Worm Farm Reviews

How to Harvest Worm Castings: 4 Easy Methods

In this article, we explain how to harvest your much sought after worm castings to use in your garden. Try one of these four easy methods to collect your “black gold”!

Reading time: 4 mins

How to harvest worm castings

Harvesting worm castings is a great way to keep your garden healthy and thriving. Famously known as “black gold”, worm castings are a rich source of nutrients and natural fertilizer that you can feed to your garden to keep it abundant and healthy. If you’re looking to start harvesting worm castings, you’ve come to the right place. 

Worm castings can help your garden and plants grow stronger, as well as produce more fruit, vegetables, and flowers. There are a variety of ways you can harvest worm castings in your compost bin. In this article, we’ll go over the four main methods that you can use to harvest worm castings and everything you need to know about how each method works. 

RELATED: What Do Worms Eat?

How are worm castings made?

As worms consume organic matter, the organic matter then travels through their digestive tract and is excreted as a pill-shaped casting. The casting itself is filled with nutrients, mucus, and bacteria that can be very beneficial for your garden!

Read More: What Are Worm Castings?

How to harvest worm castings

There are a few ways that you can harvest worm castings at home. The method you choose will depend largely on the vermicomposting system you have, and the materials you have at your disposal. Here are four ways that you can try harvesting worm castings at home.

Harvesting worm castings by hand

1. Manual method

If you don’t mind spending some time finding worms in your vermicompost, you can sort them with your hands. Handpicking castings is a slower process, but it’s also one of the easiest ways to harvest worm castings. All you need is to get a few handfuls of castings and search through them to find worms that can be put back in the tray. Some find the manual method to be tedious, but you can spend hours sorting through worms and it can also be a fun activity for kids to enjoy. 

2. Light method

Another way you can harvest worm castings is by using light to get worm-free castings. Worms hate the light and will naturally dig themselves further into darkness and away from the light. To use this method, simply put a pile of vermicompost onto a flat surface under an artificial light. Wait a minute or two for the worms to start digging themselves into the vermicompost to get away from the light. Scrape off the tops and sides of the pile, and sift through the compost until you find a few moving worms. 

It’s important to remember that excessive light or heat can dry up your worms, causing them to die. Make sure that you don’t shine a light on them for too long and aren’t using too much heat

worm castings in a worm bin

3. Bait method

If you’re a little hesitant about touching worms with your hands, the bait method may be the perfect solution for you. With the bait method, you’ll use fresh food to attract hungry worms. In a tray, make a pile of uncomposted food scraps from the castings on one side of the tray. Then, add fresh food to the other side of the tray. Wait one to four weeks for the worms to migrate toward the fresh food source. You’ll be left with many worm-free castings you can harvest, as well as remaining eggs that will give you more worms in the future. 

You can also add food and bedding to a tray, and drape a layer of mesh or burlap with worm-sized holes over the tray. Then, spread a thin layer of castings and worms over the cloth. Wait for a few minutes until the worms burrow down into the worm tray, and collect the worm-free castings.

4. Screen method

The screen method is the most popular and quickest method to harvest worm castings. You can sift worm bedding through the screen to separate the worms from the sticks and other material from the compost. There are commercial trommel harvesters you can purchase, but they are typically very expensive and are beyond the needs of home vermicomposters. 

Fortunately, you can easily DIY a manual screen that you can use to screen worm castings. It’s cheap, easy to use, and a great sustainable option for the planet. Screened compost is also often very light, fluffy, and free of debris. 

Worm castings on a spade


If you’re a vermicomposter looking to start harvesting your worm castings, you can use one of these four simple methods to harvest worm castings. Worm castings will add plenty of healthy nutrients and bacteria that will help your garden and plants grow. So get down and dirty and enjoy the benefits that nature’s very best organic fertilizer will bring to your home. Happy worm farming!

RELATED: Worm Farming For Beginners

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