To buy a worm compost bin or make your own? That is the question.
There are commercial worm farms available on the market that don’t break the bank, costing from $AU60 to $AU80. I have yet to try them out, but I believe they are adequate for the needs of home composters or the hobby worm farmer.
However, if you are going for the cheapest option available, then a home made compost bin will cost less and give you the satisfaction of using something you have made yourself.
A diy worm farm can be as simple or complex as you want to make it. In the spirit of recycling, you can re-use items you have lying around your house. This could be wood, old baths or tubs you no longer need.
For this project, I have decided to make a simple plastic compost bin, with a second tub to catch the excess water run off (leachate).
Without further ado, lets get into it.
Step 1: Gather the items you will need
- 2 opaque tubs with a lid
- a drill
- newspaper and/or cardboard
- spray bottle with water
- brick or wood block
- newspaper to use as a blanket
- garden lime
- soil or vermicompost
- small amount of food scraps
For this project, I am using 2 x 50L tubs. If you want a small compost bin for inside the house, to be able to hide in a cupboard, then you can go as small as 20L. I had trouble finding an opaque 20L tub with a lid, so I went large.
It’s important to find an opaque tub as compost worms are sensitive to light and require a dark environment. However, if you are intending to keep your compost bin in a cupboard, then it’s less important for your compost bin to be opaque as the cupboard itself will be dark.
Cost of project
Of the above items, I bought the tubs, the worm eggs and the dolomite lime. Everything else I got from around the house and from my rubbish bins.
- tubs $AU7 each = $AU14
- worm eggs = $AU24.99
- dolomite lime =$AU7.47 for 5kg bag
- Total cost of project = $AU46.46
This shows that it is possible to make and stock a diy compost bin for almost a third cheaper than it costs to buy a commercial worm farm.
Step 2: Prepare your materials
The next step is to get the materials ready to use.
I am in the habit of tearing up cardboard as I find it. This saves me from a long cardboard tearing/cutting session.
When you are ready to use the cardboard, it needs to be soaked and drained. Lots of people recommend soaking cardboard overnight to make sure the water gets through all the layers. If you’re like me and not very organised, then soak it for at least one hour before setting up your worm farm. It then needs to be drained to remove the excess water. The water content should be similar to a wrung out sponge. Draining can be done by wringing the cardboard with your hands or by dumping the cardboard on the lawn to self drain (if you don’t have a lawn, try using your shower stall).
I estimated how much cardboard I would need by filling up the tub half way. Turns out that I underestimated by half, as the volume of the cardboard shrunk when wet. Next time, I will fill the tub up when estimating how much I will need, as it is better to have to much that to little.
Which cardboard should I use?
For my first bin, I was high on the recycling bug and used any cardboard that came my way. This included shiny cardboards and takeaway coffee cups.
My observation is that these cardboards don’t break down very well and some of them have a plastic coating on them don’t bread down at all and which I then have to pick out of the vermicompost.
There is also the old saying “what goes in, must come out”. While these cardboards don’t seem to affect the worms, they are still there. Whatever compounds are used to make these cardboards will end up in your vermicompost and will be put on your garden.
If the worms ingest the compounds and you use them for fishing or to feed the chooks, then the compounds are introduced into your food chain.
So, my new policy is, if it looks glossy or highly processed, leave it out.
I tore up three newspapers into 1″ strips. It took about 5 – 10 mins to do this. This turned out to be more than I needed, which is ok. I will save the extra for new bedding when I harvest.
I happen to have a shredder in the house, which my mum used to shred important papers. I like using shredded paper as I think it sticks together a little less, but I decided to tear the paper this time for those of you who don’t have a shredder. Either way is fine. I wouldn’t recommend getting a shredder for home worm farming, unless you intend to get serious about it.
I chose not to soak the paper this time. Instead I sprayed it with the hose and fluffed it around to make sure it all was wet. This way I could avoid having to squeeze out excess water. If I was starting with live worms I would not do this but as I have bought worm cocoons, I think there is time for the moisture content to even out between the paper and cardboard before the cocoons hatch.
Update: turns out there where quite a few juvenile worms in the bag and even some adults.
Prep the tubs
This is the part where you get to mess around with tools. At the grand old age of 42, I have purchased my first drill and this is the second time I have used it. Once I got the hang of it and learnt how to use the controls, it was very simple and straightforward to use.
Firstly, set one tub to the side to remain intact. This is going to be the drainage tub to catch any leachate. In the second tub, we are going to use the drill to make airholes in the top of the tub and drainage holes in the bottom.
Worms and the microbes they co-habit with are aerobic creatures. This means they need an adequate flow of air in their environment (bedding) to survive. There are two ways to do this: drill lots of holes in the top and sides of the tub, or cut out sections of the lid and tub and cover the holes with fly screen.
Experienced worm farmers insist that the first method doesn’t provide enough air to the farm. However, I have used this method from the beginning and have harvested a nice amount of vermicompost from my tub. So, I will argue that it is sufficient for a home farm set up.
The trick with air holes is to make them large enough to let air in, but small enough to prevent black soldier flys from entering your farm. While black soldier flies are also great composters and don’t spread disease like regular flies, they will take over your farm, especially in summer and eat all the food intended for the worms. There is also the ick factor to consider, they look like ginormous maggots.
I am using a 5mm drill bit for this project and will report back on the results.
I made two rings of holes around the top of the tub as shown in the photo to the right. I chose not to put holes in the lid as my farm is going to live in a dirty, dusty shed and I’m worried about things falling through the holes, but you can feel free to aerate your lid as well as the sides.
Next, we will put drainage holes in the bottom of the tub, to allow excess water to drain out.
Worms breathe air through their skin, therefore they need to be kept in a moist environment to allow for air transfer. However, we don’t want the farm to flood, as the worms can be drowned or driven out of the bedding and we will end up with boggy, soggy vermicompost.
Water will be introduced into the farm in two ways. First, we will be spraying the top of the farm with a spray bottle, at least once per week, to keep the moisture content up. Secondly, the food scrapes we will feed the worms will release water as they decompose.
I don’t think it matters how many holes you add. However, if the base of your tub is raised, make sure you put holes in the lowest point of the base.
Step 3: Putting it all together
I set this bin up using a layering pattern. I put a layer of cardboard about 2″ thick, then a 2″ layer of newspaper, followed by the rest of the cardboard. At this point, I spread the cocoon rich material (brown) over the cardboard, along with some used tea leaves (red brown) as food, vermicompost to provide microbes required for decomposition and a sprinkle of lime (white) to maintain a pH neutral environment. I then topped it of with another layer of newspaper.
Step 4: Find a shady place
Compost worms are sensitive to temperature. Their ideal temperature range is 15 – 24°C (60 – 75°F). In this range, they will have optimal eating, pooping and reproduction.
Outside of the ideal temperature range, worms can survive highs of 35°C (95°F) and lows of 1°C (34°F). The further the temperature gets from the worms ideal range the lower their activity becomes.
Beyond these ranges, your worms will begin to die.
For this reason, its important to find a shady place to keep your worm farm. If you live in a place that snows in winter you should keep the worm farm inside. If your summers are hot you will need to consider ways to keep your worms cool.
Next, we wait
There you have it.
Over the next 3 – 4 months our worms are going to eat, poop and be merry. At the end of that time we will be rewarded with a tub of black gold (i.e. vermicompost or worm castings).
All we have to do in exchange for this is to make sure our worms are feed, watered and not to hot or cold.
I would love to hear how you get on making your own compost bin. If you have any questions or used different techniques that have worked for you then please leave a comment below and I will get back to you.
I wish you all happy Wormicomposting.