Backyard Composting with Worms

May 24, 2013

For some reason, not a lot of people associate backyard composters with vermicomposting. It’s a shame, really, because composting worms can offer a fantastic way to speed things up, and to improve the quality of compost produced in these systems.

In most cases, these bins are NOT really “hot (thermophilic) composting” since they don’t have the critical mass required for sustained heating (typically ~ 1 cu yard or more, assuming proper C to N ratio of materials). They tend to be closer to the “mesophilic” range of temps a lot of the time, and decomposition processes inside tend to occur more slowly as a result.

People often don’t really use them properly either. A lot of the time they seem to be ignored altogether, or basically used as garbage cans for random deposits of resistant organic matter.

Even the “Compost Guy” has been guilty of this more often than he’d like to admit! Below are images showing one of my neglected systems (before and after the bin was lifted away).


Well, today it’s time to turn over a new leaf (lol), and show you how you can convert your sad, underperforming backyard composter into a lean, mean vermicomposting machine!

Here are some of the KEY things to keep in mind:

1) We need to establish a high quality composting worm habitat BEFORE we try introducing the worms. You can’t just add them to a dry, neglected composter filled with old sod and sticks and expect them to turn everything into black gold!

As such…

2) LOTS of (fairly inert) “bedding” materials need to be added, especially early on.

In the same vein…

3) We need to avoid adding too much N-rich “food” material initially, since it can cause everything to overheat (among other potential problems).

4) Ongoing watering will be VERY important – especially if you are using a wooden bin. Adding lots of water-rich food waste will help, but periodic showers from your watering can will likely be needed as well. Taking off the lid during rainy weather can certainly help too.


Here are some of the supplies I used for my set-up:

1) Newsprint – used to lay across the bottom of my pit (more on that in a minute)

2) Moistened, shredded cardboard – represents a significant percentage of the initial habitat.

3) Bag of mixed compostable kitchen scraps – I want the worms to have at least some food available early on.

4) Well-aged horse manure – this is pretty well the “ultimate” vermicomposting material. It’s what I would call a “living material” since it is full of beneficial microscopic (and macroscopic) composting organisms. It provides excellent habitat AND food value, without the risk of excess heating, ammonia release etc. It should come from a heap that has sat outside, exposed to the elements, for at least a couple of months. It should be dark in colour and smell earthy. Bagged manure from a garden centre is definitely NOT the same thing!

Other “living materials” include old, rotten leaf mulch, and really old grass clippings (again earthy smells we’re after – not bad smelling stuff).

5) Worms of course! If you are fairly new to all this, you might want to set things up and leave everything to age for a week or two before adding the worms. Since I know what I’m doing, and since I had plenty of beautiful aged horse manure on hand – I felt totally comfortable with adding the worms on the day of set-up.


The first thing I recommend doing when setting up a backyard composter for vermicomposting is to dig a decent sized pit down below where the bin will sit. This will offer the worms a cooler/warmer zone (likely with higher moisture levels as well) they can retreat to during weather extremes. If you live some place that gets really cold and/or hot, you should dig at least a foot down – just make sure the diameter of the hole is smaller than that of the base of your composter!


Lining the hole is optional – but I decided to do so this time around to help keep things somewhat contained, and to hopefully increase moisture levels down below. If you live in an area with moles you may want to go all out, with something like thick landscape fabric.

NOTE: Some people might assume this is done to avoid having the worms escape into the soil (one of the concerns people seem to have about backyard vermicomposting in general). It’s important to keep in mind that the worms being used are composting worms. They are specialized for life in deposits of rich organic matter (they are not soil worms). So they will be more than happy to stick around if you give them what they need.


Next, I filled the hole with moistened, shredded cardboard, aged manure, and food waste – before mixing everything up really well.





I happened to have some rock dust on hand so I added some of that as well. This is optional, but if you happen to have some ag lime (or dolomitic lime), you may want to sprinkle some of that in as well. I next watered everything down thoroughly.



Next, it was time to add the composting worms. In this case it was probably the equivalent of 3 bags of “Euro-Red Mix”.


IMPORTANT UPDATE (SPRING 2015) – We are now selling Easy Worm Mix. It does not contain any European Nightcrawlers.


I simply dumped them on top and let them move down on their own (did so quite quickly so as to get away from the light). This is an ideal application for the Euros since they tend to do very well in larger systems that are not being disturbed regularly. Red worms will of course thrive in this type of environment as well!


Next it was time for even more aged manure, more bedding, and more water.




I then put the bin over top…before adding…

…more aged manure
…some semi-aged grass clippings (if you are new to this I recommend waiting until the habitat zone is well-established before adding any – and NEVER mix them in)
…and some straw over top to help keep moisture in.


Finally, I lay an old towel over the top and soaked in down. This helps to keep moisture while also helping with the evaporative cooling effect.


It’s important to note how low in the bin the level of materials was left. This was especially important given the fact that I was adding the worms the same day. If you plan to fill the bin with lots of materials at once, you should definitely leave it to sit for at least 1-2 weeks, and only add worms once temperatures have dropped down below 30 C or so.

The advantage of primarily focusing on creating a high quality habitat zone early on is that we won’t need to be nearly as concerned about what we are adding moving forward. As long as the worms have a safe zone they can stay down in, you can get away with adding a wider variety of materials (and more of them) than would be recommended for a typical worm bin.


I should mention that this post was partially inspired by the following video:

It’s fairly long, and it can be difficult to understand what Mick is saying at times, but it’s well worth watching if this is a topic of interest!


I’ll be sure to keep everyone posted on how my system is doing this summer – and will be exploring various related topics (including what protective measures we can take as winter approaches) here as well!

Comments

3 Responses to “Backyard Composting with Worms”

  1. Simone on January 25th, 2014 11:14 pm

    How did it work? And how do you harvest the finished product? 🙂 thanks for everything you do!

  2. Raja on August 18th, 2014 4:33 pm

    Hi,
    Great initiative!
    In Canada where the temperature drops below -35C how do the worms survive (as the frost line in most cases is 4 feet)?
    Best,
    Raja

  3. Bentley on August 21st, 2014 3:02 am

    Simone – apologies! Just realized now that I didn’t reply to your question. On that note…I tend to be pretty laid back with this sort of thing. I have loads of different systems – including integrated systems built into my various backyard gardens. So I don’t really have much need for vermicompost. Everything seems to have gone well in the system, though – and this reminds me that it would be interesting to see how things look down below, perhaps this fall.
    —–
    Raja – where there’s a will there’s a way! 🙂 For starters, I would always recommend having AT LEAST a small indoor “insurance” bin. Something that requires virtually no maintenance, won’t ever develop bad “bug” infestations – yet can still provide you with a nice little starter population for the next outdoor season. As far as the outdoor system goes, it would be a matter of digging deeper, adding more bedding/food – and adding much more insulation etc over top (with multiple tarps to block wind), and plenty of snow for good measure..

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