Checking the undersides of leaves like it's a hobby
Okay. So we've done water, we've done crust, we've done light. New module. This one's about bugs, and I'll be honest, it's my least favorite part of having plants and also the part I'm weirdly good at now.
Here's the thing about houseplant bugs. They don't show up because you did something wrong. People hear "pest problem" and immediately think they failed somehow, dirty house, bad plant parent, whatever. Not usually true. Bugs happen because you brought a living thing into your living room and living things sometimes come with hitchhikers. That's it. That's the whole moral failing.
Why the undersides matter
Most of the bugs that bother houseplants don't sit out on top of a leaf where you'd notice them. They go underneath, where it's shadier and you're not looking. Spider mites especially. They're tiny, almost see-through, and the first sign is usually a little bit of fine webbing, like a spiderweb but shrunk down to almost nothing.
I found mine on a calathea, completely by accident, morning light hit the leaf at some angle and I saw the webbing catch the sun. I remember feeling almost betrayed. Like, I water you, I rotate you toward the window, I let your water sit out overnight like a decent person, and this is what you do to me.
But that's how it goes. So now I check undersides of leaves like it's a hobby. Which, I mean, it sort of is at this point.
What to actually do, once a week or so
You don't need a schedule taped to the fridge. But when you're already watering, or wiping dust off leaves, just flip a few over. Takes ten extra seconds. Look for:
- Fine webbing, especially near where the leaf meets the stem — spider mites
- Little cottony white fluff tucked in leaf joints — mealybugs
- Tiny flying gnats when you water — fungus gnats, usually a soil moisture thing more than a leaf thing
- Small brown or tan bumps that don't move — scale, and they're sneaky because they genuinely look like part of the plant
If you see nothing, great, you're done, go on with your day. If you see something, don't panic. Almost none of these are a plant emergency. They're a plant nuisance.
The fertilizer thing, because it's related
I want to bring this up here because people conflate two different problems and I did too, for a while. I over-fertilized a peace lily once — fed it on basically every watering because I figured more food, happier plant, same logic as a teenager and a growth spurt. The leaf tips went brown and crispy and I was convinced, genuinely convinced, that it had some kind of disease. Spent a whole Saturday looking up peace lily diseases before I finally read the fertilizer bottle and realized I'd just been overdoing it.
I tell you that here because brown crispy tips and bug damage can look similar to a beginner, and they're not the same thing at all, and they don't get fixed the same way. Fertilizer damage is usually tip burn, even, symmetric, no webbing, no bumps, nothing moving. Bug damage tends to be patchier, and if you look closely enough you'll actually see the thing doing it. Different problem, different fix. Don't treat one like the other.
If you do find something
Small infestation, one or two spots of webbing or a few mealybugs: wipe the leaves down with a damp cloth, maybe a little diluted dish soap in water, and isolate that plant from your others for a couple weeks. Bugs travel between pots that are touching or close together, so distance is doing real work for you.
Bigger infestation, whole plant covered: this is where I'll tell you plainly, sometimes it's not worth saving. If it's a five-dollar pothos and it's covered in mealybugs, I'm not spending three weeks nursing it back. I'm tossing it and starting over. That's not me being harsh, that's just math. This is actually part of why I tell people to buy the cheap plant first — you learn this stuff on something that costs five dollars, not on the fancy one from the garden center.
One real caution: whatever spray or soap solution you use, test it on one leaf first and wait a day. Some plants, especially ones with soft or fuzzy leaves, don't love soap treatments and you can do more damage than the bugs would have.
Before next time
Go flip some leaves. All of them, actually, every plant you've got, just once, so you know what normal looks like before you're trying to spot what isn't.