Corking: Here’s Why Your Monstera Stem’s Brown

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Corking is one of those topics on which there is precious little information. Like some weird secret plant people keep and we’ll only let you in on it when you’re CONVINCED your plant has got some kind of hideous disease or super strong scale.

Corking is a way a plant can strengthen its stem.

It grows a bark-like layer over parts of the stem that are load-bearing, so it can better support them.

By the way, if your Monstera stem is brown and mushy, that's not corking, it's stem rot. Immediately go and read this article and prepare to chop and prop. Move quickly, this is not a drill.

Monstera do a lot of weird stuff. I’ve compiled it all into a guide here.

corking on my Thai Constellation
corking on my Thai Constellation

It’s extremely common in many plants BUT it’s more usual to see it on more mature plants, which is probably why it’s not written about more. Not that many people keep hold of plants for that long, so it’s not a common issue.

Corking is NOT scale

corking on monstera thai constellation

It’s easy to see why people get confused though. Newer corking looks like lots of tiny raised spots… sounds a lot like scale to me.

Typically with scale though, they’ll come off pretty easily if you pick them. Corking doesn’t come off easily – it’s kind of like a callus, and those do NOT come off easily.

This corking on my Monstera really, really looks like a pest/disease though (it’s not):

corking on Monstera deliciosa
It’s blurry because we’re in a heatwave and I have the all curtains closed and lights off like a sweaty gremlin

What plants does corking affect

If you look at any Cacti forum, you’ll find that corking is a very common topic of discussion there. Cacti often grow tall and thin (and are full of water) so as they age they require a stronger epidermis to stay upright.

corking on cactus

I don’t know if ALL plants have the ability to cork/produce corking, but many do. Here’s a bit on my Philodendron golden dragon:

corking in philodendron golden dragon

If you look at the front, slightly out of focus, stem, you can see that it’s starting to cork. First, the stem will go brown in colour.

I assume it’s like a primer layer before the woody bit starts growing.

(Either that or the whole thing’s rotting, but I don’t *think* so. He’s putting out a TONNE of new growth atm).

Should I worry about corking?

No! It’s just a sign that your plant is growing up and wants to start supporting itself.

Please don’t try to scratch it off. I appreciate that not everyone will like the look of it, but it’s clearly something your plant thinks is important.

If you try to remove it, you’ll end up removing the top layer of the epidermis (or skin) of the plant and potentially invite in a whole host of infections, pests, and diseases. LEAVE IT ALONE.

Erm. I appreciate that that wasn’t exactly an essay, but there’s precious little information available on the matter. If anyone has any insights into corking, leave me a comment!

Caroline Cocker

Caroline is the founder and writer (and plant keeper) of Planet Houseplant

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