Root rot: what it is and how it sneaks up
Okay. So we've done the finger test, we've talked about the guilt watering, you're feeling pretty good about your soil-checking skills…
Now I have to tell you about the thing that's actually killing most of your plants, and it's not going to be a fun lesson exactly, but it's the important one. Root rot.
Here's the sneaky part. Root rot doesn't look like too much water. It looks like not enough. That's the whole trap.
What's actually happening down there
Roots need to breathe. I know that sounds strange for something living in a pot of dirt, but they do, there's oxygen down there in the little air pockets between soil particles. When soil stays wet for too long, those pockets fill up with water instead of air, and the roots start to suffocate. Then they start to rot, actual decay, and once that starts, they can't do their job anymore, which is pulling up water and nutrients for the rest of the plant.
So the plant on top starts looking thirsty. Droopy leaves, maybe some yellowing, soil that seems dry on the surface. Your instinct — a totally reasonable instinct — is to water it more.
That's the trap closing. You're drowning roots that are already drowning, because the leaves are lying to you about what's going on underground.
How to actually tell the difference
This is where the finger test we already learned starts pulling more weight.
- If the top inch is dry and the plant's droopy, that's probably just thirsty. Water it, you're fine.
- If the soil's been wet a while and the plant's droopy, that's your red flag. Don't water. Go check the roots.
To check the roots, you pull the plant out of the pot. I know that feels like a big move, but it's not a big deal, plants come out of pots all the time and go right back in. Healthy roots are firm and usually white or light tan. Rotted roots are dark, mushy, sometimes they'll have a smell to them, kind of sour. If you tug gently and the outer layer slides off like a wet sock, that's rot. That's not a maybe.
Why I bring up the peace lily every time I talk about "reading a plant wrong"
I want to tell you about the time I nearly convinced myself my peace lily had some exotic disease.
The leaf tips went brown and crispy, all of them, all at once, and I panicked a little. I was searching things at midnight, convinced I had a fungus situation, some rare houseplant ailment I'd have to nurse it through. Turns out I'd just been feeding it fertilizer like it was a teenager who needed three meals and two snacks a day. I'd fed it constantly because I figured more food, more growth, more love. The label very clearly said otherwise and I hadn't read it.
I tell that story here because it's the same mistake wearing a different hat. I looked at a symptom and jumped straight to "something rare and scary is wrong" instead of checking the boring, obvious thing first. With root rot it's the same instinct in reverse — the plant looks thirsty, so you assume it needs water, when the boring obvious thing is that it's already had too much.
Check the boring thing first. Every time.
What to actually do if you find rot
If it's not too far gone:
- Pull the plant out of the pot.
- Take clean scissors and cut off the dark, mushy roots. Don't be precious about it. Cut back to where the roots are firm and pale.
- Repot into fresh, dry soil. Not the old wet soil, fresh.
- Use a pot with a drainage hole. I say this every class and I'll keep saying it, a pot with no hole is asking for this exact problem.
- Don't water it right away. Let it settle a few days before the first drink.
If it's mostly rot and barely any healthy root left, I won't lie to you, sometimes the plant doesn't make it. That's not a personal failure. Some of them are too far gone by the time you catch it, and that's just true.
The opinion I keep repeating
Most plants die from too much water, not too little. I said it back at the start of this class and I'm saying it again here because root rot is the clearest possible proof of it. Nobody's plant dies of thirst around here nearly as often as it dies from being loved a little too hard with a watering can.
A quick word on drainage holes and cachepots
If you've got a plant in a decorative pot with no hole — and a lot of us do, they're pretty — keep the plastic nursery pot inside it and just lift the plant out to water over the sink. Let it drain fully before it goes back in the pretty pot. Water sitting in the bottom of a cachepot with nowhere to go is basically root rot on a timer.
Before next time
Go home and check one plant you've been a little worried about. Pull it out of the pot, just to look. You don't have to fix anything yet, just get comfortable seeing what's actually going on down there.