How to Use This Guide
Simply building a worm compost can be done quickly. However, having a successful worm compost that keeps you and your worms happy requires a bit more knowledge.
This guide gives you an overview of the important aspects of worm composting. Find out what to keep in mind as well as ways of troubleshooting if something doens’t go as planned.
Clicking on the icons will get you directly to the section you need.
If you are new to worm composting this guide will give you everything you need. If you already know a bit about worm compsoting, you can skip throught the article and get the information that you were missing so far.
Happy Worm farming!
WORM COMPOST REQUIREMENTS
Life is all about learning.
Throughout the years I built different worm composting systems and learned a lot in the process.
To make life easier for you, here are a few things to keep in mind for your compost.
Reasons to start Composting
Composting is one of the simplest ways to start living a more sustainable life. Every year tons of food end up in landfills, where they rot away producing greenhouse gases.
In nature nothing is wasted and everything is reused. With composting we can imitate natural processes and help close a loop in food production.
Plants need food, just like us. Food scraps are still full of important nutrients. However, plants can’t get to it directly from leftover food scraps. That’s what composting is for.
During the composting process, numerous microorganisms and fungi digest organic matter and turn it into its more basic elements that plants can use as food.
You can build a compost pile in your garden where the microorganisms can do their work. Depending on the size of the pile and its composition, the process can take many months and will need a lot of space.
There are also faster composting techniques which can speed the process up to a few weeks but they require quite a lot of work and space.
An alternative to this process is worm composting.
Benefits of Worm Composting
Is a Worm Compost Right for You?
Worm composting is a great way to start reusing your food scraps from the scale of a small apartment all the way to a large farm.
However, it does require a bit of work to set up and a bit of care to keep running.
You are working with animals and should be willing to care for them. Wrong operation of the system can cause them to suffer and that should not be the goal.
How much Effort is Required
You can decide how much effort you want to put into your worm composting system. Some setups require more work, some require less. It depends on your willingness to put effort into it. Below, I explain different setups that you can choose from.
WORMS, WORMS, WORMS
What type of worms to choose
When we hear about worms, we usually think about earth worms that we find in the ground. However, these worms are not the ones to use in a worm compost.
Earth worms live deep down and in the soil and a closed box is not quite what they like. Compost worms don’t live deep down in the soil. They live in the intersection between organic matter and soil.
You could use different kinds of worms, but composting worms are the fastest at their job.
Which species you go for is your decision, but here are some things to consider.
Depending on where you are in the world and who you talk to, worm names differ. A read wiggler in one place might be called something different in other places. Therefore, Latin names are used.
People have success composting with different worms. However, the most common worm for composting is Eisenia Fetida. Some people even mix differnet kinds of worms to handle different tamperature ranges. Which worm you go for depends mostly on what is available. You can start with any of the common ones.
Where to get worms for a worm compost
You could go out in nature and try to collect worms for your compost, but if everyone did that, the natural ecosystem would get out of balance and we don’t want that.
Luckily, there are many people breeding compost worms nowadays. From these breeders you can order worms for your compost without interfering with the ecosystem.
It is always a good idea to support small, local worm breeders. You can ask at your local garden store or look online for good options. Feel free to ask me, if you have any questions.
How many worms are needed for a worm compost
Less is more! However, this questions depends on the size of your setup.
A starting population of worms is called a nucleus. Worms are usually sold in a nucleus of roughly 1000 worms (1KG or 2.2 pound) or half a nucleus of 500 worms. This depends on the breeder.
It is usually a good idea to start small and grow grow from there. If you have too many worms for a small bucket, they won’t feel comfortable and will try to escape.
If you are starting with a small bucket, start with a hand full and slowly add more. Worms are doubling their population roughly every 90 days. Under the right conditions you can have a lot of worms soon.
WORM COMPOSTING SYSTEMS
There are many different worm composting systems. The way they work can be divided into three main categories, which I explain below.
This a is the simplest system. Worms are placed in a bucket or container. Food is added continuously and when the bucket is full, compost and worms have to be separated.
You can use the worm castings (worm poop) as fertiliser for your plants and the worms can go back in the bucket for another round.
Horizontal systems usually require a little more space. They can be a small container or as big as a bathtub. The systems can either be one large container or with a mesh in the middle. With a mesh in the middle they are often called a worm box.
Worms move freely to both sides. Adding food on only one side makes it easier to harvest the other side.
Vertical worm composts aim to make harvesting easier.
The main idea behind these systems is that worms always move upwards towards a food source. Similar to organic matter falling from plants in nature. The finished compost can be harvested below.
In the following section, two main systems are compared.
VERTICAL WORM COMPOSTS COMPARED
A stacking system consists of multiple layers. Once one layer is full, another can be added on top.
The worms move upwards through the system, following the food
To harvest the system, you can take out a lower layer. Usually, you won’t find any more worms in the lower layers when you take them out.
After emptying, you can add the layer on top again.
Flow Through System
This system is a continuous tower with a lid on top and a smaller opening at the bottom. Food is added from the top and finished castings can be taken out the bottom.
This system requires the least amount of work to operate.
You can scratch worm castings out the bottom without disturbing the worms or rebuilding the system.
Building or buying
Buying a system is the simplest way to start composting. There are different systems to use and many of them work quite well. Depending on your budget, they can get a bit expensive.
If you want to spend the money, it is a great way to start composting with worms.
Building your own system enables you to build it exactly in the dimensions you want and is usually a cheaper option.
This is one of the many Worm Hotels from Rowin (Compostier) in Amsterdam.
His worm hotels are spread all over Amsterdam. You can buy whole hotels or just plans if you want to build them yourself.
Many years ago he introduced me to many of the fantastic concepts of permaculture and I don’t know anyone with more knowledge about worms.
Check out his website or Instagram if you are interested in his products and skills.
Where to place your compost
You can choose where you want to put your compost. A well balanced compost does not smell and doesn’t attract any unwanted animals.
However, for a beginner it might not always be super easy to get everything right from the beginning.
Therefore, it might be better for you to keep your compost on the balcony or outside your door to begin with.
THE BUILDING PROCESS
There are many differnet worm composts you can build. Over the years I have build quite a few different designs. The purpose of this guide is to get you started with composting in the simplest way.
Therefore, I decided to make the first guide about a single container worm compost.
step by step building
1. Choose your container
The size of the container depends on the amount of vegetable and fruit scraps you produce. A 20 litre bucket is usually a good starting point for one or two people.
Many restaurants and other place throw them out all the time. A bucket with a lid is the best option, but you can also use a normal bucket and use something else as a lid.
If you eat a lot of vegetables and fruits then a larger container could be a good idea. Alternatively you can have multiple buckets.
As a general guide it is usually a good idea to start with something small and test it before you invest a lot of time and money into a huge system that might not work for you.
For this guide I went with the simplest option and used an old flower pot.
2. Take your bucket and drill some ventilation holes close to the top
3. Protect Your Compost against flies
If you want to make sure that no flies can enter into the bucket, put a mesh in front of the holes.
For this system I used an old one, cut it into stripes and secured it in place with tape.
As an alternative you can also drill many small holes that flies don’t fit through.
4. Drill holes in the bottom of the container
The holes are needed for the liquid to drain out.
You can either have one hole and let everything drain out centrally or drill multiple holes.
If you use a larger container the steps are the same as for the small bucket.
If you only have one drainage hole at the side, it helps to put the bucket on a bit of an angle so the liquid flows towards and out of the hole.
5. Add Natural Bedding Material for your worms
Think about the worms’ natural habitat. They live in the layer of organic matter just above the soil. For them to feel at home, we want to create a similar environment.
Ideally you fill the bottom of your container with a mix of very small branches, leaves and a little bit of soil, just as you would find it on a forest floor.
6. Add Cardboard as Additional Bedding Material
If you don’t have access to natural bedding material, you can also use cardboard.
Rip cardboard into many small pieces and soak them in water until they are wet.
Press the moisture out of the cardboard pieces until they stop dripping. Add them in the bucket.
7. add a little bit of soil
Good soil is full of these microbes and we introduce them to our compost through the soil.
8. add worms to your compost
After you prepared your bucket it is time for the worms to move in.
Depending o the size of your system, only add a handful of worms to begin with. If it is too crowded they won’t like it and try to escape the bucket.
The worms should wiggle under the surface quickly and get used to their new home.
9. Cover the soil food mix
To keep moisture in and to add a little bit of extra comfort for your worms, cover the soil.
You can use a moist piece of cardboard or some kind of fabric. Every bit of protection and comfort counts.
10. Add a lid and drainage container to your compost
Worms need protection from the outside. That’s why your system needs a lid.
You can also prepare multiple containers this way and add more on top, when they are full. That way you create a simple stacking compost.
For this system I wanted to show how simple it can be. That’s why I just used a piece of wood and the rest of the mesh. You can leave the lid rough or cut it to shape.
To catch the liquid I used an old container from another flower pot and placed it below.
11. Find a good spot and let your worms relax
Worms don’t like stress or disturbance. Moving into a new home is very stressful for them.
Choose a spot where your worm bin is protected. Keep it out of direct sunlight or very cold temperatures.
The bigger your worm compost, the more it can handle.
Once your worms are inside, let your compost sit for a few hours or even days.
They need some time to get used to their new home.
12. Get ready to feed your worms
This is the simplest way to build a worm compost. If you want me to create guides for more complex stacking and flow-through systems, please let me know in the comments.
Feeding your worms
Once your worms have moved into their new home, let them get used to it for a while. After a few hours or days you can start to feed them.
Fun fact: Worms don’t have teeth, only lips. They move their muscles to crush up a mix of food and soil particles inside their body. Microorganisms digest everything and the leftovers are pooped out as amazing fertiliser.
What Worms Like
What Worms Don't Like
To remember what to feed them: Imagine you are a small, naked worm and you are very sensitive.
Worms will go the easy route. They will eat smaller and softer food first. They will leave the food which they don’t like and it will start to rot away and start smelling.
If you have a large compost it is more forgiving and you can add a few of the unwanted items. However, your composting process will be faster and your worms happier, if you feed them only what they like. The smaller you cut things, the faster it will get eaten.
How much food do worms need
Worms can eat around half their body weight per day. Worm populations will adjust to the amount of food and space they have available. If you only feed them a little bit, the population will stay smaller.
If you feed them too much, they can’t keep up with the amount of food and some of it might get mouldy and smelly.
As a rule of thumb: Put all your kitchen scraps into the bin until you notice they can’t eat it within a day or two.
Once the population grows, they will be able to handle more. You will learn to adjust over time.
MAINTAINING YOUR WORM COMPOST
Keeping Your Compost In Balance
If you have any experience with composting, you have probably encountered a smelly compost at some point. A very unpleasant odour and a slimy mix are a very common problem in composts.
This phenomenon is the result of a lack of carbon and an imbalance in your compost.
What is the Carbon to Nitrogen Ratio
Without going into too much detail here, every living organism has a ratio of carbon and nitrogen molecules inside it (C:N ratio). If your compost has too much nitrogen (Lower than 20 parts of carbon for each part of nitrogen), it produces a lot of ammonia gas and can get smelly.
If it has too much carbon and not enough nitrogen (50:1 or higher) the composting process will be very slow and your worms won’t have enough of their favourite food.
If you want to get scientific, you can look up the C:N of everything going into the compost and calculate it. An ideal C:N ratio for a worm compost is somewhere between 20:1 and 30:1.
Kitchen waste is usually below 15:1. Sawdust on the other hand is around 500:1.
If you don’t want to stand in the kitchen calculating ratios all day, here is a rule of thumb that will make life easier:
Simplified Carbon to Nitrogen Ratio
Nitrogen rich materials are usually called greens and carbon rich materials can be called browns.
To raise the ratio of your kitchen waste, just add a part of browns for each part of greens you put in the bin.
If it gets smelly or too wet, add more browns.
If it is too dry and not composting, add more greens.
BALANCING CARBON AND NITROGEN IN YOUR COMPOST
Every time you add food scraps, it is a good idea to cover them with brown bedding material. It helps to keep flies away and the worms can do their magic below it. The consistency of your compost should be like a wrung out sponge. It should be moist but not super wet.
If it is too wet and squishy, add some more carbon rich materials to suck up moisture. If it super dry add greens or a bit of water.
InDICATOrs of a well-funcioning bin
You will slowly gain experience with your worms. Here are a few indicators to know your bin is going well.
Harvesting YOur Compost
At some point your compost will be full. This happens usually somewhere between three to six months. How to harvest the worm castings depends on your systems.
Open the bucket and let light shine in. Worms don’t like light and will move deeper down.
After a few minutes you can take the top layer out with a small shovel or with your hands. Put any remaining worms back into the bucket.
If it is not fully composted yet, put it in a separate container to add back for a second round.
The worms will move further down and you can repeat the process until you have a layer full of worms left.
Once you reach the bottom, you can start the process over again and start feeding your worms.
Horizontal Worm Bin
When the compost is getting full, only put food on one side of the container for a few days or weeks. The worms will move towards the food and you can take out the compost on the side without fresh food.
Afterwards you add food to the other side. Once it is full you repeat the process.
Stacking Worm Bin
Every time a layer is full, you can add a new layer on top. The worms move up towards the food. When the top layer is full, you can harvest the bottom layer and add the empty one on the top again.
You can continue this process and there should barely be any worms left in the lower layers.
Once your container is getting full, you can scratch worm castings out of the bottom.
If your compost has been operating for a few months, you can take out small amounts of castings daily if you want to make compost tea or as an extra fertiliser for your soil.
The dark brown liquid that drains out of your compost is worm pee. It is an amazing fertiliser, full of beneficial microbes.
You can mix it roughly 1:10 with water and apply it to your soil and plants.
Don’t let it sit for too long or many microbes will die du to a lack of oxygen and you will lose a lot of the benefits. Without air it will go anaerob and harm your plants if you put it on.
You can also turn it into aerated compost tea, which is even better for your plants.
You can watch my tutorial video on how to make compost tea, here:
HOW TO SOLVE WORM COMPOST PROBLEMS
A well balanced compost does not smell bad and should remind you of the smell in a forest.
If your compost smells bad it usually means there is too much food in it for your worms to handle and it starts rotting. It is also an indicator of a lack of carbon rich brown materials.
You can reduce the amount of food you put in for your worms.
In addition, add and mix in more cardboard, paper, sawdust or whatever you have available to regain the balance.
It should get back to normal like that. If it doesn’t get better, because there is too much rotten material, you might have to take it out to reestablish the balance.
Check the section on the Carbon Nitrogen ratio for more information.
If you cover your food scraps with bedding material and keep a good balance of nitrogen and carbon, you shouldn’t have any problems with flies.
To be sure it helps to drill your ventilation holes very small or add a mesh in front of them to prevent flies from entering.
The consistency of the compost should be like a wrung out sponge. If it is too dry it can mean that you added too many browns and not enough greens into the compost.
Usually, the moisture inside of food scraps should be enough for the right consistency.
If the inputs were too dry, you can add a bit of water to get the balance right again.
This usually means you added too many greens and not enough browns. Add some cardboard, paper or sawdust to suck up the excess moisture and rebalance the system.
Check the section on the Carbon to Nitrogen ratio for more information
If all your worms are at the top of the compost and trying to get it, it usually means that the compost is too wet and your worms want to breathe.
Check if the liquid is draining well and nothing is blocked.
It can also mean you added too many wet greens and the compost is out of balance.
Take any large wet clumps out, add bedding material and try to reestablish a good balance in the system.
I hope you got a lot of value out of this guide and you can start your journey as a worm farmer. If you have any questions or suggestions, please let me know in the comments below.
Remember to live life to the fullest, and never stop learning!