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Ever been repotting a Calathea and you’ve discovered weird white bulbs? Those are Rhizomes, and this article will go through everything you need to know about them.
Suffice it to say, this will be a short article, because…you don’t really need to know much about them.
Do Calathea have rhizomes?
Yes! And they are actually rhizomes.
A Rhizome is a modified subterranean plant stem that grows from an axillary bud and will produce roots and shoots. This is different from a tuber, which is a storage chamber, usually for starch.
Tubers can also produce roots and shoots though, as evidenced by that one old potato that lives in the back of the cupboard.
How do you know if your Calathea has Rhizomes?
You just have to look! Here’s one on my baby Orbifolia:
See that weird hairy white lump?* That’s the rhizome.
*I tried to make a joke here, about how the hairy white lump was holding the rhizome (with me being the hairy white lump) but I couldn’t quite make it work. Never mind.
Can you grow/propagate Calathea from Rhizomes?
I wouldn’t recommend propagating Calathea rhizomes that don’t have any leaves unless you’re pretty experienced with both Calathea and propagating. Calathea are PICKY and if you don’t get the moisture just right they’ll either shrivel up or rot.
When you come to divide your Calathea, it’s easiest to remove the soil so you can see what you’re doing. You should see a rhizome (sometimes they look like bulbs, sometimes they just look like chunky roots), hopefully with roots, and be able to find the corresponding leaves attached to the rhizome.
Use scissors or a knife to separate the rhizome from the mother plant, taking care to keep the roots intact if you can.
Some plants have absolutely no issue with you slicing through rhizomes when you divide.
Rhizomes, unlike corms (such as you’d find on Alocasia), are unspecialised organs that will produce whatever’s needed – roots, sprouts, whatever.
Every cell has the potential to be whatever. Chop it off, and it’ll grow back, like a fingernail.
Corms are not like this. Don't chop them in half when you're dividing your Alocasia. It's more akin to chopping your arm off and hoping it'll regrow.
THAT BEING SAID
Calathea are sensitive, delicate creatures. Whilst botanically I’m sure it doesn’t matter if you damage a rhizome, I still recommend you avoid doing it because…weeell, you know what Calathea are like.
I would also never chop a ZZ plant rhizome, not because I think it would damage the plant, but because they look curiously egg-like, and I don’t want to inadvertently release an alien or something.
So, separate your Rhizome and some roots from the mother plant. Then just pot it up. Don’t put it in too big of a pot, because you’re more likely to get root rot.
If you buy a tiny baby Calathea, like my Orbifolia, it could have been propagated like this (more likely it’s tissue culture, but you never know). You don’t need any special care other than what you’d usually provide for a Calathea.
The fewer roots the rhizome has, the more closely you’ll need to monitor it to make sure it doesn’t dry out.
A coir/perlite/worm castings combo is perfect, because it’s water-retaining but still airy. Orchid bark is a bit too chunky for young Calathea, and can reduce the contact of the roots with the substrate a bit too much.
Do Calathea rhizomes need sunlight?
Some rhizomes, such as Bearded Irises, need to bake in the sun for the plant to, er, cook, new growth.
This isn’t the case for Calathea – the rhizomes themselves should be buried – they don’t need any sunlight at all.
Calathea come from the South American rainforests, but grow in the undergrowth. They don’t typically get a lot of light, and whilst it’s definitely nice and warm (Calathea will not thank you if you let them get too chilly), there’s no chance that they’re gonna get baked.
In the sun.
Or, you know, the other kind.
Whilst Calathea themselves don’t need a lot of light, I’ve found that keeping them in low-light places is just asking for spider mites, because low-light spots in your home typically come with added dust.
Spider mites love dust, I assume because it’s drying.
Instead, I keep my Calathea in bright indirect light but shielded by other plants.
I have a very bright living room, so my small Calathea lives on the bookcase about 10 feet from the window, but when it’s too big for that it’ll go on the floor near the window but behind the other plants.
If the leaves start looking pale and bleached I’ll move it farther away.
Calathea rhizomes can be a bit weird when you come to repot and you weren’t expecting them (they can look like fat, hairy worms) but they’re perfectly normal.
Some Calathea produce more than others, so don’t worry if your Calathea doesn’t have any – if it’s growing fine, it likely is fine – Calathea soon make it known if they’re not happy.
When you come to divide your Calathea, it’s the rhizomes you’re looking for, as they basically form a separate plant – once you clock where it is and which leaves belong to it, it’s pretty easy to gently cut it away from the main plant.