Terrarium Soil Layers and Their Functions (with Pictures) - Smart Garden Guide (2023)

Terrariums are a beautiful way to display some of your favorite little plants and succulents. In fact, they are like a mini garden display case. There are many ways to build your terrarium, but you must start with the right foundation of layers of soil to keep your terrarium and plants healthy. Read on to understand everything you need to know about terrarium soil layers.

Terrarium soil layers

To build a successful terrarium use the following layers of soil;

  • drainage layer– This layer wicks away and retains excess moisture, reducing the negative effects of plant growth in a container with no drainage holes.
  • moss layer –This layer absorbs excess moisture and is a barrier between the soil and the drainage layers.
  • layer of coal- This layer helps absorb any toxins that may affect the health of your plants or odors that may build up in the terrarium.
  • bottom layer -This is the base that will house your plants. Choosing the right soil is crucial to the health of your plants.
  • Decorative bottom layer -I like to add one or more layers of decoration material like sand, decorative stones or shells between the soil. This gives your terrarium a great aesthetic.
  • vegetable layer -These are the plants that you place in your terrarium. Suitable plants differ depending on whether you are building an open or closed terrarium.
  • decorative layer –This layer adds to the decorative appeal of your terrarium.

While not all of these layers are essential, they all play a role in creating an attractive terrarium that will help your plants thrive. A drainage layer, a soil layer and a plant layer are essential. You can choose to use the others based on your preferences and the type of terrarium you are building.

Why bother with terrarium soil layers?

Building a terrarium is like building a house. You need a good foundation, good drainage, and the right conditions for your plants to grow.

Most plants need soil that provides support and provides the roots with oxygen, water, and nutrients. Terrariums are not ideal places for plants to grow without careful attention to drainage and soil layers.

Read more about how terrariums work in this article.

By carefully designing the environment for your plants, you can create a terrarium that not only looks fantastic, but also provides an ideal place for your plants to thrive.

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Open and closed terrariums

One of the first decisions you will make when building your terrarium is whether you want an open terrarium or an enclosed terrarium. A closed terrarium has a lid that allows moisture to collect inside. These are great for tropical plants that need higher humidity and moist but not soggy soil. Read more aboutHistory of the closed terrarium.

On the other hand, an open terrarium is better for succulents and cacti because moisture can evaporate. Succulents, cacti, and even air plants do best in an open terrarium and are at risk of rot in an enclosed terrarium.

The type of plants you want to grow in your terrarium will help you decide whether you want an open terrarium or an enclosed terrarium.

Choose a container for your terrarium

You need a glass container to start your terrarium and otherwise it's your choice. You can repurpose a used cookie jar, mason jar, pitcher, or anything you fancy. When building a succulent terrarium, you don't need a lid for the container.

However, if you choose a tropical terrarium, you may want to find a container that has some sort of lid to increase humidity and retain moisture. Once you've chosen your container, make sure it's clean and dry, and then you can start adding the layers.

Terrarium soil layers

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Let's discuss each layer in turn, starting at the bottom of your terrarium.

drainage layer

This layer is essential to safely store excess water at the bottom of the terrarium without it covering the roots and risking root rot.For more information, see my article on growing plants in pots without holes.The drainage layer is usually the bottom layer, although some people prefer to add charcoal or a decorative layer at the very bottom.

Depending on the size of your terrarium, lay out one to two centimeters of drainage material on the bottom. Don't skimp here, this layer allows excess water to drain away from your plants so they don't sit in the water and end up with rotten roots.

Pea gravel is a commonly used type of drainage layer, but you can also use something like small river pebbles, colored aquarium gravel, or small interesting pebbles that you've collected. Decorative stones, marine glass or marble are also good options.

Another idea for use in the drainage layer is LECA or Light Expanded Clay Aggregate. These pebbles are made of clay and are all natural. After the pebbles are formed from clay, they are fired in a kiln to make them porous and kill pathogens.

These clay stones provide plenty of drainage in your terrarium without adding too much weight like gravel might. LECA is pH neutral and gives your plants plenty of space to take root. Its LECA layer can also act as a mini aquatic to store water, reducing the need to water your terrarium.

moss layer

If you only put some soil on top of the drainage layer, over time the soil can seep into the drainage layer and be lost at the bottom of the terrarium. In this case you could get mold and rot and your terrarium could fail.

To prevent this, place a layer of dry moss or sphagnum over the drainage layer. This will prevent the soil from being washed out and will also absorb some of the excess moisture.

The moss layer adds beautiful color and texture to the middle layers of your terrarium. Make sure it's thick enough to prevent soil from being washed into the drainage layer.

coal seam

This is an optional layer but I think it is very important to the health and lifespan of your terrarium. The carbon layer acts as a filter to remove toxins and prevent odors from building up in your terrarium.

I find this layer works best on top of the moss layer, but some people just add it at the very bottom of the terrarium.

To do this, you can use charcoal or activated carbon. Some people have even used charcoal in the bottom of their terrarium. Your terrarium can function without this layer, but you need to be more careful to maintain optimal conditions.

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throw by solo

Your plants will grow in the soil layer. The layer of soil acts as an anchor for the roots and provides the nutrients your plants need to grow.

You should consider what type of terrarium you are building and choose the type of soil based on the type of plants you plan to plant in your terrarium. There are several options for the bottom layer.

  • potting soil -The simplest and cheapest soil for your terrarium is normal potting soil for indoor plants. This is a common choice due to its availability and cost, and works well for tropical plants.
  • African violets only -The Cornell University Extension recommends using African violet soil for your terrarium. African violet soil is a very light soil that keeps plants moist but not soggy.
  • just do it yourself -If you prefer, you can make your own soil mix using peat moss, vermiculite or perlite and sterilized soil. This will promote good drainage and prevent or slow down the growth of bacteria or mold in your terrarium.
  • Land of cacti and succulents –You may need to use soil geared towards succulents and cacti if this is the type of terrarium you are building. This soil drains much faster than other types.

decorative soil layers

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Once you've chosen what to use for the essential layers, you can add a little creativity by adding decorative layers of soil. In general, the thickest layer at the bottom of a terrarium is the bottom layer, which I like to subdivide with sand or decorative stones. This will make the outside of the terrarium much more interesting and attractive.

Any inert and decorative component can be used for this layer, such as colored pebbles, glass beads, small sea shells, etc.

vegetable layer

Of course, the choice of plants is one of the most beautiful aspects of terrarium construction. Smaller plants are a better choice for small terrariums as they don't overlap as they grow.

You need to stick to one type of plant, like any tropical plants or any succulents or cacti, as they have different moisture requirements.

Succulent terrariums need to be drier and require an open top and less humidity, while tropical terrariums can have closed tops that provide wetter and more humid conditions.

Good plants for closed terrariums

  • friendship plants
  • little peppermint
  • baby tears
  • spiderweed
  • african violets
  • flame palms
  • Fittonia
  • Adiantum-Farne
  • Mooskissen
  • Phalaenopsis-Orchideen

Read my article detailing some of the best plants for your enclosed terrarium.

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Good plants for open terrariums

  • Nadelkissen Cactus
  • chickens and chicks
  • Zebra-Haworthia
  • pearl necklace
  • paddle plant

decorative layer

You can give your terrarium your own touch in the decorative layer. This layer can be an extra layer of moss or something unique like colored aquarium gravel. You can even use a layer or layers of decorative sand (colored or not) if you wish. These items protect the plant's roots, help the roots stay anchored to the soil, and keep moisture where it's needed most.

You can also add decorative elements to this layer to show your personal style.

You could consider using all-natural items like seashells or pretty rocks, or something completely different like small sculptures, decorative plaques, tiny people, or anything you can think of that won't be damaged by dirt and moisture in your terrarium. . Use your imagination and be as creative as you want!

How to make your layers look more decorative

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As you build your terrarium you will notice the beautiful contrast of textures in the layers of terrarium soil. You can use this to your advantage to add interest to your terrarium.

Make sure your layers are thick enough to see the contrast between them. You can also shape the layers to create a flow in them, for example by making them higher on one side and lower on the other.

You can use multiple layers of different colored gravel or sand to create accent patterns and even match the colors of the gravel and sand to the colors of the flowers growing in it. Be creative and have fun designing your own terrarium.


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