How to Harvest Worm Castings (While Separating Worms and Cocoons)

Harvesting worm castings can be a pain in the ‘you know what’ if you haven’t done it before and don’t have a plan.

Especially, if you just have a personal worm bin and want to harvest worm castings while separating your worms, and maybe even separate the cocoons they’ve laid.

Collecting a little bit at a time is not very practical, so what options are there for the worm poop harvesting process? Well, we’re gonna get you covered in this article and show you how to do it..


  • There are a few options to harvest worm castings, depending on cost, effectiveness and time.
  • Using light: Shine a light on the worms to have them burrow deeper and then use a scraper to harvest worm castings and eggs off the top layer of your worm compost bin
  • Add new worm food in a concentrated area away from old feeding area, wait for worms to move to the new area and harvest worm castings.
  • Sieving and Filtration: Uses a sieve or mesh size that’s suitable for the size of your earthworms. Shake to filter out most of the earthworms from your worm castings.
  • Use Large-Scale Commercial Worm Casting Sifters: These options include a vibrating screen, high-speed capture jet or a drum-type separator (expensive options).
  • Make Your Own DIY Worm Casting Separator: your own version of the above sifters.

In general, earthworms tend to pull feces into the soil, and sometimes push it to the surface of the soil.

They essentially eat and drag at the same time, and when they run out of food, they look for more food along the way.

How to Harvest Worm Castings With No (or Cheap) Equipment

This section contains the best methods for your average worm composting hobbyist with one or just a few worm bins. Making sure you have the best worm bin possible can also make this experience easier.

Here are 3 cheap, cheerful and practical methods:

Using Light Irradiation

Since they live underground and have no eyes, earthworms have a natural aversion to light and their skin is also a photoreceptor, so they can sense the direction of light and then burrow down away from it.

  1. To start with, you can find a place with plenty of light, or shine a light on them with a torch.
  2. Once they burrow into the soil, use a scraper to slowly scrape off the top layer of earthworm feces with eggs, then use light to irradiate again and scrape repeatedly until the earthworms are all concentrated together at the bottom to complete this process.
  3. Afterwards, put the earthworm feces with eggs into a hatching room with a temperature suitable for hatching (usually 25°C, but different species have their own optimal temperatures).
  4. Wait for a period of time for the new cocoons to hatch. After the young earthworms are all hatched, then use the same method again to separate them.


This method is very cheap, effective and can yield many new earthworms.


The wait time is long; it is time-consuming and labor-intensive.

Add New Food

This method is pretty straightforward.

Once you’ve determined that the old food has been mostly consumed, you can begin adding new worm food for the worms to eat and shift them towards that area.

You can find the answer to the question what do worms eat? << here in our ultimate guide

  1. First, instead of putting food on the surface, put new food in a concentrated area, away from the old feeding area, (which should already be converted to worm castings).
  2. Wait a few days and you’ll find that most of the earthworms have moved to the new bait area.
  3. Then you can remove the old feeding area (which should now be mostly castings) and either take them out of your worm farm to use as fertilizer or, if you want more worms and castings, combine the existing worm castings with the eggs on top into the new food scraps on he other side of the farm.
  4. Once the eggs hatch, and the young earthworms start moving down to eat the new food, you can slowly scrape off the top layer.


This method is less labor-intensive..


But it’s also easy to pick up earthworms still in your castings. So, it’s best to use it in conjunction with light irradiation.

There’s also, again, a long wait time between harvests.

Here’s my own example of this in action; you can see one side of my basic worm bin is full of ready worm castings, while the other (lighter) side shows new bedding made up of unprocessed material and food waste mixed in.

Dark side are my worm castings, with the light side my new bedding with food scraps buried within

Eventually, there will be very few worms left in the side with the finished compost and most worms will migrate to the other side of the container.

Alternatively, you can stack two worm bins on top of each other with small holes underneath for worms to move into the other container.

One container will have the finished compost and worm castings, while the other will have fresh food for them.

You can then easily harvest castings and then load that now-empty container with food waste and keep harvesting worm castings every few months.

Sieving and Filtration

This method uses a mesh size that’s suitable for the size of your earthworms, and filters out most of the earthworms from the castings.

  1. Purchase a sieze or a piece of mesh. The mesh size I use is around 1.3cm x 1.3cm.
  2. Place your worm castings on to the mesh and shake to separate the worms from the worm castings. The sieved earthworms are collected, and usually contains finer earthworm feces or castings mixed with some smaller baby earthworms, earthworm cocoons and smaller particles.
  3. Afterwards, if necessary, you can use a smaller mesh size for a second sieving.


Easy and works well if you have bought the right sized screens or mesh.


This method is not as clean or accurate as others, but it is ok if 100% accuracy and completely worm free castings is not too important to you, otherwise, you can use it in combination with the methods above to get better results.

Large-Scale Commercial Worm Casting Sifters

If you run a large-scale worm farm operation, the question is, if a customer wants to buy a few kilograms of earthworms or earthworm eggs, or if you just want to use earthworm soil as fertilizer, what should you do?

Of course, manually separating earthworms is time-consuming and labor-intensive, so many large-scale farms use a commercial worm separator machine.

Many separator machines have similar principles as the methods shown above, and some use high-tech methods.

Below, I will introduce you to several types of separator machines that are available on the market.

Vibrating Screen Separator

This type of separator automates the sieving and filtration method mentioned above.

It separates earthworms and earthworm feces according to the mesh size, and also separates adult earthworms and large debris.

The earthworm separation effect is decent, but it can be difficult to find small or medium-sized earthworms that slip through the mesh.

This type of machine also can’t effectively separate eggs and worm castings, and when the soil is too wet it can affect the operation.

You can see it in action, here:

Drum-Type Weight-Based Centrifugal Force Separator

This type of separator utilizes the concept that earthworms are lighter than soil.

It uses a rotating drum to first sieve the fine soil in the middle.

Afterwards, the remaining larger particles and earthworms will tend to enter the middle bucket because they are lighter than the soil and earthworms tend to stick to their surroundings.

High-Speed Capture Jet-Type Separator

This type of high-tech machine uses high-speed cameras to quickly capture objects similar to eggs and then uses jets to blow the earthworm eggs into a box.

This machine can quickly and efficiently separate earthworm eggs from feces.

See the video demonstration below:

The drawback is that these machines are expensive and add a significant extra cost, and the last machine on this list is only suitable for fine soil and earthworm egg cocoons separation, so it cannot be used to separate adult earthworms.

There are many small machine concepts that are similar, and also dry-wet separators, but these are not covered here.

These machines have different uses and advantages and disadvantages, and you can find one that suits your needs.

Make Your Own DIY Worm Casting Separator

If you only need a small one to separate worms and for harvesting worm castings, you can also DIY a simple separator machine.

It’s not only cost-effective but also environmentally friendly and efficient.

Apart from the third separator mentioned above, it is possible to make the other two types at home by yourself.

Here’s an example below of someone who made a small screening machine by himself:

This guy also made a more advanced drum-type screening machine for harvesting worm castings by himself:

With some methods, you can also make worm tea to use or sell by the bottle.

How to Separate Worm Cocoons from Castings

If you sell worm cocoons alongside your worm castings, or simply don’t want to waste perfectly good cocoons from your worm bin (you’re essentially throwing away 1-5 worms with every cocoon!), then this is important to you.

It’s hard to do with complete accuracy as worm cocoons are small unless you have an expensive machine as we mentioned above.

You’re likely to lose at least some cocoons in your worm castings when you’re selling them or if you immediately use them as fertilizer in your garden soil or for plants.

The simplest way to separate them out is to use a combination of the first 3 methods we mentioned.

Adding food to a new spot in your worm bin, then light irradiation to remove any remaining worms, and then use a fine seive to try and catch as many cocoons as you can.

This will be time-consuming, and you’re likely to take some worm castings with you when you separate cocoons, but it won’t be much.

Frequently Asked Questions

These are the most often asked questions we see about separating castings and cocoons..

How do I tell the difference between the soil I’ve used for worm bedding and castings?

When earthworm farming or worm composting, it’s not necessary to use soil as worm bedding to raise earthworms.

Instead, worms can be raised directly on feed and this, along with carbon heavy materials like egg cartons and coco coir, can make up the majority of worm bedding.

After a period of time, all that feed becomes earthworm castings.

For worms, earthworm soil is their own worm poop. They don’t mind sifting around their own worm castings in your worm compost bin to find food.

But if you did use soil, castings tend to be darker and of a more fluffy consistency.


Whether you are a hobbyist with a personal worm bin or running a large-scale worm farm for profit, you have plenty of options for harvesting worm castings and cocoons.

The accuracy, cost and ease of the harvest will vary depending on the option(s) that are available to you.

Hopefully, this article on how to harvest worm castings has given you all of your options to get your worm castings harvested in a way that makes the most sense for you.

May your worm bin and worm composting endeavors always bear the highest quality “black gold”…aka worm castings!

Alternatively, if you just want to buy the best worm castings < we’ve reviewed our favorites here, which will allow you to pick up quality castings without going through the worm compost process yourself.

REFERENCES: – “1-5 worms hatch from a cocoon”