Worm Castings Benefits: Discover What All the Fuss is About!

Worm castings deliver a bounty of benefits to gardens and gardeners alike. If nature had superfoods, worm castings (worm poop) would be at the top of the list. Let’s explore why you must get on the worm poop bandwagon today!

Benefits of worm castings

We’re just going to put it out there – you will be hard-pressed to find any negative things about worm castings.

credit: giphy

Okay, worm castings have a few disadvantages, like they take a while to cultivate. But nothing that will impact your garden negatively.

So why are we so excited about something that has come out of the digestive tract of an animal? Because it is black gold! And we’re about to dive into the benefits of worm castings.

Benefits of Worm Castings – What is so special about worm poop?

By the end of this list, you will be itching to get your hands on some worm castings. But before we jump into the benefits of worm castings, let’s quickly review what they are.

Worm castings are worm poop – there is no hiding this fact. We love playing with worm poop, and your plants will benefit from it in the process.

Worms produce castings as they munch their way through the soil consuming all the organic materials they find along the way.

It is a rich fertilizer that produces a raft of benefits for potted plants and your garden. So let’s get our hands dirty and take a closer look, shall we?

Benefits of Worm Castings for Soil

First, let’s explore the benefits of worm castings on the soil in your potted plants and garden.

Increases the Humus Content in Soil

If you have started hanging around garden communities or on socials, you may have come across the term ‘humus.’

No, it is not the same as hummus, the delicious food dip you make from chickpeas and tahini.

When we use the term humus to describe the consistency of soil, it means that the soil is rich in dark organic matter. The dark organic material is thoroughly processed and ready to release nutrients into the soil for the plant roots to absorb.

As you can appreciate, plants thrive in soil rich in humus because it contains all the essential ingredients for strong, healthy plant growth.

The source of the organic material usually comes from processed compost or (as you may have guessed) the end product of worms in the form of worm castings.

Since indoor plants do not have a local worm colony, it is wise to mix worm castings into your potted plants so they can also benefit from rich humus soil.

Increases the Microbes’ Population

Did you know there is an entire ecosystem living in your soil?

There is literally an army of bugs doing their thing to help process and break down the organic matter in the soil. They are an integral part of the cycle of plant life and vegetation that transforms unusable materials into ready-to-be-absorbed nutrients for your plants.

And worm castings contribute to this all-important cycle. Specifically, worm castings are the food source for the microbes that live in the soil.

Not only are worm castings an excellent food source. They also contain their own beneficial microorganisms, phosphate, and nitrogen solubilizing bacteria, that benefit the soil. We won’t go into the biology of these organisms, as that would take this article to the next level. But if you are interested in reading more about these beneficial microbes, check out this article by SpringerLink.

Speeds Up Composting Process In Soil

Rich worm castings are benefitical for soil

This benefit is closely related to the one above. However, the gains that it delivers are worth mentioning.

As we established earlier, introducing worm castings to your garden and potted plants helps to increase the microfauna population in your soil.

In doing so, you are stimulating microbial activity, which speeds up the composting process in your soil.

Ultimately, this means your plants can receive the nutrients faster, which promotes stronger growth.

Increase Soil Water Retention

If your soil looks tired and dries out too quickly, it may be time for a quick injection of worm castings.

Old soil, particularly in potted plants, can become hydrophobic. This means it loses its water-retaining qualities and can begin to repel water.

You can see this happening when you go to water your plants. The water will stay on top of the soil in bubbles until it can find a pathway through the soil. Which, more often than not, is via cracks in the soil.

The result is the water escaping out of the drainage holes in the pot without allowing your plant’s root system to drink and absorb any moisture.

To reinvigorate your soil and improve the water retention properties, we recommend mixing worm castings into your soil.

To reinvigorate garden soil with worm castings, sprinkle 1/2 a cup of worm casting per square foot of soil onto the soil.

For houseplants, we always repot the plant. This allows us to mix worm castings into all of the soil rather than just layering it in the topsoil.

Improves Soil Structure

worm castings improve soil structure

Besides improving water retention, worm castings deliver other benefits when added to soil in the garden and pot plants.

Worm castings improve the soil aeration and drainage. Plus they help to bind the minerals and nutrients to the soil, preventing it from leeching away.

As a humus-rich material, worm castings also increase aeration in the soil.

Not only are worm castings in on themselves good for increasing the oxygen flow in soil, but the simple act of mixing and tossing castings through your soil will also break up the soil. Once again, oxygenating the soil and allowing the roots to breathe.

Worm castings also improve the drainage of the soil. Good quality organic worm castings generally contain worm eggs (or cacoons). As the worms hatch and begin munching their way through the soil, they help to create tunnels that improve drainage, resulting in healthy soil.

As the worms eat and produce their castings, they help to anchor the essential nutrients to the soil particles. This ensures the soil mix retains its viability and prevents the nutrients from washing away from your plants.

pH Moderation

As if all the previous benefits weren’t enough, the final benefit we’ll discuss regarding worm castings and soil relates to pH stability.

Worm castings can neutralize the pH levels from becoming too extreme. This means worm castings help prevent pH levels from becoming too acidic or alkaline. When pH levels revert to either extreme, the soil becomes inhospitable for plants making it hard for them to absorb nutrients.

Therefore, if you see your plants struggling, try adding worm castings to the soil. Besides the nutrient boost, it may help to moderate the pH levels, giving your plants a much-needed lifeline.

Benefit of Worm Castings for Plants

After reading about all the numerous benefits of worm castings for soil, it is easy to think that there couldn’t possibly be any more benefits to be gained.

But, as the old retail television commercials used to say…But wait, there’s more!

Let’s look at how worm castings can directly benefit plants.


worm castings are perfect for seedlings

Worm castings are a great medium to sprout seeds and cultivate seedlings.

The rich-humus content and neutral pH levels create the perfect environment for growing seedlings.

But the main reason we like to use worm castings for our seedlings is because of their great water-retaining qualities. Seedlings need moisture to germinate properly. And worm castings have the perfect moisture levels for this very purpose.

In fact, we often find many accidental pumpkin and capsicum seedlings sprouting from our food scraps in our worm towers (permanent worm farms in our vegetable patches). All because it is packed full of the perfect seedling starter material – earthworm castings.

Reduces the likelihood of pests and diseases

Another benefit of adding worm castings to your plants is that it helps naturally fight pests and plant diseases without artificial chemicals (like commercial products).

When worm castings are applied to plants as a worm tea liquid fertilizer (worm castings diluted in water), the solution acts like an organic insecticide due to the enzyme chitinase.

It is particularly useful to protect against sap-sucking insects like aphids, mealy bugs, and spider mites.

How to Get Worm Castings for Your Garden?

Now that you know all about the benefits of worm castings for your plants and soil, the next natural question is how you get your hands on the stuff. Especially because there are so many ways to use worm castings in gardening.

Some nurseries and garden retailers do sell earthworm castings by the bag. You can even source some online from retailers like Amazon.

However, we prefer the DIY method for sourcing our worm castings with our own DIY earthworm castings farm. Check out the steps to creating your very own worm castings farm HERE.

The best thing about doing it yourself is that it is easy and budget-friendly, and it reduces your carbon footprint by redirecting food kitchen scraps from the bin into your garden.

credit: tenor



  • Hummus. (2022, December 10). In Wikipedia. https://en.wikipedia.org/wiki/Hummus
  • Chitinase. (2022, December 8). In Wikipedia. https://en.wikipedia.org/wiki/Chitinase