Creating a terrarium is incredibly easy. If you’ve wanted to make one but have been too nervous to get started, I hope that by the end of this post you are going to wonder what all the fuss was about. Anyone can make one, and this is the perfect activity to do with school-aged children—it’d start some neat conversations about biospheres and the processes of life.
First thing to note is that I am calling all of these creations “terrariums” even though in the strict sense of the word they are not: most of mine are uncovered environments, meaning they don’t develop their own little enclosed ecosystem. I call them terrariums to convey the sense that they are contained within glass. Enclosed terrariums are a lot trickier to establish than open ones but are still simple to put together.
Along with terrariums you may have also heard of vivariums. They are terrariums that function as a living environment for captive insects, reptiles, or amphibians. You have the challenge of creating an ecosystem not just for the plants involved but also for other creatures. Those are much more complicated and time consuming. For now, let’s just stick with plants, shall we?
Choose Your Container
The kind of terrarium you create will depend on the type of container you have on hand and the type of plants you are going to use. You’re going to want to match the plant to the container, or vice versa.
STEP 1: Choose a glass or clear plastic container. Either wipe out the inside with a rag or swish some water around in it if it’s used.
Pick Your Plants
My favorite type of plant is the succulent, but you absolutely don’t want a humid, enclosed terrarium for them. They like dry conditions and well-drained soil or else they rot. If you have your heart set on an enclosed terrarium, use moss, ferns, or my favorite, spider plants. Spider plants are always having little spider plant babies and in my experience aren’t deterred by an enclosed terrarium. Moss and ferns love a humid environment. I’ve never grown moss (it’s not wet enough around here to occur naturally) but I’ve had no trouble establishing ferns in enclosed terrariums.
STEP 2: Have your plant ready. Choose one that’s on the small side.
Lay The Foundation
Terrariums need some sort of rocky base for the excess water to drain into. Horticultural charcoal is really nice if you have it. It helps absorb excess moisture that could lead to fungus growth and rot. I’ve used it with good results, but then I ran out and just proceeded on with rocks and soil and it turned out fine. I’ve used decorative gravel from a big box craft store, treated aquarium gravel from the pet store, and actual gravel we just happened to have in the backyard. At first I was a little worried that the treated gravel would have wacky, unintended results in my terrariums, but I haven’t noticed anything strange because of it. The gravel from my yard worked just as well as the gravel from the craft store, but it wasn’t as good-looking, to be honest.
STEP 3: Fill your empty container with about an inch or so of pebbles. This depends on the size of your container, but an inch or two should be fine. If you are using horticultural charcoal, add it in a thin layer on top of the pebbles.
Add Your Soil
I usually use a sterile potting mix. If you get peat or some perlite mixed in that can help with drainage. I’ve also added in soil from my backyard, too when I was running low on potting mix. One time I created an enclosed terrarium but did not use sterile potting mix. A gnat of some sort laid eggs in the soil and within two days my lovely enclosed terrarium was swarming with tiny flies. It was nauseating.
STEP 4: Add your soil. Make sure it is very moist. It shouldn’t be dripping, soggy-wet, but it should be moist. I like to add about two or three times as much soil as pebbles, but this depends on your container. How much soil you need depends on the plants you choose and how deep their root systems go. Three or four inches of soil, or even more, has worked for me.
Add Your Plants
Moisten the soil and add your plants. The trick is to add very small plants. You don’t want to add a plant that looks like it would fit—you want to go much smaller. If you add a plant that fills out the terrarium already you are going to have to repot the sucker immediately or it will outgrow your container. Start with miniature-sized versions and expect them to grow.
STEP 5: Transfer your plants like you normally would when repotting. Gently pull it out of the pot, loosen the root ball, and set it in a hole you dug inside the terrarium. Cover gently with soil.
Add Aesthetic Touches
It’s traditional to add a little figure or statue to your terrarium. It’s definitely not necessary and I don’t always add them, but small toys can be an extra fun step in creating terrariums. When I bought my egg-shaped terrarium it came with two vintage, hand-painted figures: one a tiny mushroom and the other a miniature swan. Personally I like to add toys to the mix: a dinosaur, or a gnome, or tiny plastic ninja. It’s fun and cute but certainly not necessary nor needed.
Some people get very creative with their terrariums and they landscape the soil as they put it down to give their terrariums hills and valleys. Or they sprinkle the surface of the soil with gravel or sphagnum moss. Terrariums look lovely on their own but think of it as gilding the lily.
STEP 6: Add gravel, rocks, figures, or other decorative touches. Completely optional.
The frequency and amount of water will very per plant and container. If the terrarium is enclosed and the soil is moist enough, you won’t need to do more than an infrequent misting with a spray bottle. Sometimes a trickle of water from the watering can once a week is all that’s needed. Succulents like their roots to dry out in between watering but ferns like to stay moist. If you can get a good condensation going on the glass of your enclosed terrarium, then you needn’t interfere.
Terrariums do best in indirect sunlight. Never place them in direct sunlight because the temperature inside will rise and kill your plants. Too little water is better than too much water. Overwatering promotes the growth of bacteria and fungus.
Reassure yourself with the knowledge that some terrariums are not going to last forever. Sure, there’s the trial and error of establishing a plant, but even when things go well your terrarium might only last a season. Some plants do so well in terrariums I’ve had to repot them after a few months because they’ve outgrown their container. Some plants I’ve been able to keep going for six months to a year before they ran out of space, but some plants more and some plants less. This isn’t a failure—it’s a success.
My awesome friend Kate (whose home is so gorgeous her kitchen was featured in Better Homes and Garden) started this terrarium group on flickr. It is by far the coolest group and has tons of amazing terrariums for inspiration. Kate made me a moderator of the group and I invite people to participate whenever I can. If you create a terrarium please add it to the group! We’d love to have you.
I am not an expert on terrariums. I’m just someone who loves them and who has made a few and wanted to share what works for me. You can find more information about terrariums here:
Here’s a teaching activity about creating an environment in a soda bottle.
This guy’s all about terrariums.
I really like this site.
If you use this tutorial to create a terrarium, please share it! If you post yours on flickr please add it to the terrarium group and add a link in the comments here so we can see your work. If you have any questions let me know and I’ll answer them as best I can.