It’s no big secret that I love terrariums. They’re incredible, ESPECIALLY for someone with a history of neglecting my plants.
With the right equipment, you can set and forget them.
‘Set and forget’ is NOT what automatically springs to mind when you think about Calathea, but I swear, easy Calathea care is a thing if you keep them in a terrarium.
So, why are terrariums such a great place to grow Calathea?
Well, here are a few reasons. There are probably more:
- Consistent humidity
- Temperature controlled
- Consistent watering
- Consistent lighting
- Decreases the risk of spider mites
- You can start with smaller plants
- Economical use of filtered water
- They grow faster and bigger
- Calathea terrariums are great decor
- Its. Just. Easier
1 – Consistent humidity
If a plant requires high humidity, then no apparent of watering its roots or misting it can compensate for that.
Without high humidity, Calathea don’t grow well. They develop brown tips and edges to the leaves, they don’t grow as quickly or as large, and they’re more prone to pest infestations.
Humidity is crucial to plants like Calathea. If the air around them is too dry, then the stomata on the leaves with close (to stop the plant from losing too much moisture) and the plant is unable to photosynthesise.
Terrariums are typically small and damp, so they stay humid without much intervention from us. You can mist down the soil if you feel it isn’t humid enough, though try to avoid wetting the leaves – plants don’t like getting wet (same, tbh).
I have a large terrarium (it was 300ish litre aquarium) and I have a frog in there so it needs retain a high level of humidity (85%+). We opted to add a fogger that runs on a timer and produces an extremely cool mist effect.
Remember that if a plant is picky about water quality with regards to the water that goes on its roots, it’ll likely also be picky about the quality of the water vapour. I use tap water in the fogger, but it has aquarium dechlorinator added in.
It is ASTONISHING how much difference humidity makes to the growth of plants, and being able to do it in a small area means that people with cold and/or damp houses don’t have to worry about a whole room being humid.
2 – Temperature controlled
Calathea do not like to be cold, and they do NOT like draughts. Drafts. You know what I mean.
My terrarium isn’t sealed, but it does have a lid, so it stays a couple of degrees warmer than the rest of the room. The glass is pretty thick (thick enough to hold a lot of water!) so it retains its heat nicely.
We actually have a small heat lamp in ours, but it’s not necessary IMO. We wouldn’t have it if we didn’t have the frog and geckos, and tbh it burned a leaf of my Calathea velvet touch within the first couple of hours of being set up. Great.
Even if your terrarium gets a bit colder than your Calathea would perhaps choose, the temperatures fluctuate more smoothly than in the larger room around it. So even if it’s not ideal, being in the terrarium is warmer than not being in it.
3 – Consistent watering
I don’t water my terrarium. The fogger goes on for a few minutes three times a day and that provides ample moisture.
It’s important to add a layer of drainage to terrariums. This sounds contrary to everything else I’ve ever written about using rocks as drainage BUT there are a couple of key things to consider:
- I use leca as a drainage medium, which would absorb any excess water
- I don’t actually pour water into the soil, so there isn’t water pooling at the bottom
The white layer is filter foam, and it just stops the soil mixing with the leca. It also allows the roots to grow into the leca, which is better oxygenated than the soil. It’s all about air flow!
Consistent moisture means no curled leaves!
4 – Consistent lighting
Terrariums can be as simple or complicated as you’d like, but I highly recommend adding a light. Not only is it great for your plants, but it really elevates the look of your terrarium.
Calathea aren’t as picky about light as they are about humidity and water quality. They’ll adapt to a variety of light conditions, but just because they can lie in it, doesn’t mean they can reach their full potential.
Calathea in too dark of a spot are likely to grow slowly and their leaves won’t be very big. There are differences in the ways various Calathea grow, but their light requirements tend to be similar.
For example my Beauty Star grows a lot of smaller leaves very close together, whereas my Velvet Touch is very much concentrating on growing big leaves. They were both bought as babies on the same day and have been kept within inches on one another their entire lives.
Calathea that are given too bright a light can quickly become bleached. Sometimes the leaves look the same just very faded, but sometimes the colour goes completely, and the plant just grows white.
This may look cool, and I’ve grown plants like this for a long time, but they can rarely sustain more than one leaf at a time. As a new leaf grows, the previous one will brown and die.
By the way, if this happens, putting the plant in lower light will bring usually bring the pigmentation back. Plants are surprisingly adaptable for things that can die if they sit in a draught.
My terrarium uses aquarium lights, and that’s what I’d tend to recommend. Actual house plant grow lights are likely to be too bright for Calathea, plus they’re pricier. These lights usually come with an app or remote and you can play around with timers and lights.
We usually have the lights on for around 10 hours a day, but it’s in a dark corner so you may not need it on for that long if yours gets some natural light.
5 – Decreases the risk of spider mites
Ok, before you get excited, I’m not saying that it completely eliminates the chance of spider mites – just that it reduces the risk. The only pest I’ve had in my terrarium is aphids (on a maidenhair fern, obvs) and that’s just because they could reproduce faster than my frog could eat them.
There are two main reasons why there is less chance of you getting spider mites in a terrarium compared to just, er, raw in your house:
- It has a lid on it
- The humidity is very high
So basically, not only can they not get in very easily, but also, they won’t like it once they’re in there.
Spider mites do NOT like humidity, which is one of the reasons Calathea seem to attract them. A lot of people don’t have high enough humidity, so the Calathea struggles a bit. The spider mites turn up to feast on the struggling Calathea.
Struggling plants send out pheromones that pests can pick up on. If the Calathea isn’t struggling, she won’t be sending out these signals.
I have an article here on treating pests in terrariums if you do get them, but it’s best to try to avoid them all together. The most likely cause is new plants trojan horsing your set-up, so be sure to isolate them for a couple of weeks before adding them.
6 – You can start with smaller plants
Calathea aren’t particularly expensive plants, and terrariums can be quite expensive to set up, so I’m not framing this as a budget-friendly option BUT buying baby Calathea is something that only the most diligent plant person should consider.
They dry out super quickly and they’re even less tolerant of incongruent watering than their not-exactly-chill larger counterparts.
However, if you plan to keep your Calathea in a terrarium, forgetting to water them isn’t going to be an issue. You can buy a bunch of the baby ones and see who does best.
Here’s a tip from me to you: don’t try to keep a velvet touch in a terrarium. Mine is now ENORMOUS and only getting bigger and growing faster.
I have nowhere to move it to. It also has a few marks on the leaves because any tiny water droplet (I suspect from the frog sitting on it) leaves a brown mark.
Beauty stars, on the other hand, grow very compact and bushy and look really cool.
I really, really, want to try an Orbifolia in there, even though I suspect it’ll also grow too big and unwieldy.
7 – Economical use of filtered water
I’m not the world’s biggest fan of filtered water (I have good tapwater, so I don’t see the point) but obviously if you have crap tap water you don’t have much choice (other than choosing that rubber plant life).
Watering terrariums is very economical because the water is all used up – there’s no water pouring out of drainage holes anywhere. It enters via the fogger (or spray bottle to the soil), is absorbed by the soil, and then is absorbed by the plant.
The fogger is refilled every few weeks. As I said, I use dechlorinated tap water, but you can use filtered water if you prefer.
Nutrient water/fertiliser is also an option if you don’t have a bioactive terrarium – look for a foliar spray for ease, but if you want to use regular fertiliser just be sure not to get it on the leaves.
A bioactive terrarium is where you have bugs than clear up waste and produce their own waste that acts as a fertiliser. I also feed the bugs (springtails and isopods) veggies which decompose and enrich the soil
8 – They grow faster and bigger
Is this a pro or a con?
Honestly, they’re bursting out.
We’ve already mentioned that terrariums are nice and humid, well lit, and don’t dry out. This goes a long way to ensuring plants grow big leaves quickly.
The other part of the equation is consistency. Plants like consistency.
9 – Calathea terrariums are great decor
It can take a couple of months for a terrarium to stop looking like a box of soil in the corner, but once it hits its stride, they look incredible. Like an aquarium, but easier (and cheaper) to maintain.
Calathea are one of those plants that haven’t quite made it as a popular-purely-for-decor plant, despite them being incredibly beautiful and cheap. That area is still dominated by rubber plants and Monstera because they grow well in less specific Monstera.
Most Calathea, on the other hand, look great for a couple of months, then get brown leaves and get chucked out.
I think that if they were marketed more as a terrarium plant they’d do better. They look so good under lights and their care preferences lend themselves perfectly to terrariums.
10 – It’s. Just. Easier
I used to have a lot of Calathea. I think they’re incredibly beautiful IF they’re in good condition. But my tendency to neglect and my reluctance to buy a humidifier meant that for a long time we just weren’t compatible. It wasn’t them, it was me.
But in a terrarium, with an automated fogger (or even just misting the soil every day, which I used to do), lights on a timer, and a clean up crew of isopods, they are really easy to care for. And they look awesome.
Final thoughts
I understand that Calathea grow a little too big for traditional terrariums. Hell, mine is huge and is already dominated by one very fast-growing Calathea (should I pot it up and give it away as a give to some poor, unsuspecting plant person).
BUT you can buy baby Calathea for under £5 in a lot of garden centres, and they’ll stay small enough for a couple of years, at which pot you can pot them up and buy some new ones. Or, you could prune them back and start again, though they’ll grow back pretty quickly.
I’m not urging everyone to rush out and buy a massive aquarium (though you can get them cheap on Facebook marketplace/eBay – especially since they don’t need to hold water). This is more of an article for people like me that LOVE Calathea but don’t have the brain power to maintain one.
Also, it can be a fun terrarium project that’s a bit different but also, like, why is it different? Calathea + terrarium = really freaking cool terrarium AND a happy Calathea, which is a rare thing indeed.
Hope this was helpful! By the way, there are no plants that will stay small indefinitely in a terrarium unless you treat them badly. There’s always gonna be some pruning that you need to do. I know this, because I used to have a Fittonia but I had to remove it because it grew ENORMOUS.
