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House plants CAN cause damp, but as long as you’re careful not to overwater them, then you should be fine.
If you’re worried about damp, don’t worry about turning on the dehumidifier.
Removing excess moisture from the air helps to keep rooms warmer (because it takes more energy to heat water molecules than just regular air) which your plants will probably appreciate more than the humid air.
Many tropical house plants do love humidity, BUT they love staying warm a little bit more.
So, do houseplants cause damp?
Houseplants don’t cause damp, but they can make damp house worse. Soil holds water and can add moisture to the air.
However, I lived in a cold damp house and my house plants didn't make it damper. In fact, the rooms my plants were in were less damp than they had been previously.
As long your plants are in very dense soil that holds a lot of moisture, and is in the right sized pot (i.e. not too big) houseplants won’t make a noticeable contribution to dampness in my experience.
How do I check if my house has high humidity?
One sure sign is that you have mold growing – it’s common in older houses, especially in naturally humid rooms like bathrooms and kitchens.
However, low temperatures and inadequate airflow are just as likely to cause mold as high humidity.
You can get little sensors that will tell you how much light and humidity a room has, as well as the temperature. You can pick them up pretty cheap - I have a link to them on my resources page.
If you already have a dehumidifier (or humidifier), it should tell you on the display how humid your room is.
For reference, the humidity in my house is about 65%.
It’s decreased from 75% since getting the plants, but obviously, there could be other factors at play.
I’m pretty sure the plants have reduced the humidity overall though.
What does cause damp?
This is common in older houses. Make sure you’re airing the house out regularly, ensure that you have an efficient fan in the bathroom and open a few windows (yes, even in winter – if only for a few minutes) to allow air to circulate.
Be aware of anything that can add to the issue, such as drying clothes in the house. Don’t dry clothes on radiators.
By the way, if you suffer from dry air, drying clothes on the radiator is a great way to increase humidity. I’ve started doing this again after years of fearing mold, and my plants love it. No mould.
Just be sure that there’s decent air flow.
By the way, don’t worry unduly if the plants have mold on their soil, it’s rarely anything to worry about.
Heating your home will reduce condensation, and the insulation will keep the heat inside.
The biggest cause of damp and mold is poor ventilation and cold rooms.
Take your plants out of the bathroom and make sure you open the window after showers to let the moisture out. Bathrooms are cold anyway, plants won’t enjoy it in there in winter.
Water getting in
Leaky gutters or pipework can cause water to leach into your home.
Plants are unlikely to have an impact on this UNLESS you have English Ivy. Ivy can work its way into brickwork, so if you have it on the outside of your house, keep an eye on it.
I know a lot of you will keep English Ivy as a house plant and I....don't. Not because I think it'll get into my walls and cause dampness, but because it's irresistible to pests.
I don’t need the drama.
Can houseplants help with dehumidifying?
Ok, yes they can.
A little bit.
From the research, I’ve done, there are plants that like humid conditions and will absorb moisture from the air HOWEVER, these plants will not solve your damp problem overnight.
It’s also worth noting that humidity-loving plants tend to come from tropical climates. Damp tends to be more of a problem when it’s cold, so when you most need your moisture-sucking plants, they’ll not be in the mood for sucking up water.
Plants do absorb water through their leaves, but they also expel it through transpiration. It will also evaporate from the soil.
Will a dehumidifier hurt house plants?
In my experience, no.
I don’t run my dehumidifier unless the house is cold and damp and needs, you know, dehumidifying. If the atmosphere was dry enough that my plants would suffer, I wouldn’t have the dehumidifier on.
On most dehumidifiers, you can set it so that it shuts off once your desired humidity level is reached. I set mine at around 50% and both my plants and my bathroom walls are happy.
Feel free to water your plants with the dehumidifier water, BUT make sure that it comes up to room temperature first. A dehumidifier is basically a fan, and the water that it sucks in is COLD.
Will the plants enjoy the damp atmosphere?
Plants LOVE high humidity, but only on their own terms.
There are three pillars that make up the PPC (perfect plant conditions):
Obviously, they need soil and water etc etc, but if you don’t have decent humidity, warmth, and light, you’ll struggle to keep your plants happy.
But here's the thing: you really need all three to be balanced. If you have great light, high humidity, and warmth, you're golden. But you only have two, you need to carefully pick your plants so you don't end up with issues.
The problem with the UK in winter is that we don’t have much light and it’s pretty cold (and none of us can afford to put our heating on).
So it’s not just humidity, but it’s cold and dark. That’s just a recipe for mold and mildew.
Which plants will absorb water from the air?
I know we’ve already been through this, but I want to make it crystal clear – unless you have a lot of houseplants, they’ll have a negligible effect on the humidity of your home.
Conclusion: will houseplants make my house damp?
No, not unless a) you have hundreds or b) you chronically overwater them so that the potting medium is always wet.
But they won’t miraculously suck up all your excess humidity either.