DIY Closed Terrarium, Layer by Layer

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Closed Terrarium vs. Open Terrariums

It’s important not to get the two confused because they are very different! You’re not creating a self-sustaining ecosystem with an open terrarium, so those will still need to be cared for regularly like you would with other plants.

Open terrariums are best for plants that don’t need moisture to thrive, but there is a little more leeway here than using a closed terrarium, which absolutely requires moisture-loving plants. Succulents are popular in open terrariums. You’ll need to make sure to set up excellent drainage for your open terrarium, but that’s the only tricky part about them.

Closed terrariums are a bit more challenging since you’re actually creating a tiny world for your plant to survive in. They are relatively low maintenance in the long run, but you need to make sure that everything is set up correctly in order to get to that low-maintenance point.

You only need to add a couple of tablespoons of water and open the lid for fresh air every now and then. Aside from that, a closed terrarium will create its own water cycle, and you’ll notice the condensation forming on the lid. Remember, you should only plant moisture-loving plants in a closed terrarium.

Let’s review, step by step, how to build a successful closed terrarium! Please excuse the glare in these photos, it’s so hard to take nice pictures of shiny glass. But I think you’ll still get the idea 🙂

Step 1 – Find Your Container

Choose your container and make sure it’s clean. You’ll want your terrarium to look pristine, so be sure to not leave any streaks or water marks. Your container should have some depth to it because you’ll be putting down a few layers of different materials.

Also, your container should have a top that’s easy to remove with plenty of space to fit your hands in order to work. I chose this glass beverage dispenser that my boyfriend gave me a few years ago. I always thought it was so pretty but never had the chance to use it.

Below are a few container suggestions that I think would make nice terrariums. It’s important that it has a wide-enough mouth for you to work in, some depth for the different layers, and a removable lid.

• It’s a little pricey, but this is the one I was given as a gift.
• Here is a nice beginner-friendly option.
• This one is a little smaller but has a wide opening which will definitely give you enough room to work in.​

​Step 2 – Set Up the Drainage

The first layer is the drainage layer. Put down about two-or-so inches of pebbles. I didn’t have enough pebbles so I used a mixture of pebbles and perlite. Depending on how you want your terrarium to look, you may want to use specific colors of pebbles and be careful to put each layer down evenly. I wasn’t too careful with mine, but I think it still looks pretty nice.

Step 3 – Ensure Proper Air Filtration

The next layer is activated charcoal. This was the one component that I didn’t already have lying around, but you really can’t skip this. Activated charcoal is absolutely essential because it will filter out any impurities and keep your closed terrarium fresh as a daisy. Add a one-inch layer of the activated charcoal on top of your drainage layer.

Step 4 – Add Your Potting Soil

Add about two or three inches of indoor potting soil to plant in. There’s not much to note in this step, as a normal, well-draining houseplant soil will do fine!

Step 5 – Plant Your Plant

Now it’s time to get planting. Be sure to choose a moisture- and humidity-loving plant such a fern or moss. I chose a nerve plant. The plant should fit nicely into your terrarium, you don’t want it too tight against the terrarium walls. I think the nerve plant I chose was a little on the big side, but it still seems pretty happy after two months in the terrarium.

Step 6 – Add the Finishing Touches

Now that your terrarium is assembled, brush any loose soil off of the plant and the inside glass and add a couple of tablespoons of water—really, that’s all you need! If you have more space and want to add some decorative rocks, shells, etc. go ahead, just make sure they’re clean.

Put the lid back on and place it somewhere that receives low, indirect light. It shouldn’t be placed in direct light since the terrarium glass will act as a greenhouse, magnifying the light and hurting your plant. The first photo in this post is receiving direct light but I only put it there for the photo.

You will not need to water this often, so every once in a while check the soil moisture to determine if watering is even needed. I water mine probably every three to four weeks, checking the soil first. Remember, you only need to use a small amount of water, so water a little at a time and if you see it draining through to the bottom, you’ve used too much.

Remove the lid every other week or so to provide some fresh air and let out any excess condensation. Occasionally wipe down the inside of the glass. Don’t use any chemicals for this. A dry or slightly damp paper towel should work fine to remove any excess soil or grime.

Once you have your terrarium all set up, it’s pretty cool to watch the mini ecosystem form and take care of itself. While the thought of taking care of a terrarium is intimidating at first, if you take the time in the beginning to set your terrarium up for success, there is little-to-no care actually needed. It’s a fun way to add some unique decor to your space and a great project for all levels of plant parents!

Read my year-and-a-half update on my terrarium here.