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Misting houseplants does NOT increase humidity.
Let’s get that out of the way first. If you resent spending time misting your plants to raise the humidity level…stop. You’re wasting your time.
When I first got into houseplants, I was intrigued to see that people either misted (and swore by it for healthy plants) or didn’t mist (and claimed misting would cause rot and bacteria and was a big no no).
The divide is pretty much 50:50. Go to any houseplant Facebook group, search for misting post, and check out how passionate all the commenters are about their chosen side of the argument.
From this data we can conclude…misting is a VERY neural activity. Does it provide benefits for your plants? Not really. Does it do them any harm? Again, not really.
If you want to mist your houseplants, you keep on doing it. I love to spray stuff as much as the next person. If you don’t want to, don’t. Your plant won’t care one jot either way.
That being said, there are caveats, otherwise I could just end the article here. If you’re pressed for time and your plant is healthy, you can stop reading now, because a healthy plant is happy to be misted (or not, as the case may be).
What happens when you mist houseplants?
So, we’ve already established that misting isn’t providing your plant with humidity.
Humidity is the concentration of water vapour in the air. Vapour, not water that’s been put in a spray bottle.
Once the humidity level reaches 100%, then it rains (there’s supersaturation, but let’s not get into that) and leaves get wet.
When you mist a plant, the leaves get wet.
I just wanted to make that clear to illustrate my main point, which is that misting houseplants is the indoor equivalent them being rained on.
Why’s that important? Because it more or less proves my point that misting is entirely benign.
It CAN’T be that harmful because plants in the wild get rained on all the time.
Especially tropical plants (which most houseplants are) because they hail from literal rainforests.
You might be thinking ‘doesn’t that mean that misting plants is a good thing? Surely they like getting rained on?’
No. No no no no no.
Plants do NOT like getting rained on. Who does? They’d much prefer to suck it up from the soil without it ever touching them. Just because they need rain to survive doesn’t mean they like it.
What misting does
- Wets plant leaves
- Forces the plant to close its stomata
- Knocks off dust and possible pests
What misting DOESN’T do
- Increase the humidity around the plant for more than a couple of minutes, tops.
- Immediately cause a bacterial infection
There’s pros and cons to misting, but if your plant is healthy, it won’t make much of a difference. If your plant is unhealthy I’d advise that you don’t mist.
Is misting beneficial?
Misting can be beneficial, but the benefits aren’t exclusive to misting. So if you don’t mist, you can still get all the benefits, just in other ways.
You spend time with your plants
This is part of the whole ‘talk to your plants’ thing. Talking/misting doesn’t benefit plants in itself BUT the additional time you spend with them does.
The more time you spend observing your plants the more likely you are to notice when they need water, have pests, and all that good stuff.
It gets rid of dust and grime
If you mist regularly, you’ll rarely have to take the time to clean your plants more thoroughly with a cloth. The dust won’t have time to get sticky and gross, so will just fly off when you blast water at it. Easy!
Just be aware that if you just mist a very grimy plant, the dust won’t blast off – it’ll form weird swirls and circles on the leaves that will make you scour the internet for hours looking for the cause (source: me).
It’s an easy way to keep moss poles hydrated
I’m not big on misting, but I do use a pressure sprayer to hydrate my moss poles. It can be messy, and it takes a bit of practice to hit only the pole, but personally find it easier than the cup-on-the-top method.
You can blast off pests
You can blast off most houseplant pests with a water sprayer (except scale) but by far the most satisfying is aphids. Aphids are a PAIN to get rid of without resorting to harsh chemicals. The best way to keep on top of them is to regularly waterboard them.
Is misting houseplants harmful? Do plants like having wet leaves?
Plants don’t like having wet leaves, but they can survive it, otherwise they wouldn’t last long in the wild.
The issue is when the leaves are consistently wet, especially when temperatures are low and airflow is lacking.
Plants have evolved to have quick-drying leaves
Plant leaves are designed to channel water off them. There are a few different ways they do this:
- Some plants have leaves that point down so standing water isn’t an issue
- Some plants have a waxy texture to repel water
- Some plants hold their leaves vertically at night (like prayer plants) to reduce water staying on the leaves
Imagine evolving quick-dry leaves over thousands of years just to have some noob spray you down every now and again. You’d be fuming.
But why do the leaves need to be quick dry? The next reason is probably the most important:
Misting pauses photosynthesis
If you want a proper explanation of this, read this journal article.
I will do my best to explain why wet leaves halt photosynthesis:
- Leaves have stomata on their surface to facilitate photosynthesis. Plants take in carbon dioxide from the air through their stomata
- When it rains (or you mist), the stomata close to stop the leaf from taking in too much water
- When the rain stops. The leaf dries out, the plant doesn’t immediately go back to photosynthesising – it needs time to switch back from whatever it was doing whilst the leaves were wet.
As the linked article explains, the jury is still out on how the stomata-closing protocol is initiated. We don’t know if at the detection of a single drop of rain all the stomata snap shut like mousetraps, or if some stomata are slower to close than others.
What we do know is that whether the stomata are open or closed, leaves can’t absorb carbon dioxide from water nearly as effectively as they can from the air, so wet leaves inhibit photosynthesis even if the stomata remain open.
Wet leaves can attract unwanted hitchhikers
This isn’t too much of a concern with houseplants, but it could be if you put your plants outside in summer. Wet leaves provide a great environment for things like algae, moss, and lichen which may look cool, but can cover the stomata and further impede photosynthesis.
Wet leaves can cause rot/mould/bacterial infections
The most common manifestation of this is when you mist emerging leaves. The combination of the physical attack from the spray and the wet leaves can cause the new leaf irreparable damage. It’ll probably emerge, but with black marks. If water gets trapped in the unfurled leaf the whole thing can rot.
It’s a great way to move pests around
Remember that I mentioned blasting pests off using a spray bottle? Just make sure not to do it around other plants – you don’t want to spray them onto another plant.
Misting can dampen the top of the soil
Aaaand damp soil can attract fungus gnats, which we definitely don’t want.
I’ve heard a few people caution against accidental overwatering due to overzealous misting, but tbh you’d need to be misting your plants a LOT to getting them that wet.
Plants to avoid misting/getting their leaves wet
In general, try to avoid watering the leaves of your plant when you water them. Don’t go out of your way or anything, but try your best to water the soil, not the leaves.
We’ve already established that plants that can’t tolerate wet leaves won’t make it long in the wild, but there are a few that it’s best to be extra careful with.
Your plan of action with these plants is to leave them dry, not to avoid getting them wet in the first place. Don’t panic if the leaves get wet – just dry them off with a cloth or paper towel.
African violets are often cited as being a plant that can’t get its leaves wet. This obvs isn’t true, because they’ll definitely get rained on BUT there are a few reasons why it’s best to dry them off after watering:
- The leaves are flat and round, so there’s no way for the water to channel off
- The leaves are hairy, so water can get trapped on them
- Their natural habitat has a hot climate, so when they do get wet, they dry off quickly
They’re just a nightmare for getting watermarks. I kept a velvet touch Calathea in a frequently misted terrarium (we needed to provide water fo the frog and geckos) and it was perfectly healthy just covered in white watermarks.
They’re susceptible to rot, but the main reason is that they’re just not equipped to deal with it. They’re highly unlikely to stay wet for a significant period of time. Professional cactus growers even dry the soil with a hairdryer half an hour after watering.
How to mist houseplants
If you want to mist, go ahead. Avoid unhealthy plants because they’re far more likely to succumb to bacterial infections than healthy ones.
How often to mist
I’d stick to once a week, maybe up to three times in hot weather – it’s basically the same as showering your plants (with far less risk of overwatering), so stick to the same rules.
What to use to mist your plants
I’m not a fan of those little hand sprayer things – they always leak! I prefer to keep mine as decor items and use my trusty pressure sprayer. Don’t pump it up too much – you want a mist, not a blast.
Even if you don’t mist, get a pressure sprayer. They are SO GOOD for houseplant people, especially if you have a lot of plants. Read this article if you want to know more.
- Healthy houseplants are indifferent to being misted
- There are benefits to misting, like knocking off dust, but nothing major
- Misting can cause issues with unhealthy plants, but is unlikely to harm healthy plants
- Misting provides water, NOT humidity
I hope this was helpful. Leave me any questions in the comments, and I’ll get back to you asap.