As my wife will happily say (and often does!) my DIY skills are appalling.
In fact, I’m banned from doing anything in the house.
Some compost projects, though, are so easy, even I can do them.
This DIY worm bin is even easier to make, can save you $100 or more over a commercial equivalent and can easily be expanded into a larger system.
In short, it’s perfect if you just want to experiment with vermiculture (worm farming).
It’s handy to know a few terms before we start! These are:
Vermiculture: The cultivation of worms for their composting ability. (Basically a fancy word for worm farming!)
Worm leachate: The liquid that seeps out from the bottom of a worm compost bin, which can be used as a fertilizer. (Worm tea is similar, except the worm leachate is soaked in water first.)
Coir: A natural fiber extracted from the husk of a coconut, used in gardening and composting as a soil amendment.
Building a one-bin worm composting system
Cost: Under $20 (or free if you repurpose a container).
Time: 20 minutes.
What you need
- 1 storage box (stackable, not clear)*
- 2 lids, or a lid and a base**
- A drill and drill bit
- 4 bricks (or blocks of wood)
- Bedding material (see below for different options)
- Compost worms
*A clear storage box lets light into the bin, which is not good for worms! Use a stackable container so you have the option of expanding the bin into a multi-bin system in the future.
**The second lid will be used to catch worm leachate, which can be used as a fertilizer.
- Flip the bin over so that the bottom is facing upwards.
- Drill about 20 ¼ inch holes in the bottom of the storage container, about 2 inches apart.
3. Place the bin on its side and drill more ¼ inch holes along the top side of the bin. Repeat all along the sides.
4. Take a lid and drill more ventilation holes around the lid of the bin.
Don’t put too many in, as you don’t want too much light to get into the bin.
5. Collect your bedding materials and put them into the worm bin. (See notes on bedding material below.)
6. Introduce the worms gently, allowing them time to spread out.
You can create a hole for them and gently place them in the hole.
For this demonstration, I added 250 grams of worms, but see the FAQs for additional guidance on worm quantities.
- Your worms may well be in shock, so leave them for up to a week before feeding them.
When you start adding food, just add a little bit at a time to start with.
- Cover the food scraps with more bedding to avoid fruit flies. Cover with a layer of damp newspaper. (I actually forgot to do this with my first bin, and although I simply added a few coffee grounds, I soon found fruit flies had joined the worms in the bin!)
- Place the un-drilled lid in your chosen location.)
- Place bricks or blocks of wood on the tray. This will allow for both air to flow and for the compost to drain.
12. Put the bin on the bricks or blocks of wood.
(Do note the one in the picture in the sun is purely for demonstration purposes – the bin should be placed in a cool, shady place.)
Go big with a multi-bin system
When it comes to harvesting your worm compost, you might want to expand this into a multi-bin system.
Simply prepare a second box, drilling it in the same way as above. Stack the second box on top of the first box, and prepare bedding material and food.
Over time, the worms will migrate upwards into the second box, allowing you to harvest the compost from the bottom bin as you wish.
Bedding material your worms will love
When it comes to bedding material, you have plenty of choice!
This list below by no means covers every option, but it still provides you with a menu of items to choose from.
I chose to follow advice from Uncle Jim’s Worm Farm, and use a mixture of different bedding materials.
In the example bin I made above, I used mature compost, shredded paper and sawdust.
Shredded newspaper is readily available, but unless you have a shredder, it can be a pain to tear it into strips.
You also need quite a lot of it – compost author Michelle Balz recommends half a pound of paper for every gallon of capacity you have.*
One disadvantage is that shredded paper can lump together, forming a mat which is hard to bury food in.
Broken down leaves
If you have a wood or forest near you, old leaves can make great bedding for worms. However, they may contain unwanted diseases or predators.
If you’ve ever collected old manure, you’ll know that worms love it!
However, you need to be careful you don’t add too much, as it can heat up if you not careful. It’s also possible they could contain pathogens.
Coir (coconut fibre)
Coir is clean, odorless, and good at retaining moisture.
However, it does cost money and as it usually has to be transported it is not the most environmentally friendly option.
The Royal Horticultural Society (RHS) also suggests using old compost as a bedding material.
I actually used fresh compost – mostly because I had a lot of compost to hand!
Several studies have also used sawdust as a bedding material, with one finding it was the best option for worm reproduction.
Uncle Jim’s Worm Farm suggests using a mixture of bedding materials, as each material will make up for the other’s weaknesses.
Damping down bedding
Whatever bedding you use, it should be as moist as a wrung-out sponge.
If you need to add water, it is worth leaving the water for several hours first to allow the chlorine to dissipate.
Off-the-shelf worm bins
If you don’t have the time or confidence to build a system, there are plenty of off-the-shelf options to consider!
For example, the VermiHut comes with five trays, which allows worms to navigate their way up naturally through the trays.
It also comes with great airflow and uses coir for odor control and moisture control.
Worm composting does require looking after live animals, so it may need some more thought and monitoring than a regular compost bin!
On the other hand, there’s no worrying about carbon:nitrogen ratios or turning. It’s also ideal if you want to compost but have very little space.
So do give building your own worm bin a go – and don’t forget to let us know how you get on in the comments!
How big does your worm bin need to be?
If you are simply composting kitchen waste, you don’t need very much space! Most worm composters use around one pound of worms per square foot.
Where can you get your worm’s from?
Worms are easily ordered online. I got mine from Wriggly Wigglers, as they use a mixture of different types of worms which are suited to slightly different conditions. If you are in the USA, I’d suggest Uncle Jim’s Worm Farm.
How many worms do you need?
If you’re just trying out vermicomposting to see if it’s right for you, start with a small amount of worms to keep costs down.
Don’t forget that the worms will breed, and you can always add more.
If you want to compost all your food waste, you need at least the same weight in worms as the scraps you produce.
Remember to start slowly, and make sure you don’t overfeed them.
Will the worms escape from the bin?
If you were in a comfortable, air-conditioned apartment with a well-stocked fridge, you’d probably stay there, right?
It’s the same for worms – if the conditions are right, they’ll stay in the bin. As long as you look after and maintain the bin, they should stay.
Composting for a New Generation: This excellent book (see review) is full of DIY projects like this one, and includes a chapter on vermicomposting.
Worms Eat My Garbage: The seminal book on worm composting, this book covers everything from vermicomposting to worm reproduction.
Worm Composting, Royal Horticultural Society: A good, clear introduction to worm composting from the masters of British gardening.
Uncle Jim’s Worm Farm: Full of helpful guides on vermicomposting, backed by 40 years of experience in vermicomposting.