You often read in books on indoor plants or on the internet that plants which require high humidity should be misted or vaporized with water at least once or several times a day.
But does this really help to raise humidity?
No, actually not. After no more than five minutes the water has spread across the room with air circulation.
Note that it is not about draught but normal air circulation that takes place in every room, even if it is closed.
Air circulates simply because there are warmer and colder zones, humid or dry zones: hot air rises, moist air is heavier and sinks.
So, after having been misted, your plants spend the rest of the day at the same level of atmospheric humidity as before misting.
What is humidity anyway?
Air humidity is relative humidity or hygrometry, it indicates in percentage how much water vapor is in the air compared to the maximum amount of water vapor (100%).
Usually indoor relative humidity is about 40-60%, depending on the temperature, if you heat, ventilate…
Some plants require 80% or more relative humidity, while othersmay thrive with less although in their natural habitat the relative humidity is high.
How then can you raise the humidity?
You can place your plants on top of a tray filled with pebbles and water.
This will increase the air humidity around the plant somewhat but is still not sufficient for plants that require 80-90% humidity.
Group plants together:
By placing plants close together, you create a small micro climate with higher humidity.
But again, the humidity will never achieve 80-90%.
Electric room humidifier:
This will increase air humidity a bit but again not enough for plants that need 80% or more.
Humidifier for heating or the stove:
That’s basically what your grandmother probably did: hang a ceramic pot filled with water to a heater or put a pot filled with water on the stove.
It increases air humidity only slightly, never enough for plants that need 80% or more.
Open or closed terrarium:
An open or closed terrarium or orchidarium is actually the only thing that can provide sufficient air humidity to plants for which it is indispensable.
In a closed terrarium you can obtain 90-100% humidity, in an open terrarium around 70-90%, depending on the exposure, location, temperature…
Vaporizing to get the dust off of your plants:
Uh no, again not a good idea. By misting you obtain only one result: the impurities will clog together but remain on the plant.
If you want to remove the dust from your plants, give them a shower so that the dust gets washed away.
Plants can indeed absorb nutrients through plant parts other than roots.
Although not in large quantities but in a very efficient manner.
This is a very suitable technique for plants which are not in great shape as well as an additional food supply to supplement the nutrition contained in the soil.
But this is a fairly extensive topic in itself, for which I will write a separate article.
It is impossible to obtain an indoor humidity of 80% or more by misting, water tray or a humidifier.
The only way to grow plants that really need such a high humidity, is to place them in a terrarium or orchidarium.
In horticulture, air humidity is raised in greenhouses by misting or wetting the ground.
But this is not possible nor even desirable indoors, unless you wish to grow mold on your walls and get the wallpaper to fall off.
- Plant vaporizer: Own work