In the previous post, we have discussed choosing and buying a terrarium for your crested gecko. After you have bought a terrarium for your crested gecko, you need to start the setup. In this post, we will talk about the best substrate options for your crested gecko’s terrarium/vivarium and how to make bioactive soil mix.
The substrate that you choose for your crested gecko should depend on its age. As with all other pet lizards, you need to remember that very young crested geckos are curious and learn about their surroundings.
This can mean that your baby crested gecko might try the substrate to learn about it. This can cause impaction, so you must be cautious to prevent that.
What are the best substrates for a crested gecko’s terrarium?
- Paper towels/newspaper/paper. Towel or newspaper is the best substrate for hatchling, baby and juvenile crested geckos. Using towels or newspaper will help your crested gecko avoid gut impaction. You can also use a thicker paper (for example butcher paper) if your crested gecko is ripping and ingesting it.
- Soil mix. Crested gecko’s require high humidity levels in the tank, so substrate that can absorb moisture is suitable the most. Start using soil only with sub-adult crested geckos, to minimize any ingestion. This will be when your crested gecko weighs around 10 grams, or is around 7 months old. We will discuss which soil to use and how to make it in a second.
What substrates should you not use for your crested gecko’s terrarium?
Carpet liner is not the best bedding for a crested gecko
- Sand. Never use pure sand in a crested gecko’s terrarium. There is a big misconception that crested geckos are tropical lizards and that you need sand for creating a naturalistic environment. That is not true, and sand in completely unsuitable. Sand can cause impaction in crested geckos, and is not what cresties have as a substrate in their habitat.
- Any granular or small particle substrates. These can be pebbles/rocks, sawdust, ‘pure’ potting soil only (it will be compacting) and any dusty sand/calcium carbonate.
- Carpet liner. Even though carpet liners might seem like a good option, but they don’t add to the naturalistic environment in gecko’s vivarium. What is more, high humidity levels in a terrarium might cause bacterial or mold growth on the carpet. This is because carpet liners barely dry in a crested gecko’s terrarium, also causing unpleasant smells. It is a good idea to avoid using any carpet liners or other artificial mulch liners for a crested gecko’s terrarium. If you decide to use a carpet liner, wash and dry it very often (every day or every other day).
What is the soil mix for crested gecko’s tank and why is it a good substrate?
As we have discussed, the best substrate for sub-adults and mature crested geckos is a soil mix. But why is it the best substrate? The soil mix is the substrate because it will absorb moisture and keep optimal levels of humidity in crested gecko’s tank.
It will also not need frequent changing, and you will only need to spot-clean and spray the soil with water. What is more, it will look naturalistic and allow digging.
Your crested gecko will dig to relax or to hide and cool if it gets too hot in the tank. The soil mix will bioactivate in the vivarium and help break down the feces and urates. You will be able to spot-clean the mix by scooping out the feces.
Impaction risk with the soil mix substrate
Even though the soil mix poses some risk of impaction from ingesting small particles of soil, coconut fiber or other materials, it has many benefits. Some owners choose to use only coconut fiber (coir), but crested geckos can ingest it.
It expands a lot when in contact with water, so expanding in a stomach can cause big problems. That is why you need to mix it with other ingredients.
To minimize the risk of impaction, make sure to mix coconut coir with soil and sift out any large pieces of substrate. The risk of impaction will still be there, but it will be lower.
Crested geckos will greatly enjoy the soil mix substrate that will allow digging and burrowing. This soil mix will also be bioactive, requiring less cleaning.
What is bioactive substrate? And how to bioactivate it?
If you prepare the soil mix with ingredients that we mention, you will create bioactive substrate. 
Being bioactive means that the soil will have bacteria and small organisms such as springtails and isopods, that will break down the feces (poop) and urates in the soil mix. These can look like small flies or bugs, but they are actually normal and important.
To bioactive the substrate, you will need to spray the surface of the ready substrate with water regularly. Make sure that the soil is always damp, but don’t spray any water before it dries a little.
Often, spraying once a day in the evening can be enough. The substrate should be damp, but never soggy. Once a week, wear gloves and use a scoop or something similar to mix the soil and pat it to settle. This will help move the waste and speed up its breakdown. Wash your hands afterwards.
If you care for the substrate correctly, it can remain bioactive for a 5-6 months or more. The best idea is to change the substrate every 6-8 months. The substrate should not smell.
How to make the soil mix for crested gecko’s terrarium or which one to buy?
- The first ingredient is the soil base/potting soil. You can buy ready potting soil (that will contain sphagnum peat moss), but make sure it doesn’t contain any wetting agents, perlite or vermiculite.
Orchid bark
The best idea is to get some organic potting soil without these added ingredients. As you will only need to change the substrate completely once in only 5-6 months, why not buy good potting soil? One of the examples of organic potting soil with natural fertilizers is this FoxFarm 12-quart ocean forest organic potting soil like this.
- The next step is to mix in some ingredients that will add structure and body to the soil and make it water-retentive – cypress mulch (such as this one by Zoo Med), peat moss (if potting soil doesn’t have it already) and coconut husk (such as Eco Earth, Coco Husk, or plantation soil from Exo Terra) and some sand (add around 10% of non-toxic play sand or other coarse sand).
- To make sure that the soil will have good drainage, add some turface (high fired calcined clay) and orchid bark.
So, to sum it up, you will need these ingredients to make airy, well draining and full-bodied soil mix.
40% of organic potting soil (and add 10% peat moss if there is none in potting soil, otherwise skip)
30% coconut husk/coir. If you are using a brick coco fiber, you will need to put it in a bucket and pour water on top of it. Follow manufacturer’s instructions.
After adding water and waiting roughly 30 minutes, the coconut coir will expand greatly. It is a good idea to start preparing the soil mix with coconut coir to see how much product you have once it is mixed with water, because it will expand a lot.
10% sand (coarse sand or non-toxic play sand)
10% turface
5% orchid bark
5% cypress mulch
Coconut coir (fiber)
But if you don’t wish to mix so many ingredients, try this mix:
45% of organic potting soil (if there is no peat moss, add it yourself)
40% coconut husk/coir
15% sand (or better 10% sand plus 5-10% orchid bark + turface if possible. If not, use 15% of sand).
This mix will be easy to make – just wet the coconut coir, mix with soil and sand, orchid bark and preferably turface. It will be also cheaper.
A very useful tip would be to keep adding dead leaves on top of the soil because it will minimize any chances of your crested gecko ingesting the soil mix and will help with fertilizing the soil.
You can also put this reptile moss in some areas of the terrarium, on top of the soil mix. This will add water retention qualities to the soil mix. If using leaves, make sure they have not been sprayed with anything.
Can I use only coconut coir (fiber) as a bedding for a crested gecko?
Generally, it is not recommended because of the risk of impaction. But if you can’t create the soil mix, you can try use a coco fiber as a substrate, but only with mature crested geckos, that are around 10 months old, or 20 grams. If ingested, coco fiber will expand, so the risk of impaction from using only coco coir is high.
How to lay the soil in the crested gecko’s vivarium?
The best idea is to have a ‘drainage’ level under the soil mix in the vivarium. To make this drainage level, add around two inches of clay pebbles, gravel or rocks. Drainage level will soak in excess water and prevent the soil mix from becoming soggy.
On top of the drainage level, add around 2-3 inches of the soil mix that you have prepared. Make the soil mix moist by spraying the soil with water and pat it to make flat. It’s ready!
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