Misting & Foliar Feeding - Orchid Board

HiOrcDen · #1 05-15-2022, 03:24 AM

Just a couple quick questions...

Should I necessarily be misting my orchids, especially with low humidity? If so, is it possible to mist too much, in case of mildew or something similar?

And what about foliar feeding? I have seen Miracle Gro Orchid Mist, but a small bottle costs about twice as much as the crystal Miracle Gro Orchid Food, which of course renders hundreds of gallons. Can I foliar feed with a dilute fertilizer solution, such as I use with every watering, or maybe even less than that? And if so, how often should I foliar feed?

estación seca · #2 05-15-2022, 03:47 AM

Misting leaves to raise humidity just doesn't work except inside tightly closed spaces. In very humid conditions it keeps leaves wet and promotes rot. So it doesn't usually work, or it's harmful.

Few orchids are able to take anything in through their leaves. Phals have the ability to do this but they also readily take up fertilizer through roots. There is no benefit to foliar feeding of most orchids with normal roots.

Ray · #3 05-15-2022, 05:06 AM

If you want to raise the humidity, you want to put water into the air, not wet the leaves. READ THIS.

As far as foliar feeding is concerned, ES' comment that few orchids are able to take up "anything" is a bit too "black and white" for my (nerdy) liking, but is correct from a practical perspective, as many orchids have waxy layers on the leaves that are an evolutionary adaptation intended to reduce water loss. If those layers can slow loss, they can slow uptake.

tmoney · #4 05-15-2022, 06:43 AM

howdy!

well, having investigated and researched both topics at length (and note, we do NOT foliar feed as of yet) i would add a couple things. misting,agreed, is not so good at raising humidity. but, we have seen some good results from heavily spraying the media surface of some plants (expecially seedlings just to slow the rate of evaporation). we also will occasionally spray earial roots, but only with plain tap water. but this is not really what i think you mean by misting. we don't spray leaves or stems or flower spikes (although ray has postulated on spraying buds and developing spikes based on comments from other growers, i believe)

there are lots of interesting resources for foliar feeding, and for a couple species in particular (phal gigantea and doweryenis being the ones we grow and are interested in) some professional growers promote it as the way to fertalize, and some articles i found support this theory. but, it is very method dependent, focusing on spraying the bottom of leaves (where uptake can occur) and spraying at night (when uptake can occur). also good airflow is necessary to avoid rot. it seems also roots should be avoided because they can burn easily in fert solution. but, it seems very niche and is not intended for our entire collection of plants. most resources i found noted a frequency of once a month at most, sometimes longer.
if you mix your own feed, you need a wetting agent to help the plant uptake, and thats what the premixed things give you as opposed to just mixing fertilizer in water. i would suggest googling and reading up on the subject before you just go around spraying and praying.

Roberta · #5 05-15-2022, 11:27 AM

Quote:

Originally Posted by HiOrcDen

Just a couple quick questions...

Should I necessarily be misting my orchids, especially with low humidity? If so, is it possible to mist too much, in case of mildew or something similar?

And what about foliar feeding? I have seen Miracle Gro Orchid Mist, but a small bottle costs about twice as much as the crystal Miracle Gro Orchid Food, which of course renders hundreds of gallons. Can I foliar feed with a dilute fertilizer solution, such as I use with every watering, or maybe even less than that? And if so, how often should I foliar feed?

For dealing with "hot and dry" (and we have been experiencing both) in an enclosed area you can raise the humidity with mist and get cooling too... that is what I do in my greenhouse, use a fogger for cooling. That works because humidity is low. (People in humid places need to approach cooling more directly) But in the open, not going to do much. I just hose things down more for cooling than anything else. The orchids that I grow outside have evolved to handle varying amounts of drought - that waxy layer on leaves that makes foliar feeding fairly useless is one of them That, and they close stomata to reduce water loss, they basically "circle the wagons" until the emergency passes, which it does in the evening. Fertilizer is most efficiently absorbed through the roots. And they don't need much. Orchids grow slowly. Fertilizer is "vitamins" not "food". (Food, i.e. carbs, are produced by photosynthesis which the plant takes care of) Get everything else right then worry about the fine points of fertilizer to optimize.

With just some shading and a light bath once or twice during the day, even my little cloud-forest Pleurothallids, many mounted, are doing fine. 90 deg F/32 deg C, RH around 15-20%. But it cools off at night. Not ideal conditions, but not the average which is better... orchids have evolved to deal with the extremes for short times.

SADE2020 · #6 05-15-2022, 06:36 PM

As Roberta, I have a misting system in the outdoor growing area and the intention is to cool down the 90°< during the days in summer. It works great for me. Then, I do mist spray here and there the plant in display in my house...but just because I like it!

And then again, as mentioned by ES, in a terrarium misting is what creat humidity; enclose small place but circulation is critical.

Roberta · #7 05-15-2022, 06:48 PM

Your system sounds great. While sitting in the growing area with a glass of wine, the cooling mist is nice for people too.

SADE2020 · #8 05-16-2022, 03:01 AM

right on!

HiOrcDen · #9 05-16-2022, 06:15 AM

Quote:

Originally Posted by estación seca

Misting leaves to raise humidity just doesn't work except inside tightly closed spaces. In very humid conditions it keeps leaves wet and promotes rot. So it doesn't usually work, or it's harmful.

Few orchids are able to take anything in through their leaves. Phals have the ability to do this but they also readily take up fertilizer through roots. There is no benefit to foliar feeding of most orchids with normal roots.

Quote:

Originally Posted by Ray

If you want to raise the humidity, you want to put water into the air, not wet the leaves. READ THIS.

As far as foliar feeding is concerned, ES' comment that few orchids are able to take up "anything" is a bit too "black and white" for my (nerdy) liking, but is correct from a practical perspective, as many orchids have waxy layers on the leaves that are an evolutionary adaptation intended to reduce water loss. If those layers can slow loss, they can slow uptake.

Quote:

Originally Posted by tmoney

howdy!

well, having investigated and researched both topics at length (and note, we do NOT foliar feed as of yet) i would add a couple things. misting,agreed, is not so good at raising humidity. but, we have seen some good results from heavily spraying the media surface of some plants (expecially seedlings just to slow the rate of evaporation). we also will occasionally spray earial roots, but only with plain tap water. but this is not really what i think you mean by misting. we don't spray leaves or stems or flower spikes (although ray has postulated on spraying buds and developing spikes based on comments from other growers, i believe)

there are lots of interesting resources for foliar feeding, and for a couple species in particular (phal gigantea and doweryenis being the ones we grow and are interested in) some professional growers promote it as the way to fertalize, and some articles i found support this theory. but, it is very method dependent, focusing on spraying the bottom of leaves (where uptake can occur) and spraying at night (when uptake can occur). also good airflow is necessary to avoid rot. it seems also roots should be avoided because they can burn easily in fert solution. but, it seems very niche and is not intended for our entire collection of plants. most resources i found noted a frequency of once a month at most, sometimes longer.
if you mix your own feed, you need a wetting agent to help the plant uptake, and thats what the premixed things give you as opposed to just mixing fertilizer in water. i would suggest googling and reading up on the subject before you just go around spraying and praying.

Quote:

Originally Posted by Roberta

For dealing with "hot and dry" (and we have been experiencing both) in an enclosed area you can raise the humidity with mist and get cooling too... that is what I do in my greenhouse, use a fogger for cooling. That works because humidity is low. (People in humid places need to approach cooling more directly) But in the open, not going to do much. I just hose things down more for cooling than anything else. The orchids that I grow outside have evolved to handle varying amounts of drought - that waxy layer on leaves that makes foliar feeding fairly useless is one of them That, and they close stomata to reduce water loss, they basically "circle the wagons" until the emergency passes, which it does in the evening. Fertilizer is most efficiently absorbed through the roots. And they don't need much. Orchids grow slowly. Fertilizer is "vitamins" not "food". (Food, i.e. carbs, are produced by photosynthesis which the plant takes care of) Get everything else right then worry about the fine points of fertilizer to optimize.

With just some shading and a light bath once or twice during the day, even my little cloud-forest Pleurothallids, many mounted, are doing fine. 90 deg F/32 deg C, RH around 15-20%. But it cools off at night. Not ideal conditions, but not the average which is better... orchids have evolved to deal with the extremes for short times.

Quote:

Originally Posted by SADE2020

As Roberta, I have a misting system in the outdoor growing area and the intention is to cool down the 90°< during the days in summer. It works great for me. Then, I do mist spray here and there the plant in display in my house...but just because I like it!

And then again, as mentioned by ES, in a terrarium misting is what creat humidity; enclose small place but circulation is critical.

Quote:

Originally Posted by Roberta

Your system sounds great. While sitting in the growing area with a glass of wine, the cooling mist is nice for people too.

Quote:

Originally Posted by SADE2020

right on!

Thank you guys! Lots of concepts and info, and checked all the links. Would an evaporative cooler work well, or is a simple fogger better? (and what about fogger vs. mister?)

Oh, and if keeping plants indoors, under lights, and near open windows, would I then use a humidifier, instead of the three devices I mentioned?

Ray · #10 05-16-2022, 08:42 AM

Quote:

Originally Posted by HiOrcDen

Thank you guys! Lots of concepts and info, and checked all the links. Would an evaporative cooler work well, or is a simple fogger better? (and what about fogger vs. mister?)

Oh, and if keeping plants indoors, under lights, and near open windows, would I then use a humidifier, instead of the three devices I mentioned?

In some parts of the world, evaporative coolers are used to cool homes.

Read the post at the link I offered earlier. It’s all about evaporation rate. An evaporative cooler passes a large volume of air over a wet substrate and relatively large volume of water, so the heat energy removed from the air is quickly absorbed. A fogger disperses tiny, individual drops of water in the air. Heat is absorbed as they evaporate, but the process is slower because it is more-or-less “stagnant”, having far less air movement than does a cooler.

Foggers work, but not as efficiently, and there is a risk of droplets settling and wetting things.

Switching back to foliar feeding, one of the more interesting things I learned was about the relative uptake rates of the three forms of nitrogen: nitrate and ammonium-based nitrogen are preferentially absorbed by the roots and poorly absorbed by the leaves. Urea is just the opposite.

We’re still somewhat limited by the waxy cuticle layers, but as they develop over time, younger plants are better at foliar uptake than more mature ones.