5 Key Elements to a Terrarium Ecosystem (Self-Sustaining Terrarium)

A perfectly balanced terrarium ecosystem can (in theory) last indefinitely.

Something we can all aspire to. I mean, who wouldn’t want a zero maintenance plant terrarium?

Though, in practice there are a variety of important elements that need to be balanced to make a truly self-sustaining terrarium.

Each one plays their part in mitigating a problem or supporting a process, and getting each one right further increases your chance of a thriving ecosystem. Creating a terrarium that’ll live a long, healthy life (and you can leave for a few weeks without a babysitter).

In this article, you’ll learn all the important ingredients to a thriving closed terrarium ecosystem, and how to avoid creating a hot mess.

Let’s see the recipe shall we?

Terrarium Ecosystem

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What is a Terrarium Ecosystem?

To me, ecosystem is a word that often conjures images of the lush green Amazon rainforest, or the circle of life played out on the African Savanna.

But, an ecosystem isn’t defined by its size or complexity. It’s defined as “a biological community of interacting organisms and their physical environment” – and that goes for the plants in your terrarium too.

What makes a true ecosystem is the ability of its inhabitants and their environment to work together to support the system. A series of finely tuned life cycles and energy transfers that will make or break the system.

A closed terrarium ecosystem must replicate a variety of natural processes that’ll allow it to feed, clean and restore itself.

Sounds difficult to create, but we simply need to look to the natural world for inspiration.

How to Make a Self-Sustaining Terrarium

#1: Plants

As the most important (and exciting) element of any terrarium, there’s a lot to balance here.

  1. Select the right plants (that will grow well, but not too well).
  2. Plants that are hardy and pest/disease resistant (some plants are more prone to these than others).
  3. Provide enough plant biomass to sustain efficient life cycles.

Remember, a zero-maintenance plant terrarium is one where we should never need to prune or remove plants that get too big. So, we must choose plants that won’t outgrow the container – even when fully mature.

Dwarf varieties and curated miniature terrarium plants will be your best friends here, e.g.

Something like these mini ferns from PetrichorBotanical on Etsy (Image credit: PetrichorBotanical).

On the flip side, it’s also important to have a sufficient amount of plants to support the water cycle. Like coal in a furnace, you won’t get the fire burning till you get it hot enough and have enough material to keep it going.

More plants = more biomass = more transpiration = more condensation = more free water.

> Check out the Terrarium Plant Index , or my Definitive List of Closed Terrarium Plants for more help!

Moss can be helpful here too, in adding biomass without filling up your terrarium (yes, I’ll take any excuse to add as much moss as is humanly possible).

#2: Container

I’m afraid, when it comes to terrarium containers size does matter.

I mean, you’ve nothing to prove here… but you will need enough space in your container for free gas exchange. 

It’s important that oxygen and CO2 be circulated properly, as anaerobic conditions lead to unwanted bacterial growth and decomposition. If your terrarium is crammed in with material, it can develop air pockets, starving some plants of their much needed sustainance.

Containers with awkward shapes are also a no-no, they’re much more likely to trap liquids and gasses.

Broad, evenly shaped containers like cubes, spheres, fish tanks and wardian cases are best. See my guide to Glass Terrariums on Etsy for some inspiration.

Wardian case by LeadHeadGlass on Etsy (Image credit: LeadHeadGlass)

#3: Light

Consistency is key to sustainable terrarium lighting. 

Of course your plants need to get enough light to respire and thrive, but they shouldn’t be at risk of being scorched by direct sunlight. 

Bright, indirect light is pretty much the gold standard for most terrarium plants. 

North facing windows are often a great choice, as they never receive direct sunlight, but they are still well lit throughout the day.

Or, you could always put your terrarium under a grow light if you really wanted to control the lighting as much as possible.

#4: Water

A functioning water cycle is the lifeblood of a terrarium ecosystem. And just like the circulatory system in the human body, it has a lot of moving parts and doesn’t do well when it’s blocked up.

Building a terrarium foundation that supports the movement of water – whilst retaining it where necessary for plants to access it – is the key to a healthy water cycle. You’ll need:

  • Proper drainage – excess water must be able to pass through the substrate. We’re creating a moist environment, not a swamp. Having the right kind of terrarium substrate with great drainage and water retention is a critical component.
  • A reservoir – somewhere for excess water to collect at the bottom of the terrarium. The water in the reservoir helps keep up humidity, prevents the substrate from becoming oversaturated and helps facilitate the water cycle. In terrariums, these are often called “false bottoms“.
  • The right balance of water – ideally there’d be just enough water in the system to facilitate the water cycle.

For more help on watering, see my full guide to watering terrariums.

#5: Microfauna (Insects)

The decomposition process of the natural world is perhaps the most difficult part to replicate in a terrarium. There are probably thousands of different species at work in your local woodland, all working in harmony to break down and regenerate biomatter.

So yeah, that’s quite hard to orchestrate yourself…

However, we do have some species available to us that can do a good job of it all on their own

Cue, the isopods and springtails.

Springtails Culture
Yes, those tiny white blurs are springtails.

These tiny natural cleaners make a great addition to any terrarium. As long as you’re not scared of bugs… If you are, the springtails are significantly smaller.

They’ll happily go to work breaking down any dead or decaying matter. Transforming it from a potentially deadly terrarium hazard to a wonderful new source of nutrients. Mould is their favourite food, so you can say goodbye to those awful white fuzzy blooms. 

Plus, they’ll even help aerate your substrate, keeping your plants happy and improving drainage.

Grab yourself a springtail starter culture here on Etsy.

Terrarium Ecosystem FAQ

What is the terrarium ecosystem definition?

A terrarium is a self sustaining plant ecosystem that’s calibrated to effectively replicate all the necessary natural cycles for a thriving community of organisms.

Can you really create a closed ecosystem in a bottle?

Of course, any container that you can seal off to create a unique internal environment can form the basis of a closed ecosystem.

Can you build a self sustaining terrarium with animals?

Absolutely, a self sustaining terrarium with animals if often called a bioactive vivarium.

Where can I find a self sustaining terrarium for sale?

It’s rare to find terrariums for sale with all the necessary components needed for a full terrarium ecosystem. But, most closed terrariums for sale can be modified to become self sustaining.

Over to You

How long have your bioactive terrariums been able to go without any intervention?

Let us know your secrets in the comments below.

21 thoughts on “5 Key Elements to a Terrarium Ecosystem (Self-Sustaining Terrarium)”

  1. Your website is awesome I make terrariums as a hobby, and I have a terrarium clôche I just made with dried/petrified grapewood and it’s producing some of those white fuzzy mold – it’s good to know springtails will take care of that!

    1. Thanks so much! It means a lot to hear that. Yeah, driftwood can often cause mould blooms (even after it’s been boiled and scrubbed in my experience). Springtails should do the trick.

  2. Im buying my boyfriend the bits and bobs he needs to make a closed terrarium for Christmas, this has been a massive help, i was gonna use woodlouses, will they survive well in a closed terrarium?

    1. I’m so glad you found it useful Ellis 😀 Absolutely, woodlice (or isopods as they’re often called in the industry) can be a great addition to a terrarium, though different species will have require slightly different conditions and might have slightly different behaviors. Experts often recommend a little ventilation for isopods too, so if your terrarium is completely sealed you might want to think about adding a small hole or opening it up semi-regularly.

      1. I was wondering about the critter-to-ecosystem ratio, the size of the container and the biomass itself determine what a particular system can support, I reckon; any advice regarding how many and of what, that sort of thing? Thanks very much, great article.

        1. You’re absolutely right but there’s no hard and fast rules. You typically get springtails in 16oz cultures and that’s probably enough to seed a handful of small terrariums or a single large terrarium.

  3. I am planning on making one of these after seeing my science teachers self-sustaining terrarium and was wondering if a snail could survive in there? Also my teachers had a plastic wrap as a lid, would a regular jar lid (with no holes) work? And lastly, with a large jar, other then the aforementioned snails, what would be the best animals to have it there? There’s a lot of space to work with, I’m thinking creatures that are more on the cute side. Thank you!

    1. I’m sure a snail could survive (though I’d add some air holes or make it a loose seal). That being said, they’ll munch all your plants so I wouldn’t personally add a snail to a plant terrarium. Most people add springtails or isopods for their cleaning function, but whether they’re cute is definitely down to personal preference – the rubber ducky ones are kinda cute 🤔

    1. You can, but bringing in garden soil also brings in a lot of other unknown factors (e.g. bacteria, fungus, etc) so there’s an extra element of risk to your terrarium.

  4. Renz Joshua De Vera

    Hi! I’m planning to create connected biospheres. One terrarium, one desserted and one aquatic. More of like a mini world. Is that possible?

    1. Really interesting concept! A terrarium connected to an aquarium might work as it’ll help to boost the ambient humidity, but that extra humidity would probably harm a connected desert biosphere.

      1. Renz Joshua De Vera

        I placed the desert terrarium way higher than rainforest terrarium. Then i placed the aquarium beside the enclosed terrarium. I do it so that the humid air (since it is heavier than dry air) will just settle at the bottom. There is a thin tube connected to the desert above just to continue water cycle and balance out the temperature in the rainforest terrarium. So far, it turns out quite well and the desert terrarium is not affected but still contributing to the whole biosphere. I’m just worried in the next months. I would love if i can upload pictures here. Thanks! You are an absolute help.

  5. Would a big jar like a cookie jar (clear glass) w a lid work to create terrarium? 64oz? basically, a cylinder that is semi-tall with a glass, lid.

  6. Is any time of predation needed for a self sustaining ecosystem? Wouldn’t the wood louse and spring tails just consume and breed until they wipe out any plant life?

    1. They seem to be self-regulating for the most part. Springtails will never eat your plants and can only grow their colony to a size that’s supported by the natural decay of your terrarium.

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