Humidity in Terrarium

How to Increase Humidity in a Terrarium

Most terrariums are designed with airflow in mind. They have vents on the bottom and a screen lid on top, which allows air to circulate in the enclosure and exit through the top. Because of this, it can be difficult to keep the humidity inside. This is both a good thing and a bad thing. Reptiles and amphibians need fresh air but, without the proper tools, it’s hard to retain the humidity. That’s the topic of this article; how to increase humidity in a terrarium.

I’ll show you the best ways to increase humidity without sealing your terrarium. From programmable misting systems to moisture retaining substrates and everything in between, you have an array of options available.

The Basics

Before we look at the different ways to increase humidity, it’s important to know the basics; how to check the humidity level in the first place and how temperature affects it. If you already know this information, feel free to skip this section.

Temperature Affects Relative Humidity

You’ve likely heard the term “relative humidity” when watching your local weather station on tv. This refers to the amount of water relative to what the air can hold. Warm air can hold more water than cold air; this means the relative humidity for cold air is higher than that of warm air.

Here is a simple illustration; you have two 10-gallon aquariums, both tanks are half full of water. One aquarium is in a room where the temperature is 50 degrees Fahrenheit and the other one is in a different room where the temperature is 100 degrees Fahrenheit. Well, the relative humidity will be higher for the aquarium in the room that’s 50 degrees. This is because cold air cannot retain as much water as warm air.

This should go without saying but, you shouldn’t decrease the temperature in your terrarium just to increase the relative humidity. Keep the temperature at the recommended levels for the species of frog you’re keeping.

How to Check Humidity Level

Checking the humidity level of your pet’s enclosure is the first step in determining whether or not it needs adjusting. This is most easily accomplished with a hygrometer.

Hygrometers are cheap and easy to use and you can find them at pet stores, lowes, home depot, Walmart, etc. What you’re most likely to find is a digital hygrometer thermometer combo. You place a sensor inside your reptile’s terrarium and it reads the temperatures and humidity levels. Some brands are stuck to the glass on the inside of the tank.

So, once you have a hygrometer you’re able to read the humidity level and determine whether or not it needs adjusting.

Misting to Increase Humidity

The first and most obvious method for increasing humidity is to mist the terrarium using a spray bottle. Fill the bottle with clean water, open the terrarium and mist the inside. Misting the enclosure adds water vapor into the air which increases the humidity. After finishing, close the terrarium and wait a few minutes for everything to settle. Watch your hygrometer and you should see the levels increase.

If your frogs require daily misting, you might consider investing in a portable spray bottle. These misters give you more control over the spray, hold more water, and, most importantly, are sprayed by holding down a button rather than repeatedly squeezing a handle.

Misting Systems

Programmable misting systems are among the most popular and utilized systems for misting terrariums. Once they’re set up, they do all the work for you. And as the first sentence suggests, they’re programmable, allowing you to determine when water is misted and how much is used. Clip the nozzles on the enclosure’s lid, run the hoses to the water tank and let it do the work for you.

Monsoon Misting System
Monsoon misting system

Exo Terra’s Monsoon misting system is a little pricey but, considering the amount of money you’re investing into your frogs, it’s well worth the price. There are more/less sophisticated misting systems you can check out by reading our review of the best reptile misting systems.

Humidifier / Fogger

The most appealing way to increase the humidity, in my opinion, is by using foggers; also known as humidifiers. These systems do exactly as they suggest, they blow fog (water vapor) into an enclosure. This fog looks neat but more importantly, it adds to the humidity level.

Terrarium Fogger
Fogging system in a terrarium.

Many keepers utilize foggers in vivarium tank builds, where the fog is blown through a moss-covered landscape to create a more naturalist appearance.

The Evergreen Pet Supplies fogger holds a half gallon of water, it’s quiet, gives a consistent output, shuts off when the tank is empty, and it allows you to adjust how much fog it outputs.

Moisture Retaining Substrates

Using a non-porous substrate can help increase humidity as well. The substrates you should use largely depends on the species you’re keeping; some species require sandy substrates while others prefer coconut husk, mulch, soil or something else.

When dealing with moist substrate, it’s in your best interest to add a drainage layer with a substrate barrier. This is another topic entirely, but the point is to keep your substrate from becoming soggy. It should be damp but not oversaturated. I encourage you to learn more about this topic if you need a high-humidity enclosure. Having said that, substrates like cypress mulch, orchid bark, and coconut fiber retain a lot of moisture. Exo Terra has a tropical terrarium substrate called “Plantation Soil” that has great reviews online. I’ve personally never used it so I cannot confirm whether its good or not, but it’s worth checking in to.

Coconut fiber substrate

The depth of the substrate makes a difference too. Having more substrate to retain moisture means you’ll have more humidity. A good depth is around 3 inches. If you have too much substrate it can become over-saturated, which can cause mold to grow. After all, while adding more substrate can help increase the humidity, it’s not worth jeopardizing your frog’s health.

Decrease Ventilation

Having air circulation is a good thing but too much will result in a decrease in humidity. Covering all the ventilation will definitely help you retain humidity but it’s not good for your reptiles. You can, however, decrease some of the ventilation.

Decreasing the ventilation is the best way to retain humidity in a terrarium; assuming you mist the enclosure, of course. Most terrariums have a screen lid on top, which is where all your humidity is going. You can cover up to half of the screen lid with a barrier.

Its common-practice for amphibian owners to place a sheet of glass, plexiglass or other water-proof material over half the terrarium’s lid. Do a quick google search for a local glass company. Most are willing to cut a piece of glass the exact dimensions you need. It’s cheap too, depending on the size. I recently bought a 1/8 inch thick piece of glass measuring 24″ x 18″ and it cost just over $15. I don’t recommend covering more than half the lid with glass. Air circulation is a good thing!

Other Ways to Increase Humidity in Your Terrarium

As I’ve already mentioned, this information all centers around the species in your terrarium. If you have a frog that does well with either a small water dish or a full water-bottom setup but you’re using the water dish, then change your setup to include more water. Use a large water dish or consider rebuilding their terrarium to include a partial or full-water bottom with cork bark flats and branches for walking.

Create a Waterfall

Adding a waterfall feature is easier than you think. Whether you want to build your own or buy a fancy waterfall decoration, there are plenty of options. And it’s a great way to increase the humidity in your frog’s enclosure.

There are lots of waterfall decorations available online or at your local pet store. Some of these are designed to sit in water, which would be great for frogs that do well in partial or full-water bottom enclosures. Some hold all the water inside itself and there are even a few DIY waterfall kits available. I recently made a post suggesting three kits and, if you’re interested, you can read it by clicking here.

ReptiRapids Waterfall
Repti Rapids Waterfall

If you’re up for building your own waterfall, you’re going to need a water pump other materials. Because this is a big topic, I won’t be covering it in this post. I have, however, found a great video that takes you through one man’s process of creating an amazing waterfall. He’s funny, it’s an entertaining video, and it’s definitely worth watching if this is something you want to learn more about.

Rain chamber & Drippers

Water drippers and rain chambers will greatly increase humidity in your terrarium. As the name suggests, rain chambers are meant to mimic rainfall. In these systems, you’re dealing with a lot of water movement. Drippers simply drip a little water at a time. It’s easier to manage and adds a decent amount of water vapor into the air.

Fun fact, rain chambers are often used when breeding frogs. Because frogs in captivity don’t experience the seasonal conditions of their native habitat, they’re less likely to reproduce in captivity. This is where the rain chamber comes in. Many species mate during a rainy season, where warm air, higher water levels, and rainfall are plentiful. People are successfully breeding frogs by replicating two seasons over a period of time. First, a season with cooler temperatures, less food, and less water is held for 4 – 6 weeks. After that, a rise in water level accompanied by rainfall (via rain chamber) and higher temperatures replicate spring-time; the breeding season.


Using moss in a vivarium build not only adds a naturalist appearance, it also retains water like a sponge. Water which is slowly released into the air. Unfortunately, moss isn’t easy to keep alive. You need the right type of moss, proper substrate and a lot of patience. It takes a long time to establish. It can take up to a year to achieve a thick, mossy covered terrarium or at least 4 to 5 months before you can see notice growth.

Moss in a Terrarium
Moss in a terrarium

Remember, your pet’s need should always come first when decorating your terrarium. Thick substrates with moss and waterfalls are pretty, but if you add more humidity than your frog or toad can handle, after a sustained period of time, it will have a negative impact on your pet. I hope this guide helped you! If you found this information useful, please consider sharing with friends and family.

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  • Was just wondering does my Frog Hotel need a small Pump with an Air Stone connected to keep water clean, I have Frog Foliage in the Hotel 🐸🐸

    • Hey, Lyn! I think I replied to your email. It’s not necessary but won’t hurt anything. Check your email for a better explanation!

  • Would a fogger work for my columbian red tail boa? I have 180 gallon tank with a screen lid idk how much a glass company would charge for that to cover half of currently having trouble with his humidity.

    • Yep! It will help but finding something to cover a portion of the screen lid will benefit you the most.


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