Calculate How Many Worms You Need to Start Your Worm Composter

For beginners we recommend starting with 1 pound of worms for every 4 square feet of your worm bin’s top surface area.

Experienced vermicomposters can start with more worms and we recommend 1 pound of worms for every 1 square foot of you worm composter’s top surface area.

Try out our worm density calculator below and carry on reading where we walk you through figuring out your personal composting requirements, the size of bin you need and the number of worms you want to start with.

Worm Density Calculator

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What Is Your Composting Requirement?

The first question that you need to ask yourself before getting to the number of worms you need in your compost bin is what are your composting requirements.

Every person has different composting requirements, depending on how much waste is being produced by them and their family, or the number of plants that they have to use the compost on.

Other considerations extend to the size of the worm composting bins — which will be discussed in the next section — and the type of worms you are going to use. Here, we will be concentrating more on the amount of food and organic waste that is being produced by you and your family.

The best way of calculating the number of composting worms you need for your compost bin is by tracking the amount of vegetable food waste that you create with the help of a family food waste audit. This is very simple to carry out regardless of whether you are living alone or with other people.

First and foremost, you will be required to collect the amount of vegetable food waste that you create in a day, which could have otherwise been fed to your compost bin. This should include all the food waste that worms can ingest with ease, so avoid things like meats and dairy. Once you have collected all the scraps for the day, put them in a bag and weigh it using a kitchen scale. For one week, you will have to repeat the exercise every day and then take out the average of the results on the last day to know your total vegetable waste creation.

What Is the Size of Your Worm Bin?

Another factor that influences the number of worms that should be added to the worm bin is the size of the container itself.

The larger your bin’s surface area, the more worms you need to add to keep it in the best possible condition.

If you keep the temperature and moisture conditions right for the growth and subsistence of the worms and give them the right amount of food to eat, the worms will expand to incorporate the entire container that they have been poured into. As these worms work in the top inch of the compost pit, the size of the compost bin and the number of worms that are at work in it are intrinsically linked.

This means that the larger your bin’s surface area is, the more the number of worms you need to add to the bin to keep it in the best possible condition.

Usually, the ratio between the surface area and one pound of red wiggler worms — which are the most popular type of worms used for vermicomposting — is 1:1. Keep in mind that we will be going into further detail about how many worms are in a pound of red wigglers at a later point in this guide.

It is very easy to start a composting pit in a regular plastic storage box but if you need a larger composting pit, the number of worms will also have to be increased.

How Many Worms for Beginner Vermicomposters?

As a beginner who doesn’t have too much experience when it comes to vermicomposting, you may be more inclined towards depending on a fixed formula to determine how many worms should be added to your worm composting pit. To help you through this predicament, we have put together this guide that will help you reach the right number.

First and foremost, you will be required to answer the two important questions that have been mentioned earlier in this piece — how much food waste you produce on a regular basis and what is the size of the container in which you are setting up your composting pit.

With regards to the first question, the general consensus is that worms eat about 50% of their weight in food every day. Some research takes this amount even higher to approximately 100% of the worms’ body weight. Using a general figure here, it is safe to assume that one pound of worms will be consuming anywhere between 1.75 pounds to 2.45 pounds of food per week.

For beginners we recommend starting with 1 pound of worms for every 4 square feet as discussed in Mary Appelhof’s “Worms Eat My Garbage”. Her advice was first published in 1982 and has stood the test of time with new worm composters around the world.

Example

Let’s work this out using the VermiHut 5-Tray Bin as our example, which we think is the best budget worm compost bin.

The length and width of each VermiHut tray is 11.25 inches x 11.25 inches.

Using our worm density calculator we input our length and width, select the “beginner” option, and press calculate.

The worm density calculator has worked out that using Mary Appelhof’s “1 pound of worms to every 4 square feet of top surface area” rule we will need approximately 0.2 pounds of Red Wigglers to start 1 tray given that the top surface area of 1 tray is  about 0.9 square feet.

If we wanted to start all 5 of the VermiHut’s trays we would need to times that number by 5 giving us 1 pound of worms to start our compost bin (0.2 pounds * 5 trays).

How Many Worms for Experienced Vermicomposters?

While most beginners prefer the “x lb of worms per sq ft” approach that is mentioned in the section above, as you gain more experience in vermicomposting and familiarize yourself with the functioning of the Red Wiggler worms that are most commonly used for the purpose of composting, you might find yourself feeling a little restricted by the method that was discussed earlier.

This does not take away from the validity of the approach, but if you are looking to change up the way in which you ascertain how many worms should be appropriate for your vermicomposting bin, it may be beneficial to add worm-rich material without worrying about putting in exact quantities.

As an experienced vermicomposter, you can allow the worm population of your bin to expand in a more natural manner depending on the resources that you have available. This also requires the addition of a lot of starter material that allows the worms to settle into the bin with greater ease.

While eyeballing the entire process may seem a little risky to beginners, experienced vermicomposters already have the necessary skills to use this “natural” approach to determining the right number of worms that need to be added to a composting bin.

To give you a good base to work with, a more experienced worm composter will probably want to use a less conservative ratio such as the “1 pound of worms to every 1 square foot of surface area” rule. So let’s work that out using an example.

Example

Using the Hungry Bin Continuous Flow-Through Vermicomposter which we rated the best overall worm composter you can see it has a top surface area of approximately 25 inches x 25 inches.

If you input these numbers into the worm calculator, click the experienced option, and click the calculate buttton it works out that your top surface area is 4.3 square feet and recommends you start with 4.3 pounds of worms!

Related Questions

How many worms are there in a pound of Red Wigglers?

The red wigglers that make all the difference to your composting pit are usually available for sale from retailers who sell the worms by the pound. While this tells you about the total weight of worms that you are getting as a part of the deal, there is no indication of the number of worms there are going to be per pound of worms that you are receiving.

In order to figure out the number of worms that you will be receiving, there are a couple of things that you should keep in mind. First and foremost, most people who harvest worms for sale do not separate the worms one by one and check how many are being sold, or what is the age of the worms being sold.

You stand to receive a mixed bag of worms, which will include some egg sacks, some juveniles, and some mature worms.

The general consensus is that a pound of worms measures about two full measuring cups and a total of approximately 1,000 worms. This can then be broken down into egg sacks that hold anywhere between 1 and 5 worms each, juveniles that have come out of their egg sacks only weeks ago, and mature worms that are anywhere between 3 months and 5 years old.

Most of the worms you get as a part of the pound will be mature worms, while some may be juveniles or egg sacks.

How much do Red Wigglers eat?

Red wiggler worms survive on a diet of vegetable scraps from the kitchen waste and remnants from your gardening waste, but the most common query that both beginners and experienced vermicomposters have is how much do these little composting experts eat on a regular basis?

If we look at the theoretical consensus, the worms are likely to eat approximately half of their body weight in food each day. However, you must keep in mind that this is only true for mature worms that are living in the optimal conditions when it comes to space, temperature and moisture. If you are just setting up a composting bin, it is highly likely that the conditions are not so perfect.

In the initial phase of setting up a bit, it is recommended that you add ½ pounds of food for every pound of worms that you have added. During the initial adjustment period, you might find that the worms may not be as quick as you expected them to be, but as they start to adjust to the bin, they will multiply and require more food to be added.

As the bin turns into an established compost pit, you will be required to set a pattern of feeding, but keep in mind that too much food could have a detrimental effect on the health of your bin.

How fast do Red Wigglers reproduce?

By nature, worms are known to reproduce rapidly to offset the chances of predators targeting them. In a composting bin, it isn’t very likely that a predator will harm your worms.

Red wigglers — like most other worm species — are hermaphrodites. This means that they have both female and male sexual organs. Despite this, they cannot produce offspring on their own — they need to mate in order to reproduce.

If the conditions are favorable for the growth of red wigglers, they can reproduce quite quickly. Once a red wiggler has reached the three-month point in its life, it can produce anywhere between two to three cocoons each week. Each of these cocoons will average about three hatchlings. While it takes about 11 weeks for the cocoons to hatch, the hatchlings require another two to three months to develop into full-fledged mature worms that are ready to breed.

After getting to know a little more about the nature of the red wiggler worms, you will find yourself better equipped to understand the entire process of vermicomposting, especially if you are a beginner with not too much experience in the field.

Getting the right number of worms in your composting pit is very important if you want to get the best results at the end of the process. The entire purpose of this piece is to make you aware of the different components that come together to give you the right number of worms for your composting pit.

The number of worms in a pound, the nature of food that you will be feeding these worms, as well as the size of the composting pit are all important determining factors.

Sources

Red Wiggler photo by Rob Hille [CC BY-SA 3.0], via Wikimedia Commons

Worms Eat My Garbage by Mary Appelhof