Vermicomposting Trays

Worm Tub

Ok – time to get back into the topic of vermicomposting…

As promised, I’m going to tell you about a new type of worm system I’ve been testing out over the last few months. They are certainly nothing revolutionary, and plenty of other people use similar containers, but I thought it would make for a good topic of discussion nevertheless.

I came across these tubs while checking out the plastic bin section at the local hardware store back in the spring. Like an serious vermicomposter, I am always on the lookout for potential new worm bins. Having recently started up my own vermicomposting business, I was especially eager to find something more useful than Rubbermaid tubs. I wanted something that would fit nicely on a shelf, wouldn’t be impossible to move when full, yet would still be able to hold multiple pounds of worms at once.

These tubs seemed to fit the bill. They are approximately 28″x19″x6″ and seem to be made of PVC plastic. As you can see, they offer an outstanding surface-area-to-depth (or -volume) ratio. This is really important, especially when you want to keep a lot of worms in a relatively small space, and have an interest in harvesting castings as well.

So far I’ve been blown away with how well these tubs work. The combination of high worm densities with ample air flow results in very fast vermicompost production, and much easier worm harvesting. Gone are the days of mucking around (literally) with unfinished compost months after a bin was set up, trying to get it separated from the worms.

Don’t get me wrong – those enclosed tubs definitely work well in certain applications. I see them as ideal worm breeding/nursery bins. When it comes down to it, a Rubbermaid bin is actually closer to a worms ideal environment than a tray – unfortunately that doesn’t correspond to the ideal situation for a worm farmer!

If you start the worms in bins, then move them (and the unfinished compost) to these trays once they are larger I think you will end up with the perfect combo system. I’ve actually been keeping some aged manure (cleaned of larger worms a while ago) in a plastic garbage bin (which does NOT have a good surface-area-to-depth ratio). What’s amazing is that the material is now LOADED with worms – clearly the conditions in there are good for worm development. These cans are also great because they take up a lot less space than a Rubbermaid tub with a similar volume.

I am planning to start up a series of these cans with material that’s had most of the worms removed (but is loaded with cocoons) and see how many worms I can produce. Once the worms are larger I will once again remove them (moving them to the tray systems) and repeat.

Should be interesting!

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    • Kim from Milwaukee
    • October 14, 2008

    Bentley, did you have to put holes in the bottom of these black trays? I wonder if you can stack those, or do you have to keep an air layer over the tray….so many questions I have. Are you covering them with anything? How often can you harvest the castings from this system?

    • Bentley
    • October 15, 2008

    Hi Kim – definitely no need for holes. Moisture leaves the material quickly enough as it is, so drainage is not necessary. I definitely wouldn’t stack them directly on top of one another though – this will compact the material in the bins and impede air flow. The worms would likely just start crawling out of the material that remains exposed to air (since these bins aren’t inter-locking). If you made special shelves you cold likely get away with only having a very small air space in between the bins.

    I don’t cover them with anything, but have been a little bit more careful with them – generally keeping at least one or two fluorescent lights on (in the same room) at all times since the worms have been pretty crowded at times.

    Castings production has not been my focus thus far – will be more so as spring approaches. I have however seen how quickly materials are converted into castings. With a decent density of worms in one of these tubs (say 2-5 lbs) you could have good castings in a few weeks. You’ll more than likely need to screen them, the cool thing is they will be in good shape (as far as moisture content goes) for screening by that point.

    • Kim from Milwaukee
    • October 15, 2008

    Excellent!! I like this idea, Bentley. Seems to take up less space, and it could easily go under my kitchen sink (the Rubbermaid’s too tall). Please keep me informed on your progress with this setup.

    • Adam
    • October 16, 2008

    I am also going to start a 6 inch deep bin that is about 36 inches x 15 inches. I am planning on about 3-5 pounds of worms in order to process it quickly and avoid the bad fruit fly problem that my large bin has.

    My question is how many pounds of scraps and bedding would you add? As much as it will hold? A certain number based on worm poundage?



    • Bob Packard
    • October 17, 2008

    Hi Bentley, my comment is a request. Could you elaborate more on the surface-area-to-depth-ratio? Have you arrived at some formula? I have different size bins, tubs etc. Also different type and size worms. Red wigglers, ENC’s and Jumpers. Capsules, babies, juniors and mature adults. I’m still one of your avid readers.
    Thanks alot. Bob

    • Bentley
    • October 17, 2008

    Hi Adam,
    I haven’t really been using food waste in these systems thus far. What I am doing is adding the worms then layering aged manure on top. If I were going to consistently use food waste I would think very seriously about grinding it up in a food processor first. I would likely add it in layer 1-2 inches thick and let the worms’ response be an indication of how much and how often I should feed (with multiple pounds of worms you will very likely want to add at least one layer per day).

    I haven’t yet determined the maximum amount of worms these trays will hold. Under bright lights I suspect it would be a LOT (10+ lbs), but I’d recommend testing it out, starting with 2 or 3 lbs.

    • Bentley
    • October 17, 2008

    Hi Bob – glad to see you’re still stopping by.

    Unfortunately I don’t have any actual numbers for you. Not sure I have ever come across a recommended range – I’ll see if I can track something down though. Again, it also depends on what you are trying to accomplish. As mentioned, I’ve found that deeper bins with a lot more moisture are far more successful for worm breeding, whereas the shallow trays are better for castings production (due to increased air flow).

    Different worms certainly have different requirements as well. I suspect that ENCs and Jumpers will prefer deeper bins with more moisture.

  1. oh man.. I really like the idea… I just fear the great worm escape.

    I’ve found that the past two months have been so busy that I’m not eating at home enough which means I’m not producing much OM to feed my worms… they’re getting hungry and trying to wander… othertimes I produce so much OM that the worms can’t use it all (before it goes stinky)…
    πŸ™ it’s feast or famine boys… feast or famine….

    • Eve
    • October 22, 2008

    Bentley your bin looks just like the bins sold for mortar at home improvement stores. They are easy to find. They are also made of rubber are yours plastic? Do you think rubber would harm the worms. I am thinking how many people are sensitive to it.

    • Patricia
    • October 22, 2008

    Eve, you answered my question. They come in two sizes and my guess is that this is the smaller of the two. These are exactly the same trays that I have underneath my rabbit hutch and I put my worms directly into them and I only have to occasionally add a bit of water. I recently started using smaller containers so that my “batches” werent so big and this tray is really a good size. Also using cat litter boxes that come with a lid and I just set the lid on top for air. good job Bentley.

    • Bentley
    • October 22, 2008

    These ones are definitely made of hard plastic – and seem to be designed for gardening (holding soil etc) based on the picture that comes attached to them. That’s my story and I’m sticking to it.

    L. Bo – escape is always a risk with open systems, but the key is to keep them in a dry location (ie not a dark, damp basement) and make sure to provide them with a good habitat to they won’t want to leave. I now keep some fluorescent lights on at all times, but even when I didn’t there didn’t seem to be too many worms brave enough to venture all the way out.

    • Bentley
    • October 22, 2008

    Forgot one of your questions, Eve. I don’t think rubber would harm worms, but you never know.

    • Bob Packard
    • October 22, 2008

    Hi Bentley, I know that Jerry G. has used this type bin (mortar tub) for quite some time. He probably can lend some expert comment to the the pros and cons of its use. All we need do is ask him. Jerry is never at a loss for advice. Bob

    • CHAD
    • October 23, 2008

    Hi Bentley,

    Been awhile. Love the tray idea. I just recently expanded to 2 bins. Not sure if I have enough worms yet but they are multiplying. I noticed you mentioned blending the kitchen scraps. Have you found that this works. We talked about it a few months ago and I haven’t had a chance to try yet. My wife and I are eating very healthy so we have alot of scraps. I am toying with the idea of blending the food and mixing it with card board and wood shavings(extra crumbly) to get a thick, damp, fibrous salad. MMM, MMM, good! I was thinking to aim for about the consistency of aged manure. This may work for those who don’t have axcess to the real deal.

    Keep up the good work.


    • Bentley
    • October 24, 2008

    Hey Chad!
    Good to see you ’round these parts again.
    Re: blending food scraps – I used to be leery of this, based on the potential for creating an anaerobic, goey mess – but the idea is definitely growing on me now that I’m looking for ways to speed up the process and ensure that the worms remain well-fed. Your idea re: mixing up the food with bedding materials is definitely right on the money! I’m actually planning to try this out myself (my dad has agreed to part ways with his old, neglected food processor).


    • Magpie
    • October 24, 2008

    G’Day from Oz, Bentley!
    Re: blending food scraps….my BIL always blends his worm scraps and absolutely swears by it. Tried it this week for the first time, put in what would have been a weeks worth, blended instead of just finely chopped it as usual, and it was gone in three days!! Amazing the difference it makes!

    And L.Bo Marie has the same problem that I faced this week – a surplus of lovely potential worm food PLUS I’ve also struggled with the idea of having to get out the blender and cleaning it all up every time I want to feed the little darlings, so, lateral thinking – I blended all the scraps I had, put portions in daggy old plastic bags (more environmentally friendly than tossing them or using good clean ones) and froze batches of the blended mush. Two problems solved!!

    I will defrost the mush before putting it in with the worms, although my BIL puts a chunk of ice on top of his bin in the summer to cool it down as it can get very hot where he is.

    Hope this is of help – your site has inspired me to start a worm farm and now I’m totally hooked. It would be lovely to think I can give you something back!
    Thnaks!! M πŸ™‚

    • Bob Packard
    • October 24, 2008

    Bentley, If I may. I bought very inexpensive food processor at the Wally store, B&D model FP1450 comes with 1 year warranty only $30.00 US. It works great on food scraps, not very good on paper and easy to clean. Worms eat really fast, 1 week scraps gone in 3 days. Worms are getting fat fast. Bob

    • Bill Hartlin
    • February 2, 2009

    Gd Day:

    Two I say 2 questions.

    Will red worms survive on paper & cardboard only? &

    From mating to a mature worm, how long does it take?


    • Bentley
    • February 4, 2009

    Hi Bill,
    Red worms should be able to survive on paper and cardboard only, but they may be pretty stunted in terms of size – unless that cardboard/paper happens to be soaked in some sort of rich liquid (contain nitrogen etc).

    The time from mating to maturity can vary WIDELY. Please refer to the following post to see what I mean:


  2. The Morgan family from Michigan uses these trays stacked in vertical frames to grow millions and millions of worms. When used correctly these worms will really produce.

    Check out this video

    • Mark
    • October 13, 2009

    Hi Bentley, trying this idea out also. I’ll be interested to see how it goes. I’ve got some nice trays set up with shredded cardboard and I have added some worms. Seems like a great way to keep worms! I am also a bit worried about escapes. Would you cover the trays with something? I know some people recommend black plastic, but doesn’t that stop the air flow? I tend to use a sheet of cardboard.

    • Bentley
    • October 19, 2009

    Hi Mark,
    I do not use lids at all. I should mention that I DO however keep a couple of fluorescent lights on at all times in my basement ‘worm room’. It can be interesting during blackouts (haha) – the worms often come up and start crawling on the surface. I’ve never tested to see how many will actually try to escape if the lights are left off indefinitely though.
    A thick layer of dry absorbent bedding may be helpful in terms of keeping the worms down but I have not tested this out (with open systems) myself.

  3. It may be too late to add a comment but here goes. I used these “mortar trays” successfully before transitioning to OSCR bins. I had some old ugly carpeting around and cut strips of it to cover the trays. it kept the worms in and still allowed good air flow. I think that landscape fabric might also work and may actually be better since it’s generally thinner than carpet. These trays hold a LOT more than they appear to hold.

    In addition, I had an extra black plastic shelving system that was just used to store junk. I cleaned off a couple of shelves and put two worm trays per shelf. It was amazing how many worms could be in a 8 sq ft area when stacked up. It also made for easier work not having to lift all the containers as high.

    I saw the trays the Morgan family uses in their environmentally controlled room. Does anyone know what the “food balls” are made of. The son was shown in one video braking up food balls and gobs of worms appeared. I’d love to know what they use.

    • Brian
    • January 23, 2010

    I’m experimenting with a 2 x 3 plastic tray like this one. I buried it about 6 inches in my garden and then covered it with a plywood lid. I don’t know if this will work well, but my wife doesn’t want horse manure in the house and doesn’t like the look of concrete blocks in the back yard. We’ll see how it works out. I’ll be looking for a piece of old carpet or burlap sack to help hold the moisture in.

    • Bentley
    • January 26, 2010

    Hi Brian,
    That sounds like a good idea – my only concern would be extreme weather conditions. A system like that (assuming fairly shallow) would more than like overheat and freeze quite easily in the summer and winter, respectively. If you are lucky enough to live in a location with fairly moderate weather all year long you should be totally fine.

    • Brian
    • January 26, 2010

    It only freezes a night or two per year. However, temps do rise into the 90’s in the summer. I have a good four months to experiment before it gets really hot. Maybe this approach will only work for Fall and Spring, but it should help me build my worm population.

    • Betsy
    • November 5, 2011

    Not sure if this thread is still active, but wanted to add that I am using two of these trays now- emptied my WF tower in one and a rubbermaid bin into the other. I cover them lightly with cardboard, and then with a lid from the rubbermaid tub, fitted loosely for air. Had to put some shredded paper on one to keep the worms in, but they both are doing extremely well. Worms are breeding and eating. Haven’t had to add food other than coffee grounds once in a while, the existing vermicompost still had plenty of ‘stuff’ in it. If we get a freeze I will put a tarp over them. My plan is to take worms out and put them in my raised garden beds, for the winter and let the cocoons hatch as they will.

    • Mary Ann Smith
    • September 20, 2014

    The last comment was almost 3 years ago, but thought I would add a little. I have about 50 of these bins with 1-2 lbs. of worms each in a root cellar type room on shelving. I have been bedding with peat and since the C:N ratio has tested high in the vermicompost, I have added paper and cardboard. I feed with worm chow, and am slowly adding coffee grounds and going to try rabbit manure. As far as light, since it is a damp room, like Bentley said, I leave on a fluorescent light. Most of my bins have no covers, but the newer ones I put landscape fabric on them so the worms will come to the surface and munch on the paper. πŸ™‚ I have found if the worms are happy (right amount of moisture and food) that they do not want to go anywhere. This is a great system for producing worms AND vermicompost!

    • Mae
    • September 20, 2014

    How many worms do you start with and how many pounds of casting will come from each tray?
    Anyone know this answer?

    I haven’t yet determined the maximum amount of worms these trays will hold. Under bright lights I suspect it would be a LOT (10+ lbs), but I’d recommend testing it out, starting with 2 or 3 lbs.

    • Bentley
    • September 25, 2014

    Mary Ann – Not sure I follow. You said that since the C:N tested high (presumably 30:1 or above) you added paper/cardboard – materials with VERY high C:N. Aren’t you needing to go in the other direction? Perhaps I have misunderstood your meaning.
    I personally don’t worry too much about C:N (within reason) – and in my experience, paper-based wastes can be great for stimulating cocoon laying, so regardless, it does sound like you are on the right track.
    Mae – I wouldn’t ever try to hold 10 lb of worms in one of these trays, unless it was for a very short period of time (ie unless you were just using them as a temporary holding bin).

    • Don
    • October 24, 2015

    Hello Bentley, it’s been a little over a year since the last comment, I am thinking of a setup using these trays and light. I live in Massachusetts and it can get really cold in the winter here, I’m concerned I would not be able to keep them alive in the basement or a shed or garage and I have all three. And the cost to try heat one of these areas I think would be a little much any ideas to keep the worms alive in the cold?

    • Bentley
    • October 26, 2015

    Hi Don,
    I think you should be fine in a basement. Literally, as long as the system doesn’t freeze solid the worms should be ok. BUT it’s important to note that it won’t perform nearly as well as a warmer system!

    For some helpful winter worm composting ideas you may want to check out the “Winter Worm Composting” section on the “Hot Topics” page:

    In particular, have a look at the ones without dates that relate to smaller worm bins (several listed right in the middle of the links)

    • Don
    • October 28, 2015


    Thanks for the information it’s a great help. I stumbled across a few video’s from WormzOrganic (Remember them?) the company that scammed a bunch a people out of money? Well I liked how neat and organized the procedures were using nothing but those black trays. One of the video’s I thought stuck out from the other’s of being over simplified. ( I will send a link of the site.) And that one video on the site that I am referring to is called “Harvest”, it looks as if the castings are dry as a bone and has been sifted before hand then they made the video and there were very few worms coming out the other end. I know that probably is unrealistic but what about the rest of the video’s? Are they really unrealistic also? Here is the link.


    • Don
    • November 29, 2015


    I think the tray system is for experienced worm keepers and since I’ve never done it before I’m going to take a step down to an easier system that I think I will have more success with starting out. I built a system that works like the easy roll worm bin but on a larger scale probably more than 4 times as large and it rolls in place to access the castings from the bottom.

    I would send pictures but I don’t know how. I have a place that is local where I can get the “Red Wigglers” and I’m making sure I have everything in place before I start. I like your idea of homemade manure but I don’t know if I should start out right away making homemade manure to put them in as soon as I bring them home or just use regular bedding? Any ideas on that?


    • Daniel Vachon
    • November 10, 2019

    I build 2 racks like these and i’m planning to build more….. I put 10 trays on each rack ….When the trays are full….it’s quite heavy….my next build will be rack of 5 or 7 much easier to deal with….I also post other ideas for vermicomposter that i have built..

    click on my link:

    Thanks !!!

    Daniel Vachon Montreal, Canada

    • Daniel Vachon
    • November 10, 2019

    Also to cover the trays on each rack…..i’m using this “Refelectix” Foil insulation material from Home Depot here in Canada for 16 inch by 25 feet .

    ( I cut 2 feet per trays 24″ x 16″) I keep my trays in the garage for winter @ 16 Celcius
    the insulation foil is bended in extremities and attach with staples to give more weight) enough air circulating….no worms escape….This also help keeping the trays moist and give a very good insulation in winter and i can re-use it each time…

    If you any questions…please do not hesitate….


    Daniel Vachon
    Montreal, Canada

    • Chris
    • February 19, 2021

    Can anyone give me any sort of instructions on how to build the shelving system for the mortar trays? Materials, spacing between trays, dimensions? It seems like a real space saver!

    • Bruan
    • February 25, 2021

    If you gain experience, these types of trays will really produce. I think you can comfortably hold 4 to 5 pounds in a tray but for me the big benefit is to grow my numbers so I rotate the trays regularly and reduce worm mass by starting new trays.

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