Earth Machine Vermicomposting

When most people think of vermicomposting, they think of starting up some sort of typical “worm bin” – often a fairly small system kept indoors or at least inside a garage or shed. Backyard composters aren’t often thought of as ideal vessels for the process.

In all honesty, the way many people seem to set-up and use their backyard composters, they absolutely aren’t the ideal “home” for Red Worms. Whether they’re using them as a garbage can for sod, grass clippings and/or bulky yard wastes, or simply failing to maintain them properly, the likelihood of them having any sort of composting success with these systems is pretty low, let alone being able to turn them into a lean, mean vermicomposting machine!

Well, the good news is that your typical medium-scale backyard composter – whether its an “Earth Machine”, a “Soil Saver” or really, any other commercial or DIY bin – can actually serve as a fantastic outdoor vermicomposting bin!

One caveat I should mention right off the bat though! I can’t promise that this will necessarily be the case in every location and climate! Somehow I suspect that it might be difficult to use an Earth Machine as a vermicomposting system during the summer in Texas, for example. But I think it’s safe to say there are ways to make it work pretty well anywhere in the mid-to-northern temperate zones of North America (and similar climatic regions around the world).

As you might imagine, there are some important considerations to keep in mind when planning to add Red Wigglers to a composter. Rather than obsessing over C:N and “browns” & “greens”, it’s helpful to think in terms of “habitat” and “food”. Since we are all well-versed in the fundamentals of vermicomposting (right? haha) we know that composting worms need a habitat that provides moisture, oxygen, and warmth (but not excessive heat) in order to thrive. We also know that they need to have access to lots of rich, microbially-active “waste” materials for sustenance. If we can provide all of these requirements, while avoiding some of the hazards, such as excess ammonia volatilization, we are good to go!

The beauty of these bigger outdoor systems, as compared with our run-of-the-mill “worm tub” type of systems is that they tends to have much better air flow, and a much larger “buffer zone” for the worms once you’ve established the “habitat” – so they can be a lot more forgiving. During warmer times of year these systems can produce better vermicompost faster than some of the more traditional worm composting approaches as well!

OK – let’s start talking about how we do this…

The very first step I recommend – and this one is very important in my humble opinion – is to dig a decent sized pit down below where our composter is going to sit. Make sure to keep the diameter a fair bit smaller than the lower diameter of your bin, and dig it to at least 10-12″ deep. This is basically going to be our “worm safety zone” – even if you don’t plan on actively vermicomposting, it’s beneficial to set up this zone since the native soil worms will thrive there, and you’ll leave behind a nice rich deposit of material if you decide to re-locate your composter at some point (composter rotation can be a great way to fertilize different parts of your yard).

Fill this pit solely (or at least mostly) with some sort of absorbent, neutral bedding material. My favorite choices include shredded corrugated and “egg carton” cardboard. If you soak your cardboard in a bucket of water (something you should have on hand for the set-up process anyway) it will be much easier to tear and will be nicely moistened for the worms!

This pit will serve as a cooler zone during the heat of the summer, and a warmer zone once the weather gets cold – helping to ensure that our wiggler population is able to survive in the system all year.

On top of this moist bedding zone I recommend adding some good “food” materials for your worms. In the case of this system, I added coffee grounds and a nice “homemade manure” mix I’d recently mixed up using multiple bags of frozen food waste (among numerous other things). This way you basically have an active vermicomposting pit, and the worms can choose to move upwards from there as they see fit. As such, if we are planning to add the worms the same day we set up the bin – this would be a good time to add them. I generally recommend adding the worms a week or two later though (if still hot above, you should be able to add them to the pit zone via the compost access door at the bottom).

Moving upwards from the pit, my general recommendation is to set up the bin in a typical “lasagna” fashion. Alternate thin layers of “browns”, “greens” and a sprinkling of “living” material (coarse compost, rich garden soil, well-aged manure etc), making sure to moisten each time the three have been added.

Adding moisture is very important, but so is moisture retention (more so in a vermicomposting bin than in a regular composter), so make sure you include some absorbent materials (like shredded cardboard) among your browns. Bulky browns are also really beneficial as well, though, so I recommend adding some chopped up dry plant materials – even some woody wastes if you happen to have some on hand. These types of waste are excellent for increasing air flow in the system.

Even with a basic set of hand loppers you can make short work of a heap of bulky, fibrous/woody waste material – I recommend using them for all plant materials that go into the bin! Remember – we are trying to optimize for microbial colonization, and the greater the available surface area, the faster (and in greater abundance) the microbes will set up shop. This also helps us to get much more material in the bin!

Once you are up past the soil level it will make sense to put your composter in place over top of your pit – now you’ll be able to add quite a lot more material while still keeping your layers thin!

As you continue upwards, it’s not a bad idea to periodically mix your layers a bit using a rake or garden fork. This will really help to kickstart the composting process and establish the early “heating phase”.

Again, don’t forget about that watering can! Doing all your moistening as you go will be MUCH easier (and more effective) than trying to water down a mostly-dry system once it’s set up!

How much material you add initially is up to you. If you DO have enough to fill the bin, you may want to do so – if set up the way I’ve described, over the course of the next couple of weeks the materials should settled down quite a bit anyway. I recommend topping everything off with a nice thick layer of straw or some other carbon-rich cover material (shredded newsprint for example). This will help to keep moisture in (especially important if there isn’t a lid on your particular bin) and flying pests out.

If you have a long-stemmed compost thermometer, I recommend monitoring temps during the next 1-2 weeks. As mentioned earlier, even if conditions are still pretty hot up above (35 C / 95 F +) you should be able to add composting worms via the compost door at the bottom (but do check temps in the pit just to be sure).

Once you have a nicely “pre-composted” habitat zone, the worms should start moving up and processing these materials quite readily. Moving forward – while I still recommend adding materials in the same manner as described above, if you DO decide to get a bit lazy (dumping more than a “thin layer” of grass clippings for example – haha), your worms should have a nice protective buffer zone by then that will help to prevent them from being harmed!

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    • Justin McCreary
    • May 12, 2011

    Two questions:

    Do you just let the worms come and go through the vent holes already in the bottom of the composter?

    We have a mole/vole problem here, will that get in the way of this outdoor method?



  1. This was a really great article, Bentley. It summed up a lot of important concepts and gave a practical step by step to accomplish finished vermicompost.
    I’m in Texas and I’ll be interested to find out if this type of system can hold up all summer. I think it could with 100% shade, enough moisture, and enough mass.

    • Anna
    • May 12, 2011

    Ditto Cassandra on this being a great article :). What are your thoughts on turning outdoor systems with worms?

    • DaveG
    • May 12, 2011

    Thanks Bentley! I just acquired a “Soil-Saver” somebody was getting ready to throw into the landfill(ironic, eh?) and was wondering how to best put it to use. Do you think EH’s would do well in something like this?

    • Astrid Styles
    • May 13, 2011

    Very interesting Bentley, thanks. I have moles in my garden. Do you think they will eat up my worms? Also, will harvesting not be an enormous task or do you leave the worms in the ground if you place the composter on another spot.

    • Bentley
    • May 13, 2011

    Thanks everyone!

    Cassandra – DO keep me posted! I’d love to know if it can be done! I would think that in a full shade location, perhaps with a really deep pit and some material mounded up around the base you should be able to do it.
    Anna – I might loosen things up a bit with a garden fork, but that’s about it – definitely wouldn’t do much in the way of turning once the habitat zone is well established.
    Dave – that’s awesome. I have a Soil Saver (along with my two EMs) too – even acquired it in the exact same manner (someone had kicked it to the curb). I think EH’s have the potential to do fairly well – they seem to like deeper systems, so they’d likely concentrate themselves down in the lower regions and the pit. Haven’t tried them myself, but would be curious to know how well they work.
    Astrid – great question! Mole would likely make it necessary to put up some sort of screening or tough landscape fabric. If I was going to move the composter, I’d likely put a nice heap of aged manure (or some other inviting mix) over top and try to draw out as many of the worms as possible That being said, because my yard is basically one big system in a sense (so many different smaller systems) I might not even worry about it since the worms seem to have no trouble finding my other rich waste zones on their own!

    • Kamala
    • May 14, 2011

    I love the idea, but I would think you would have to keep this in a fenced in location because of pests. I started vermicomposting in my garage because my compost trenches were attracting possoms, rats, and god knows what else. And when I had a compost tumbler it became an apartment building for rats. I live by a brook which has all kinds of wildlife. Any thoughts?

    • Bentley
    • May 17, 2011

    Justin – sorry for delay. I’m not 100% sure what vent holes you mean – when you say “bottom” are your referring to the lower sides of the composter? The actual bottom is completely open. I don’t imagine the worms will come and go all that much via the side vents, but they can certainly come and go as they please from the bottom. As is the key with any outdoor vermicomposting system, when you create a rich habitat for them they will stick around

    Good question re: moles – if you know they are in the area definitely take some precautions. You might try some hardware cloth or something lining your pit, or not even worrying about the pit and simply putting it directly under the composter.
    Kamala – depending on your location, some precautions may need to be taken or it may not even be feasible at all. I suspect that how you are using the system can make a big difference in terms of attracting unwanted visitors, but I have little doubt that there are some regions where you just won’t easily be able to do something like this.

    • Justin McCreary
    • May 17, 2011

    Thanks for the response, I guess being new to this I didn’t imagine the bottom was open but now that makes complete sense. Thanks for the reply man.


  2. When I decided to bring my army outside year round, I used a composting ring, exactly like this one. [img][/img]
    I started with loose brush at the bottom for air circulation and added layers of organic brown matter like leaves and small sticks then added the household compost and shredded paper. They made it through the past winter in Massachusetts without much loss and in March when I looked they were already busy multiplying under the frost layer. I wouldn’t recommend using it in full sun and always make sure it stays wet but you don’t need an elaborate system to keep tons of worms happy.

    • Rich
    • September 22, 2011

    I’m looking forward to using the system with a large PVC pipe, just outside my bedroom window in Southern CA. It’s fairly shadey where I plan to put it, and it will be used exclusively for cat waste in that Green friendly litter made from Corn husks. No urine clumps, though I wonder if watered well enough if they would be that big of a deal.

  3. I have a problem with this… Our earth machine is 1. in sunny Florida and 2. has an extreme infestation of black soldier fly maggots. My mom and I (I’m currently a 7th grader) have tried to kill off the maggot with boiling water to no prevail. plz help!!!

    • Bentley
    • October 17, 2011

    Hi Kevin,
    Unfortunately there’s not a whole lot you can do to get rid of BSFLs. You MAY be able to prevent them from laying eggs if you can somehow enclose the composter with a screen of some sort but once they are established it will be tough to deal with them. In the Florida heat I suspect a backyard bin is better suited for BSFLs anyway (they are more heat tolerant etc).

    • miccc
    • November 26, 2011

    I have one of these earth machines that I put on wheels. I thought I would have a nice composter, however it turns out I have a great worm bin. Here on the Cailfornia central coast I don’t have any problem with it ever getting too hot for my worms.

  4. I’d like any updates you have about Earth Machine worm bin. Thanks

    • Andy
    • October 2, 2014

    I have been doing this for a couple years now. I just keep dumping scraps, shredded cardboard and dirt into my compost bin. It is a giant worm bin, and works great. I get occasional maggots, but I have learned a trick: I keep the top partly open. Birds actually sit on the adjacent fence, you can see them grabbing flies as they go in and out. Also I hung a hummingbird feeder near by, and they now love it for the fruitflies that come up and out of the bin. They are very active near the bin! I live in KY and it gets hot in the summer, but does not seem to be an issue. In the winter the outer edges sometimes freeze, but it keeps working in the center. And in spring it is instantly back to full speed. The are no longer just reds, I get a lot of earthworms up thru the bottom. But hey, who cares?

    • Leslie Jo
    • March 15, 2015

    I accidentally colonized my earth machine with compost full of redworms when I first got it about 5 years ago. The worms did much better than the composting did – so I got into the habit of digging hole to dump scraps into and then covering it up with drier material to stop the fly problem. It was pretty amazing! The next time – a few days later, or a week later- that I’d go to add saved scraps, all signs of the last load were gone. The overwintered a couple of years here in Washington State also.

    When we moved out of the house that goes with the garden, took down the composter and moved probably 30 pounds of castings and worms into the garden. Success.

    • Dorothy
    • March 30, 2015

    Aloha from Hawaii…it may sound silly but for people doing this indoors when it comes to knats and such…turn on the kitchen light at night and fill your sink with water…I bet when you get up in the morning all the Knats and stuff will be dead in the water…just drain and rinse the sink out….tada….the mess and the knats will be gone….during certain seasons you may have to do this nightly…but it works like a dream…..Mahalo

    • JOLJ
    • April 15, 2021

    “mole/vole problem” Milky spores to kill grubs, so the moles will leave, MSpors will NOT harm earthworms, only grubs, which are mostly Japanese beetles & the larger Fruit beetles. For vole(mice) use hardware cloth/rabbit wire to keep them out of your raised bed & redworm containers. Cat will go a long way to stop both moles & voles. I use a trench & had no problem with any animals.

    • Maureen
    • September 14, 2021

    Someone in my New England neighborhood had an old Rubbermaid insulated worm composter, about 3’x3’x3’. She keeps it rolling all year long. Wish that were still made. Any ideas for DIYing something like that!

    • JOLJ
    • September 14, 2021

    Good deal.
    I use five gallon buckets for this.

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