Composting Worms In Your Backyard Composter

Backyard Compost Bin

Spring is finally in the air here in Ontario and it’s time to start getting back to our outdoor gardening activities! One of those activities is of course composting.

As many of you know, I’ve continued to compost outdoors all winter long, but for most people, outdoor composting comes to a grinding halt as soon as the mercury starts dipping below the freezing mark in the late fall.

While composting worms are generally more often associated with ‘worm bins’ than your typical backyard composter, adding some of these garbage-hungry wigglers to your backyard bin or heap can be just the thing to help you start producing high quality compost much more quickly.

There are cetainly some important things to keep in mind if you plan on adding worms to a backyard composter though, since the process is quite a bit different and worms have certain requirements.

Moisture is likely one of the most important considerations. When you are employing traditional backyard composting methods, having too much moisture can really put a damper on things (no pun intended…well ok, maybe just a little bit – haha). I should know! A couple of summers ago, after rescuing a composter (pictured above) from curbside abandonment, I decided to set it up as a normal backyard bin.

Being the confident ‘compost guy’ that I was, I thought I knew what I was doing – forgetting that the techniques used to set up a vermicomposting system don’t necessarily apply when setting up a regular system.

Long story short, the bin ended up stinking to high heaven, primarily due to excessive moisture levels. Not only was it a huge blow to my ego, but it actually created a pretty worrisome situation – I was literally hit with the stench as soon as I stepped out into my yard, so needless to say, my neighbours and anyone walking by could probably smell it too!

Thankfully, Red Worms (Eisenia fetida) came to my rescue! I decided to add a bunch from my big outdoor worm bin to see what would happen – the result was nothing short of miraculous! Literally a day or two after the addition of the worms the smell was gone!

The moral of the story (in a round about way) is that the “wrung-out sponge” moisture recommendation often cited in composting instructions is not necessarily ideal for vermicomposting – at least not in an outdoor bin with lots of ventilation and drainage (it’s actually a pretty good guideline when setting up an enclosed plastic worm bin!). Composting worms thrive in very moist conditions – the challenge of course is to make sure they also have enough oxygen!

In order to hold plenty of moisture, while still allowing air flow, you will want to include some ‘bedding’ types of materials, such as shredded cardboard/paper, coco coir, peat moss etc. A mixture of bulkier materials (cardboard etc) with more absorbent materials (coir/peat) helps to create the best of both worlds.

Manually adding water is going to be especially important with the covered bins (like the one in the picture), since rain water won’t be able to get in – this even holds true for typical backyard composting, and in fact is probably one of the main causes of poor bin performance (which of course fools a lot people into thinking that they have no composting ability). Needless to say, during the hot, dry weather of summer this becomes even MORE important!

The location of your system is also quite important when thinking about adding worms – not as big a deal when using a really well ventilated bin, but the solid black plastic composters can certainly heat up a LOT when sitting directly in the sun. This extra heat can actually help the process along when you aren’t using worms, but for obvious reasons it can cause issues for a vermicomposting system.

Lastly, WHAT you add to the bin will also be an important consideration. As I wrote in my recent ‘Reader Questions’ response, you can’t just haphazardly add any type of yard waste and expect great results (with regular composting you can get away with this since everything will eventually work itself out). Huge amounts of grass clippings, woody materials, and anything containing toxins will impede the process, potentially even killing off your worms.

When you start off by creating a good worm ‘habitat’ (including plenty of those bedding materials discussed above), it definitely helps a LOT, but you still need to be aware of the worms’ needs, as you continue to add materials to the bin over time.

One approach that can work really well is to set up multiple backyard bins or heaps, with worms only in one or two of them. Start off by simply doing ‘regular’ composting with all your waste materials (also referred to as ‘precomposting’), before adding the partially composted waste into your worm system. This will greatly speed up the process, and if you do full-scale ‘hot composting’ first (requires a larger volume of waste than can fit in one of your typical backyard composters though) you can even potentially get rid of weed seeds and plant diseases prior to vermicomposting.

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    • Anna
    • April 26, 2011

    When you say “huge amounts of grass clippings, woody materials, and anything containing toxins will impede the process, potentially even killing off your worms,” what are you thinking of with respect to toxins? Are you thinking of naturally occurring toxins (e.g. juglone from black walnuts) or something else.

    • Bentley
    • April 26, 2011

    Hi Anna,
    Not sure about natural toxins (although you certainly wouldn’t catch me tossing in fresh materials from any known toxic plant, just in case) – was thinking more in terms of pesticides/herbicides etc.
    Lots of grass clippings at once can be an issue because of ammonia volatilization. Woody debris just takes forever to break down and (unless really rotten and/or chopped to bits) isn’t really a great vermicomposting material.

    • Anna
    • April 26, 2011

    Thanks :). That’s what I was imagining but would hate to assume.

    • Johanna
    • September 8, 2013

    Hi there, we are newbies – who just bought a lakeside cottage with a nasty old mildly-abused black backyard composter (located in the shade). We’ve started it up again with our kitchen scraps, but have no yard waste (yayy – no lawn!) We do however have lots of seaweed that washes up on our beach, which I’ve raked up (catching some sand with it) and added in equal parts to the kitchen waste in the bin. Is the seaweed (and the sand) going to cause a problem if we want to add worms. Can we use dew worms instead (my fishermen always have plenty around), and what if anything can we do to ensure that they survive over an Ontario winter? Thanks

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