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Bioactive Soil as a Substrate Choice


Bearded Dragon Veteran
Ive had a few people ask about my substrate choice, and thought I would go over it on its own thread so as to not hijack others. Its a little long, so I had to break it up into a few posts.

I, and a growing number of other keepers, have made the switch to a more natural substrate choice, namely bioactive soil. I would like to premise this by saying that this is not the best choice for everyone. It does require some maintenance, and a certain commitment. It is not overly difficult or indeed really any harder to maintain than other substrates, but it does take some setting up and continued attention. If you neglect your tile floor, you just get a gross dirty floor, but if you neglect your soil, you can have other issues. I give this qualification because I have helped some to set this up, only to come back a few months later to see a bone dry, dead dusty substrate and keepers shrugging their shoulders like somehow it was the fault of the soil that their dragon is now having issues. Soil is a great choice, but you must pay attention to it like you pay attention to your animal. You are creating a living thing, a tiny microhabitat with its own inhabitants, its own nitrogen cycle, its own breath, in essence. If you take care of it, it will flourish and take care of your dragon. If you dont, it will die and be a rotting thing that can cause problems.

Ok now that the warning is over, lets get to the fun stuff. Like all wild things, dragons are part of a complex ecosystem, and are adapted to such. Its no mistake that they taste everything, and their bodies are adapted to the results of that. I believe they are not meant to be in a sterile environment, and that doing so creates its own problems. So instead, I started using a bioactive soil within the enclosure to create a mini ecosystem. It allows for more natural behaviours, looks and smells great, and if maintained, will be self cleaning for the most part. Ive had a few people ask how to set it up, so the following is a basic outline of how to begin.

First, make sure you have a waterproof enclosure. It doesnt have to be glass or plastic, but that is the easiest way of course. If you have a wood enclosure, you can seal it with an epoxy resin or multiple layers of a good polyurethane. Just remember that this will be heavy, so if its wood, it will need to be sturdy and sealed. For first timers doing this, I always recommend an aquarium or glass/plastic enclosure so that you can see how much you are watering.

To start with, you will need to create a drainage layer. This is so that when you water the soil, the bottom does not become waterlogged. With a drainage layer in the bottom, the excess water will flow through and then drain out of the soil and into whatever you use for your drainage layer, keeping the soil moist but not wet. There are many ways to create a drainage layer, but probably the easiest and cheapest is with what are called expanded clay pellets/balls, also known as hydroton balls. You can find them at any garden center, hardware store, etc. They usually come in big bags for about $10. Here is an example:

How much you need will of course depend on your enclosure size. You want to have a layer about an inch thick over the bottom of the entire enclosure. Some people also use that plastic grating that you see in fluorescent light fixtures in offices, often called plastic egg crate. Personally I think its a little harder to work with, and more expensive, but its up to you. Here is an example:


If you are needing to be even more frugal, then you can use just good ole gravel too. Get the bigger size, around 3/4"-1" size gravel, that has been washed already. Youll probably need to wash it again when you get it so that there is no fine material in the bottom of the enclosure, but otherwise it will do just fine. Again, all you are doing is providing a place for the water to drain out to. Again, this can be found at any hardware or garden centre. I think the last 25 pound bag I bought was around $4.


Bearded Dragon Veteran
Once you have your inch deep drainage layer, you need to cover it so that the water can get through but the soil doesnt filter down there too. Some people use the fancy weed cloth like this:


Personally, I just use fibreglass window screen like this:


It does the same job, but usually comes in smaller sizes so you dont have to buy 25 feet of the stuff. Often times the big hardware stores will just have it on a roll and you can buy however many feet you need. I think its usually about $2 for a piece thats 2 feet by 2 feet. When you have this just cut a piece big enough to cover the entire gravel/hydroton/egg crate layer completely. You dont want any holes or corner not covered or your soil will just fall down in the drainage layer, so make sure its covered well.

Once this is done, its time to mix your soil. Now there are many different ways to mix it but for burrowing animals, generally you want something like this: 50% topsoil, 30% sand, 20% humus (coconut coir, peat moss, etc). Topsoil can be bought in any garden or hardware store this time of year, for about $2 for a big bag. You dont want potting soil, or Miracle Gro or any of that stuff, just straight up topsoil. Like this:


If you happen to be lucky enough to live where you have soil that you are certain is free of pesticides, herbicides, toxic wastes, etc then just go out and dig your own! This will give you the added advantage of having the good bacteria and nitrogen cycle thriving already. Use the top 6" or so only as this is the most air rich, and so good bacteria rich, part of the soil. Break it up so that you can still mix it with the other stuff I mentioned, but leave all the worms, inverts, etc in there. For those of us using the bagged stuff we have to wait a little bit for the nitrogen cycle to get up to speed. For those of you that can go out and dig it up, your good to go right away.

For the sand, just buy some childrens playsand from any garden or hardware center. Its usually just a few buck for a 20 pound bag, but make sure its the childrens playsand so that you dont have to worry about any other junk in it. Its looks like this:


Then add to this any type of humus (no, not hummus like the delicious spread, but humus as in stable organic matter that doesnt break down and keeps your soil airy and light). The easiest and cheapest is usually coconut coir, and its best as its a renewable resource. You can use peat moss, which is also cheap, but not a very environmentally friendly choice. The coconut coir usually comes in huge sizes for gardens, so just get the smallest one you can find. It comes in compressed bricks that you soak in water or break up and mix with the soil, so the smallest size will be enough for just about any size enclosure. Here is a link for more than enough coconut coir:


Now take all that and mix it up at the ratios I mentioned above. It doesnt have to be exact, but roughly around those amounts. Make sure it is nice and moist, not wet, but moist. Once you have it all mixed up, take some in your hand and make a ball with it, like you would a snowball. You want it to hold its shape, but not be super compacted. That means that the dragon can make a burrow that will hold, yet the soil can also 'breathe' and have air transfer. Once you have a good, moist mix, then put this on top of the screen at the very least four inches in depth. It doesnt have to be perfectly level, so I usually build up one side a little higher, say 8-10 inches, and I usually dont go less than 6" anywhere. Tamp the soil down, but not super hard. You want it to be able to hold the burrow when you dragon decides to dig, but dont want to compact it too much. If you decide to plant live plants in the soil, then of course now is the time to do that also. Take them out of their pots and break up the soil ball they come in. Get rid of the soil it comes with as that is probably depleted anyway and may contain fertilizers. Then plant them directly in the soil as normal.

Once you have sculpted your soil the way you want it, its time to add the buffer. Because of the hot lights and ventilation, the soil would normally dry out quite quickly, especially if its only a few inches deep. You can help maintain the moisture, and keep it from increasing the humidity of your enclosure, by adding a buffer on top of it that is dry. This is usually through the use of leaf litter or moss. Dried moss can again be found at most garden centers and is usually used for decoration around plant pots inside the house. Id recommend the tree, feather or sheet moss, but make sure not to use Spanish moss. For dragon enclosures I usually use leaf litter though. It gives a good natural looking ground cover and stays dry. I usually use Live Oak or Magnolia leaves, but generally any leaves will do. Because I live in the city I have to have everything shipped to me, but again if you live in an area free of pesticides, herbicides, toxins, etc then feel free to go gather your own. This is another way to import some beneficial invertebrate life.

Which brings us to our last step, which is introducing invertebrate life to your microhabitat. The soil will harbour its own bacteria and nematodes, which are what power the nitrogen cycle, however the conditions for their health are further helped by adding some added invertebrates. The most common are isopods, springtails and earthworms. Isopods are usually the easiest to get, as our native isopods do very well within a dragon enclosure. Go out into any wooded area and lift up a rock or log and you will almost always find some. You can order tropical species in too, but Ive found that they dont do quite as well in more arid enclosures like this. Here are some examples of good isopods to use, Id recommend the Porcello scaber or Armadilladium sp:


For springtails, its easiest to just find the tropical kind. Both these and the isopods are usually bred by dart frog keepers. There are quite a few sites that sell them, so search around for the best price near you. With both the springtails and the isopods, just dump the little cup, with the substrate they come with, straight into the enclosure. They will find their way under the leaves and rocks and logs just fine. Here is an example of a page for springtails (actually I love these guys for just about anything vivarium related. Great customer service and very knowledgable):



Bearded Dragon Veteran
For earthworms there are a couple different choices. I usually use african nightcrawlers (Eudrilius eugeniae) for my enclosures as they do very well in warm soil. Most earthworms you get here have a hard time with such warm soil, but the african ones thrive in it. They are especially fast breeding too, which is nice for the soil. They will come out at night and eat any bits of salad or vegetables that are on top of the soil too, which is great. Plus they aerate the soil very well. You can also use red wigglers (Eisenia fetida) but the only disadvantage is that the dragons will generally not eat those. They produce a mild toxin when disturbed, to keep from being eaten. They are also much smaller worms, if that makes any difference to you. I like the idea that my lizards might eat some of the african ones if they dig them up as they are incredibly good nutrition (high in Calcium and other minerals), so I usually stick to the nightcrawlers. DONT use Canadian nightcrawlers for your soil. They require cooler soil (which is why they are kept in the fridge) so if you put them in warm soil they just turn into goo and stink up the place. Here is a good place for buying bulk worms (you can feed some to them and put the rest in the soil).


As I said before, the worms and isopods will dig their little tunnels and help aerate the soil, plus allow for a more evenly moist soil. The reason that is important is because the good bacteria (aerobic) and invertebrates (nematodes) that will break down the nitrogen and wastes for you love oxygen. The gross and bad bacteria (anaerobic) and fungus that can cause problems love it when there is less or no oxygen. So you want to keep in mind that there are certain things you will do to your soil to help it retain its oxygen. One of those is by turning the soil every two or three months. Just get a sturdy little hand rake, clear off your top layer of leaves or moss, and churn up that soil. That will aerate the soil while still keeping the bacterial cycle in place. If you have plants planted in the soil, be careful of the roots of course, but get as close to the plant as you can so that you can cycle the dirt close to it.

Its also important to make sure to keep the soil moist, but not wet. Depending on how much ventilation you have in your enclosure (open top or closed top) will dictate how quickly it dries out. I have open sides on mine, so I have to water the soil once a week to keep it moist. You want to allow the top to dry out a bit, so maybe the top 1/2 inch can dry out before you water again. Do not let it go much longer though. If you let your soil dry out totally and then water it, then dry out again, etc you will create great conditions for fungus. Fungus can kill off a lot of the good stuff, and is just generally not good.

I have a rainwater can, like used in gardens, so that I can simulate rain once a week. As your invertebrates thrive youll notice them all come out when it 'rains', which is kind of cool. (Sounds funny to say, but baby isopods are pretty cute). You'll notice when you water it that you can see the water rush down at certain points (earthworm tunnels especially) and filter through into the drainage layer. You dont want your drainage layer to get full, but each time you water some will go down there. I usually do a bit of watering, wait for it to soak in a bit, then go over it again, then wait and see how much trickles through to the drainage layer, then hit it again. For the first few times, wait about ten minutes between the waterings so that you can really see how much is going down into the drainage layer. After youve done it a few times you'll get used to how much you actually need to water. If you have live plants in the soil, you may need to water the area right around them a bit more often, so keep that in mind.

Remember, you are creating a biological cycle, much like you do in a fish tank with the water. It takes time for the good bacteria to thrive. So if you can, its best to set up your enclosure a couple of weeks before you put your dragon in. (Thats not always possible of course, so dont let it stop you from doing it) If you are putting your dragon in right away after you put in the soil, then for the first couple weeks just spot clean the dragon wastes out when you see it. After a few weeks, when the bacteria, nematodes, inverts, etc are thriving, youll notice that the wastes gets taken care of within about a day or two. All that will be left is the hard white urates. You can either remove them if you like, or they will naturally powder and breakdown into the soil.

Part of the cycle in the beginning is a sort of evening out of the various life in the soil. That means that sometimes you will get molds or fungal blooms. Its natural and should even out in a couple weeks, as long as you are not keeping the soil to wet. The isopods and springtails will eat the molds and the fungus should get outcompeted by the various bacteria as they thrive. Dont freak out though if you find some green or white stuff growing in a corner though. Just churn up the soil a bit and let it cycle through normally.

Now, I know that many times we are told two things that might make you hesitant about using a moist soil substrate. First, that this will raise humidity, and that this is bad because it causes respiratory problems. That comes from a bit of a misunderstanding in the first place, but is not totally without basis. In the wild these animals inhabit a very wide range of habitats, with humidity anywhere from 15%-65%. What that tells us is that they can handle varying levels of humidity quite well. However, the problem arises in a sterile enclosure with bad ventilation (and often times too cool temperature), which unfortunately is often the case with dragon enclosures. When you have a sterile enclosure with stagnant, very humid air you will get fungal and bacterial blooms quite easily. Breathing these in all the time will obviously cause lung problems for your dragon. Keeping a bone dry enclosure however, also has the potential to cause just as many issues as the lining of the lungs struggle to stay moist and so compromise their natural immune function. However, a healthy soil will counteract fungal blooms naturally, and proper ventilation will also keep blooms from becoming an issue. Basically, just keep your enclosures well ventilated and at proper temperatures and you dont have to worry about humidity. Do make sure that your humidity is around at least 30%, or you are going to be causing dehydration pretty easily.

The second thing that we often get told is bad is that all loose substrates cause impaction, so dont use any of them. This is probably the one I have to discuss the most as it gets drilled into everyones head, even by some well meaning vets. Let me be plain, substrates do not cause impactions. A healthy dragon could eat just about anything and it would pass through, just like you or I (I ate a couple pennies when I was a kid, and yet here I am). If it isnt digested, it will simply pass through the flexible intestines. Even larger things or sharper things are compensated for by the colon producing a mucus around the object so that it will get pushed through easier. However, there is one very serious stipulation here. This is only true of a healthy, hydrated dragon, because digestion and mucus creation require quite a bit of moisture. Without proper hydration just about anything can cause impactions, which is why you hear of too many mealworms causing impactions, or sand causing impactions or too big a piece of vegetables causing impactions. If your dragons digestive tract cant motivate enough moisture to process what it is ingesting, its going to be too dry in their and its going to get stuck. Your dragon can eat dirt, just like it does in the wild (some scientist have suggested that this is an important part of their diet for the absorption of minerals and why they touch their tongue to literally everything) and pass it easily, as long as it is properly hydrated. The wonderful thing about a soil substrate is that it allows your dragon to stay hydrated more easily. They burrow in the wild both to retain heat at night and also to retain moisture when its too dry. Down a burrow, the humidity is much higher than it is above ground. So with each breath (all animals must have the air moistened in their lungs to allow for air transfer) depending on the humidity of the air, they will lose their own moisture more quickly or slowly. Giving them a moist soil allows them to control their moisture loss in a much more natural way, rather than just having us as keepers dictate it to them. Like the heat and UV exposure, they know best what they need and we are just trying to provide a gradient for them to choose from.

I think thats covered pretty much everything, but please feel free to ask any questions you may have or share your experiences below. Thanks for reading!


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Jarich - thanks so much for sharing all of that wisdom. It certainly took you some time to put all of that in order. Your courtesy is sincerely appreciated. This looks like an awesome way to go.


Bearded Dragon Egg
Jarich, this is a well-written and thorough article, thank you for posting it! When I am ready to move our juvenile to her adult home, I will start a bio-active soil substrate for her. I garden and use a technique called "lasagna gardening" that uses layers of materials to build up a nutrient-rich bedding for the plants and encourages worm and isopod activity. Many of the layers are materials that you've used in your soil, so I will have a starter culture to incorporate.

Again, thank you!


Bearded Dragon Veteran
My pleasure, and glad to hear of others willing to give it a go. Please let me know how it goes with your new enclosures!


Hatchling Dragon
Very we'll written and informative! I love the idea of providing my dragons with a healthy ecosystem they can thrive in! Two of my dragons are already in their adult tanks but my third is waiting for hers. I will definitely try this for her so I can have time to really work on it and get it down before putting one of them into the environment. Then once I feel more confident, I will try it with my other two also. It's always bothered me that all the substrate forms (including tile and reptile carpet) seem to accumulate bad bacteria unless you can clean them constantly!


Bearded Dragon Veteran
Pics of said substrate and enclosures

Hi Luvthemanimal, was that post in reference to me or the above poster? Sorry not sure if that was for me or not. If so, here you go. If not, well he is pretty and everyone needs to see more of him anyway. ;)



Bearded Dragon Egg
This is a wonderful post jarich, thank you so much for all of the information. I am taking the plunge on this and have a question about the invertebrates (also sorry to revive an old post but i feel it's a relevant enough question) - how many african nightcrawlers are needed for say 3-4 cubic feet of soil in my 75 gallon terrarium?

looks like a pound of african nightcrawlers (smallest quantity available in your link) is about 100-300 nightcrawlers - that seems like a lot, especially if it's not the only thing in there and given that they reproduce quickly. is that too much or is it a good amount?

What about isopods/springtails (the isopods you link come 15 to a pack which seems like too few?)

please let me know your thoughts on invertebrate quantities.

Edit: if it matters, Yoshi is 3.5 years old and 22 inches


Bearded Dragon Veteran
If its just for the one enclosure, then yes, that will likely be too many nightcrawlers. Im sure there are other companies out there that sell them, that was just the one I happened to use as I had numerous enclosures to supply and I fed off my extras (they are great nutrition). For just the one enclosure I would think you could easily start with 30-50 or so and be great.

As for the isopods, most places sell them in about those quantities (15-20 per cup). These are just starter amounts, as they tend to breed fairly readily and quickly. You can definitely buy more if you want to have a good number right off the bat. I would personally get two or three different species and put them all in. That way you can see which species really thrive in your enclosure. I usually do the same with the springtails, put in a couple different species and see which do the best.

Hope this helps, let me know if you need any other questions answered.


Bearded Dragon Egg
Thanks a bunch jarich. Some really fantastic info. Yoshi already seems happier in his new environment and I can't wait to get some inverts in there to kick off the bio activity.

I do have one more question - the final dirt mix (3 parts topsoil including peat moss to 1 part sand) doesnt hold it's shape like a snowball as you mentioned in your post - but it's also barely moist. should i add water until it holds its shape better, or do you think i just picked a bad ratio?


Bearded Dragon Veteran
My guess would be that you might have a bit too much of the peat in it. Add some more topsoil to it and give it a mix if you can. You want it to stay moist though or you will start to kill off your bacteria in the soil, so you may want to add some moisture to it as well.


Bearded Dragon Egg
Thanks for the info. I had a lot of trouble finding safe topsoil that wasnt pre-mixed with peat moss, but I will keep looking. might be tough to mix very well at this point since it's all in his terrarium but hopefully i can till some in at least some or most of the way down.


Bearded Dragon Veteran
Excellent read; and awesome resources as always Jarich.

Always a pleasure learning from your experience. My 40Gal Breeder is way too small for this type of build; but when I move into my next house I will be upgrading to a large enclosure and trying this out for sure. Bookmarked for future reference. Thanks again for your great write up and resources!


Bearded Dragon Veteran
Thanks and glad to help.

Minispeck, if you have a spot that you know isnt sprayed with pesticides/herbicides then just go dig up your own topsoil. Its got the microbiota already thriving so its the best by far.