So you want to start composting food waste with compost worms and wonder where to start? Before even buying your worms, you should buy or build your own worm bin/worm farm and prepare the bedding so that everything is worm friendly.

DIY Worm Bin

Building a worm bin will be subject of another post but if you are handy and resourceful then here is a checklist of points worth paying attention to.

Aeration

Even though worms don’t have nose they do breathe through their skin and need oxygen to live, additionally vermicomposting is an aerobic process (that requires oxygen) and does involve microorganisms that also breathe oxygen. Thus, having a properly ventilated bin is critical for bringing in that precious gas and evacuate the nasty ones that are generated during the composting process. Drilling small holes on the lid and the side of your bin, most of the time, won’t be sufficient. For best performance, you’d better cut out a large section from the lid and/or the sides and cover it with a fly screen. This will allow a much better airflow while still preventing access to most critters.

The lack of aeration is one of the three most common mistake done by a new worm farmer.

Drainage

With time, the food scraps you will be adding to the worm bin will break down and release a lot of moisture that will gradually leach down the bottom of your bin. Too much water sitting for a long time will prevent oxygen from reaching inside the wet block, this anaerobic block will start developing bad bacteria and will be smelling foul and you really don’t want this to happen.

So unless you are good at moisture control, it is highly recommended to have a liquid collection tray underneath your active tray (where your worms live and where you feed them). That collection tray would have a drainage hole and if your bin is indoor you could install a spigot to allow regular emptying of the collection tray. The liquid from the collection tray is called leachate (commonly and wrongly called worm tea or worm wee), we will go into details later on. Later on, as you will improve your kills, the tap can be left open to provide extra air input.

Stability

It would be frustrating if after several months of successful operation to one day find your bin on its side and all the content on the ground. Make sure the construction is sturdy and if the bin has legs then make sure they are strong enough because a worm bin full of moist finished vermicompost can weigh a lot. Also, is the material you chose is suitable for long-term contact with a moist environment?

Contact

If you have constructed a multiple stacking tray system then make sure the trays are not just sitting on top of one another. It is important that each tray can partially slide into the tray below it, this is because you want the bedding in one full tray to be in constant contact with the base of the tray above. The reason being worms, even though they can, don't like climbing walls and ceilings and a gap would prevent them from migrating upwards towards the new empty tray above.

The lid

A lid is useful to create obscurity for the worms as they don't like the light. It is also one way of preventing the worms from escaping the bin. They can also help invasion by other critters such as flies.
However, it is actually not required.

The worms usually try to escape a worm bin if they are stress (after shipping from their original farm for example) or if something went wrong in their bedding (too much food that creates heat, acidity etc...) or if they lack of oxygen. So a better way to make sure the worms are happy is to provide them with enough air and make sure you don't overfeed and adopt best practices (not watering, adding a lot of bedding material at each feeding etc...).

If the bin needs protection from external critters, it can also be replaced by a sheet of fly screen or geofabric held in place with bungee cords. Those materials are breathable so will provide better aeration than a solid lid.

Choosing where to install the worm bin

Your worm bin can be installed indoor, the worms will actually appreciate the stable ambient temperature of our homes. However, make sure the place needs to be well ventilated (so under a kitchen sink is not ideal) and away from any unexpected heat wave (such as on a balcony or behind a window that might receive a lot of sun). A laundry room or garage (if it does not get too hot during the summer) can do. Some people have installed their worm farm in their bathroom or in a corner of their living room. If you have the chance to have a basement, then this could also be a great location for a worm farm. Well maintained, a worm farm should not smell bad but rather have a nice earthy smell just like when you walk into the wood.

A worm farm will do perfectly well outdoors (most of mine are outdoor) as long as you can find a place that is constantly in the shade or only receives a very short time under the early morning or late afternoon sun: under a pergola, a tree, a coop house etc...

Extremely high and low temperatures can kill the worms. Even couple of hours in direct mid-day sunlight during winter might still be fatal.

Stacking tray vs single compartment bins

With single compartment bins such as a simple Rubbermaid style container, it is easy as you just use that directly. However, with stacking bins you usually have the base that is on legs, it is called the collection tray. Its purpose is to collect the leachate, which is the excess moisture that comes from the feeding (top) tray and leaches all the way down to the bottom. Depending on the model you have bought, there could be two or more extra trays with holes in the bottom, those are your active trays, one of them will be the feeding tray sitting at the top of the stack and the others will contain the vermicompost/castings that will sit for maturation. Start by adding one active tray on top of the collection tray and prepare a bedding for it.

Preparation of the bedding

Now that you have chosen a location and installed your worm farm, the next step is to prepare a bedding for your wiggly friends.

What is a bedding?

The bedding is where your worm will be living when they are not eating the food scraps. It is a safe place for them to retreat to, away from the layer of food that can heat up and become acidic. Even if you made a big mistake, on occasion, the presence of a good layer of bedding will save your worms from certain death. This is one of the most important part of your worm bin and also one of the three most common beginners issue.

Why do you need to add bedding materials?

Most people think they only need to add the worms and then throw food scraps in the bin and it’s job done. A worm bin is not a garbage bin! While this may work for some, it is also a great way to kill all your worms at once, especially in a small enclosed system such as a domestic worm bin. If you’ve ever run a regular compost or have piled up grass clippings you would know how hot the compost or grass pile can get. Throwing heaps of scraps in the bin will heat up, release too much moisture, ferment, become acidic, release gas and smell and sooner or later kill the worms or repel them.

Food scraps are, in composting terms, called “green” materials. They are rich in nitrogen (N) and feed the bacteria. The bedding is made of “brown” materials rich in carbon (C). Just like with traditional composting, a good C:N ration is critical to a good performance. Bulky and moisture retaining material are preferred such as cardboard, egg boxes or newspaper. The bulkiness will increase airflow and a good moisture level is important.

A good layer of bedding is important, so if you've accidentally added too much food scraps, the worms have somewhere safe to retreat to. In the summertime the worms will also dive down into the cooler bedding to avoid the heat on the surface that has been made worse by the presence of fresh food waste. With time, the bedding material will break down and become worm food, this is especially useful if you need to go on holiday for an extended period of time.

So you should start with 6 to 30 cm of bedding material depending on the depth of your bin and remember that this material will start breaking down and drop in volume in a couple of weeks. I usually go for half the effective depth of a tray full of initial bedding.

What material can be used as bedding?

To make your bedding you can use one or more types of bedding material, they need to be carbon-rich materials ("browns" such as dry leaves, paper etc..).
I highly recommend using cardboard, egg boxes and newspaper because they can be easily obtained and you are recycling more materials. If you have a paper shredder that can handle cardboard (10 sheets of paper) then you can use it but hand tearing them into palm-sized pieces is all you really need.

Some people also use aged grass clippings, horse manure, coco coir, peat moss etc... but there can be risks associated to grass clippings and horse manure; coco coir and peat moss can be expensive and the production of peat moss is not sustainable. Corrugated cardboard, newspaper and egg boxes can be obtained for free and are excellent materials.

How to use the bedding material?

For creating your initial layer of bedding, first wet down or soak the material for a moment and then squeeze all the water out of it so it is just moist with a couple of drops coming out. Then add the bedding material directly to the tray, you can first add a layer of newspaper sheets if the bedding material is so fine it could go through the holes of the tray. Fill the tray up to half way or at most 30 cm thickness.

When feeding the worms, use the same quantity of dry bedding material under the food scraps, this bedding material will absorb excess moisture leaching from the decomposing scraps. Cover the fresh scraps with more bedding materials to restrict access from the flies to the scraps.

Adding the worms

Ideally, you would have set up the worm bin and bedding a week before receiving the worms and while waiting for the delivery you would have added a handful of food scraps on top of the bedding. This allows time for the beneficial bacteria and microorganisms to populate the bedding so the worms are less stressed up compared to being added to a sterile bedding.

Step by step with photos

Here are the steps I took to setup my homemade wooden worm bin which is a simple box. The steps can be reproduced for any other types of worm bins, you just need to scale up or down the quantities.

First I gather the bedding material. I like using egg boxes and shredded corrugated cardboard as they are very absorbent and add bulk for better aeration.
I add a layer of egg boxes at the bottom, this creates a gap between the base and the rest of the bedding which is great for bringing more oxygen at the start to help breaking things down.
I then add the shredded corrugated cardboard on top of the egg boxes. I can keep adding up to half to 3/4 the depth of the worm bin, it will eventually break down and become worm food, but in this case I will make a bedding from various materials.
I'm adding some garden litter that includes some leftover mulch and aged grass clippings.
I then add some shredded fall leaves, if you can have pre-decomposed leaves (moist and very dark) or leaf mold then it's even better.
I now start watering the bedding using a watering can and water from my homemade rainwater tanks. This is a large bin made of wood so water will drain out easily from the gaps and the wood is breathable so I don't mind overwatering the bedding here. If you are using a smaller plastic worm bin, just moisten a little bit.
I now add some food scraps in the form of lettuce leaves I collected from the local supermarket and sprinkle them with few handfuls of garden lime (calcium carbonate) to help buffer the pH.
I then cover the food waste with more carbon-rich material here some shredded leaves, small leaves and hand-torn newspaper and then I water some more. This will help control the smell and prevent flies from accessing the food layer
Now go order the worms or if you know someone local who can give you some, book a pickup time in about a week
After a week or so, just deposit the worms on top of the bedding and forget about them for another week.

These steps done in advance should reduce the chances of the worms trying to escape because you have created a worm-friendly environment for them. If you however still notice some worms trying to crawl out, try to remove the lid and place a light above the bin shining onto the bedding. This does three things:

Allow more air to get in. Worms and other microorganisms in a worm bin need oxygen, they are anaerobic organisms.
More air getting will also prevent condensation on the sides of the bin. When the sides are wet, the worms crawl up more easily.
Worms are photophobic, they are afraid of light, so they will stay in the bedding.

I hope this (not so) little tutorial would be helpful for those of you who want to start diverting some of their food waste from landfills.

If you want to learn more about worm farming, check out this awesome book:
Worm Farming Revolution

As usual, don't hesitate to ask questions in the comments below.

How to setup a new worm compost bin