For the last few years we have been using Sphagnum moss as our barrier layer in terrariums.

What is a barrier layer?

A barrier layer is the layer in between the drainage layer and the terrarium soil. It prevents the soil from falling down into the drainage pebbles and mixing with them.

What are the issues with Sphagnum Moss?

We are finding it difficult at the moment to ethically source it. Sphagnum moss is normally the main species of moss found in wetlands and excessive harvest of it can mean the reduction of biodiversity in wetlands and loss of fragile habitats.

It can also cause issues in a terrarium such as:

  • pH Levels: Sphagnum moss is naturally acidic, which can alter the pH levels of the soil and harm certain plants. This is especially true for plants that require a neutral or alkaline soil pH.

  • Water Retention: Sphagnum moss is excellent at retaining moisture but  it can also hold onto too much water, leading to soggy soil and plant root rot. This can be an issue in closed terrariums where air circulation is limited.

  • Fungal Growth: Sphagnum moss can also promote fungal growth, which can be damage your plants. This can happen if the moss is not sterilised before use.

  • Thick Layer: Sphagnum moss is bulky when hydrated and it takes up a lot of room in a terrarium, especially if it's a small one. We would prefer more height for the plants and moss to grow.

What are you using now as a barrier layer?

Because of all of the above reasons we are moving to fiberglass mesh. Using fiberglass mesh as a barrier layer in a terrarium has many benefits.

  • It provides a sturdy physical barrier that prevents the soil from mixing with the drainage layer. This helps to maintain a healthy and stable environment for the plants in the terrarium.

  • The mesh allows for good drainage of any excess water, preventing water from accumulating at the bottom of the terrarium and causing root rot. The mesh also helps to distribute water evenly throughout the drainage layer, which promotes healthy root growth.
  • Fiberglass mesh is very durable and is a long-lasting material. It can withstand the moist and humid conditions of a terrarium without degrading or rotting. This means that it can be reused multiple times, making it a cost-effective option in the long run.
  • Finally, fiberglass mesh is very easy to work with and can be cut to size to fit any terrarium. It can also be easily cleaned and sterilised to prevent the growth of harmful bacteria or fungi.

We have been testing it for many months in our new terrarium builds and are very happy with the results. Adios sphagnum moss!


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