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?
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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
As the most important (and exciting) element of any terrarium, there’s a lot to balance here.
- Select the right plants (that will grow well, but not too well).
- Plants that are hardy and pest/disease resistant (some plants are more prone to these than others).
- 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.
- Fern: Nephrolepis cordifolia ‘Duffii’ (Lemon Button Fern) – See on Etsy
- Foliage: Macodes petola (Lightning Jewel Orchid) – See on Etsy
- Vine: Syngonium podophyllum ‘Pixie’ (Dwarf Arrowhead Plant) – See on Etsy
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 for an extensive selection of plants.
Moss can be helpful here to add biomass without filling up your terrarium (yes, I’ll take any excuse to add as much moss as is humanly possible).
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.
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.
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.
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
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.
Of course, any container that you can seal off to create a unique internal environment can form the basis of a closed ecosystem.
Absolutely, a self sustaining terrarium with animals if often called a bioactive vivarium.
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.