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Misting?

Posted by greenwood85 6 (My Page) on
Fri, Jul 18, 08 at 18:31

How often do you mist your houseplants, if at all? I saw Paul James say you should do it frequently and I'd say I do it rarely. I have a lot pothos and wandering jew. Should I be misting?


Follow-Up Postings:

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RE: Misting?

Hi,

I've just gotten interested in some of the higher humidity houseplants this year and have started misting daily with a cheap $1 squirt bottle from the cleaning rack at the Dollar Store down the road. I do it every morning when the sun is low, as my plants are out on the porch for the summer and the sund's rays would magnify thru' droplets and burn little holes in the leaves.

During the summer I water with a homemade fertilizer mix someone told me about, and use it for misting as well. All of my plants really seem to grow better now that I do this.

It's 1 can of beer, 1 cup of epsom salts, 1/2 cup ammonia, and 2 cups of water. Whenever I water I add a teaspoon per gallon of water. Same strength for misting fluid.

All my plants perked up when I started using this and misting with it daily.

Yeah, I know, more info than you asked for...


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RE: Misting?

I do mist plants occasionally in the winter, when our air inside is likely to be hot and dry. In the summer I don't bother. Opinions vary about whether or not it's useful; I tend to think that it is probably not, but it's a subject about which reasonable people can disagree.

Neither pothos nor wandering jew are likely to care one way or the other.


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RE: Misting?

I mist at night or in the morning, sometimes both. I read it helps to bring out new leaves. A local garden store sprays water on their indoor plant nursery twice a day.


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RE: Misting?

I'm not so sure that misting is actually effective in raising the humidity level enough for a real tropical plant, although it surely doesn't hurt. Two more suggestions which require a little less work:

1) group your plants together. A group of plants creates its own moist microclimate in a room.

2) use a humidity tray. Stores that sell orchids will probably have them, or you can easily make your own.


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RE: Misting?

I mist more in winter when the house is dry, but certain plants get sprayed yr round..high-humidity loving plants.
It wouldn't hurt spraying WJ in winter, pinching keeps it looking good, too. Toni


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RE: Misting?

Thanks for the replies. I don't really have any tropical or humidity loving plants. I was wondering if people misted ALL their houseplants. It doesn't sound like it's all too necessary/beneficial.


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RE: Misting?

I have read that it makes the gardener feel better than the plants. Misting really helps if you have it on a timer, like in a greenhouse, and mist every five minutes or so. Not too good for the wallpaper! Think they said it only takes five or ten minutes for the air to dry out.


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RE: Misting?

  • Posted by tapla z5b-6a MI (My Page) on
    Sat, Jul 19, 08 at 23:20

I really don't think it useful at all, and probably detrimental. The only time I EVER mist is when there is a mite problem, and then it's just because I use the water as the vehicle to deliver alcohol, insecticidal soap, or some other anti-pathogen.

I also think that in almost all cases where growers are seeing poor foliage during the winter, it can be attributed to the plants inability to take up water efficiently because of soils with a high level total dissolved solids. Poor, or slow soils that need to be watered in sips, absolutely guarantee progressive accumulation of salts from both fertilizers and the solids dissolved in tap water. These solids make it increasingly difficult for plants to take up water, and can even reverse the flow of water so it is drawn from cells instead of entering them. (like salt draws moisture from dried meat and fish) Since humidity levels are low in the house and the roots cannot move adequate water to compensate - we see necrotic leaf margins & tips.

This might be too long and technical for most to want to wade through, but it illustrates how misting actually is detrimental to most plants. I wrote it for a club newsletter:

Misting

I personally view misting as an exercise in futility when raising humidity is the goal; and there are some compelling reasons, rooted in plant physiology, why we may wish to reconsider the habit/practice of misting, even if we set aside the fact that it helps for only a couple of minutes and has no residual benefit. There is also the possibility that water dripping from leaf to leaf or plant to plant will carry and spread insects and other pathogens, especially fungi. Misting does help satisfy the nurturing side of growers who adhere to the practice, though. ;o)

There is something very important about misting that no one EVER mentions on these forums. In many, probably more than half of all plants, exposure to rain causes rapid suppression of photosynthesis by inducing stomatal closure and causing temporary decrease or cessation of the photosynthetic mechanism. Examining plants exposed to several minutes of misty rain often reveals complete stomatal closure within 2 minutes, with a 30-40% decreases in photosynthetic ability within 1 hour. In addition, it often takes many hours to several days for plants to return to a "pre-rain" ability to carry on the efficient business of photosynthesis.

Moisture on leaves and/or in the air surrounding plant foliage will determine the humidity difference (gradient) between the inside of stomata and outside of the leaf (this is termed the saturation deficit). Humidity level just inside stomata is very high as they are normally full of water vapor, which will move out rapidly if there is a steep concentration gradient in humidity, i.e. if the surrounding air has a low humidity. This causes a drop in turgor which closes stomata. If you equalize the gradient, or raise surrounding (relative) humidity turgor remains constant so stomata remain open.

Misting:
Some discussion of "diffusional resistance", or things that slow down the diffusion which would occur naturally based on the water vapor concentration gradient (slow water loss through leaves) is required to understand the effect of misting. Primary considerations: the "stomatal pore" and the "boundary layer". Most, (almost all) transpiration occurs through the stomatal pores. We already saw that plants slow water loss by closing their stomatal pores when water is in short supply, but it occurs when something slows transpiration as well.

The blanket of unstirred air on the outer surface of the leaf is called the boundary layer. It helps insulate the leaf against water loss because it becomes nearly completely saturated with water vapor. The thickness of the boundary layer might only be a few thousandths of an inch, but depends on the degree of air movement, which blows away the boundary layer. If there is no air movement, a thicker layer and slowed transpiration results. More wind gives a thinner layer and rapid transpiration. At high wind speeds, the stomata usually close to prevent this rapid water loss (see above).

You can see examples of how the boundary layer works in cacti and plants that are pubescent (hairy). Most are slow-growing. I have read that the primary reason, indirectly, is stomatal closure due to the more effective boundary layer slowing transpiration and thus slowing photosynthesis.

So - weve seen that rain or mist on leaves obviously slows water loss from foliage by making (near) perfect the boundary layer. Since this slows transpirational loss, it closes stomata and also slows photosynthesis, which is not a good thing.

Even though we may not be able to expect the a negative impact on every single species of plant, I have concluded (for my own purposes) that an increase in relative humidity in air surrounding the plant is the most effective way to keep stoma open and insure optimum photosynthesizing ability and vitality. Remember, that there are abundant other factors that influence stomata function - light, temperature, internal plant rhythms all play into the equation, but far more plants will experience reduce photosynthetic ability when exposed to rain or mist than will not.

Al


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RE: Misting?

Excessive misting can cause mold problems on the soil and on the leaves.

Your plants would benefit just by opening up windows and doors (in summer) and using something like a tabletop fountain(s) around plants and using pebble trays like suggested in the winter.The cooler the room, the better the humidity.

Billy Rae


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RE: Misting?

I finally decided I saw no need for misting except to clean the dust off some large ficus.

An interesting think I discovered, at least I think it's interesting, is that these cleaning devices sold as "steam cleaners" with a wand produce steam that is about skin temperature at about 8-10 inches from the wand. So now I clean my large dust collecting ficus with the wand of my "steam cleaner". Try it on your arm like a young mother testing the baby's milk. You will find the right distance and it won't harm you or your plant. I clean it at most twice a year, perhaps.


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RE: Misting?

Al, thank you very much for the in depth explanation. I love understanding why things work (or don't work) rather than hearing the same old advice being propagated just because it "seems" to make sense. Maybe I'm glossing over some very obvious bit, but there's one part I don't understand. Why does slowing transpirational loss cause the stomata to close? I thought that slowing transpirational loss would keep the stomata hydrated and therefore open.


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RE: Misting?

A recent post made me think of this thread and since I still haven't found the answer to my above question, I thought I'd toss it out there again. I've read that plants can regulate stomatal closure by pumping potassium into or out of the guard cells and I understand why the plant would benefit from stomatal closure when transpirational loss is high, but why would reduced transpirational loss also cause the stomata to close? How does that benefit the plant?


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RE: Misting?

Country Kitty has the right idea, plants can be fed through their leaves by spraying. Not to be confused with how a plant is routinely fertilized, but spraying such fertilizer is one option that some plants can benefit from.

Misting provides moisture, to the air, to the plant.
One other benefit it can have besides defeating spider mites is it can often serve as a cleanser for leaves that draw dust.
Of course, some plants, such as African Violet, should never be misted.

A nozzle that can give a fine spray is I think worthwhile,

Misting should be done in the morning--never at night.
Misting should surround the plant so that it covers both sides of the leaf. Morning spray allows the plant to evaporate such wetness during the day.

But, misting never replaces watering at the prescribed times.

Misting should be done with regard for furniture the plant is sitting on. Spraying of pests on plants, should also be used where the plant sits. Window sills, saucers they sit on, tables and such should also be either sprayed or washed to kill what eggs might be there just waiting for the host plant to be returned to the spot.

As with letting water gain room temprature, misting should also have regard for its temperature.
Plants should, after misting, look like it has a fine dew on the leaves, not be dripping wet.

One other thing you can do with a mister/atomizer is spray a fine mist of half white vinegar/water into the air to overpower perfume that some guests leave behind after a vist.


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RE: Misting?

I'd far sooner put out a dish of baking soda to neutralize perfume left behind rather than be inhaling fine mist of vineger water. Then too, open the windows.

I would ask pls. that advice not be given here suggesting folks do things which will become airborne & inhaled.

This is potentially problematic especially for kids, pets, asthmatics & the immune impaired. As a former sinus sufferer myself, I NEVER would have risked that. Bad idea!


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RE: Misting?

tapla, I am sorry, but how can you compare rain to misting? When someone is misting, their light source is constant but when it rains, there is a huge cloud cover and it prevents most of the light from the sun. This is why photosynthesis decreases.

How could you miss this step?

Rainforests, as we all know have natural misting(more than 50% precipitation) from the trees, produce substantial growth in the plants when little sunlight gets past the trees.

Another counter example is greenhouses.

I know this is an old thread but I thought I make my view known.


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RE: Misting?

  • Posted by tapla z5b-6a MI (My Page) on
    Sun, Apr 25, 10 at 12:21

I don't think I missed a step. I was speaking from a physiological perspective that takes into account the influence misting has on the entire organism. I also made a qualifying statement in the last paragraph I wrote in my most immediate post above. Your view is noted.

FWIW - I'm almost NEVER one to use 'it works for me' as any sort of scientific proof to support what I say, but it might be worth noting that I grow hundreds of plants in containers. I over-winter at least 100 plants under lights in my basement, and another 100 or so over-winter in an unheated garage. Add to that the 100 or more containers that contain plantings I give away or that I discard at summer's end, and you can see that I have more than a fair amount of experience growing things in containers.

The only water the foliage on any of my plants, indoors or out, ever sees is rain. None of the plants I overwinter indoors or outdoors, and none of the plants I maintain outdoors during summer are ever misted.

Since I have posted hundreds of pictures of perfectly happy, healthy plants on these forums, we are able to draw one conclusion. That is, that at best, misting for a huge % of plants is completely unnecessary and ineffectual, and at worst has or can have any one or more of several consequences that negatively affect the organism.

Al


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RE: Misting?

Al,

Yes, surely I am not arguing misting as being neccessary. If anything, I am trying to water my plants efficiently while minimizing the amount of water used.

While looking into misting, I ran across your post. That is all.


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RE: Misting?

  • Posted by tapla z5b-6a MI (My Page) on
    Sun, Apr 25, 10 at 18:19

OK - I hope you found something useful in my offerings. ;o)

Take good care.

Al


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RE: Misting?

By the way, countrykitty's two year old comment about water droplets burning little holes in the leaves is a myth. We've 'almost' beaten that one into oblivion, but not quite.


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RE: Misting?

  • Posted by tapla z5b-6a MI (My Page) on
    Tue, Apr 27, 10 at 18:51

Almost .... within the last short while, I ran into someone arguing vehemently that it's not myth - that it was proven in a laboratory ....... no link to anything supportive. Maybe it was that 'Myth thread' on Container Gardening? ..... dunno.

Al


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RE: Misting?

Rhizo and Al,

This myth lives on - I can tell you that it pops up repeatedly on the C&S Forum, where it must be beaten until apparently dead, yet like Lazarus, rises from the dead to plague us again. As of this writing, there's no apparent life in it, but I'm sure it will come again into discussion. Geez, it's as bad as the birthers (but not as stupid).


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RE: Misting?

Water droplets burning holes? Yeah, that's why when it's hot out, I mist myself. I can't even begin to go on about the many ways that doesn't even make sense. I think that if it were true, no plant would survive here in CO, where it rains and is then very sunny again within about five minutes. Or when it rains and is sunny at the same time.


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RE: Misting?

Well not to start trouble, but try watering your green grass in the hot sun and see what happens when the water droplets are sitting of the grass and the sun is intensified by the droplets, magnifyed..

Or better yet, water a Jade in full sun and see what happens..I myself have burnt many leaves with water droplets on one of my Jades just recently, and some very sensitive plants..Landscapers and nursery men alike will tell you not to water your lawn during the afternoon to avoid burning it, and that early morning is best.

Fyi, misting your grass during the night or early evening can cause mild and desease..It can also cause disease and mold on your succulents, gardenias, plumeris, pothos,and clivias....

I think some can handle misting while others can not..All my citrus like a shower everyday, all day if they could along with many of my orchids.....:-)

Mike


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RE: burning holes in Leaves!

I used to believe that old Myth, too....
along with drainage layers of gravel/shards in the bottom of a pot.

I still avoid wetting foliage, in general, but for different reasons now.

I have, however, recently discovered one very good reason to mist my hot peppers:
to provide moisture for the ladybug larv eating the aphids on the plants... ;)

Josh


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RE: Please alliviate my fears..

Oops, maybe I am still a firm believer..lol NO body hate me for this, please and don't think I am dumb..

I really am scared to death to let water touched most of my plants while the sun is high in the sky..I alwasy rush out their in tgh early am when the sun isto water them all, top to bottom and have no fear at that time...

Please, alliviate my fears...Thank guys..:-)

Mike


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RE: Misting?

Hey, Mike!
I didn't see your post until I'd already replied! ;)
Don't worry, I won't hate on you...

Josh


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RE: Misting?

Mike...the reason that water droplets aren't likely to burn holes in your plants is because of the shape of the droplets. The light energy is DISPERSED when it hits the droplet, rather than focused like a magnifying glass. If the droplets remained on the leaves so that the convex side rested against the tissue, we'd have some potential for burning.

By the way, go out on a golf course in the middle of a blistering hot day and see if they don't run a quick irrigation cycle in order to cool the grass. Misting or syringing of greens, in particular, is a very important maintenance task.


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RE: Misting?

Hey Rhizo,

Hi there, I applaud your good intentions, but I think some folks really prefer to hold onto their old, outdated, disproven fears. If your say so & Al's still isn't enough for them, I can't imagine what ever will be!


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RE: Misting?

It's almost like an old wives tale. If nursery people tell you not to water your lawn during the day...go to another nursery or ask them how can you control the rain during the day. Surely it rains in your area and the sun shines afterwards. It is just ludicrous.
Early morning is best cuz the grass can absorb it more.

If true and watering grass during the day fries it then all of my neighbors including half of southern california would have fried grass instead of the lush green lawns they have.

Mike, when you water your jades why are you letting it get on the leaves anyway. You want their leaves firm. Leaves in jades absorb and hold water.
Pinch one off and see how moist it is at different times between waterings.


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RE: Misting?

I for one DO NOT intend on holding on to my fears. That is why I came here, to get comfort and seek truth...

I for my part have been helped dozens of times by people like Al and Rhizzo, and I too applaud their efforts to help us all out. Sorry if I held on to this fear this long. I am glad I can finally let go..I hoe many others here can too..

Thank you for the resaoning and just maybe, just maybe, I can print this out and show the owner of my nursery and all my landscaping friends that mytths still exsist..

Thank you Rhizzo, and gobluedjm for the facts.

Than you PG for encourageing me, and maybe a few others not to hold on to old disproven fears..You are all so kind.:-)

Mike..:-)


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RE: Misting?

It is always best to water early in the day so the foliage can dry out before night. You can get fungal problems if plants are kept damp at night. Also, watering early allows the plants/grass to take up the water before the heat of the day. Mid day sun will dry up any watering quickly.

Don't get mad at your nursey, Mike. It is good advice just for different reasons.

Jane


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RE: Misting?

Hi Jane..lol

It was the man in the barn house for grass seeds and fertilizers, working there for 35 years, and a lawn expert himself, that told me that grass can burn from the droplets of water that magnify the sun..lol

Thank you for your input..

I am glad I came here to get the truth about all this..

Mike


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RE: Misting?

Hi all,

I did yard work for 10 years, in Lincoln, Nebraska, in another life and I have never heard of water on grass to burn in the hot sun. I now live in Colorado and the "experts" say that out her, on a 95 degree plus day, to turn on the water for a couple of minutes on each spot to give the leaves "a little drink". When the temperature reaches about 100 out here you can be assured that the rel humidity is about 8% to 10%. It's hard for the grass to pull up water from the ground fast enough to replenish from evaporation.

Larry


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RE: Misting?

I've never heard of doing that here in CO. Guess that makes sense though. Then again, I don't care about my lawn too much to ever have looked into much about it.


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RE: Misting?

Earlier in this thread, Al wrote,
"So - we've seen that rain or mist on leaves obviously slows water loss from foliage by making (near) perfect the boundary layer. Since this slows transpirational loss, it closes stomata"
(end quote)

That sounds backward to me. Stomata should open when there's plenty of moisture, all else equal. That's when they can get CO2 most cheaply, in terms of work the roots have to do in order to replace the water. Here's what a search turns up.

When the leaves of a plant were wet by dew or rain, or wet artificially, the stomata usually opened if closed, or opened more widely if partially open.
http://books.google.com/books?id=CBUoAAAAYAAJ&pg=PA75&lpg=PA75&dq=stomata+rain&source=bl&ots=OHXooQEPZX&sig=VnRDj1fwARuoWe7xr-kUSRJt3hI&hl=en&sa=X&ei=16XvUJYyy-_RAfPLgOgC&ved=0CFUQ6AEwAw#v=onepage&q=stomata rain&f=false

In case that link doesn't work, here's another source saying somewhat the same thing.

In nature, many foliar bacterial disease outbreaks require high humidity, rain, or storms, which could favor stomatal opening
http://www.ncbi.nlm.nih.gov/pubmed/18422426

This post was edited by dsws on Fri, Jan 11, 13 at 16:33


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RE: Misting?

  • Posted by dsws none (My Page) on
    Fri, Jan 11, 13 at 8:47

I looked a little more for anything saying that photosynthesis slows down after rain. I found one mention of waterlogged roots, which certainly makes sense.

--

I don't see any need to bump two misting threads, so I'll quote and link the other one instead.

Mike writes that misting "slows down transpiration, slows the rate at which water in the soil solution is used....which also reduces the amount of 'nutrients' delivered via the nutrient stream."

According to Transpiration, a prerequisite for long-distance transport of minerals in plants?
W. Tanner*� and H. Beevers�, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC55440/, the answer to their article's title is no. Mineral nutrients are transported by the circulation of water through the xylem and back through the phloem. It made no difference whether minerals were provided to experimental plants only at night or only during the day, whereas it did make a big difference when higher levels of minerals were supplied, showing that the plants were indeed limited by the mineral levels rather than by something else.

Here is a link that might be useful: Do I dare ask...Misting plants...


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RE: Misting?

  • Posted by dsws none (My Page) on
    Fri, Jan 11, 13 at 12:58

If guttation is a way of excreting harmful materials, then misting could be helpful by rinsing away guttation fluid or removing dried guttation residue from the leaf surface.


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RE: Misting?

I didn't get that from the reading above. Who said the minerals were harmful?


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RE: Misting?

  • Posted by dsws none (My Page) on
    Fri, Jan 11, 13 at 16:24

Those are two completely separate points. The only connection is that they're both about misting.

The rest of the guttation discussion is in the guttation thread. In brief, the idea is that guttation is plant pee: the plant takes encounters minerals in whatever ratio happens to be in the soil, and absorbs minerals at a very good approximation to what it can use. But when the ratio of minerals is too far off, it gets an excess of some. The only mineral it's actually been proven for is boron. Interfering with guttation can make boron toxicity worse, if there are toxic levels of boron there to begin with. In the guttation comment I'm giving a completely new (to these forums) reason why misting might sometimes be beneficial.

The stuff about transport of minerals, and how it doesn't depend on transpiration, is in response to a post in the other misting thread. This is about the normal case, where there's no boron toxicity or anything like that, so the minerals being transported are entirely beneficial. In the transport comment I'm disputing a reason why misting is claimed to normally be slightly detrimental.

Here is a link that might be useful: the guttation thread


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RE: Misting?

I used to follow the herd and mist my plants, but unless you mist constantly all day youre wasting your time. Misting wont increase humidity because it evaporates or is absorbed too soon for it to increase humidity.

And if raindrops on leaves caused scorching then nature would have accounted for that! Either that or we'd end up with a lot of extinct plants!

What will burn the leaves is the salts left behind in the warer that we use with its various chemicals.


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