A foolproof, hassle-free and effective outdoor vermicomposting system

6 months ago
last modified: 6 months ago

I have developed a home vermicomposting system which is easy, effective, efficient, inexpensive and very low maintenance. This system has evolved mainly through trial and error. It allows me to convert all of my household food waste into vermicompost.

In order to carry out vermicomposting, there is absolutely no need to buy an expensive layered bin. In my experience, these types of bin are unnecessarily complicated and not particularly effective.

I have three large dalek-type composting bins outside in my garden. They are between 200 and 300 litres in volume. I will refer to them as bins A, B and C. At any point in time, one bin will contain finished vermicompost (A), one will be the active bin (B) and the final one will be full of material which is in the process of being broken down (C).

I have a small food waste caddy in the kitchen. It has a volume of around 5 litres. All of my food waste goes in there, including cooked food, meat, orange peel and onion skin. It usually takes two or three days to fill the kitchen caddy.

I have a larger caddy out in the garden. This is a little over 20 litres in volume. When the kitchen caddy is full, I empty it into the garden caddy. It usually takes a week or two to fill the garden caddy. When the garden caddy is full I empty it into outdoor bin B.

I then fill a 14 litre bucket with finished material from bin A and tip this over the top of the food waste I have freshly added to bin B. I make sure that this finished vermicompost is spread out, so that the freshly added food waste is completely covered.

I repeat this process over a number of months until bin B is full and bin A is empty. So bin B ends up being composed of layers of food waste and finished vermicompost. This layering completely eliminates the problem of flies and smell. Once bin B is full and bin A is empty, the material in bin C will have been completely broken down by the worms. Bin A becomes bin B, bin B becomes bin C and bin C becomes bin A for the next cycle.

Eventually there will be enough vermicompost in the system that some can be spared for other purposes. This can be taken from bin A as and when it is needed. A slight issue is that when starting the system, you need a certain amount of finished vermicompost (for layering) to get it up and running. Of course you could use old potting compost, leaf mould, aged horse manure or any other suitable material you have handy to substitute for the vermicompost when you are starting off.

Once the system is up and running, it is self-sustaining and does not require any new material to be added apart from food waste. Of course you can still put other biodegradable material (such as cardboard and paper waste) into the bins if you want to.

I think the layering of food waste and finished vermicompost has the effect of inoculating the freshly added food waste with the microbes needed for decomposition. As stated, it also completely solves the problem of flies and smell. The movement of finished material from one bin to another has the effect of keeping the worm population high. When adding finished vermicompost to the active bin, you are usually importing lots of worms and cocoons with it.

The large garden compost bins required can often be obtained very inexpensively on Gumtree. They are in fact frequently given away for free.

I thoroughly recommend this system to anyone with enough space for three compost bins in their garden.

Ben Crabb
14 November 2021

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