Worm Composting

Worms, like cockroaches, are awesome composters. Worms are a bit different since they really feed on microbes as much as the stuff you feed them. So this is more like a traditional “composting” technique – but works wonders on kitchen scraps, just like cockroach composting. I first got into worm composting after reading Bentley Christie’s excellent site on red worm composting. In fact he sells an excellent introduction to worm composting that is far more comprehensive than what I’ll get into here. However for a great intro to the topic, yet another method of turning your kitchen waste into amazing garden compost, read on.

What is Worm Composting

Worm composting is simple – it just involves keeping a whole bunch of worms in a bin and feeding them organic scraps that you want to turn into dirt. Just like cockroaches, worms have a tremendous capacity to turn almost any kind of food source into nice rich dirt ready for the garden.

Worms are a little different in how they process food. As much as the food itself, worms feed on the microbes inhabiting it. This is an important distinction since it will help you set up a really nice worm bin. If you simply put in fresh food, worms can’t do much with it. It is tough and chewy and just not appetizing to them. But, after a little while the food gets infected with microbes that start to break it down. It starts getting mushy and really microbe-rich. Now it is really attractive to worms and they come in for a nice feed.

As worms eat this partially degraded food, their own microbes that inhabit their gut get involved. The food matter is further broken down by the action of these microbes and a nice, microbially super-active, dark brown soil-like substance is excreted. This is the precious worm casting that you are looking for.

Why Worm Composting?

Worms eat everything. They are awesome composters! Manure, coffee grounds, food scraps, meat, milk, etc all can go into the bin to be turned into worm casting compost (caveats noted in the feed section). This is important because it is one more outlet for your kitchen scraps that might not be ideal for the compost pile. For example just throwing half a pound of kitchen scraps on your compost pile every day will likely lead to a stinky, wet mess. But if you have a worm bin with a healthy population of worms, you will be able to add kitchen scraps each day, and the worms will turn them all into compost – no smell, no mess, just nice clean worm casting compost.

Worm composting provides much more benefit than just consuming your kitchen scraps however. Worm cast, or vermicompost, is called ‘black gold’ for a reason. It is a spectacular fertilizer for the garden. It has all the microbial benefits of traditional compost (high beneficial microbe counts), but also contains high levels of bio-available nutrients. The action of the worm gut microbes breaks down the nutrient rich substrate into incredibly nutritious vermicompost.

Basic Principles of Worm Composting

Worms are an awesome composter because they are so easy to keep and they eat everything. There are just a couple main points to keep in mind when raising worms:

Bin setup
Bedding material
Moisture level
Feeding

I’ll cover each of these points and then look at the worm bin in action. Worm composting is pretty easy and I’m sure most readers here are familiar, but for new folks this should be great.

The Worm Bin Setup

The ideal worm bin is a flow-through system that allows you to harvest pure worm castings without disrupting or removing the worms. If you want to purchase the ultimate worm bin, that is also very affordable, you can buy a continuous flow worm bin system – they are the best worm bin design I’ve seen. If you want to make your own system, you can make one cheaply and easily. While a less ideal system, this will work great for the beginning worm farmer.

I’ll just describe a stacking system since it’s so easy to make. Here’s how you would set it up:

Get bins that stack – ideally they would nest a bit. This is so you can get direct soil-bin contact so worms can move up. Those big plastic tote bins are perfect.
Start with the bottom bin. This has no holes in the bottom and is just there to catch the fluid that leaks out as food decomposes and you water the system.
Stack the next bin inside the first one, so it’s ‘nested’ in the first one. This second bin has many holes cut in the bottom to allow water to drain. This is your worm composting chamber. In this bin you will put the worms, their bedding and food.
As the second bin starts getting full, you will stack the third bin on top of it. Right on the top of the bedding. This bin has holes in the bottom as well. The fresh bedding and fresh food will lure the worms up into this bin.
Once all the worms are attracted to the top bin, you can remove the second, middle bin.
Now you have a bin full of awesome organic compost – worm castings!

That’s a basic worm bin system that is cheap and effective. It takes minutes to make and allows you to harvest castings without fussing about with the worms.

Now let’s look at the second main factor – the bedding.

Worm compost bedding

Worms are pretty tolerant creatures. I mean, they live in the dirt. Clearly they don’t require 5-star “digs”. But there are some things you can do with bedding to help keep your worms happy and healthy. Stick to these guidelines for bedding success.

Use a TON. You can’t have too much bedding, but you can have too little. I recommend at least 6 inches deep worth of bedding in your worm bin.
Try to use bulky bedding that doesn’t compact very easily. This will help keep the system light and aerated. Worms are aerobes they need oxygen. So keeping aerobic conditions is important. That’s why we don’t use soil – too dense and compact, it can get anaerobic easily and that’s bad for your worms.
Don’t use anything that could be toxic. This is obviously a no-brainer, but just be wary of chemicals, salts from fertilizers, stuff like that. You want nice clean bedding for your worms.
Any high carbon bedding will be great as it doesn’t break down too fast, doesn’t compact too badly, holds and drains water well, and breathes well.

Some examples of great bedding would be:

Shredded newspaper, cardboard, egg cartons
Shredded brown paper
Straw: all kinds – in the Philippines we use rice straw, in the states straw hay (ideally composted a bit already)
Coco peat/coco coir – make sure it is low sodium
Peat moss
Very aged manure – vegetarian only (horse, cow, sheep, etc)
Leaves – shredded so they don’t stick together and clump (ideally composted already)

So now you have your bin setup and you have added a ton of really good bedding. The next step is moisture level.

Worm Bin Moisture level

Worms breathe through their skin, and require a moist environment to exchange oxygen across their membrane surface. However you don’t want to drown the system and produce anaerobic conditions. Think of it like a compost pile or garden soil – nice and moist without being dripping wet.

The moist environment is not only for the worms. You are cultivating their food – microbes. This is where the compost pile analogy really makes sense. You will be adding food to the system, burying it under the substrate where it will start to decompose. You want a nice healthy aerobic microbial population to work on it just like what happens in a compost pile. If the environment is too wet, the food you added will sit in anaerobic conditions and just like when a compost pile ‘goes bad’ from being too wet, your system will go bad and stink and not be productive.

So for worm composting moisture level is like the goldilocks phenomenon – not too much and not too little. Keep the system moist by misting it every day during dry conditions, but don’t dump water on the system to make it wet. Some things you can do to keep the moisture level correct:

Ensure your worm bin has plenty of drain holes in the bottom to drain excess fluid
Don’t overload the system with food scraps
Mist only, don’t dump water on system
Mist regularly to keep system moist
Keep in mind the type of food you are adding – wet or dry – and add water accordingly

Feeding

Feeding is the most frequently questioned of the worm composting factors. How much to feed worms? How often to feed worms? WHAT to feed worms? These are all great questions when you are getting started, and fortunately the answers are pretty straightforward. One thing to note – experience helps here. As you become more experienced, you will become confident in your feeding practices. So dive in, feed those worms and learn from your mistakes. I’ll give you some tips now to get you started.

First, what to feed your worms. This is an easy one since we can just make a list:

Anything plant matter – veggies, fruits, leaves, berries, even stems and roots(in moderation)
Coffee grounds
Egg shells (crushed up ideally)
Bread/pasta
Manure/feces (vegetarian) – aged/composted ideally
Meat scraps*
Dairy*
Fats/oils*
Manure/feces (meat eater)*

*in moderation: these items are generally seen as BAD and never to be used in worm composting. But I don’t like something that only does 90% of the job. I want to be able to add everything to the bin for composting. So I included those items with a big warning: add these items sparingly!! Not more than 1/10th the total food added at any given time, even less for the grease, oils, and meat-eater feces.

What to feed is the easy part – almost anything. How to feed is where it gets a little more complicated. Just to give a little background, worms are attracted to the food source as it becomes infested with microbes and starts decomposing. The earthworms feed on the decomposing food source and the microbes living in it. So keep that in mind for feeding – you want a nice healthy population of microbes more than anything. Just like other forms of composting!

How often to feed compost worms? Add food every few days. How much to feed your compost worms? To start with just a little food, like less than 1/4 the weight of worms you are keeping. So the amount of food depends on the number of compost worms you have – a pound of worms may eat around 1/2 lb food per day or up to 2 lbs per day depending on species and environmental conditions.

However, I don’t like thinking in strict numbers since feed rate is such a subjective thing. Things like temperature, moisture, humidity etc can all affect the feed rate of your worms. I prefer to just watch the bin. I call it the “watch the bump” technique. When you add food to the bedding you typically dig down a few inches, put the food in and then cover the food. This creates a little mound in the bedding where there was none before. As the food decomposes and the worms eat it, the bump goes down. When I see the bump fall down, it’s time for the next food. This way you can kinda gauge how much they eat and learn the best amount to feed your worms depending on conditions.

Watch out for bad smells coming from your bin. If you smell something rotten, chances are you fed too much or got it too wet where you added the food. It’s gone anaerobic and the wrong microbes are at work. No need to panic, just back off the food and water until the system recovers. It will naturally recover without you intervening as long as you didn’t add something really toxic.

There are some things to keep in mind when feeding:

Moisture: things give off water as they break down. Especially veggies and fruits. So keep in mind when feeding that you are affecting the moisture level in the system. Avoid too much wet food at a time, so you don’t get anaerobic conditions.
It’s easy to feed too much but hard to feed too little: so don’t feed much! Especially at the start. Feed a little food to start with, and slowly work up from there as you get to know your worms’ feed capabilities.
Everything in moderation: don’t feed too much of any one thing, ideally. Mix it up and feed your worms a variety of items.
Food types: What you feed needs to break down a bit before the worms can eat it. But everything breaks down at a different rate. Be aware of what you are adding, for example things like broccoli stalks, raw carrots and things like that will take much longer to be available to the worms than something like oatmeal or fresh leaves. If you add too much wet mushy stuff you will cause anaerobic conditions but if you add only stalks and woody stuff it will take a long time to be available to the worms. Mix your feed types to achieve a balance.

The Worm Composting System in Action

Here is the step-by-step setup and operation of the worm bin. It draws from the concepts above, showing them in action.

To start your worm farm, start with the bottom bin that will catch the drippings. It is solid and has no holes, because you want to keep the liquid that drops there and feed to your compost pile/garden.
Place the next bin, this one with holes in the bottom, inside the first bin. Prop it up a bit with blocks if it nests all the way down – you need space to catch the drippings (worm leachate). You can put a piece of newspaper over the holes to cover them initially so your bedding doesn’t fall through. The paper will rot away and the liquid will drip through eventually.
Fill the second bin with your bedding. Add a good amount, 3-6 inches at least.
Now add your worms to the bedding.
Wait for a week or two before first feeding. This is just to let them get acclimated to their new habitat.
- Note: You may have many worms trying to escape in the first month or two – that is fine, they are just getting used to their new home. Leave a light on above the bin if you want to discourage that.
Now add a bit of food to the bin. Dig a little hole a few inches deep in the bedding, add your food and then cover it and mist with water. This should cause a little bump in the bedding.
- Start with very little food initially – it is far easier to overload the system with food than to starve your worms. You can build up as you get comfortable with the setup.
Watch the bump you made over the next several days. When it has dropped back down, add more food to the bin, in a different location.
Mist your bin when you notice the surface get dry, but you don’t need to dump water in it. The idea is to keep it moist but not super wet.
When you notice the bottom bin getting full, you can use that worm leachate on your garden. Pour it straight into your compost pile, or dilute it to use in the garden, at least 1:1 but preferably more like 1:10 with water.

Worm Composting Summary

There you go. The worm composting system for getting rid of your table wastes. Now we have yet another cheap, simple, sustainable way to eliminate your kitchen scraps while producing amazing fertilizer for the garden. What a neat way to compost! You can do this anywhere, even in your house! If you are doing things correctly, there won’t be any unpleasant odors coming from the bin.

If you haven’t started worm composting before, I hope this article helps convince you of the ease and effectiveness of this natural farming technique.

Ready to get started? You can order worms online easily. Once again you can purchase from Red Worm Composting, a trusted supplier of composting worms. If you’re ready, buy compost worms from Bentley and get started worm composting today.