Earthworm Castings (Vermicompost)

Worm castings have been used for centuries by generations of gardeners and naturalists for the improvement of soil health, fertility, and organic matter.

These castings consist of nutrient-rich organic matter that has been digested and excreted from the body of earthworms.

This makes them one of the most powerful soil conditioners money can buy.

This article will provide a full guide on What Earthworm Castings are, their properties, how they can be used within a terrarium, and much more. 

Quick Stats:
Scientific Name Lumbricus Rubellus
Botanical Name Earthworm Castings
Common Names Vermicompost, Worm Compost, Worm Castings
Origin Worldwide (Subtropical – Tropical)
Size grain of sand
Color Dark Brown
PH Impact Neutral

What Is Worm Castings?

Worm castings are the earthworm digestible matter that is made from the organic materials it processes.

Earthworms consume soil, dead leaves, food scraps, and other organic matter and then convert it into a nutrient-rich material called worm castings.

Worm casting consists of essential minerals, essential elements such as phosphate, potassium, ammonium, and more, beneficial bacteria, and coatings of mucus for fertilizing soils. 

A Guide To Earthworm Castings "Vermicompost" For Terrariums

Worm Castings Facts

Earthworm castings have been used for centuries as a natural soil amendment in gardens and terrariums.

Earthworm populations have been on the decline, but they are becoming increasingly popular as people become more aware of their benefits to soil health and plant fertility.

The Lumbricus Rubellus species is the most popular species of earthworm; they are found in most parts of the world and are known for their brown-red color.

Earthworms are beneficial to the soil they grow in, which is why they are prized in many cultures. 


Worm castings are usually dark, and crumbly, and contain a sweet, earthy scent.

They can vary in size, depending on the type of earthworm used.

Generally, they are small grains, around the size of a grain of sand.

These castings have been proven to be great for adding nutrients to soils and promoting healthy vegetation and microorganism activity.

They are also known to help increase moisture and aeration, making them an excellent addition to terrariums. 


Earthworms inhabit a variety of habitats, from forests and agricultural fields to urban gardens and terrariums.

They are found in most regions of the world but are most common in temperate, subtropical, and tropical climates.

Earthworms prefer damp, moist soils with plenty of organic matter, but they can survive in a variety of soil types.  

Environmental Influence

Worm castings are natural soil enhancers, and are beneficial to the environment to which they are added.

They are known to improve pH levels, increase aeration, and add much-needed organic matter to soils.

Earthworm castings allow for improved drainage, increased plant growth, and increased microbial activity in impacted soils. 

Vivarium Type

Earthworm castings can be a great addition to many terrariums, as they help keep the soil moist, provide beneficial nutrients for your terrarium occupants, and promote healthy microorganism habitats.

Terrariums that focus on soil-dwelling species, such as hermit crabs, are well suited to the inclusion of castings.

They provide a nutrient-rich substrate in which they can thrive.

Worm castings can also be beneficial in paludariums with aquatic species, as they help to improve the water quality by adding important organic matter. 

Here is a recommended list of vivarium types coconut coir is commonly used in:

  • Paludariums – Half aquatic/ half terrain-based enclosure.
  • Terrariums – Fully terrain-based enclosures with little to no aquatic features.

Vivarium Usage

Castings can be used in a variety of ways in terrariums.

They can be mixed with soil as a top dressing, used as a soil amendment, or added directly to the substrate in order to provide essential nutrients, aeration, and moisture to the ecosystem.

Earthworm castings are also a great way to help reduce the amount of solid waste created in the vivarium by consuming organic matter and converting it into a nutrient-rich substrate. 


The advantages of using castings are numerous.

Earthworm castings are a great way to add essential nutrients, organic matter, and beneficial bacteria to terrarium ecosystems.

They also help to aerate soils, improve drainage, and keep moisture levels stable.

By providing numerous nutrients, worm castings help improve the overall health of plants and animals, while also benefiting microbial activity in the soil. 


One potential downside to earthworm castings is the smell; they can be quite pungent and may be unappealing to some terrarium keepers.

Additionally, since castings are derived from organic matter, they can introduce potential contaminants to the terrarium ecosystem if not used properly.

It is important to ensure that any organic matter added to the terrarium is free of any potential toxins or contaminants. 

Buy Worm Castings

Earthworm castings can be purchased from a variety of online and brick-and-mortar retailers, as well as from worm farms and compost centers.

The best source of castings is going to be from a worm farm.

They are dedicated to the breeding and care of earthworms for the production of compost and worm casting. 

Worm Castings Preparation & Usage

When using worm castings in terrariums, it is important to ensure that the castings are of high quality and free from any contaminants.

It is also important to ensure that the worm castings are completely dry before using them, as moisture can disrupt the environment of the terrarium.

Additionally, since the nutrients in earthworm castings are released slowly, they can be mixed with other soils or soil amendments to help speed up the release of the nutrients. 

Worm Castings Alternative

There are other soil amendments and fertilizers that can be used in the terrarium, such as perlite, coconut coir, and composted manure.

These can all be used to maintain soil health, aeration, and nutrient levels in terrariums.

Additionally, there are specifically designed fertilizers that can be added to the terrarium in order to maintain optimal soil health. 

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Earthworm castings are a powerful soil amendment and an excellent addition to any terrarium.

They are a great way to add essential nutrients, organic matter, and beneficial bacteria to the terrarium, while also promoting healthy microbial activity.

Additionally, worm castings can help to improve drainage, aeration, and moisture levels in the ecosystem, making them an invaluable component of a successful terrarium.

Frequently Asked Questions

Both compost and vermicompost are beneficial to garden soil, but in different ways. Compost is made from decomposing organic material, while vermicompost is produced by worms digesting organic material. Vermicompost contains more microbes and nutrients than regular compost, leading to better soil structure, increased fertility, and better water retention.

Compost is better for adding bulk and matter to the soil, while vermicompost contains higher levels of minerals and micronutrients. Ultimately, both compost and vermicompost are beneficial for gardens and the choice ultimately depends on the needs of your soil.

Yes, earthworm castings are a natural, nutrientrich fertilizer that can be used for all types of plants. Earthworm castings provide essential micro and macronutrients to help plants grow healthy and strong, making them an excellent choice for gardeners and farmers alike.

Additionally, they can help improve soil texture and drainage, reduce the need for chemical fertilizers, and increase drought resistance.

Yes, you can put worm castings on top of the soil. Worm castings help to improve soil aeration, density, and waterholding capacity which can result in better root growth, enhanced water infiltration, and better nutrient availability.

When using worm castings as a soil amendment, it is best to evenly distribute them throughout the soil to ensure even nutrient distribution.

It is recommended to add worm castings to the soil every 34 months. This will add essential nutrients and help to improve soil structure and aeration. Worm castings can also help to create a more balanced pH level in the soil.

No, it is nearly impossible tooverdo worm castings, as they are highly bioavailable, meaning that they provide beneficial nutrients to plants in an extremely effective form.

Worm castings are great for promoting plant health in gardens, lawns, and potted plants, and you can use them a generous amount without fear of over-fertilizing.

Yes! Worm castings, orvermicast,” are a fantastic organic fertilizer that has numerous benefits compared to traditional inorganic fertilizers. They are an allnatural, nutrientrich soil amendment that is loaded with microbes, fungi, bacteria, and other enzymes.

Worm castings add key essential minerals to the soil that create a healthier environment and help plants grow stronger and larger. They also help to break down clay and compacted soils which increases water penetration and waterholding capacity in the soil. Overall, worm castings are a great alternative to fertilizers and can help increase soil health and a plant‘s ability to take up nutrients.

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