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Yes, Calathea live can live perfectly happily (at least, for a Calathea) in LECA.
IN FACT if you’re a bit on the lazy side, like I am, LECA might be the preferred substrate, because you don’t need to worry about accidentally letting them dry out to a husk when you turn your back on them for twenty minutes.
Just in the interests of transparency, I currently don’t have any Calathea in Leca, but not because I don’t think it’d work. It’s because all my Calathea now live in my terrarium, where they grow very happily and healthily (albeit with a few chomp marks on the leaves, courtesy of the slugs).
If something were to happen to the terrarium, they’d for sure go into leca. Calathea + soil + regular ambient humidity = dead/raggy Calathea in my experience. There’s no point putting either of us through that!
Calathea aren't necessarily difficult to care for IF they're given the correct conditions in which to thrive. I'll go through them in more detail later on, but in a nutshell, they like warm, humid conditions, and like water that doesn't have a lot of impurities in it.
How to transfer a Calathea to leca
1. Start with a healthy Calathea
Calathea are picky and prone to hissy fits at the best of times, so let’s go in assuming that your plant is going hate the transition.
Just remember that (IMO) Calathea can really thrive in leca because their number one enemy – drying out – is less of an issue.
Even the smoothest of transitions will likely result in your Calathea losing a few leaves. Or possibly all of them. THe good news here is that Calathea are pretty happy to drop all of their leaves and then regrow new ones, but if you have one that’s huge and lush and beautiful and your favourite plant ever…maybe take an offshoot and move that to leca rather than risking losing every leaf.
2. Clean the roots REALLY WELL
The best way to approach Calathea care is to think of it as needing the same care as most tropical plants, but, er, more. More humidity, more moisture to the roots, better quality water, and a spot that’s not too bright but not too dark.
So transferring it leca is the same as it would be for any other plant, but each step needs to be a bit more thorough.
(Well, only this one, because the other steps are just things like ‘plant the plant’ which isn’t something one well or badly.)
You know all that dead matter that hangs around at the base of plants, between the roots and the leaves? Get rid of all of it. Any dead leaves or rotten matter needs to go, because it’ll rot in the leca and could be the cause of further rot down the line. Dunk in hydrogen peroxide if you have some.
I have a full guide to leca here that goes through the various techniques for cleaning the roots off, but basically, we just need the soil off them. Calathea roots are, in general, pretty hardy actually (at least one part of the plant needed to be, I guess) so whilst you need to be fairly gentle, don’t be afraid to give them a blast with your hose or go at them with a toothbrush.
Personally, I’d go for a prop here if possible. Calathea have rhizomes and are propagated by division so that’s not really possible here, BUT if you’re switching another prayer plant, like a Maranta or Ctenanthe, to leca, I’d water prop one and then put the prop in leca.
Maranta, for some inexplicable reason, have roots that soil clings to. Wash the roots off by all means, but don’t come for me when you’re hours into cleaning the roots and the soil still won’t budge.
3. Put in water first
This is very much a bonus step, and it’s one of those things that some people like to do because they find it easier, but others don’t because they, er, don’t.
I like to prop in water before leca because I like to be able to keep a close eye on the roots without having to rummage around.
Superthrive is a bit of an optional step when tswitching plants to leca, but I’d recommend it here. It’s not a fertiliser, but more of a soothing supplement to chill your plant out whilst it transitions.
Lazy people: put the prop somewhere where you’ll not only see it every day but also somewhere close to water, so you can easily change the water. The more often you change the water, the more oxygen you’ll have in there. The more oxygen the roots get, the faster they’ll grow.
If you want to put your plant straight into leca, move to step 4. This is just a matter of personal preference.
4. Pot up in leca
Calathea are typically pretty thirsty plants, so I usually keep the reservoir quite high – Usually about halfway up the roots and then top up when the water reaches the bottom of the roots.
Don’t add fertiliser yet. Wait for new growth.
One good thing about leca is they’re used to quite thick, dense soil, so you don’t need to worry *too* much about airflow. Therefore, you can repurpose an old mason jar or similar to use as a pot.
Be extra thorough when washing your leca. Take the time to rinse it through until the water is running clean. I don’t know why, but I have a very strong feeling that a Calathea will NOT enjoy being in a grubby substrate.
5. Keep an eye on it
Once your Calathea is in leca, you just need to wait, for it to start to grow. There’s a pretty decent chance that it’ll look a bit sad and droopy, or even shed half/ of its leaves. If you’re worried, check the roots. I have tips below on what to do if it’s all going south.
Always, always be on the lookout for spider mites. ALWAYS.
How to reduce the impact of transplant shock on your Calathea
Keeping Calathea warm will help with shock
You try a warm windowsill but Calathea aren’t overly fond of bright light, so you risk bleaching. Heat mats are another option, but unless you have a lot of plants, probably aren’t worth the investment (unless you pick up a lot of sick wildlife, which is why we always have one hanging around).
A bright windowsill + a sheer curtain/blind will do perfectly well.
Also, maybe don’t try to switch your Calathea to leca in cold weather.
Keep Calathea in humid conditions with help with transplant shock
Humidity is the biggie with Calathea, hence mine living full time in the terrarium. They don’t get fancy water or food, but they have all the moist air they could possibly want.
You don’t need a terrarium for this, but if you have one big enough, pop your whole plant inside. A clear plastic box will work JUST AS WELL. Put some soil/sphagnum on the bottom, put your Calathea in and spray it down every day. The water in the soil will slowly evaporate and increase the humidity. Adding a heat mat to this (or putting it near a radiator) will really get it going.
A humidifier would also work, but I’ve found that humidity of around 75% is best for Calathea (in terms of fast growth and recovery from ill health) and that’s a bit high to have in your house.
How to fertilise a Calathea in Leca
In my experience, Calathea aren’t particularly heavy feeders, so I’d stick with my standard leca fertilising schedule, which is the General Hydroponics Flora series every six weeks. There are instructions on the bottles for how much to add. You can use another fertiliser, but make sure it’s suitable for semi/hydroponics.
Every six weeks flush your leca, then fill the reservoir with nutrient water. Top up the reservoir whenever required with plain water.
I’ve found that Calathea are quite partial to a bit of aquarium water in lieu of ‘proper’ fertilising, so if you have a fish tank, just use that in your reservoir every time.
What water to use, flushing, etc etc etc
I’ve never had a real issue with using just tap water with Calathea BUT if I don’t use a dechlorinator (I use Seachem Prime) I’m more likely to get crispy tips.
Tap water varies a LOT, but here in North Yorkshire it’s pretty good.
Rainwater is another option.
Filtered water is great BUT you may need to be more on it with your fertiliser game, because it filters out a lot of the minerals that plants need. Don’t bother with distilled water.
Flush your Calathea before you add new nutrient water, so every six weeks HOWEVER as we all know, Calathea can be a bit funny about impurities. If you’re noticing imperfections on your plants, you may need to start flushing more often – either every month or every three weeks,whatever suits you best.
Most of the brown spots on Calathea leaves are due to lack of humidity but it could be impurities on the leca (those white crystals you get from water and fertiliser build up) working their way into the roots.
Hope this was helpful, feel free to leave questions in the comments!