Gardeners have known about the benefits of compost for a long time. And with more and more people becoming environmentally conscious, many of us choose to try homemade compost. It’s a fantastic way to use up food scraps and make that “black gold” that our plants adore.
With so many composting methods out there, it can be hard to choose which one to try. That’s why we’re here to help! In this post, we’ll talk all about worm composting, how it works, and how you can get started.
So, if you:
Have a garden or indoor plants and want to make your own fertiliser;
Are looking for a way to use up your kitchen scraps;
Are interested in composting with worms, but don’t know where to start,
Then read on! Our comprehensive worm composting guide has everything you need to get started!
Before we get to the nitty-gritty, let’s cover the basics.
What is worm composting?
Worm composting (or vermicomposting) is a method of making compost by feeding your food scraps to worms and collecting their castings. It’s a great way to reduce food waste at home and make sure your plants are thriving at the same time.
The resulting material – the worm castings – are one of the best organic fertilisers out there. That’s why this composting method is so popular. The worms’ diet often consists of food scraps and other materials with tonnes of nutrients, making for highly nutritious compost that your plants will love.
Vermicomposting is a great method if you want to start composting in a flat, too. Most worm bins are compact, and they won’t cause a mess indoors, as they’re designed to make harvesting the compost more straightforward.
How does worm composting work?
So, how does this composting method work exactly?
The process is pretty simple:
Once you add your food waste and other organic materials to the worm bin, they slowly decompose and soften.
The worms munch on the scraps and convert them into a fantastic fertiliser that then leaves their body.
The resulting materials are worm castings (a solid compost with a coffee ground-like consistency) and worm tea (a liquid fertiliser).
Both the castings and the liquid can be used to give your plants a nutrient boost. We’ll get into the proper way to use them later on in this guide.
Composting worm types
If you want to make your own worm compost, you can’t just grab a handful of worms from your garden and let them go to town on your food scraps. Earthworms like burrowing deep into soil and won’t do as well if kept in a small bin, so they’re not a great choice for worm composting.
There are two main types of compost worms – red wigglers (Eisenia fetida) and redworms (Lumbricus rubellus), with red wigglers being the more popular choice. These species like living close to the surface, and they thrive in organic materials. And, due to their choice of food and habitat, the castings they produce are far richer in nutrients than those of plain earthworms.
To make sure you get enough worms, you can note how much food waste you need to process. For a starter vermicomposter, 1000 worms or so (roughly 500g) should be enough. They can eat about half of their body weight per day, so you can easily determine how many you’ll need.
Now it’s time for the main event – teaching you all that you need to know about making worm compost at home!
What conditions composting worms need
First, let’s go over what conditions you need to provide your compost worms with so that they can thrive and do their job.
Temperature Worms can generally survive in both hot and cold weather, but they’re usually not too happy about it. They prefer temperatures between 18ºC and 25ºC, which is why they tend to do best indoors.
Moisture To keep your worms happy and ready to work, you need to provide them with moist bedding. Keep in mind that they don’t do very well in dry or waterlogged soil. The substrate should be as damp as a wrung-out sponge.
pH levels Compost worms don’t like highly acidic conditions. For best results, try to keep the pH levels between 6.5 and 7.
Oxygen Like any living thing, worms need oxygen to survive. That’s why any worm bin should be well-ventilated and why waterlogged soil is often a problem.
Light Since worms have photosensitive skin, the vermicomposter should be dark and sheltered.
Improvements A worm with teeth sounds like the stuff of nightmares, doesn’t it? But that lack of teeth makes eating a bit more difficult for these little creatures. To help your worms grind the food, you might want to introduce a gritty substance into the worm bin. You can do this with a bit of soil, sand, or rock dust. Just make sure it’s sterilised.
If you provide your composting worms with the conditions they like, you’ll be able to keep a happy and productive worm farm for a long time.
Setting up a worm composting bin
Next up, let’s cover what you need to know about starting a worm compost bin properly.
Purchasing a vermicomposter
The easiest way to go is to buy a ready-made vermicomposter. There’s a wide range available online or in stores, so you can choose the one that suits your needs best.
Most worm bins you can purchase are multi-tiered, and for good reason. The several “storeys” make adding food scraps and harvesting the compost easy and, best of all, completely mess-free!
Different types have a different number of tiers, but they all work in the same way.
The top bins hold the fresh scraps and bedding. This is where the worms live and feed.
The lower tier contains the processed compost (worm castings), and you won’t typically find many worms there, so all you need to do to harvest it is to take the tops bins off and scoop out the compost.
The bottom tray collects the liquid (worm leachate). Typically, it has a faucet that you can use to drain the liquid easily.
Worm composters also have legs to prop the bins up. Some types may not have a compartment with a faucet; these usually just have drainage holes at the bottom. In this case, placing a tray underneath is recommended.
If you choose to buy a vermicomposter, you won’t have to worry about proper ventilation and drainage – it’s all set up and ready to go!
How to make your own worm compost bin
If you’d rather go the DIY route, that’s fine – you can easily make a worm compost bin by yourself!
Since this is worm composting made easy, we’ll talk about how to make a multi-tiered vermicomposter. We want a simple composting process, after all.
All you need to make your own worm bin is three plastic buckets or containers. They’ll need to fit inside each other with enough space left for the composted material. The size of the containers will depend on the number of worms and the amount of food waste you want to compost.
Also, make sure that the bins you get are opaque, since worms prefer to stay in the dark.
Got your containers? Good. Here’s what you need to do next:
Drill holes in the bottom. With a 5mm drill bit, drill holes in the bottom of two of the containers. Space the holes about 25 mm apart. Do not drill holes in the third bin – this one will go on the bottom and collect the worm tea.
Drill ventilation holes. With a 3mm drill bit, drill a line of holes near the top of the same two containers. These will make sure that the contents are well-ventilated and regulate the moisture.
Drill holes in the lid. Once more, take the 3mm bit and drill a bunch of holes in the lid to provide some extra aeration.
Stack the containers. Place the bin without holes on the bottom. Stack the other two containers on top, and cover the last one with the lid.
And there you go! You’ve made your own easy-harvest vermicomposter.
Compost worm bedding
Once you’ve got your worm composting bin, be it homemade or purchased, you can start filling it up. This can be the tricky part for some – figuring out what sort of bedding to use.
Don’t worry – it’s not that complicated. You’ll just need an organic substrate. Some worm composting bedding materials you can use are:
Shredded paper (not bleached) or newspaper (not coloured)
Shredded brown cardboard
Aged garden compost
Aged horse or cow manure
You may want to use a mixture of beddings to give the worms more variety.
You can also use leaves or straw as worm bin bedding if you’ll be keeping it outside. However, for indoor worm composting, it’s best to leave them out since they can bring insects and other undesirable creatures inside your home.
Where to place the worm bin
Now, what the best spot for your vermicomposter is will depend on lots of factors. How much space you have, what the weather is like, etc. Still, there really are only two options here: outdoors or indoors.
Composting with worms outside – in your garden, for instance – is convenient because you can use up a lot more space. You can get a bigger vermicomposter, a few small ones, or even several large ones! Still, if you don’t produce enough food waste, there’s no point since there won’t be enough scraps for all those worms.
Outdoor worm composting can also eliminate your fears about smelly compost. If you do it right, odours shouldn’t be a problem. But if you happen to leave the castings or worm leachate in the tray for just a little bit longer, it won’t matter since your bins are outside.
However, outdoor vermicomposting might not be a great choice if you live in a cooler climate (such as the UK). As we said earlier, compost worms like a moderately warm temperature, so you’ll end up having to bring them inside during cold spells anyway.
Composting with worms indoors may be your only option if you live in a flat or if you don’t want to move the bins back and forth all the time. Your worms will be happy and toasty all the time if you keep them inside. And again – proper vermicomposting doesn’t emit any nasty smells, so you don’t need to worry if you do it right.
The downside to indoor worm composting is that you can process a limited amount of waste. The little creatures can only eat so much in a day, after all. If you overfeed compost worms, you’ll probably end up dealing with a bunch of other problems.
What to put in a worm compost bin
Now that you’ve got your vermicomposter set and ready to go, it’s important to know what you can feed your worms.
Technically, compost worms can eat almost any food waste. However, there are some things you should avoid if you want a successful, odour-free worm farm.
Most of your fruit or veggie scraps are a great addition to your worm bin. But there is some produce that worms aren’t fans of. Onions and citrus fruits are among them, so you might want to find another purpose for these scraps. Limonene – a compound found in citrus fruits – is toxic to worms. You can add some citrus peels to your vermicomposter, but they shouldn’t make up more than 1/5 of the food waste you feed the worms.
You should also steer clear of all animal products – bones, meat, dairy, etc. Compost worms can process them, but it takes much longer, and you’ll likely have to deal with odours, pests, and bacteria. Don’t feed your worms any carnivore animal faeces, either.
Keep in mind that composting worms need a healthy balance of carbon and nitrogen. Adding something other than just your kitchen scraps can help balance out the nitrogen content.
So, here are some things you can safely use as compost worm food:
Fruit and veggie scraps (except for onions, garlic, and citrus)
Herbivore animal manure
Aged grass clippings
Shredded newspaper (black ink)
Shredded brown cardboard
Cleaned and crushed eggshells
When adding the scraps to your worm composting bin, it’s best to chop them up into small pieces. Large waste slows down the process as worms take longer to eat it.
If you notice lots of food leftovers when harvesting the compost, pay attention to what sort of food it is. The worms may not like it, so you can avoid adding it in next time.
When you’re just getting started with worm farm composting, add fewer food scraps at first. The worms will be a bit slow in the beginning since they need time to get comfortable. When they start eating faster, slowly add more until you reach the right amount – half of the worms’ body weight.
How to harvest worm compost
Once your farm is working at full capacity, you’ll need to start harvesting the worm compost. But how do you know when the compost is ready?
Well, you have to check. If you’ve chosen a multi-tiered worm bin, then it’s easy – the worms will have moved to the upper level to get fresh food, leaving the finished vermicompost in the compartment below.
It’s not difficult to tell when you should harvest the worm compost. When it’s ready, it will be a dark brown colour with a coffee ground-like consistency. Finished compost doesn’t smell, so if you open up the bin and get hit by an unpleasant odour, then you’ve probably let it sit for too long.
Collecting compost from a multi-tiered bin is simple:
Check the worms. Look in the bins. If the worms have moved to the upper tier, then the compost underneath is ready.
Take off the top. Take the bin with the fresh food and worms off to get access to the container below.
Harvest the compost. Collect the finished worm compost with a trowel or by simply dumping it out. A worm or two might still be lurking there – just take them out and put them back with the rest.
Refill the bin. Take the bin where the worms are and put it back. Place the newly emptied container on top of it, fill it with bedding, and add new food scraps.
And that’s it. Once the worms have finished composting the old scraps, they’ll move to the upper level to munch on the new ones, and the process repeats.
How to harvest worm compost from a single bin
If you’re using a single worm bin, you can dump out the contents, worms and all, onto a tarp. The worms will burrow down to escape the light, leaving a heap of castings above. Carefully scrape off the compost until only the worms remain, refill the bin with fresh bedding and food waste, put the worms back, and you’re done.
This method is more suitable for outdoor use, though, as it will most likely cause quite a mess indoors. That’s why multi-tiered worm bins are highly recommended if you opt for indoor worm composting.
How to use worm compost and tea
Now that you have your black gold, you can give your plants a good nutrient boost.
You can mix the worm compost directly into your potting soil or use it as a top dressing. Both your indoor and outdoor plants will be thankful for it. If you like growing your own plants from seed, worm compost makes a fantastic seed starter mix.
If you want to store your compost for later use, you’ll need to dry it out to prevent moulding.
When it comes to worm tea, on the other hand, it can get a bit tricky.
Worm leachate is the liquid that collects at the bottom of the worm composting bin.
Worm tea is the liquid that results from steeping worm castings in water.
Both substances can be used as liquid fertiliser, but they need to be prepared in different ways.
Worm leachate is highly concentrated and can do more harm than good if applied directly to your plants. To make it usable, you will need to dilute it – combining 1 part leachate with 10 parts water should do the trick.
Leachate can potentially contain harmful pathogens, so using it on edible plants is not recommended.
Worm compost tea
Worm tea is a fantastic liquid fertiliser and is relatively easy to make. It just takes a little longer.
Prepare a “teabag”. Fill a porous, natural fibre bag with worm castings. Tie the bag to seal it.
Steep the castings. Fill a bucket with distilled or rainwater and soak the teabag in it. For extra aeration, you can use a fish tank bubbler – this will encourage beneficial microbes.
Soak the teabag overnight. Let the castings sit in the water overnight. The worm tea is ready when the liquid turns a light brown colour.
Dilute the worm tea. Take the bubbler and castings out of the bucket. Dilute the worm tea with some more water.
And there you go – your own worm tea! You can use it to water your plants and give them a nutrient boost. It’s best to use a fresh batch every time, but you can store any leftover liquid in an open container for a little while.
Worm farm vs compost bin – which is better?
This is a tricky question, as which composting method is better depends on your circumstances.
A standard compost bin is usually best for people with a garden and lots of food scraps to deal with. You can process a lot more waste this way, but it can take a long time. That’s mostly because of the volume and because there’s nothing to speed up the process. You’re just relying on nature to do its thing.
Some people also consider compost bins to be more high maintenance than worm farms. That’s because, unless you use a tumbler, you’ll need to turn the compost manually.
Worm composting bins are the preferred choice if you want to compost indoors. It’s a lot quicker than regular composting, it doesn’t smell when done right, and takes up very little space. This makes it perfect for people who live in an apartment or don’t have much garden space.
With vermicomposting, you’re pretty limited in the amount of food waste you can process. Plus, you end up with a lot less material in the end. But if you don’t have a large garden to take care of and just want to feed your houseplants, this shouldn’t be an issue.
Worm composting problems to look out for
Even though vermicomposting rarely causes any trouble when done right, there are still some worm composting problems you should watch out for.
Pests Fruit flies or mice can sometimes attack your worm bins. To avoid this, you just need to make sure they can’t get in and that nothing attracts them. To prevent fruit flies, make sure you bury the food scraps in the bedding instead of letting them sit on top. For mice and rats, you can secure the worm bin lid to stop them from getting in. Regularly checking for rotting food and removing it is also crucial if you want to prevent pest problems.
Odours If your worm bin smells unpleasant, there’s probably rotting food inside. You just need to remove any food that starts to rot regularly to prevent this. Cutting the food up into small bits will help the worms process it before it starts to rot and mould. Foul odours can also mean the bedding is too wet, so make sure to monitor the moisture in the bin and adjust it as needed.
Escaping worms If you’ve provided the worms with good conditions, it’s unlikely that they will try to leave. However, if you notice a lot of them making their way out, then there’s probably an issue with the environment. You may need to adjust the moisture, temperature or ventilation, or there could be a pest infestation.
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