Tarantula Substrates: What’s Best?

Tarantula keeping has come a long way since its early days.

We now have more species available, new types of cages and a better understanding of tarantula husbandry than ever before. In terms of keeping tarantulas, one of the most hotly-contested subjects is that of tarantula substrates.

Each have their own strengths and weaknesses but what really is best?

Best Tarantula Substrates

Let’s start with the good substrates; the ones I strongly suggest that you focus your time on. Use one or more of these (in combination) and you shouldn’t go too far wrong…

Coco Fibre (Coir)

Coco fibre, also known as coir, is an eco-friendly product which has long been popular with gardeners.

This product looks and behaves quite like compost, but comes from renewable resources (unlike peat moss).

Josh's Frogs Coco Cradle (10 liters)
  • ECO-FRIENDLY ORGANIC and 100% BIODEGRADABLE unlike some reptile substrates that are contributing to deforestation and then go to the landfill
  • INCREASES HUMIDITY for animals that need moderate to high humidity
  • ABSORBENT composition allows it to soak up messes and odors, leaving a cleaner habitat for your pet

These are simply soaked in water for a few minutes, whereupon they will absorb water and expand. Simply drain away any excess water and use in your tarantula cage.


  • Looks great
  • Easily stored in brick form
  • Excellent for digging species
  • Good water absorbency


  • Not the cheapest substrate available
  • Takes up to 30 minutes to fully expand so not ideal for a quick clean-out

Vermiculite & Perlite

Scorpion on vermiculite substrate.

These two products are inert mineral compounds, capable of absorbing huge amounts of water.

When I first started keeping tarantulas back in the early nineties (I kid you not) vermiculite was considered the “ultimate” tarantula substrate.

These days things have moved on rather, with many keepers believing that their pets dislike standing on it.

While vermiculite still certainly has its place, it is now more commonly used as a mixer – such as with potting compost.

Josh's Frogs Sprig & Stone Vermiculite (1 Quart)
  • Allows better drainage & aeration when mixed with soil
  • Great soil conditioner
  • Ultimate incubation media for many reptile species

Using it in this way the substrate isn’t unpleasant to stand on and yet helps to retain moisture in the cage.

Related:  Can Tarantulas Climb Glass?


  • Absorbs plenty of water
  • Rarely if ever attracts mould
  • Very light
  • Freely available from garden centers


  • Looks pretty unsightly
  • Some tarantulas don’t seem to like it

Potting Compost

Potting compost is another popular substrate which is available cheaply from most garden centers. It looks attractive and provides excellent opportunities to burrow for those species so inclined.

The only real downside I have found while using it is that some composts dry out quite quickly – hence why some people choose to mix in some vermiculite.


  • Cheap to buy
  • Easy to source
  • Looks good
  • Ideal for burrowing


  • Can be heavy
  • May attract mould
  • Avoid composts with added chemicals (fertilizers etc.)
  • Avoid composts with large chunks in them


Moss can be bought in compacted blocks from many reptile stores, soaked in water and then used as a tarantula substrate.

Exo Terra Forest Plume Moss, 7 Quarts, 2-Pack
  • Natural Substrate: Exo Terra Forest Plume Moss is real, completely natural compressed moss grown in tropical Asia.
  • Ideal Use: Ideal for increasing humidity in the terrarium and is totally safe for frogs, salamanders, amphibians, wetland environment reptiles, and burrowing or digging animals.
  • Humidity Enhancing: Extremely absorbent and is great for use in humidifying shelters.

The good thing about moss is that it can look really smart in a tarantula cage and is excellent at absorbing water.

On the downside, of course, moss doesn’t allow your tarantula to burrow which for some species can be a handicap.


  • Looks awesome – rainforest setup anyone?
  • Absorbs loads of moisture
  • Lightweight


  • Useless for burrowing species

Want some inspiration? Check out this collection of exotic pet set-ups I’ve been gathering to see just what’s possible with a little time and effort…

Follow Keeping Exotic Pets’s board Reptile Enclosures & Terraniums on Pinterest.

Bad Tarantula Substrates

So that’s the winners out of the way.

However while it would be impossible to ever list every bad choice of substrate, it does make sense to list some of the more common suggestions seen so that you can understand why they should be avoided…

Related:  Why Do Tarantulas Lose Their Legs?

Bark Chips

Bark chips come in a range of forms. There are fine dark chipping often sold as “rainforest bark” in reptile shops and there are lighter chippings such as beech which is popular among snake keepers.

All of these options though have a number of weaknesses.

Not only do they absorb very little moisture but they’re also highly likely to go mouldy and start rotting in the warm and humid environment that tarantulas need.

Added to that the fact that they aren’t ideal for burrowing, these substrates generally have very little application for tarantula keepers.

Corn Cob Granules

Corn cob granules may be environmentally sound, and popular with reptile owners with desert-type reptiles, but once again these granules tend to rapidly go mouldy and need to be constantly removed and replaced. Not an ideal substrate.


Sand isn’t necessarily the worst substrate out there, but tends to be very heavy and doesn’t make for very good water retention.


Tarantulas seem to dislike standing on gravel and will spend much of their time trying to climb up the walls of their cage away from it. This can lead to damage if the spider falls so should be avoided.

While it doesn’t tend to go mouldy, for obvious reasons it is next to hopeless for retaining moisture in the cage.

Conclusion: What Is the Best Tarantula Substrate?

Personally after keeping literally thousands of tarantulas over the years I believe that the very best substrate for tarantulas is coir.

It is light, friable, excellent at retaining moisture and just looks great. As a second choice I would opt for potting compost combined with some vermiculite to retain moisture (3:1 ratio or there abouts).

On top of this I often (but not always) use small amounts of moss just to decorate the cage. As I’m  very into naturalistic setups for my exotic pets,

I love nothing more than to buy a new Exo Terra and spend some hours with bags of moss, bark, wood and so on to turn it into the semblance of a tropical rainforest.

What is the best tarantula substrate? In this guide a tarantula keeper with 20+ years of experience delves into the various options to see which ones really perform best. Handy hints for anyone keeping pet invertebrates.

Tarantula substrate pictures c/o The_Gut Furryscaly & @TripDawg

Richard Adams

14 thoughts on “Tarantula Substrates: What’s Best?”

  1. I read your whole article. I have a question can I put in shrubs in the tank to give it a more lively place to live? If so what do you recommend? I have a Mexican Fireleg Tarantula I got her today . The guy recommended meal worms but she did not even try to get it.

    • Hi Dawna – some keepers use live plants in their tarantula cages, though of course you’ll then likely need a suitable light to ensure the plants grow successfully. Personally I use high quality silk plants in many of my cages. Regarding the mealworms, tarantulas can refuse to eat for a range of reasons. If the spider is new to you then it might just be taking some time to get used to its new surroundings. Some tarantulas in my collection seem to find mealworms less appealing than more “active” prey like locusts or roaches, so if your issue continues then you could try an alternative food source.

  2. Ive had a Chilean rosehair for 11 years. Although literally *everyone* says not to use bark/chips, its the only bedding my tarantula seems to tolerate. Ive tried coco fiber, she dislikes it, and climbs the wall of her tank. Using the chips makes me nervous, so i add moss around the edges. She seems to like the moss…she even moves it around in the tank. “Redecorating “, I call it. 😉

  3. I read the article and I have a questions, I have a mexican red rump tarantula and I got het today, what substrate is the best to use for a mexican red rump tarantula? Because I’m not really sure what substrate to get

    • Hi Rylee – I’m keeping mine on coconut fibre (coir) and they do really well. It also allows allows for burrowing. Potting soil is also popular among many tarantula keepers as a second option.

    • Hi Jeff – to my knowledge there is no real difference in terms of the substance. Many people like the compressed bricks as they save space when stored (dry) at home. Personally I prefer the looser coir substrates. I find they need less/no soaking, so are less likely to create an overly-damp environment for your spider. Coir bricks that have been heavily soaked can take quite a long time to dry out to a suitable level.


Leave a Comment