Almost all houseplant books advise misting for keeping humidity high around a plant. Though here I read many people saying it does more harm than good. What's the truth nad why?
Hi Miss GF,
I don't think we know the truth or even how to find out (on this topic). I will say this topic can get quite heated & has in the past.
Personally, I rarely mist -- when I do it's only my Hoyas, Ceropegias & maybe a couple of Holiday cacti & Epis.
Misting increases the humidity for about 5 seconds.....
if you want to increase humidity, you need an enclosed space or an actual humidifying system. Flat trays with stones and water with a fan blowing over the trays can help, as can grouping plants together.
A lot of house plants come from rainforests, cloud forests, near waterfalls, etc., where misting is constant or at least frequent. But a large part of the atmosphere (ground level) is humidified and stays that way. But if you're in a dry climate the volume of dry air is too great for misting to have a significant effect. And any wind blows whatever humidity you may have added away and replaces it with more dry air. It's not an impossible task to benefit plants with misting, it's just a short term effect, depending on your climate. I have some plants that I mist/dampen and you can see the benefit. But not being there all the time means they still have to cope with some dryness in dry weather. Fortunately for my plants humidity is high most of the year. Even in the hot dry weather humidity at night sits around 80 - 90%.
I don't bother misting my plants when they're inside for the Winter. I'd have to agree that misting doesn't really increase the humidity. My place [unfortunately] uses gas heating, which severely dries out the relative humidity of my whole house. I have a digital weather station that I use to monitor both inside and outside conditions. During the winter months, while heating my home, the RH plummets down to just 2% and pretty much stays there. Last Winter, I kind of did a little experiment. I boiled a pot of water for a while, to see if the steam would have any significant impact on the RH. Seeing as my digital weather station is in my bedroom on the opposite end of the house, I didn't think that there would be any affect at all. What surprised me was that the RH almost immediately started to climb upwards, and reached 20-30%. But once the heat kicked on again, it dropped back down to 2% and stayed there. So unless I stopped heating my house, there would really be no point in trying to humidify my home. If boiling water wasn't much help [with my heat running], then misting [for me] is nothing but a complete waste of time.
That being said, I do keep my plants pretty much well watered throughout the Winter. With my air being so dry during that time of year, my plants tend to drink up quite a bit of water. Just as long as I keep them from drying out too much, they tend to tolerate it for the most part. Throughout the rest of the year, when it's warm enough outside, they get to enjoy all the humidity that they could ever want, HaHa. Which they do, as they are right now. One of the *very* few advantages of living here in the hot and humid South.
Misting can also spread disease propagules and spider mites.
On the plus side, it can help remove dust from the plant. Misting also makes the humans feel better, more nurturing. That human factor is not unimportant.
Pros, you get to spend time around your plants.
Cons, it doesn't change the humidity or help the plants.
Tommy, I just now read your post carefully and had tl comment. I think that something must be wrong with your hygrometer...I'm not sure that a rh reading of 2% inside a home is possible! I'm serious.
A very low % would be in the 20% range, and that's low enough to cause problems for the house, the furniture, and any living inhabitants. An ideal (and healthy) range is between 30% to 50%.
If the RH drops in the lower range in the winter, we need to think about adding moisture to the air in a serious way. Room humidifiers, whole house humidifiers are very common.
We try to maintain a humidity level of around 40% in our home in the winter. If it gets much lower than that for a few days, our eyes, skin, lungs, and nasal passages all suffer.
In the warmer temperatures, it could become very humid inside....unconfortably so. But our central AC takes care of that nicely.
Rhizo_1, it works perfectly fine. To be fair, it doesn't always stay at that level. This only occurs during the coldest part of Winter. I had an older digital model before this one, with the same readings. Even tho it remains humid outdoors, the air in my home really does dry out to 2%. This is why I tried that little experiment of boiling water, just to see if it would change. Which it did. It stayed at that higher level too, up until the heat kicked back on. Then, I watched it begin to drop back down. You can see a slight elevation after I've showered or cooked, but when the heat kicks back on, it goes back down. However, this only occurs during the coldest part of Winter. The rest of the time, it'll just stay at below average levels. It's the only thing I really hate about my place during that time of year.
In hard water areas you end up covering the plant with water marks if you're not careful.
Use a bit of water based leafshine in the sprayer, e.g Pixie Sparkle. That stops the marking.
RH fluctuates with temperature changes even when water content in the air remains the same. At higher temperatures air has the potential to absorb more water, RH is basically a measure of that potential. If that same air mass cools the potential for water absorbtion drops and the RH goes up without there being any added water.
There are still some plants that benefit from misting. It forms droplets on leaf surfaces which last for a while (depending on the ambient RH). I use water with low TDS because apart from what is absorbed it's only the water that will evaporate. The salts stay behind.
So if I use distilled water for misting that won't leave watermarks and salts on the leaves, right?
And definitely have to agree with whip1! Being around and misting here and there feels good :)
Misting the *soil* can be a way to cope with a tendency to overwater. Think it needs a drink but it probably doesn't yet, but you want to anyway? Happens to me too, mist the soil a bit, makes me feel better. For plants that seem difficult to get moist in the middle of the root ball this can help also. Unless/until repotted, the more slowly water is added to these, the more thoroughly it can soak in.
Does misting with distilled or any other form of water stain leaves ? To respond, what happens to foliage when we blast an entire plant with a hose or spray bottle when watering ?
Every plant on earth is fasioned to accept any volumed amounts of water on the foliage at one time or anouther
Misting can make a difference if your plants , lots of them, are confined to a non heated room with the door shut...
Misting one plant will do nothing to raise humidity.
If you have a dedicated room like that then misting makes a huge difference in humidity...One has to be watchful they don't encourage mold and mildew on the wall and such as I had to, even with a fan in motion.
I could keep the humidity in that room up to 70 percent all day if I wanted to by misting all my plants in the a.m. BUt the what's the point if I had to open the windows in the middle of winter to prevent mold even on the ceiling, window sills and walls? The condensation was horrible on the glass.
This post was edited by meyermike_1micha on Sun, Jul 27, 14 at 13:44