The Best Substrate for Blue Tongued Skinks main picture

The bedding or substrate that you choose for your blue-tongue skink has an immense effect on its mental as well as physical health and well-being.

But, when you have literally dozens of substrate options, which one is the best for your little bluey?

In this article, I am going to answer just that.

For the short and quick answer, I would recommend:

Why Substrate is Needed

Substrate is needed for a few reasons, but most importantly;

  • It is needed to maintain the humidity of the terrarium or vivarium
  • It is needed to allow for your blue-tongue skink to burrow and hide when it wishes

The humidity level inside your terrarium is crucial.

There are 8 separate species (and more subspecies) of blue-tongue skink, and many of them require quite different humidity levels.

Northern and Eastern Australian Blue-Tongues come from sub-tropical areas with a humidity level generally between 30 to 50%, while Indonesians, Maraukes and Irian Jayas come from tropical, jungle areas with higher humidity levels.

If the humidity level inside your terrarium is inappropriate, it can have serious health consequences for your blue-tongue’s respiratory system, and can eventually lead to it falling ill or even dying.

Thus, the substrate that will be best for you, is ultimately going to depend on what specific species your blue-tongue is.

Humidity is important, but so is the ability to burrow and hide.

This also plays a crucial factor, as blue-tongues in the wild live in burrows, and tend to “hide” themselves under piles of leaves or plants, allowing them to get out of the open and feel safe and secure.

So, any substrate that you use that doesn’t allow for this is going to have a huge, negative affect on your blue-tongue’s mental health.

Since I am on the topic of physical and mental health, I want to make one last important note, which is to, whatever bedding you choose, make sure that it is completely free of any reptile mites before putting it into your live vivarium.

Reptile mites are a giant pain-in-the-you-know-what, and believe me when I say that an ounce of prevention is worth twice the cure. If you purchase any bedding or substrate from any store that has live reptile animals, there is always the possibility that the mites have gotten into some of the substrate.

You can 100% ensure that no mites will get into your terrarium by either baking or freezing your substrate before putting it inside the cage.

To bake it, divide up the substrate into sections, place it into separate baking pans and bake it, it at least 215 F for at least an hour. Mites can’t survive in temperatures over 130 or so.

The other solution is to freeze them. You can do this by putting the substrate in a freezer for a few days to a week (close to a week is better). This also will kill everything inside.

Now, when it comes to the best substrate for your blue-tongue skink, I need to divide things here.

The best bedding for your skink will depend on whether it is a high humidity animal (Indonesian, Irian Jaya or Marauke) or a moderate humidity animal (Northern, Eastern or other).

However, many substrates are good for both high and moderate humidity types, so there is a lot of overlap here.

Also, you will need to monitor your lizard for a few weeks, as even if the substrate is considered very safe, if it’s feces is full of substrate, that is evidence that your lizard has been consuming it, and you will need to immediately change it.

Best Substrates Indonesian Blue-Tongue Species

 Cypress Mulch 

If you have a blue-tongue skink, and you are unsure about what species it is, or you are just unsure about any particular substrate, the best thing you could do is to go with cypress mulch, at least as a base.

Cypress mulch is awesome.

It retains humidity very well, so it works well with high-humidity animals, but it also works well with the moderate-humidity Australian species as well.

It comes in two forms:

  • Mulch
  • Bark

Mulch just refers to any kind of organic compost that you put over soil, usually to protect the roots of plants that you are gardening. The cypress part comes from what is added in; shredded cypress trees.

This substrate works well by itself or mixed in with other compounds, especially sphagnum moss, coco-fibre and coco-husk.

The advantages of cypress mulch:

  • excellent at retaining humidity and moisture
  • nice, soft and pliable bedding
  • easy to burrow in and hide
  • can be sprayed with mists
  • works very well with Australian species by itself, and Indonesians and Irian Jayas when mixed with other substrates
  • inexpensive

The only real downside to cypress mulch is that if your skink drops some food into it, it can be easy for mold to grow and spread, so you’ll have to keep it clean.

The cypress mulch from Zoo Med is ready to go as is, but if you decide to get it from a local shop, you have to make sure that is isn’t dyed, and has no chemicals or additives mixed in.


Topsoil is, as it’s name suggests, soil that is often jam-packed full of organic matter that makes up the outermost layer of soil.

It’s also great for high-humidity Indonesian species too.

The biggest advantages to topsoil are:

  • usually quite inexpensive
  • usually easy to get
  • very good at maintaining a high-humidity
  • can easily be fixed with other substrates, such as coco-fiber
  • replicates the Indonesian species’ native habitat quite well

If you do decide to go with topsoil however, make sure that you it is organic and free of any toxins, and doesn’t have any of those white-ball looking things inside (those are for plants and will be harmful for your skinks).

The downside to topsoil is that it is quite difficult to keep clean (basically impossible, being soil), and you’ll have to stay on top of scooping out any feces or food that gets dropped onto the soil as mold can quickly grow.

Coco-Fiber & Coco-Husk

Coconut is another great choice for Indonesian species, especially mixed in with other substrates such as topsoil or cypress mulch.

It comes in 3 forms:

  • bark
  • husk and fibre
  • soil

All coconut products retain moisture very well, but of the 3, it’s the husk and fibre that you want the most.

Coconut husk and fibre are different however; husk is very fine and ground-down, whereas fibre is a bit blockier and bigger. Both husk and fibre can be used wet and dry, and both are best when mixed to a ratio of 1-to-1.

It’s excellent at helping to keep the humidity level high, and also gives a “native” feel to the terrarium.

Sphagnum Moss

Sphagnum moss is a type of moss that is found in places like New Zealand, North America and Ireland, in mild, temperate climates. With sunlight, it grows in abundance on topsoil.

What’s so special about sphagnum moss?

Quite a few things, as it is one of the best things that you can put into your terrarium with your Indonesian species blue-tongue:

  • it is very mold resistant
  • mixed with other substrates such as cypress mulch, it will increase the humidity level of your terrarium (perfect
  • if you are having trouble getting your cage humid enough)
  • looks very “native”

Sphagnum moss isn’t typically used on its own, but more as a “supplement” to a good cypress mulch or topsoil base.

If you decide to go with some shagnum moss, make sure that you get it from a specialty pet store instead of a general gardening warehouse, as it may be dyed, which will be harmful to your skink.

You’ll also need to bake it or freeze it for a week before placing it into the vivarium as reptile mites often find their way into this type of moss.

Lastly, whatever you do, make sure that your sphagnum moss isn’t labeled as “peat sphagnum moss” as peat moss and sphagnum moss are very different. Peat sphagnum moss is more like a bog of moss, and doesn’t have the same properties as regular, organic sphagnum moss.

Fir Bark 

Fir bark is a potting soil that uses, you guessed it, the bark of fir trees.

It’s very good when used as a supplement or mixture to cypress mulch or topsoil, and helps to keep the humidity high, but you can’t use it on its own.

You can mix it when dry or damp, and it mixes rather well with sphagnum moss, so it’s very multi-purpose.

In my opinion, it also looks quite nice in terrariums as a contrast to something like sphagnum moss or coco-husk or fibre.

This supplement to your base is sometimes referred to as orchid bark or orchid mulch, but just beware that some brands use pine rather than fir trees, so double-check the label before buying any.

Best Substrates for Australian Species

Aspen Wood Shavings 

Aspen wood shavings come from Aspen, which is a type of tree that grows in colder climates. It is firm, but soft, and lacks any of the phenols (an aromatic organic compound that gives off a scent) that are inherent to other woods, such as pine and cedar.

Aspen wood shavings are one of, if not the most popular forms of bedding for Northern and Eastern Blue-Tongues.

Here is why aspen rocks:

  • It allows your blue-tongue to easily hide and burrow
  • It can be safely ingested in small amounts, and will pass through your blue-tongue easily
  • Looks nice in the terrarium
  • Does a good job of keeping the humidity at 20-40%

Aspen shavings will suck a lot of moisture out of the air, which is they don’t work for Indonesians and Irian Jayas, but it works very well with Australian species.

This also comes in a shredded form, but you should avoid that however as these are very thin, small pieces that have been known to become stuck inside skinks’ noses when they burrow.

Some types of aspen shavings are known to be a bit dusty, so you can avoid this by only getting filtered aspen. Likewise, avoid rabbit aspen, as it’s not made for blue-tongues and, like the shredded, too “splinter-like.”


Sani-chips look great in terrariums. Basically, these small chips are a type of aspen wood bedding that are extremely small, much smaller than regular aspen shavings.

They absorb moisture very well and do a great job of keeping the humidity level stable, plus because they are small, but not splinter-like and thin, they won’t get stuck or lodged anywhere up in your lizard’s nose or eyelids.

They are very soft and pliable, and easy for blue-tongues to move around on and burrow into.

The only downside to them is that they can mold quickly when they are wet, so you’ll have to often do terrarium checks.


Care-Fresh is a type of pet bedding free that is made up of fiber and old paper, free of any dye, toxins or other harmful chemicals and additives. They are often used with animals such as hamsters, but can be safely used for blue-tongue skinks as well.

Like the Sani-Chips, they Care-Fresh is very small, easy to burrow in and is good when used as a base or stand-alone substrate.

The downside to it is that it can mold quickly when it is wet, and some pet owners have noticed that it dries out blue-tongues stomachs quickly and sometimes causes shedding issues.

I haven’t used Care-Fresh myself with any of my blue-tongues, so I would probably advise you to first go with something like aspen or Sani-chips as a substrate before trying out Care-Fresh.

It can also be quite expensive, which is another reason to start with something else.

Substates to Avoid

Sand or Calcisand or Gravel 

Never, ever use sand as a substrate.

At first glance, you’re probably thinking, but Northerns and Easterns live in the outback, they live on sand.

Well, for starters, they might sometimes wander on sandy surfaces here or there, but they are generally found in burrows, or under bushes and foilage for a reason.

This also applies to “calcisand” or calcium-sand too.

Basically, the risks involved with sand are too great considering any potential upsides, the only real upside being that it usually looks nice in a vivarium.

For starters, it can cause impaction, which is basically when the internal digestion system of a blue-tongue skink becomes blocked or clogged from consuming too many grains of sand. This then, can ultimately cause an early end to your blue-tongue skink.

It does retain heat well, but you would need to constantly stay on top of keeping it clean, and you would need to have a separate feeding area for your skink to eat in.

Sand can also be rough on skinks’ bellies, and cause them to dry out.

But worst of all, sand (and especially calcisand) can cause your blue-tongue skink to lose its toes.

This happens because a blue-tongue skinks toes are incredibly thin, delicate and susceptible to low-moisture environments. And because sand and calcisand basically sucks the moisture out of the air, it will suck out all the moisture of your blue-tongue’s toes, cause reduced circulation and with that, lost toes.

This is, unfortunately, common simply because most blue-tongue owners are unaware of this.

Your better off simply avoiding it at all costs.


People is definitely a bit of a mixed bag, which some saying that some forms are OK to use and others advocating that you just avoid it.

Personally, I think the cons simply outweigh the pros.

Paper comes in many forms:

  • shavings
  • pieces and shreds
  • pellets
  • cotton-like fluffy balls

Never use any type of dyed forms of paper, such as newspaper. The ink on the paper could possibly be toxic to your blue-tongue.

And it also has a huge advantage in that spot-cleaning is incredibly easy and simple.

However, the pros just about end there.

First of all, paper is absolutely terrible at retaining humidity, which means that it is unusable for any Indonesian species. It’s not really fit for Australian species too though, because it gets soggy and falls apart when you wet it during misting.

Also, paper tends to have a drying effect, and while it’s not as intense as calcisand, it will suck moisture out of your blue-tongue skink’s toes and eventually, lead to toe loss.

So, if you’re going to use it, I would suggest only using it for temporary periods of time, or in limited amounts.


Carpet is absolutely one of the worst types of substrates for blue-tongue skinks.

There are specially-designed carpets just for reptiles, but I would steer clear from them for blueys.

Carpet has a few advantages, in that it looks very nice, can come in any color you want and tends to be resistant to bacterial and mold growth, but it has one huge, major and debilitating flaw:

Skinks cannot burrow into it.

This is crucial, as skinks in their native habitat live in burrows and in things like bushes and foliage. It psychologically makes them feel secure and safe, and so depriving them of this ability is going to tax them mentally.

It would be like forcing you to walk around naked everywhere. You could do it, but you’d feel incredibly awkward without your clothes.

Skinks need the ability to burrow and hide, so just ditch the carpet.

Pine or Cedar 

Pine and cedar are both big no-no’s. Never, ever use any product that is made with either.

It looks nice, and may smell nice to you, but that’s about it.

They both have oils that are irritating to the skin of skinks, but more frightenly, contain aromatic compounds called phenols which are toxic and quite harmful to your blue-tongue skink’s respiratory systems.

Corn or Walnut Shell 

Corn shells or cob, walnut shells, and any other type of shell for that matter is better just being avoided.

For starters they are terrible at humidity retention, but more importantly, they can be (and probably will) be ingested by your skink, probably at some point causing impaction.

That’s notwithstanding the fact that they can be crushed up into jagged, irregular pieces that can get lodged up in your skink’s nose or even eyelids.

Avoid them.

Cat Litter 

This is quite possibly the absolute worst substrate to use.

Never, ever use it!

It cannot keep humidity high, which means Indonesians can’t use it, but even more dangerously, it completely sucks the moisture and oxygen out of everything that it touches.

You can’t really mist it either because cat litter becomes soggy and clump when wet.

If your vivarium uses cat litter as a bedding, your blue-tongue will become dehydrated, and probably at some point, die.

It is also quite dusty, and can cause eye and respiratory infections.

Sand, calcisand, paper, carpet, shells and cat litter are just a few of the substrates you need to avoid. By no means is this list comprehensive, as there are quite a bit more, including:

  • Alfalfa pellets
  • Astroturf
  • Untreated topsoil
  • Larger rocks

Generally, you’d be wise to choose from any of the recommended substrates on this list above.

For an overall best blue-tongue skink substrate, I strongly recommend that Australian species use Aspen, Sani-chips, cypress mulch, or topsoil as a good base and mix in things sphagnum moss, coco-fiber or coco-husk.

For higher humidity Indonesian species, start out with cypress mulch or a topsoil as your base, and add in something like sphagnum moss, coco-fiber, coco-husk or fir bark.