14 Ways to Create a Humid Terrarium


Keeping your terrarium at an optimal humidity level is essential for many tropical and aquatic reptiles and amphibians. De"mist"ify humidity with these 14 tips. 


1. Go Glass

Glass enclosures help to keep the humidity in the terrarium higher.  Most mesh enclosures provide great ventilation but at the cost of a lower humidity.

2. Choose Porous Substrate

Substrate choice makes a big difference in keeping humidity higher.  Substrates such as Exo Terra plantation soil and Jungle Blend absorb large amounts of moisture, slowly releasing it throughout the cage. Avoid non-porous substrates such as sand or crushed walnut.

3. Think Deep

Keeping deep soil in the cage prevents it from drying out quickly, even in a tropical setting.  Try to keep at least 3” of soil.

4. Mix the Soil 

Mixing the soil once a week allows moisture on the bottom the tank to be brought to the top and allows dry soil to be rehydrated.  If the soil has dried out too much, add some water into the mix and stir.  Be sure to not to make the soil marshy as this can cause the tank to become a breeding ground for mold and bacteria.  A good consistency is one where you cannot squeeze out water but the soil keeps its shape when balled up.

5. Add Moss

There are a few types of moss that when added into the soil will increase the amount of liquid the soil can absorb and will make it lighter.  Mix forest moss or add it in layers on the top of the soil to simulate a natural forest floor.

6. Mist Often 

Mist your tank frequently, taking special care to spray down dry areas.  Generally, misting 2 to 3 times a day is sufficient to keep even the most sensitive reptiles satisfied.

7. Choose a Large Water Dish 

If you notice your animal’s water drying out over night, increase the bowl size.  Many reptiles and amphibians, for example, frogs, enjoy having an oversize bathing area.  Be careful that the animal can still exit the bowl; drowning is always a risk – especially in young reptiles.

8. Select a Special Terrarium 

Exo Terra terrariums provide wonderful humidity control with their front ventilation and top screening.  The lid can be form-fitted directly on the top with Exo-Terra Hoods.  If there is no need for another hood and you would like to decrease ventilation, you can enclose the top in plastic wrap.  Remember, it is crucial to keep a cross draft in the tank. If the tank is completely enclosed, the air becomes stagnant and mold becomes an issue in the tank.  Certain species, for example, chameleons, need extra ventilation.

9. Check Temperatures 

If the bulbs are too hot for the tank, the tank can dry out too quickly.  Conversely, if the temperature is too low, the moisture from the soil does not have a chance to evaporate.  Match temperatures with your animal’s ideal temperature threshold.

Make sure you have an accurate thermometer and hydrometer to keep on top of both humidity and temperature. 


10. Get a Mist System 

If you live in a dry climate and do not have time to spray the tank regularly, invest in a mist system.  There are a few types of systems, depending on your needs. Some systems are enclosed in a waterfall, providing drinking water as well as humidity, whereas other systems are outside the tank and pump a fog into the terrarium. 

11. Relocate the Tank

Ensure that your tank is not directly by a window or under a heat/air conditioning vent.  The increase in air circulation can dry out the tank very quickly.

12. Create a Moisture Gradient

If you do not want to invest in a mist system, another approach is to create a natural moisture gradient in the soil using hydro-balls.  These are natural clay balls that absorb lots of water as well as provide surface area for beneficial bacteria that help clean tank.  A 2” layer of these balls on the bottom of the tank acts like an underground waterway that provides moisture throughout the cage.  Covering the hydro-ball layer with mesh followed by your regular substrate prevents the soil from sifting down into the balls. Top up the hydro-balls using fish airline hose as a siphon to the bottom layer.  After a little tweaking, this technique works very well and can be very rewarding.

13. Add Live Plants

Adding live plants into a terrarium will help increase the natural humidity in the tank.  This can be done in most tank sizes, but the larger, the better, so as not to crowd the animal’s space.  Do your research when choosing a non-toxic plant to ensure you find the best fit for your tank and animal.

14. Replace the Soil

In some cases, the soil (especially plantation soil) becomes old and does not absorb as much water as it did at one point.  Replacing the soil allows you to increase the humidity as well as clean the tank

Posted by Amy Dyck

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