If you’re brand new to worm farming there are a few things to consider when learning how to compost with worms. Adding worms to your garden’s ecosystem can be extremely beneficial. Worm farming (also known as vermiculture) is the process of using earthworms to turn organic waste (in most cases food waste) into worm castings. Worm castings are full of micronutrients that help your plants grow. While most people seem to prefer raising their worms in containers feeding your earthworms in the garden is also possible.
Worms help break down organic material in your soil and make the nutrients available to your plants. Its poop, which most people refer to as worm castings are full of beneficial microbes which are needed to maintain the soil food web and healthy soil for your plants. In this post, I will attempt to go through everything you need to get started raising earthworms and producing the most sought after compost in your backyard.
Table of Contents
The best worms for composting
There are three broad categories of earthworms. All species of earthworms break down organic matter into compost However, some are better at it than others. The worms that live in the top eight inches of your soil are the best at breaking down organic matter.
When choosing a type of composting worm I always recommend choosing one that is native to your environment. There are many examples of humans introducing species into an environment only to have them displace other animals native to the area. Most American worm farms use red wrigglers (Eisenia Fetida), where I am and throughout most of the Caribbean African Night Crawlers (Eudrilus eugeniae ) are both amazing composters and native to or soils.
Where to buy earthworms
If you are in the US you can buy earthworms online through amazon. There are also quite a few active online communities where you should be able to find a supplier in your area. A quick search on Google or social media should bring up someone in your area. If you are in Trinidad and Tobago, we post earthworms for sale when available on our online store.
But! If you have time and you want to find composting worms instead of purchasing you can. Earthworms exist in your natural environment. Composting worms love animal manures. If you would rather forage rather than purchase the well-aged manures from most farms will have some composting worms living in them. As long as the animal waste is in contact with the earth, you are likely to find them crawling around in their poop. If you are looking for ANCs they tend to be a deep purple and the adult worms would be around 8 inches long. 50 to 100 earthworms should be enough to get your bin off to a good start.
Choosing a worm bin
When choosing a set-up for your worms one of the first things to consider is the size. How large do you want your bin to be and, what quantity of castings do you want to produce? The larger the bin, the easier it is to manage. This is because if there is something wrong in one area of the bin the earthworms can move to another area if the bin is large enough.
Generally, it is more important for your bin to be longer than it is to be deep. Composting worms generally live in the first 8 to 12 inches of soil. Earthworms are also very sensitive to light. Always use a dark container for your worms. While managing your bin you will need holes or a pap at the bottom of the worm bin for any excess liquid to drain. Lastly, there should be some space at the top to allow airflow. Once all these conditions are satisfied you should be able to raise your earthworms successfully in a container/vessel that meets those criteria.
Of course you can make your own worm bin. However, if you would prefer to purchase one there are a few options below.
Worm Factory 360 | Urban Worm Bag Worm Composting Bin | Hungry Bin |
|---|---|---|
Bedding for your earthworms
Your earthworms are no longer in the soil and need a place to call home. The bedding in your worm bin is essentially that, the material your worms will be living in.
Worm bedding should:
- Be High in carbon
- Absorb and retain water easily
- Allow airflow
There are many worm bedding options that can be used things like cardboard, newspaper, dried leaves, straw or coconut cocoire are all good bedding options.
Grass would not be my first option because it can compress easily reducing airflow and if it isn’t well broken down it can raise the temperature of your bin beyond what is tolerable for your worms. Also, you should be sure the grass you put into the bin is free of any pesticides that may harm your worms.
Glossy paper and plastics should also be avoided.
While you can overfeed your worms you cannot give them too much bedding. Your worms will consume the bedding over time. When starting your bin you should have at least six inches of bedding. Every time you add more food, add more bedding.
Ideally, your bedding should be free or as close to free as possible.
Choosing a Location for your worm bin
Most composting worms will do well between temperatures of 60 – 85F or 15 to 25 C. The more consistent the environment the better. Keep your bin out of direct sunlight and rain as much as possible. Under a shady tree, a shed or a garage is usually an ideal location for your worm bin.
For home composting your worm bin should be small enough to move around. This allows you to be flexible as things inevitably get rearranged in and around your home. You don’t have to keep your worms outside, you can keep them indoors, you can even keep them in an apartment if you so desired.
Because we are below the hurricane belt (currently, we are in Trinidad and Tobago) hurricane prep hasn’t been an issue so far. But for our neighbouring Caribbean brothers and sisters, this is something that should be planned for in advance if possible. If you live in a temperate climate you may need to move the worms inside for the winter. In most cases, a heated garage, barn or basement would be sufficient.
How to take care of your earthworms
Feeding your worms
One of the most common mistakes when raising worms in a contained system is overfeeding. Add about as much waste as you have worms. Only feed the bin when most or all of the food is gone. Add more bedding with the waste
If you are adding garden waste ensure it hasn’t been treated with any weed killer or other sprays. If the material is fresh/green material such as leaves, grass or anything with a high moisture content it should be treated as food (not bedding) and only be added in small quantities at a time.
Nothing in the onion family, no peppers or anything with a pungent odour. Especially in small bins. Avoid anything that has a lot of tannings or is used as a meat tenderizer these foods could be very harmful especially if the worm population is small.
Don’t add too much acidic foods such as Oranges or pineapples as these can make your worm bin acidic. Rotting food will likely become acidic and harm your worms. Do not overfeed your worms. Underfeeding is always better than overfeeding.
Don’t add bread, pasta, fats or oils.
Waste from vegetarian animals can be added if it is well-rotted and past the thermophilic decomposition stage (so it won’t heat up the bin). Not cat waste, dog waste or waste from any carnivorous animals should be added to your bin.
Powdered eggshells can be added to help manage the pH of the bin. Some worm farmers say it adds grit and helps the worms’ digestion. Still, others claim it makes the worms multiply quickly. I am not sure if either of these claims are true. But, at least we can all agree that powdered eggshells are a useful addition to your worm composting system.
If you are using the bokashi composting system you can use your bokashi compost to feed your worms
Moisture
The bedding of your worm bin should be as wet as a well-wrung sponge. It needs to be moist; not too wet but not too dry. Worms breathe through their skin. If it is too moist (i.e. the bin is flooded the worms won’t be able to get enough oxygen) and if it’s too dry they will become dehydrated and die off.
Drainage
Your worm bin needs to be well-drained to maintain an aerobic environment. Ensure some liquid is coming out of the bottom of the bin periodically. If you aren’t seeing any liquid leaving the bottom of the bin move the material and ensure the water isn’t pooling at the bottom. This can happen when the holes become clogged.
This issue is more likely to happen if you’ve gone the DIY worm composting route. You can solve this problem by either adding more holes, adding bigger holes, or both.
Temperature
The biggest difference between traditional aerobic composting and worm composting has to be temperature. In our traditional compost set-up, we want the temperature in our aerobic composting piles to increase. In our worm composting system we don’t. At temperatures above 90F, the worm population begins to die off due to the heat and at temperatures below 55F the worms will stop reproducing and reduce activity.
The optimum temperature for different worm species will vary slightly but this general range given in the table below is a reasonable guide.
| Common Name | Scientific Name | Optimum Temp. Range (F) | Min Temp (F) | Max Temp(F) |
|---|---|---|---|---|
| African nightcrawler | Eudrilus Eugeniae | 75 to 85 | 60 | 90 |
| European nightcrawler | Eisenia Hortensis | 68 t0 75 | 85 | |
| Read wrigglers | Eisenia Fetida | 55 to 70 | 40 | 85 |
| Tiger worms | Eisenia foetida or Eisenia fetida | 70 to 80 | 33 | 90 |
| Asian blue worms | Perionyx Excavatus | 7o to 80 | 45 | 90 |
Ventilation
Worms need oxygen. Ensure there is adequate fresh air flowing through the bin. You can do this by having ventilation holes in the cover or by leaving the cover slightly ajar so adequate air can circulate.
Harvesting your castings
In most systems, if you’ve started with a pound of earthworms you should be able to harvest them in about 2 to 3 months. There are various methods for harvesting castings. The one you choose will depend largely on the type of system you have and your personal preference.
Worm bin with trays
If you have a tiered bin system most of the worms will migrate out of the castings in the lower tray and move up into the food and fresh bedding. This method can be used in the worm tower or if you made a DIY system with multiple trays/containers that fit one inside the other
Harvesting part of your bin
Worms, like most animals, don’t like living in their own poop. If you have a long enough bin you could just feed one side and encourage the worms to migrate. For this to work effectively the bin must be longer than 3 feet
Harvesting your entire bin
If you are using a single bin you could just harvest the entire bin. If you are harvesting the entire bin you will need to separate the castings into piles and harvest off the top. If you start seeing worms give them 15 to 20 min to retreat deeper in the pile and then harvest again. Once you’ve gotten to the bottom of the pile you can place the worms and any material that didn’t completely break down along with fresh bedding (at least 6 inches of fresh bedding) back into the worm bin.
Which option will you choose?
It’s up to you if you would like to harvest your castings all at once or if you would prefer to harvest as you go along. When you decide which option you are going to use please let us know in the comments.
Escaping worms
If you notice lots of worms at the surface or trying to crawl out of the bin something has gone wrong. Worm trying to escape is a clear sign that the worms are not happy with their current home and this must be corrected immediately. Some of the most common reasons why your worms are trying to escape are:
- The lower part of your bin is flooded and your worms are trying to save themselves from drowning.
- The bin may be too acidic this is primarily caused by overfeeding or
- the temperature may be too hot making it an uncomfortable place for them to live
Signs of a healthy bin
When managing your compost bin there are a few things that will let you know you’re on the right track
- Little or no smell. A healthy bin won’t smell at all or have a very earthy smell, similar to that of a natural forest. This is a good sign the pH of the bin is well maintained.
- Lots of worms I the top 4 inches of the bin. Composting worms generally stay close to the surface. If there is a pest problem or the pH near the surface is unbearable you may notice your worms burrowing into the deeper areas of the bin. Lots of worms at the surface is a really good sign your worm population is in a comfortable environment
- Leachate is the colour of a strong tea with very little smell
Why are worm castings so expensive?
Worm castings are extremely beneficial to your soil. I often hear people compare the cost of worm castings to the cost of cow manure. Which is a little crazy when you think of the size of a cow compared to the size of an earthworm.
It isn’t extremely labour intensive just to do castings at home, but as you scale it’s easy to see how the cost can go up. It also requires a lot of initial material to produce the final vermicompost to use in your garden. The initial composting process will decrease your waste by more than half. And when the worms shred the waste to produce their castings the volume will go down by more than half again. By my estimate, about 10 to 15% of the original material will result in castings.
The positive thing to remember though is that worm castings are extremely concentrated. You only need about a handful around your plants to start seeing its benefits. Adding more than 20% worm castings to your soil mix won’t produce any notable benefits.
Final thoughts
Vermicomposting is a great way to turn your food waste into black gold for your plants. It is largely inexpensive and relatively easy to set up and maintain. When starting your first worm bin try to be patient. With a brand new bin, it could take a couple of months before you have enough castings to harvest for your garden.
In the beginning, it is very easy to “over” care for your worms. Keep your bedding moist but not dripping wet. Don’t overfeed your worms. This is the most common mistake first-time worm owners make. Underfeeding with lots of extra bedding is always better than overfeeding. Worms do best when they are left alone, near neglect really.
Worm castings or vermicompost add a wide range of nutrients, and more importantly beneficial microbes to our soils. Worm castings aren’t lacking in versatility as they can be added as a top dressing, mixed into the soil or the castings can be used to make a compost tea. While worm castings are more expensive than many other soil amendments. Don’t be fooled, by its size. It is a rich natural fertilizer for your garden. I little can go a very long way in helping the soil retain moisture and add a wide range of micronutrients to the soil.
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