Misting & Foliar Feeding - Page 2 - Orchid Board

Roberta · #11 05-16-2022, 11:36 AM

If you are not in an enclosed space, the fogger won't be useful, and they are expensive. But you can get patio misting system such as what SADE describes. such as this: Amazon.com

You can put it on timer. (Attach to hose bib)

Dimples · #12 05-16-2022, 05:38 PM

Quote:

Originally Posted by HiOrcDen

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?

If your plants are sitting out in the open, not inside a terrarium or enclosed container, you can run a fleet of humidifiers when the windows are open with low outdoor RH conditions and barely notice a difference. It would be like trying to humidify all of Southern Ca with your machines. Open the windows, enjoy the breeze, and turn the humidifier on once you close up.

If the orchids are in a room that can be closed off from the rest of the house with the windows kept closed, the humidifier should help keep the humidity up in that one room.

Roberta · #13 05-16-2022, 05:51 PM

If they are indoors, most orchids really don't need anything added where we live in coastal southern Californa, unless you are growing plants that really need high humidity (in which case you're probably looking at a grow tent, and tighter environmental controls with attendant complexity...) When I bring my blooming plants in to enjoy them, I just have to remember to water them... outside they get their regular bath and that is fine. And I grow quite a few Pleurothallids and other sensitive orchids, many mounted, outside. So it depends on just how close to the coast you are. More of an issue in the hot inland valleys. And also depends on exactly what you are growing. There are so many that will adapt to our outdoor climate, but certainly there are exceptions.. So if you are concerned, you need to get down to the details of particular species. Hybrids, there are very few that are that picky.

HiOrcDen · #14 06-02-2022, 03:22 AM

Quote:

Originally Posted by Ray

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.

Again, thanks for the concepts! So an evaporative cooler both cools and humidifies at once. So I imagine, in a small greenhouse, I would connect it to a thermostat (and not to a humidistat, or both) considering that temps too high for, say, a Phalaenopsis I would keep in a greenhouse, tend to come with low humidity. But then I understand that winter weather is dry as well. So how do you accommodate humidity control in winter as well? And possibly, as Roberta explained to me, maybe one can manage to keep a Phal outside all year

estación seca · #15 06-02-2022, 04:12 AM

Evaporative coolers use a fan to propel air through wet pads of some material, kept wet by a pump with a reservoir. It takes energy to evaporate water. As water evaporates from the pads the air passing through cools.

They use large amounts of water. My evaporative cooler in my sunroom can go through 50 gallons or more of water in a day during hot, dry weather. I know this because it is capable of being filled via bucket or with a hose attachment and float valve. When I set it up I filled via bucket for a few days to find out how much water it uses.

There needs to be a low humidity fresh air intake for the cooler and exhaust of old air from the space, usually at the far end of the space cooled. They don't work if the air intake is humid greenhouse air.

Evaporative coolers function well when the dew point is under 55 degrees F / 13C. Dew point is calculated from temperature and relative humidity. If you click on the weather forecast under my signature block you will see the dew point here when you click. The US Weather Service provides this information for the whole country. Right now the dew point here is 22 F / -6C so evap cooling works extremely well.

At temperatures over the dew point the air is too humid for the cooler to evaporate enough water to cause substantial cooling. But over the dew point evaporative coolers can still raise the humidity to the maximum.

Evaporative coolers tend to be used in dry hot climates. Where you live it's probably too humid most of the year for them to be effective, which is why houses in coastal Southern California have traditionally not used evaporative cooling. (Plus there is the water issue.) I just checked the dew point at my mom's house in California; she lives about 5 miles inland, and the dew point is 55 degrees. An evaporative cooler would not do much cooling there right how. (But then its 57 degrees F / 14C.) Here in Phoenix it works well for the hot dry parts of the year, but not well at all during the summer monsoon.

My weather is so predictable I don't use a humidistat nor timer for my evap cooler. During hot dry parts of the year with cooler nights, like now, I use it at night to cool down the sunroom. I open access to and egress from the sunroom for air circulation. In the morning after the sun no longer enters the sunroom windows I shut off the pump and leave just the fan running. I close the doors to the sunroom to hold in humidity.

During the very hottest part of our summer I leave the cooler pump running. While not cooling well it does keep the space under about 85 degrees F, and keeps it humid. The orchids that survive here do OK without much of a night drop in temperature.

Relative humidity depends on temperature. When it's cool, air can't hold as much water as when it's hot. So cool air holding as much water as it can is at 100% relative humidity, but the same number of grams of water in hot air would not bring it to 100% relative humidity.

In winter just spraying the ground of an enclosed growing are with water is usually enough to raise the humidity adequately for almost all orchids. During hot times an evaporative cooler or humidifier may be needed depending on how much external air exchange there is.

Realize many orchids - especially American and Himalayan orchids - come from tropical areas with dry, cooler winters. Many orchids do well with substantially lower winter humidity than summer humidity. High relative humidity is generally more important during periods of heat and active growth than during resting periods.

HiOrcDen · #16 06-02-2022, 05:12 AM

Are Himalayan Orchids the Cloud Orchids I have heard about? Sounds a bit surreal

Thank you again for the clarifications! I get the sense that in my area, humidity is not a major worry? There are tricks that can be used, that you guys have mentioned, such as double clay pots, or moss substrate. I suppose if absolutely necessary, I could use my miniature greenhouse (I think about 2' x 2') with ice for my high humidity cool temp Masdevallia. However it has been suggested to me here that might not even be necessary. Am I correct?

---------- Post added at 01:12 AM ---------- Previous post was at 12:39 AM ----------

Quote:

Originally Posted by Roberta

If you are not in an enclosed space, the fogger won't be useful, and they are expensive. But you can get patio misting system such as what SADE describes. such as this: Amazon.com

You can put it on timer. (Attach to hose bib)

Cool, moderate price for what you get, it seems. So would you say it's very advantageous to use one, in our climate?

Roberta · #17 06-02-2022, 12:03 PM

Cloud forest describes a particular habitat. Cool, moist. I think of the Andes more than Himalayas. A characteristic of the orchids of the Himalayas (such as Dentrobiums) is that they experience definite seasonal variation of moisture - moonsoonal summers with lots of rain and cloud cover and bright, cooler, drier winters. (But not bone dry... they don't get 10% humidity) Temperature varies with elevation.

Those patio misters could be handy - I don't have one, but I have an automatic sprinkler system that includes misters in one area, where I have a lot of mounted plants.

estación seca · #18 06-02-2022, 06:58 PM

There are many different climates with differing temperature and rainfall patterns. Cloud forests tend to be at higher elevations in mountains - cloud level. There may be very wide temperature swings day to night. As evening approaches temperatures drop, water in the air condenses into fog and everything becomes wet. Much of the available water comes from fog condensation, not rain. The next day may warm up enough the fog burns off or it might not. Lots of orchids come from cloud forests. They typically expect cool to cold nights, lower light levels than full sun and lots of very pure water. Examples include most Pleurothallid orchids from the Americas and Angraecum magdalenae from Madagascar. You need a waterproof jacket and boots to prowl around cloud forest.

A monsoonal climate has a regular annual period with high humidity and rainfall. It is often much dryer with less humidity at other times. This pattern is common in south and southeast Asia. Orchids from these areas expect brighter light in winter, when trees drop leaves. Examples include Dendrobiums like farmeri and densiflorum, and many Cymbidiums.

Tropical deciduous or thorn forests usually are at low to middle elevations. They are warm to hot all year. Rain usually falls in summer and winter is dry. Some have extremely wet summers and others less wet. Most of central and western Mexico not in the mountains is like this. Orchids from these regions also expect more light in winter. An example is Brassavola nodosa. Western Madagascar has this kind of forest. Australian Cymbidiums come from this kind of forest.

Tropical evergreen or semideciduous forests get enough rain all year that some or all trees retain their leaves. They are generally lower in elevation and warm to hot all year. They may have weeks-long dry spells during which trees may drop all or many leaves. Rhyncholaelia (Brassavola) digbyana comes from the Yucatan Peninsula, which is covered with this kind of forest. Gallery forest is a subdivision of this. It refers to forest along perennial streams, where there is more water and trees are taller. In most of western Madagascar gallery forest in steep gulleys along streams is the only remaining forest; people burned the remainder to grassland beginning about 2,000 years ago.

Tropical lowland and tropical rain forests are even wetter than the above. Water is almost never lacking; in rain forests it is plentiful all year. There was never much rain forest in North America. The Olympic Peninsula in Washington State has temperate rain forest. Veracruz State in Mexico has a narrow band along the coast, most of which was cleared thousands of years ago for maize farming. Madagascar east of the mountains has rain forest as well as tropical evergreen and semideciduous forest.