Terrarium Substrate Layers (Ultimate guide)

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Terrariums are wonderful for showcasing your succulents and plants, but have you ever thought about terrarium substrate layers? Your terrarium’s success or failure will depend on the substrate you use. Your terrarium jar will be the same. Soil is literally and metaphorically the foundation of an ecosystem.

Before we get into the Terrarium Substrate Guidelines and Instructions, let’s first define the terms and clarify any misconceptions. While materials and shapes can vary, the fundamental process of building a Terrarium is the same. It is all in layers, starting from the ground.

What is a Terrarium Substrate?

Substrate is a general term that refers to dirt and other growing media. Terrarium substrates are often slightly different than other media, as most terrariums don’t have drainage. Therefore, they must be modified.

There are two options: buy ready-made or make your own. But there are some qualities that you need to consider before making your choice.

  • Water retention – How high is the substrate’s moisture? The composition of your substrate will determine this.
  • Nutrients – Generally, it is not a good idea to add too much fertilizer to terrariums. It can cause plants to “burn”, as the fertilizer cannot be washed away. It is important to select a substrate that has enough nutrients.
  • Compaction of soil – Repetition in a watering can leave some soil crusty and hard. This makes it hard for air to flow through the soil, spreading the roots. Perlite and float are two examples of additives that help to keep the soil crumbly and loose.

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What is a bioactive substrate?

A bioactive substrate is a substrate which is designed to adapt the life cycle of microfauna or microflora that live in it. A robust microbiome is essential with a wide range of decomposers, beets and other fungi. Healthy soil is essential for the resilience of an ecosystem.

A bioactive substrate does not need to be purchased. You can make your own. You can simply take some dirt from a healthy country and add it to any country that you have. Simply inoculate the purchased land with all of the outdoor creatures.

Bioactive systems are more resilient and durable than non-bioactive systems, but they can also change over time. If you’re building an aesthetic terrarium, this may not be a problem. You want it to stay the same as before. It’s worth it because watching the growth and fall of plants or fungi is half of the fun of terrariums.

Terrarium substrate layers

Terrariums are becoming more diverse in terms of the substrate they contain. This includes gravel, charcoal, earth, sphagnummoss, and any decorations or plants you might need.

You don’t need to use Terrarium substrate layers. It doesn’t matter how you place the substrates. As long as the plants don’t attempt to root in charcoal or gravel, it won’t matter. Because they have no real purpose other than aesthetics, it doesn’t matter how they are separated.

Although stratification is evident in natural substrates, it is not on the same scale as what we can create in our ecosystem. The O layer is the first layer of soil in real life. It is also known as soil horizons. It is mostly composed of partially decomposed plant matter. It is between 0 and 6 inches deep, before the second layer (layer A), begins. This layer is also known as the top layer of soil.

These 6 inches are deeper than most Terrariums, and wild plants seem able to live together without the need for 4 layers.

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The key Terrarium layers

Each step builds upon the previous, so it’s helpful to think of them like layers when we build our terrariums.

While some layers are essential (e.g., you won’t be able to get very far without a substrate), others are optional and/or variable. All of this will be explained later.

Without delay, I present the order of the Terrarium layers.

Drainage layer

A variety of approaches to building a solid foundation for your terrarium. You can choose from a simple drainage layer or a more complex false bottom approach (and all the additional layers that may be added).

Substrate/soil layer

Supporting structure and medium for the growth of our plants. How to calculate how thick it should become and how to modify it to improve its size and aesthetics.

The Hardscape layer

Everything that is solid and does not live in reality, but we are mostly talking about stones with a dynamic look and wood that give a certain natural flair.

Plants layer

The plant layer is obviously the best part. These include terrestrial terrarium plants but also epiphytic species and mosses for 3D gardening.

Decorative layer

All the finishing decorative elements you want to add. You could add a sign, a figurine of a person or a water element. You can make it yours, like in the photo below!

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Barrier layer (optional)

The drainage layer must be able to allow water to flow freely in order for it to work effectively as a reservoir.

If it becomes clogged with dirt or other debris, the whole process will stop quickly.

You can also use a barrier to seperate the drainage layer and the substrate layer.

You can use:

  • A natural solution, such as a layer of sphagnum moss. You can reap multiple benefits, including water retention and antibacterial action. However, you might need to apply a thick layer (and it may not be to everyone’s liking).
  • A carbon fiber mesh is an artificial option. This mesh is thinner and more visible, but it must be water-resistant, as steel mesh can rust.

Both can be successful, but I believe networking is the better option.

Because of this, I believe that a light, fluffy base will not cause it to fall as much. This is why I don’t recommend using a protective layer.

Charcoal layer (optional)

Water purification can sometimes be done with activated carbon (though it is not clear how effective it is).

It really is a matter personal preference.

Keep in mind that if you choose to use charcoal as a layer, it is better to use thicker charcoal than fine powder. Even though the protective net is not completely closed, fine powder can easily flow through the drainage layer.

You have two options: activated charcoal or Horticultural charcoal. Both can be filtered but the first is more efficient and therefore more expensive.

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Closed terrariums substrate

Closed terrariums require different requirements than open terrariums. Like most soils, we are concerned about how it interacts and reacts with water.

Closed terrariums with sufficient light will only have a small version of the water cycle. The water will evaporate, condense and drip back into the soil. The water will have nowhere else to go so the container will retain more or less the same amount as the day it was closed.

This means that there are no additional ingredients to retain water on the substrate. It will always be wet 100% of time. You will need plants that can withstand constant root flooding for indoor terrariums, such as Pothos. However, you can expand your selection of suitable plants by increasing the airflow through soil.

Perlite is an example of an inorganic material with large particles that will help to prevent soil from becoming too dense. It should also allow for some airflow.

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Open terrariums substrate

Open terrariums can have a wider variety of substrate quality as you can adjust your watering schedule to fix any issues. Coconut coconut fiber, or something similar, can be added to the substrate to increase water retention. This will allow you to water less often and allows you to water more frequently.

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The best terrarium Substrate

The wrong question is asking about the best substrate for terrariums. The container doesn’t need a particular type of soil – you aren’t looking for the best soil to make terracotta pots.

There are a few things you should consider when constructing a terrarium base.

  • What are the needs of each individual plant or animal in the Terrarium?
  • What are the care requirements of the community? What are the care needs of all organisms? This will ensure everyone is happy with the care provided to the entire terrarium.
  • Is the terrarium properly drained? It is not. To make up the difference, will you have to modify the composition of your substrate?
  • Optional – Base aesthetics Beautiful dirt can also look great. Even if the substrate is not required, layers of substrate can make terrariums look better.

How to make a substrate for terrariums

You can make your terrarium soil as simple or as complex as you like. You can use dirt from outside, provided you don’t intend to provide it with orchids or other delicate plants.

This recipe will help you make terrarium substrates that are easy to maintain.

Terrarium filtration:

  • Half an inch activated carbon

Terrarium floor:

  • 2 pieces of regular potted soil
  • 1 part perlite, or float

Optional: Top Dressing

  • Sphagnum moss, living or dead

Place them in this order in your terrarium. However, you might want to plant something before they are fed.

Here is a list of common ingredients for terrarium substrates (and their uses).

This article is trying to show you that there are many ways to do things. It all depends on what plants you have and how often you maintain your terrarium. Here’s a list of soil- and terrarium equipment that you can add to your terrarium:

  • Potted soil is sterile and fertile soil that plants’ roots can use. This does not include microbiome
  • Perlite – Reduces soil compaction and increases air flow
  • Float – Reduces soil compaction and increases air flow
  • Vermiculite – Retains water and slowly releases it over the course of time
  • Coconut shell/coconut fiber – Retains water and slowly releases it over the course of time
  • sphagnum Moss – Mix in soil to retain water, or use mercury as carpet
  • peat moss – lower soil pH
  • Activated charcoal, an antifungal agent that reduces odors
  • Pea gravel is purely decorative and not functional.
  • Sand – Sand is used for decorative purposes only, and not for any functional purpose.

Pre-made substrates are the best for terrariums

You don’t have to mix dirt and create layers. I recommend buying a ready-made substrate mixture for your terrarium.

These are difficult to find because most searches for “terrarium substrates” will only return results for reptiles and amphibians. It is not possible to tell if the product is still suitable for growing plants if you aren’t interested.

Josh’s Frogs, a leading authority in bioactive terrariums or vivariums, has the best pre-made blend. It retains water and is suitable for all plants.


Unless you have your soil layers and draining system in check, terrariums are not suitable for plants to thrive. All the fun comes in the end with decorating your terrarium according to your liking. I hope this article on terrarium substrate layers was useful for you, if not please let me know down in the comments section and I’ll reply.

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