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Composting / Worm Farming

How to Make the Best DIY Worm Bin

Compost is debatably the most important ingredient needed to create healthy soil in your vegetable garden. One way to create this ‘black gold’ is through worm farming. In this article, I’ll show you how to create a DIY worm bin at home, how to harvest worm castings and the benefits of homemade worm bins. 

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What is Worm Farming/ Vermicomposting?

Vermicomposting is an ideal way of using food scraps rather than throwing them in the trash. A worm bin creates two by-products; 

  1. Worm castings (aka worm poo!) which is incredibly nutrient-rich compost for the soil
  2. Worm tea. The moisture that leaches out of the bottom of the worm farm is still full of nutrients and can be diluted and used as a fertilizer for the garden.

Red Wigglers are the preferred earthworm for worm composting as they reproduce quicker than other worms, can withstand an array of environmental conditions (65 F to 8 F), and thrive in various food waste. 

Worm tea is one of the benefits of a diy worm composter

Indoor Worm Bin

Some gardeners have tiny spaces and produce less kitchen waste. A small worm bin kept indoors is easy to maintain and perfect as you can place it anywhere – such as in a garage, laundry room, or under the kitchen sink. And with a homemade worm bin, you can customize it based on the available space. 

Outdoor Worm Bin

If space is not an issue for you, then an outdoor homemade worm bin is a good option. With a larger bin you’ll end up with more worm castings and the bin will decompose more food waste. 

The downside of an outdoor worm bin includes extra upkeep and care from temperature fluctuations. Direct sunlight, for instance, may dry up the worm decomposer and kill the worms. On the flip side, if too much rain gets in it could drown your worms. So choosing the right position is crucial.

What Are The Benefits of a DIY Worm Bin?

There are many benefits to creating a homemade worm bin, but here are my top 6:

  1. Reduces food waste: DIY worm bins reduce your household waste by decomposing kitchen scraps and creating nutritional fertilizer. Along with bokashi composting, in my opinion there’s no better way of recycling food waste than setting up a DIY worm farm.
  2. Produces worm castings: The worms decompose kitchen waste and produce worm castings (a nutrient-rich organic fertilizer) which can be mixed directly into the garden.
  3. Free compost: Once your farm is up and running, you essentially have free compost! There are no ongoing costs. Plus, as your worms start to reproduce you may even want to start a little side business selling worms. 
  4. Easy to maintain: Once you’ve set up your worm bin, you have two simple jobs; regularly feeding the worms and keeping an eye on the bin’s moisture. If there are any snags, it’s easy to fix with a few tweaks.
  5. Space efficient: A homemade worm farm can be customized based on the space you have available. Suitable both indoors and outdoors, anyone can start vermicomposting no matter their space.
  6. Produces Worm tea/worm farm leachate: Homemade worm bins create a worm tea solution from the excess fluid that drains from the worm bin. Worm tea is high in nutrients and can be diluted and used as an organic fertilizer for the garden. 
how to make a diy worm bin in 5 simple steps

5 Simple Steps to Make a DIY Worm Bin

Now that you know the benefits of a DIY worm farm and have an idea of the space and location of where you’ll put one, you’re ready for the next step. Making a worm bin is something you can easily do, and with the right materials, you’ll be able to harvest worm castings in no time!

1) Gather Your Tools and Materials

Choosing a Container for Your DIY Worm Bin

To set up a DIY worm composter, you must first select a container to use for your main worm bin. Red wigglers prefer living on the top of a warm bed, so the bin should be expansive and shallow. A plastic bin or container that is stackable and not too deep is perfect. You can start with a container as small as 5 gallons or as big as 27. It all depends on your space requirements.

How to select a container for your worm bin:

  • Stackable: You will need two bins stacked one on to top of the other
  • Look for a container that is wide and shallow like this storage box
  • Choose a dark-colored container with a solid-colored lid, as worms dislike direct UV light.

2) Assemble the Bottom Bin 

Place 2 or 3 bricks or pieces of wood in the base of one bin. This is the bin that will collect the leachate.

3) Drill Drainage & Ventilation Holes in the Top Bin 

In the second bin and the lid of your DIY worm composter, you’ll need to drill holes to create airflow.

Proper airflow/ventilation and drainage are crucial factors for a homemade worm bin. Poor ventilation attracts fruit flies and creates anaerobic conditions, which are toxic to the worms and create a smelly worm bin. 

Take your power drill and every two inches along the base of the bin, drill 1/8” holes. This is big enough for the leachate to pass through to the catchment bin below but not big enough for the worms to fall through.

Next, a few inches from the top of the bin, drill 1/4″ holes every one to two inches around the outside. Do the same every few inches on the lid. This will provide good ventilation and airflow. 

You’re welcome to drill larger holes here but be aware that it could allow pests or vermin to enter the bin. Larger holes will maximise airflow but this will also cause the bedding to dry out quicker so be aware that it may require additional watering. 

drill ventilation holes long the top when making a worm bin

4) Assemble Your Homemade Worm Farm

Finally, create a tray system by simply stacking the holey bin on top of the base container filled with bricks.  

The top bin is for depositing food waste and other worm-related waste. The bottom bin acts as a catchment to keep the moisture levels stable and collect worm tea.

For an outdoor worm bin, locate a sheltered area away from direct light.

5) Filling Your DIY Worm Bin

You’re now ready to assemble your DIY worm farm. 

  1. Create a worm bed approximately 4 to 6 inches thick using a mixture of organic material such as shredded newspaper, coconut coir, dry leaves, lawn clippings and soil. This will provide the necessary microbes to kick start your worm farm.
  2. Next, add chopped up kitchen scraps to the worm bed. Vegetable peels, crushed eggshells and fruit are all good options.
  3. Then lightly sprinkle /spray water to create moisture, and cover with a lid. 
  4. Add worms! Read more here about the various types of worms to choose from and which are the best worms for composting.
  5. For feeding, it’s best to start slowly and monitor how much the worms eat. Start by feeding them every one to two days with 1 cup of food. As a rule of thumb, worms eat half their body weight a day, so if you start with 1lb of worms, they’ll need half a pound of food per day.
  6. Check the moisture levels regularly by squeezing a portion of the bedding; only droplets should trickle out.

TIP: The contents of your worm farm should resemble a damp sponge. If it’s too dry, spray a light layer of water over it. 

How To Harvest Worm Castings

Harvesting worm casting shouldn’t worry you. After all, a gardener must be prepared to get their hands dirty every now and then!

Once you notice some rich, black, soil-like material in your worm farm, it’s time to harvest. You can do this in several ways.

1) Hand Harvesting

This is the simplest method and if you have kids around, trust me, they’ll enjoy it.

Grab a handful of castings and sieve through them for worms that you place back in the container. If it’s a complete harvest, you sort out the entire container, but bear in mind this can be quite time-consuming.

hand harvesting is a popular method to harvest worm castings

2) Light Harvesting

As mentioned earlier, worms dislike light, so you can utilise sunlight or artificial light to harvest worm castings. You do this by:

  1. Putting vermicompost in sunlight or under direct light. 
  2. Leave for a few minutes while the worms move their way down through the soil surface away from the light.
  3. Scrape the worm castings from the sides and top surface of your DIY worm farm container that no longer contain worms.

3) Screen Compost

This method uses a screen to remove the worms, wood, and undecomposed debris from the completed compost by filtering the worm bedding through a screen. The final castings are fluffy and debris-free. You can opt to make or purchase a screen like this one.

4) Bait Method

Here, you bait the worms by failing to feed them for a few days to a week and then placing fresh food on the top of the worm bin. The worms quickly move to moist food surfaces and you can move them to the side while you dig out the castings from the base.

the light method is one way to harvest worm casting

Where To Buy Compost Worms

Unfortunately, you can’t use just ordinary garden worms in your DIY worm composter. A worm farm demands special worms that you’ll need to buy. The most common worm farm worms are red wiggler worms. You can buy worms on Amazon or look for a local worm breeder.

A pound will cost around $40-50, and depending on the size of your worm bin, you may need half or a full pound. The good thing with red wigglers is their reproduction rate, and in no time, they’ll multiply.  

Final Words on Making a DIY Worm Farm

I trust by now you’ve learnt how beneficial it is making a worm bin at home. By following my 5 simple steps you can make a cheap DIY worm bin that will provide rich worm casting compost for your garden for many years to come! Alternatively, if you decide to go for a done for you worm bin, check out my top 8 worm bin recommendations.

FAQs

How many worms do you need to start a worm bin? 

This depends entirely on the size of your worm bin. For an average worm farm you’ll likely need 1lb of worms. For larger worm bins, 2lbs may be necessary.

How deep does a worm bin need to be? 

A suitable worm bin should be wide and shallow. Aim for a container between 8-16 inches.

What not to put in a worm bin? 

Citrus fruits, meat, dairy products, oils, and bones are some food waste that should not be fed to compost worms. Vegetable scraps work magic and should be cut into small pieces for quick decomposition.

How can I separate the worm castings from the soil in my worm bin? 

There are several ways to harvest worm castings. Some of the most popular methods include the bait method, use of light and hand harvesting.

Where is the best place to find red wigglers for your worm compost bins?

The best place to find the right quantity of red wigglers is to purchase them online. Uncle Jim’s is one of the most popular worm breeders in the USA. Alternatively, do a Google search for compost worms for sale near me.

Should I put my worm bin in the shade, or does it not matter? 

Yes, it matters, as compost worms hate exposure to light. So it is best to select a shady area. They must be well-covered to block light and prevent the bedding from drying out too quickly.

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About the Author

Elle Reed is a passionate gardener and advocate for teaching beginner gardeners how to grow their own food. Elle’s mission is to inspire and empower people to get back to basics, grow their own produce, and embrace a sustainable lifestyle. “Whether it’s a few herb pots in an apartment, a potager or a full garden plot, we can all ‘start somewhere’ to grow our own food, and in doing so, provide healthier food for ourselves and those we love”.