Note: This section was first posted on my other site, Red Worm Composting, but I decided it would be very helpful to have it here (with slight modifications) as well.
The purpose of this page is provide you with an overview of worm composting. Be assured that I will also be providing many other articles and blog posts that explore the various aspects of vermicomposting in much greater detail.
You may want to watch this video I created before reading the content down below – it is basically my attempt to provide a “big picture” overview of worm composting (including the key components/requirements).
There are a wide variety of options when it comes to choosing the type of worm bin you want to set up. If you are the handy type you may want to build your own creation, OR if you don’t mind spending the money perhaps you will opt for purchasing a complete worm bin system (which may come with bin, bedding and worms).
For anyone interested in simply trying out vermicomposting (or if you want to save some money), I would recommend heading to your local hardware store and grabbing yourself a standard Rubbermaid tub (with lid) or something similar.
Some things to keep in mind when you choose your vessel – 1) Light penetration, 2) Surface area vs depth. An ideal bin will be opaque (ie not allowing in light) and will be relatively shallow.
Red worms (and earth worms in general) are very sensitive to direct light – it can lead to considerable stress and even death if they unable to escape from it.
As far as depth goes, you don’t need to worry too much about exact dimensions but you definitely do want to put more emphasis on the surface area – this allows for greater oxygenation of the bin and also allows the worms to spread out more.
In other words, a Rubbermaid tub will be much better than a bucket.
Something I would recommend is either setting up multiple small bins OR one decent sized bin. The larger the system the more buffering capacity it will have. For example, I have a very large outdoor bin (5X3X3 feet). All worm composting experience aside, the sheer size of this system makes it very worry free. Even if there are unfavorable conditions in one section of the bin, the worms can easily move into many other favorable zones.
Similarly, I tend to keep 2 or 3 small indoor bins at one time, plus an “overflow” bucket (for excess food waste), thus making it much easier to ensure that balanced conditions prevail.
All that being said, there is nothing wrong with a single worm bin in the size range of a typical ‘blue box’ recycling container. This size of bin should be large enough to provide both buffering capacity and waste-processing potential for a typical household (especially if you use an overflow bucket and/or an outdoor composting heap as well).
Another important thing to mention is aeration. If you are using a typical Rubbermaid type of bin its not a bad idea to drill some holes in the lid and along the sides prior to adding your bedding/worms etc. This allows for more air flow in and out of the bin. If you have your bin sitting on some sort of tray you may even desire to drill a few holes in the bottom of the bin – a great way to ensure bin contents don’t get too waterlogged.
Composting worms not only need food, but also some sort of habitat to live in – bedding materials provide both. Ideal worm living conditions can be created initially by adding lots of bedding material with a decent amount of waste material (and likely some water to ensure adequate moisture conditions).
People often refer to the ideal composting moisture content as being similar to that of a wrung-out sponge. Higher moisture levels do tend to work better for worm composting, but this is definitely a good guideline to start with (especially when using a water-tight bin).
Some great materials for bedding include shredded cardboard (my favorite), shredded newspaper, aged straw, coconut coir, fall leaves and peat moss (although I prefer not to use this material since it is not harvested in a sustainable or environmentally-friendly manner). Worms seem to absolutely love rotting leaves, so definitely don’t be so quick to kick those bags to the curb in the fall. The downside of using leaves (aside from seasonality) is the fact that they don’t really absorb much water – this is why my ideal bedding will consist of a mix of leaves and brown cardboard (another material worms seem to have a real affinity for).
Bedding materials will typically need to be moistened before worms are added. In fact, a practice I highly recommend when starting a new bin is mixing bedding with a decent amount of moist food waste, then simply letting the mixture sit in a closed bin for a week or so before adding worms. This way you are creating a very friendly environment for your worms to live in. Aside from activating the important microbial community, this also allows for moisture to makes its way throughout the bin materials.
Usually people set up their own worm bin at home so they can compost their food scraps and leftovers. Unfortunately not all waste materials are created equal from a worm’s standpoint (or a human health standpoint for that matter), so we should talk a little about what should and should not be added to an indoor worm bin.
- Vegetable & fruit waste (citrus fruit should be added in moderation when using smaller bins)
- Starchy materials – bread, pasta, rice, potatoes – all in moderation (beginners may want to avoid these altogether initially)
- Aged animal manures (careful with rabbit and poultry – need lots of bedding to balance)
- Shredded newspaper, used paper towels (common sense applies here), cardboard (great idea to add these carbon rich materials at the same time you add any wet food waste)
- Egg shells (best if ground up and in moderation)
- Coffee grounds
- Tea bags
- Human/pet waste
- Non biodegradable materials
- Harsh chemicals
These are fairly basic guidelines and of course there are exceptions under certain circumstances. I will definitely be going into much more detail in later articles.
Something I alluded to in the previous section was the fact that letting your waste material sit for a period of time is better than adding it right away. Often people assume that the worms feed directly on the waste materials themselves. In a sense they do, but more specifically they are slurping up the microbial soup that forms on rotting materials. If you throw in a bunch of fresh carrot peelings the worms won’t be able to start processing the material until sufficient microbial colonization has occured.
As I mentioned above, a fantastic way to ensure that your new bin takes off successfully is to mix a decent quantity of waste material in with your fresh bedding, then simply letting the bin sit for a week or so before adding the worms. I know this can be a challenge for those people anxious to get started, but it will go a long way in terms of ensuring your success.
Should you choose not to wait (obviously if you get your worms at the same time you get your bin it doesn’t make sense to wait) I would highly recommend that you at least try to add some partially rotting materials so that the worms have something to feed on.
I like to keep food waste in an old milk carton that sits under my sink. Aside from the convenience of not needing to take it down to the basement (where my indoor bins are located) or outside (to my outdoor bin) multiple times per day, this also allows time for microbial colonization of the materials – and don’t worry, you won’t have a stinky mess in your container if you do it properly (I’ll definitely write more about that in another article).
One of the common misconceptions amongst vermicomposting beginners is that any earthworm can be used for worm composting, or kept in an indoor bin in general.
I can still remember the disappointment of discovering (during my teenage years) that I could not keep a population of soil dwelling worms in a bucket. Before becoming interested in worm composting I was an avid aquarium hobbyist, always looking for ways to raise live food for my fish. Having heard that people were able to keep thriving “worm bins” in their house I naturally assumed they were raising the same kind I found in my garden.
Eventually I learned that most of my yard worms were of the “anecic” type – that is to say they were soil dwelling worms that create burrows and tend to lead a somewhat solitary existence (they need their space). The worms ideally suited for composting on the other hand are referred to as “epigeic”. This group tends to live in rich organic material (not soil), and are adapted to crowding and warmer temperatures. So its not difficult to see why epigeic worms would do much better in an indoor composting bin than their soil dwelling cousins.
By far, the most common variety of composting worm is Eisenia fetida / andrei – also known as the red worm (aka red wiggler, manure worm, brandling worm, tiger worm). If you are looking to start up your own worm composting bin this is probably a good one to start with. Another great composting species is the European Nightcrawler. They are considerably larger than Red Worms – so they’re an excellent choice for those interested in raising their own bait worms – and produce beautiful granular worm castings. We are now offering a Euro/Red mix – an excellent choice for those who want the best of both worlds.
When it comes to adding worms to a new system, I like to err on the side of caution. I prefer to build my population up to the ideal level, rather than using standard guidelines. This is one of the reasons our worm mixes are so great for starting up a new system. Rather than dumping in a pound or more of worms, only to then have the population thin itself out (not to mention the mortalities involved with packing a shipping those densities of worms), you are adding a mix of adults and juveniles/cocoons, along with a fair amount of rich food/habitat material the worms love – thus helping them to quickly acclimate to their new environment (and helping to inoculate the new bin with lots of other beneficial organisms). Stocking a medium-sized worm bin with 2-3 bags of worm mix should work well.
If you want to learn more about setting up your own system be sure to check our our ‘How to Make a Worm Bin’ page.
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