How Many Worms Do I Need For My Compost Bin?

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Vermicomposting is the mechanism of using worms in a compost bin to help to speed up the conversion of organic waste material to usable, nutrient-rich compost. There are several criteria you need to consider when first setting up a compost bin that you want to use to house worms to assist with the decomposition of the organic matter. One of the questions we often get asked is how many worms do you need for your compost bin, so let’s investigate this a little further.

If you are using red wrigglers for your compost bin, then you will need half a pound of worms per square foot volume of your compost bin. Half a pound of red wrigglers will equate to 400 to 500 worms. For other species, you may have to increase the weight value to increase the number of worms added.

When including worms into the production of compost in your composting bin, you want to choose the right worms for your compost bin and use the right quantity of worms to encourage a healthy population in the mix. You want to prevent overcrowding in the compost, bearing in mind that the worms that you add are going to reproduce if the conditions are correct and conducive for breeding.

How Many Worms Do I Need In My Compost Bin?

A compost bin is a great way to create rich, fertile soil for your garden. But how many worms do you need for your compost bin? There are a number of aspects of establishing a compost bin that you need to consider when determining the answer to this question.

Some of these considerations will include the type of worms you intend to use, the size of your compost bin, and the amount of food scraps or organic waster that you will be using in the vermicomposting bin.

Buying Worms Online

If you’re interested in getting the best quality of worms for your garden or your compost bin you’re probably going to have to source them online. The likelihood of finding a worm breeder the is near you, has varied inventory, and can provide what exactly what you need is very unlikely.

I have purchased worms online several time (and from several different places and have received the entire gamut of what you can expect. I’ve received a smelly box of mostly dead worms (which is unusual) and several boxes of thriving worms that have done an amazing jobs in my compost and dirt.

The one place that has never let me down is Uncle Jim’s Worm Farm. He has been in business for over 40 years and can get you what you need super fast. If you need worms, trust me and don’t buy from anywhere else.

The Difference Between Vermicomposting And Composting

The first aspect that you need to understand if you intend to use worms in a vermicompost bin is that the process is different from straightforward composting.
In traditional composting, you may find worms that inhabit the compost pile, but you are not actively encouraging the worms to participate in the process. The traditional compost pile relies more on the mixing of certain organic waste materials that will encourage bacteria and other microbes to break down the plant matter and produce the compost.

This process is typically slower than vermicomposting operations and requires more attention to the mix of materials that you add. Also, in traditional composting methods, once you have added the organic waste to the pile, you should not add fresh organic waste to the pile as this will slow down the process.

With Vermicomposting, you will be relying on the worms as the primary method to process the organic waste and transform it into compost, rather than the action of microbes. Although there will still be some microbial action in a vermicompost bin, their action will be secondary to that of the worms.

With vermicomposting, you will also be adding a constant supply of organic waste to the bin on a regular basis to provide the worms with enough food to eat as well as to encourage the breeding of the worms.

Number Of Worms Needed For Your Compost Bin

So, let’s get down to the number of worms that you are going to need for your compost bin to benefit from the action of the worms and increase your compost production.

The general consensus is that the rule of thumb for a beginner composter is to use half a pound of red wriggler worms per square foot of your compost bin. This will get your compost bin off to a decent start and will not require you to add a huge amount of organic waste to the bin from the get-go.

The worms will take some time to process the organic matter that is already present and won’t need additional food for a week or two. It will also take some time for their numbers to increase, which will give you time to adjust and store up organic waste to feed the worms.

If you are confident that you can provide enough organic waste to feed your worms, then you can be a little more adventurous add 1 pound of worms per square foot to your compost bin.

These quantities are based on using red wrigglers as the worms of choice for your compost bin. A half a pound of red wriggler worms will equate to about 400 to 500 worms. If you are using European nightcrawlers, these worms are much larger, so half a pound of worms would only give you 150 to 200 worms.

Because the nightcrawlers are larger, you will get fewer worms by weight, which may require that you increase the ratio to 1 pound of worms per square foot of compost bin to have the correct population density of worms to start out with.

Thus, red wrigglers would be the preferred type of worms to procure for your compost pile since you would get a higher quantity of worms pr weight. This means that there will be more worms to build a thriving, breeding colony of worms that will process more organic matter and reproduce faster to turn your composting bin into a compost-producing machine!

How Much Will My Worms Eat?

Composting worms can easily eat their own weight value each day in organic matter. What this means is that essentially 1 pound of worms will eat 1 pound of organic matter each day.

Using this rough calculation, you will be able to determine how much organic matter you need to feed your worms.

Don’t forget that as your worm population increases due to their reproduction, you will need to increase the amount of organic waste that you supply your worms to cater to the increase in numbers.

The best way to monitor the consumption of organic matter is to measure the amount that you give them and then keep track of how long it takes for this supply to become depleted.

As the number of worms increases inside the compost bin, the organic material will disappear at a faster rate. As the consumption increases, you will need to increase the amount of food that you give to the worms or increase the frequency with which you feed them.

How Often Should You Feed Your Worms?

The frequency with which you feed your worms will vary from season to season. As the temperatures drop in the wintertime, the worms will become less active and will eat less, which means that you can decrease the amount of food that you supply.
As the temperatures warm up in the summer, you will notice an increase in the consumption of organic waste, and you will need to increase the frequency or quantity with which you feed the worms.

The frequency with which you feed your worms will therefore depend on the number of worms in your compost bin and the current environmental conditions.
You will need to establish a frequency and quantity based on your circumstances.

One of the easiest methods to achieve this is to feed your worms and then see how long it takes for the organic matter to disappear. The organic waste should not sit long enough in the compost bin to form mold, so if this is happening, you need to feed the worms less food at a time.


Turning your compost bin into a vermicompost bin will certainly speed up the process of turning organic waste into useful compost that you can use to enrich your garden soil. However, it adds a management component to composting that traditional methods require less of.

The additional management required by adding worms is not too onerous, and as long as you have enough organic waste coming out of your home to keep your worms well-fed, you will not have a problem.

If you are new to composting and this will be your first compost bin, the recommendation is to start on the conservative side and add half a pound of red wrigglers per square foot volume of your compost bin.

This will give enough number worms to the compost bin to get the process going and give them room to reproduce and increase in population.

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