimensions: 24″x16″x8.75″ (LxWxH). This is as close to a ‘perfect’ DIY tub for vermicomposting as you can get (in my humble opinion) – it’s cheap, durable, holds a lot of worms/compost, and has a great surface-area-to-depth ratio.

Getting back to the topic of discussion…

Essentially, what David does is let a given worm bin mature over the period of time (hopefully he’ll chime in and let us know approx how long it takes before he harvests). As you can see in the pic below, the bin is full of vermicompost with very little (if anything) in the way of recognizable ‘food’. If you saw a close-up of the original photo, you’d see that it was also full of Red Worms.

Once mature, a new system is prepared so that the worms have a tempting new habitat to migrate into (the photo below shows what the new system might look like). The tub harvester is then placed on top of the new system (sans lid, of course) and the contents of the mature bin are added. Next, two desk lamps are positioned over top of the harvesting tub to help encourage the worms to migrate downwards. After 12 hours or so, the material is mixed up to help the compost to dry out a little more and encourage any of the remaining stragglers to make the journey to the new bin.

According to David, this method has worked extremely well – I seem to recall him mentioning that only 5 or so adults were left after his last harvesting session.

Of course, people are going to naturally wonder about cocoons and hatchling worms – always the main issue when it comes to harvesting vermicompost. Like any other method, this approach will almost certainly result in plenty of cocoons and young worms being left behind. If this is a major concern I suggest letting the material sit for at least a few weeks in a new bin with some tempting food material (aged manure, water melon etc) sitting on top. Any worms left over should congregate in this area, and there should be some hatching of the cocoons as well. You won’t likely get every last one, but at least you’ll be able save a lot of little wigglers this way.

I personally don’t worry too much about this sort of thing. I have such an extensive system of trenches and compost ecosystem zones out in my yard that I feel secure in the knowledge that any left over worms will be able to find a safe haven without too much difficulty.

Anyway – that’s basically it. As you can see, this is a nice easy (and inexpensive) way to move your worms to a new bin, and end up with some fantastic compost in the process!

Thanks again David for allowing me to share this on the blog.
8)


All images courtesy of David Lozowsky, Brampton Ontario

Written by Bentley on June 18th, 2009 with 25 comments.
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Get your own gravatar by visiting gravatar.com Cindy Anthony
#1. June 19th, 2009, at 12:28 AM.

Thanks… this is an idea I can work with. I was struggling with the logistics of the whole bag with holes scenario. I also use these totes and I have an extra right now…so drill time.

Get your own gravatar by visiting gravatar.com Cindy Anthony
#2. June 29th, 2009, at 1:22 AM.

This is working great! I made a bin as described. I put my new bedding in a larger bin with newspaper, peat moss, and food scraps. then placed the transfer bin on top and dumped my aged worm bin into the transfer bin. I put a screen top over the bin with a 100 watt light bulb. Like you might see on a lizard cage. It has been 24 hours, and when I checked the aged bin tonight there are very few worms left. I found a couple food clusters & broke them up. I think by tomorrow the transfer will be done! 100% improvement over my prior method of picking and hand sorting. Thanks for the practical idea.

Get your own gravatar by visiting gravatar.com Ann Monroe
#3. July 14th, 2009, at 8:44 PM.

This method is even easier than he says, as you don’t really need the lights. We just left the top off and stirred the bin up several times a day. It took longer, but within 4-5 days most of the worms had moved down. At which point we put the lid on the bottom bin and put the old bin on top of it; any remaining worms crawled out onto the lid and were easily brushed into the new bin. MUCH easier than any other harvesting method I’ve seen.

Get your own gravatar by visiting gravatar.com rusty mounsey
#4. September 7th, 2009, at 12:33 PM.

I used a small id metal screen and just layed it on top of the new bedding turned on the light and the worms went down took the top layer every 2-3 hrs done in a day 2- 5gl buckets full

Get your own gravatar by visiting gravatar.com Bentley
#5. September 10th, 2009, at 2:05 PM.

Thanks everyone for chiming in with your results!
8)

Get your own gravatar by visiting gravatar.com Chris
#6. March 4th, 2010, at 3:10 PM.

This looks great but I am wondering whether you couldn’t put the new bin on TOP of the old one, with something tasty in it, and let them migrate upwards. You wouldn’t need a light. Would that work?

Get your own gravatar by visiting gravatar.com Bentley
#7. March 11th, 2010, at 3:00 PM.

I’m sure this could work as well, Chris! You certainly don’t “need” a light with the other approach – it’s simply a suggestion to help speed up the process.
Not sure if it was you who emailed about this, but someone commented on the fact that worms naturally move up anyway, so it would be interesting to do a comparison of the two approaches and see which works better.
I think that’s a great idea!
8)

Get your own gravatar by visiting gravatar.com Jason Whitney
#8. August 9th, 2011, at 9:03 AM.

Although, I also use a modified light harvesting method in most cases, I do have several bins that I use a mesh filing box with handles that I originally purchased from Ikea for my office. The mesh box has approx. 1/4” holes. I fill the mesh box with fresh aged horse manure mixed with something pre composted fruits/veggies. The worms move up into the mesh quite quickly and I simply dump the contents into a new system.

This example is similar to the mesh crate that I use. Note that the bottom is mesh also. http://www.walmart.com/ip/Neu-Home-Stackable-File-Crate-Silver-Mesh/10529564

Get your own gravatar by visiting gravatar.com Scott Bryce
#9. November 10th, 2012, at 12:06 AM.

By putting the new bin on top, you have effectively created a stacking tray system. I have done this and found that even months later, the lower bin still has a significant number of worms in it.

Get your own gravatar by visiting gravatar.com Bentley
#10. November 10th, 2012, at 9:56 AM.

Hi Scott,
A stacking system works on the principle of upward migration. Davids method involves dumping mature bin contents into another bin with large holes in the bottom, which then sits on top of a newly set up (but hopefully still aged) system. Worms are then encouraged to move down via disturbance, bright light, and drying of their habitat. Of course, the new bin down below should help draw them down as well.

Interestingly enough, I tried this same approach with trays of my stacking bin and it worked MUCH better than waiting for upward migration of worms.
8)

Get your own gravatar by visiting gravatar.com Lisa L.
#11. February 13th, 2013, at 6:00 PM.

Ok, I’m confused. This will probably sound stupid to most but the only way to figure it out is to ask for help.

The instructions say:
“The tub harvester is then placed on top of the new system (sans lid, of course) ”

To me this says – the OLD tub of finished material is placed on TOP of the brand new system – so the old tub will now be sitting on top of the new one.

The next sentence says: “and the contents of the mature bin are added. ”

There lies my confusion – if step one is to put the OLD tub of nearly finished material (the mature tub) on TOP of the brand new tub, what contents of what bin am I adding to what?????

I invision this as the old tub sitting on a brand new tub. what contents am I adding to what?

I’m obviously not getting it – no lightbulb moment for me ????

Help?
Lisa

Get your own gravatar by visiting gravatar.com Julie Silver
#12. February 16th, 2013, at 9:16 PM.

I have a worm factory with three trays in use right now. The bottom most is the oldest and most mature. I took that tray out (Yep, they are supposed to migrate up, but many have not, and there are a TON of worm eggs), sorted as many of the obvious worms out and put them in the lower bins, and moved the oldest tray to the top. If there was left over egg shells, they got moved to the less mature trays as well. I have left the now top tray open. I am still concerned about the worm eggs. I wish the worms were like ants and moved the eggs when they sensed danger! Alas, the worms only seem concerned for their own well being, and not that of their offspring. I will do my best to get as many of the worm eggs out before I finish harvesting. Thank you for the great start for my wormies!

Julie

Get your own gravatar by visiting gravatar.com Bentley
#13. February 19th, 2013, at 9:14 AM.

LISA – no such thing as a stupid question around here! The idea here is that you create a harvesting bin (with holes drilled in the bottom) and THAT is what sits on top of the new bin. You simply dump the contents of the old bin into the harvesting bin.
I don’t think my wording choice was perfect, so that likely led to confusion.
Hope that helps to clarify!
—————————————-
JULIE – thanks for chiming in. It reminds me I should include a link to my post on harvesting with a WF-360. It was a similar process to “David’s Method”, but the cool thing is the trays already have holes in the bottom of them so you don’t need a separate harvesting tub/tray.
Here’s the link to that post:
https://www.redwormcomposting.com/worm-bins/worm-factory-360-3-02-12/

Get your own gravatar by visiting gravatar.com Micki
#14. March 21st, 2013, at 2:49 PM.

Hey, awesome post. How moist should one’s castings be? If using for indoor plants, do you recommend baking the compost? Thanks :)

Get your own gravatar by visiting gravatar.com Bentley
#15. April 1st, 2013, at 1:19 PM.

Hi Micki,
It should feel somewhat moist to the touch, and you should be able to create a ball that kinda holds together when you squeeze the material in your hand. It shouldn’t be really wet and sludgy. If you squeeze it and water drips out (and it looks like a ball of mud) you might want to let it dry out some more.
Baking vermicompost will destroy the community of beneficial microbes so it’s not something I recommend.

Get your own gravatar by visiting gravatar.com Tom G
#16. June 26th, 2013, at 3:36 PM.

When a worm bin is considered mature, should all of the bedding above the worms be decomposed or is it removed and allowed to mature before going through this process? My bin has about 6″ of compost in the bottom with about a 4′-6″ layer of moist newspaper on top. Should all this bedding be removed? Thanks.

Get your own gravatar by visiting gravatar.com Lisa L.
#17. June 30th, 2013, at 12:51 PM.

@Tom G:

“When a worm bin is considered mature, should all of the bedding above the worms be decomposed or is it removed and allowed to mature before going through this process? My bin has about 6? of compost in the bottom with about a 4?-6? layer of moist newspaper on top. Should all this bedding be removed? Thanks.”
********
There’s no one right or wrong way or time to harvest worm castings or vermicompost. Some folks stop adding food altogether, allow the pile to totally finish off, remove the material and put the worms into a freshly started bin. Others follow a windrow method where new material is added to one end of a row and as the worms finish off the material, the move horizontally through the pile toward the fresh material and the finished material at the start of the row can be used.

You can also simply scrape some or most of the finished material off the pile for use and leave some unfinished material behind and add new material for it to keep it going – so its never ‘totally’ finished, but you gather compost from it regularly.

In my 30+ years of experience I find that the worms do far better if you remove compost from an existing pile and simply add more food than if you allow one to finish off completely and move the worms to a fresh pile.

I have a heat lamp (designed for a reptile cage) and when I want some material I set the light over part of the pile which drives the worms down and way from the light/heat. I scrape off material until I hit worms, then leaving the light on, wait for them to go deeper, scrape again, repeat until I have the amount of material I need. I then add more food to replace the compost I took.

This is one of several methods I’ve used over the decades. Like I said – there is no right or wrong way. As long as you can gather some material without destroying your worm population (keeping a bed thriving), then whatever you do is fine.

Get your own gravatar by visiting gravatar.com Lisa L.
#18. June 30th, 2013, at 12:51 PM.

@Tom G:

“When a worm bin is considered mature, should all of the bedding above the worms be decomposed or is it removed and allowed to mature before going through this process? My bin has about 6? of compost in the bottom with about a 4?-6? layer of moist newspaper on top. Should all this bedding be removed? Thanks.”
********
There’s no one right or wrong way or time to harvest worm castings or vermicompost. Some folks stop adding food altogether, allow the pile to totally finish off, remove the material and put the worms into a freshly started bin. Others follow a windrow method where new material is added to one end of a row and as the worms finish off the material, the move horizontally through the pile toward the fresh material and the finished material at the start of the row can be used.

You can also simply scrape some or most of the finished material off the pile for use and leave some unfinished material behind and add new material for it to keep it going – so its never ‘totally’ finished, but you gather compost from it regularly.

In my 30+ years of experience I find that the worms do far better if you remove compost from an existing pile and simply add more food than if you allow one to finish off completely and move the worms to a fresh pile.

I have a heat lamp (designed for a reptile cage) and when I want some material I set the light over part of the pile which drives the worms down and way from the light/heat. I scrape off material until I hit worms, then leaving the light on, wait for them to go deeper, scrape again, repeat until I have the amount of material I need. I then add more food to replace the compost I took.

This is one of several methods I’ve used over the decades. Like I said – there is no right or wrong way. As long as you can gather some material without destroying your worm population (keeping a bed thriving), then whatever you do is fine.

Get your own gravatar by visiting gravatar.com charles
#19. September 20th, 2013, at 3:23 PM.

Ok let’s see if i got this right….you make a new bin and place the old mature on top of the new one and the worms go down into it?

Get your own gravatar by visiting gravatar.com Lisa L
#20. September 21st, 2013, at 12:36 PM.

@Charles – that’s it! ? However since worms aren’t natures smartest creatures on the earth, there are those that simply don’t make the migration and will stay in the finished material on top, so once ‘most’ of the worms have moved downward, go through the finished material by hand to check for the slackers :D

Also, make sure the top material is *REALLY* finished off well, if there is still food in it, there’s no reason for the worms to move.

In my experience with this method, its best to let the 1st tub finish thoroughly AND let it really dry out; stop adding moisture. This way the worms that might be ok scavenging off the little food in the old bucket will still move downward for moisture reasons.

Good luck.

Lisa L.

Get your own gravatar by visiting gravatar.com charles
#21. September 23rd, 2013, at 11:41 AM.

thanks so much Lisa!!!!

Get your own gravatar by visiting gravatar.com Mary
#22. April 20th, 2014, at 4:20 PM.

I couldn’t wait 3 months to harvest compost from my home made flow-through bag-in-a-laundry-bin containing about 1 lb of worms! After a month I lifted it out, turned it upside down on a tarp (it weighs just under 20 lb total, starting from about 7 1/2 lb), opened the drawstring bottom and scraped a bit of compost of the bottom in bright light, rescuing the few straggler worms and any unfinished compost. I got about 6 oz of finished compost, no cocoons or babies. That was 2 weeks ago. I cinched up the drawstring, returned the bag to its upright position in the laundry bin, returned the straggler worms and unfinished compost, and two weeks later the worms are doing fine. One question: what happens of the finished compost is allowed to dry out? It’s crumbly…

Get your own gravatar by visiting gravatar.com Adam J
#23. July 8th, 2014, at 7:47 PM.

I had very little success with a split-level tub system of basically this same design. I tried to motivate the worms to migrate downward by leaving the upper bin un-fed for ~10 weeks, but my worms chose to escape the bin rather than migrate downwards.

In my experience I’ve found that the absolute easiest, most fool-proof method is to just starve the bin about a month past finishing, and, after shifting all the bin contents to a secondary container, put down a deep layer of bedding with a moderate amount of organic material. Lay some strips of cardboard or newspaper on top, then add back all the finished compost+worms. Within a day or so every worm will be happily tunneling through the fresh bedding, and you can skim finished compost right off the top. One dual-layer bin took me about 5 minutes to set up, and another 5 to harvest- ten minutes work for >3 gallons of soil.

In parting, thanks to the author and all those who contributed to the discussion! I’m constantly benefitting from your experience. :)

Get your own gravatar by visiting gravatar.com Jacob Boswell
#24. July 23rd, 2014, at 3:32 AM.

You know I was thinking that for harvesting your worms using the box that put your scraps in you know what would work perfect? A kitty litter box you can drill your holes in the bottom of the box put your food scraps in the top and set it in your bin and the worms come up into the litter box. Simple and cost effective

Get your own gravatar by visiting gravatar.com peggylee
#25. May 28th, 2015, at 2:54 PM.

when you harvest your worms (compost) using the bin method. You put the new bin with new bedding on the bottom….sit the tub with the worms in it (old bin) on top of the new bin. Put several large (how large) holes in the bottom of the old bin before you put it on top of new one….Do you dump all the compost into the new bin? of course that does not make sense because that is the gold that you want….(right)? But, do you use some of the old compost in the new bin? How long should I let my bins sit feeding the worms before I begin my first worm transfer. Will it be ok if worms get into my compost that I am going to put in my flower garden?
thank you for your patience and your answers.

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