Guide towards a Naturalistic Spary Foam based Terrarium

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Remember that for these types of projects, it is usually advised to have a specific area designated for it, as in the following days it will get a lot messier. You will be working with a lot of non-edible materials, so remember to put on gloves and close off the area if you have pets.

First steps: Define the Purpose of the Terrarium

I believe the first step is often overlooked, but I truly think it is one of the most influential and determining factors of terrarium designing. This step is called: understanding what you want and how you want to pull it off. Imagine having all the possible materials that you needed but not having an idea of how you are going to utilize them. Well, believe it or not, this happens to a lot of reptile keepers, including myself. Truly think about how you want this environment to be and look, since most of the time there will not be any going back. Consider factors such as basking spots, enclosure size, budget, and the time you are willing to sacrifice for maintenance.

The Second & Third Steps: Start spary foaming!

Clear, silicone and wait!

Start by cleaning your empty habitat with a bit of water and paper. Then you will start to add silicone glue to all of the clean background. Make sure to cover all of the areas in which you will be spray foaming later. My suggestion for this part is to use transparent silicone so that if some silicone is spilled in another part of the terrarium, it will only blur the part a little, considering sometimes it can be hard to clean 100%.

Please consider using silicone glue that is appropriate for glass and that the packaging clearly states 100% Silicone, and double-check that it does not contain any harmful chemicals or mold inhibitors that could be toxic to your animals.

Time to Spray Foam!

Now let's dive deep into the third step: Time and Spray Foam. Let the silicone you have just applied to the background cool for at least five to eight hours so it generates a stable texture that the spray foam can adhere to.

Now that it has fully cooled, place some wood, platforms, and decor on the background with your hands. Start spray foaming the areas around these platforms, holding them in place from the top. Once the platforms are stable with the newly applied spray foam, you can repeat the process in other parts, eventually covering the entire terrarium. Remember, nature does not promote perfectly balanced backgrounds, so give it depth and texture—do not just apply the spray foam in straight lines.

It is key to know exactly what you are aiming for in this step, as there will be no going back. Now let that spray foam cure for at least 28 hours. I know you want to work on it sooner, but the wait is worth it!

Please note that spray foam expands approximately six times its initial volume, so do not overfill the terrarium with foam.

Let's dive deep into the fourth step!

Now I want you to wait about one or two complete days so that the spray foam can fully cure. You may then start cutting any unwanted spray foam parts so it can look even more natural. My suggestion is to use a really strong cutter, as from experience cheap ones tend to break under pressure, and the broken part can go flying off. After achieving the desired shape, apply silicone glue all over the cured spray foam, and once it is fully covered, add a generous amount of dirt, covering every desired area. I suggest that the dirt be well mixed with coconut fiber and some sphagnum moss to enhance realism. Make sure to do this while the dirt is completely dry, and also ensure that the terrarium side covered with spray foam is horizontal to the ground. Now, let’s wait for about one or two days (yes, I know it is boring, but it is necessary).

The final one: Step Five

Fifth Step:

Now we are almost at the end of this journey!

At this point, you may start thinking about whether you want to add additional features to your terrarium. Most of these things are just suggestions, but they can be very useful. I would recommend that you add a waterfall system, which is shown in the "Tips" section, or simply refine any special details you feel need a “touch.” These may include a small uncovered part of the spray foam. Try to fully cover all of the spray foam, as an uncovered space may result in humidity affecting the layout.

Now just wait until there is no longer any silicone or chemical smell, and you may start adding additional decor till you feel it is finished and ready.

¿Questions?

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This article is maintained by Iago Rivadeneyra (author and content).

Last updated: April 16, 2026.

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