Vermiculite,how is it prepared and should i bother?


Mar 20, 2017
So i was shopping for groceries last week and came across with a bag of vermiculite,it came across to me when i was reseaching for good substrate and additives, i never did much research about it in particular and bought it on the spur if the moment, i did some experimenting and on its as is condition(uncompressed),
I placed some of it on a bowl of water for 24hrs to see just how well it can retain moisture and it seems i was giving it too much credit,it didnt really retain a lot of water.sure it does compared to cocopeat(my main subs btw) but relative to its volume,it seems like its more of a packed air than water. Maybe thats why it retains moisture longer,because there is almost none in the first

I plan to place it underneath the enclosure of my fossorials to give them a cooler bottom.but the problem is,it seems like it wont really do that much difference than i was hoping that it would(based on my little experiment),so for the sake of those Ts that I prefer more moisture in the substrate,should i bother with it?or should i just stick with what i got,which is purely cocopeat.

And how do u guys prepare your vermiculite?i am assuming that it should be soaked in water before placing it in the terrarium yes? And how do you replace the moisture lost by the vermiculite overtime,just plain spraying?

I could really use your opinions folks,i dont wanna cause stress(for me and my Ts) from rehousing when there is nothing gained. :)

cold blood

Staff member
Jan 19, 2014
Its popular in Europe and is generally mixed into the sub in fairly small amounts. That said, I have been keeping ts from all over the place for a good long time, and I haven't ever even considered using its by no means something you need.

I personally just see it as more work, and a little more cost.

IMO if you want a good sub for burrowers that holds water for long periods, just use peat moss or mix it in. Its super light, which is nice for enclosures that demand a lot of it, and although hydrophobic when dry, eventually it does soak up the water, and when it does it holds moisture like nothing I have used.

What sub you use is purely your choice, which you choose will simply alter how much and how often you are adding water....for species kept dry, they're all going to be the same. Top soil dries quickest and is heaviest...its also the only sub that wild tarantulas actually live on and its by far the least expensive. Its density also means this is the one sub that doesn't need to be tamped down....its what I use for most of mine.

D Sherlod

Dec 30, 2016
Vermiculite is usually mixed with top soil to help retain moisture. As Cold blood said topsoil is the worst at holding moisture so additives are used.


Dec 25, 2014
I use vermiculite fine grain (fine, not heavy/rough one) only for the archnids/inverts that needs a more 'humid' environment... like Asian/Tropical burrowers or centipedes.

I just mix a (large) tea spoon of that in the substrate and I have the right level of moisture-balance for months u_u