Greenhouse shade advice needed.

[K-Sci]

Originally Posted by Roberta

Plants with dark flowers can have red in the leaves even if they aren't at the "suntan" intensity - if there is lots of anthocyanin around, expressing it in the leaves is very common.

I agree with this. I have seen orchid leaves turn red or red-purple in response to high light levels in the red end of the spectrum, but not the blue. I base this conclusion on a high intensity LED plant light I've used for several years. It was sold for growing marijuana and has separate controls for the red and blue end of the spectrum, but it has way too much red. It turns the leaves of most of my orchids anything from slightly reddish to a very deep red or deep purple - but this only happens only when the red LEDs are turned on. And it does this without heating the leaves and at the relatively low levels of 2500fc, which is lower light than my greenhouse has been for most of this summer.This summer many of them have lost most of the red.

[Roberta]

Originally Posted by K-Sci

he heat.

Oddly, our weather has been crazy lately here in S. central Mississippi. Tomorrow our forecast is 88F high/ 55F low - that's a 33F day-night swing. It's been like that for the last 4 nights. A 20F swing is pretty typical.

Sounds like perfect Cymbidium weather...

[K-Sci]

Originally Posted by Roberta

Sounds like perfect Cymbidium weather...

I have three warm-tolerant cymbidiums, but I'd bet they would benefit from the large temperatures swings too. Maybe I should take them out of the greenhouse until it gets down into the 40s.

When I lived in California I grew standard cymbidiums I got at Santa Barbara Orchid Estates. At that time they had a much larger number of offerings than they do now. I've not grown warm-tolerant ones before this year, but genetically I think they are hybrids of both warm and cold growing types and would be stronger with cool nights.

-Keith

[Roberta]

Depends on the parentage... the so-called "warmth tolerant" ones are more like "hot muggy nights" tolerant... don't need the diurnal change in the fall. (I have never met a Cymbidium, with exception of some high level Chinese species, that balked at triple-digit F temps) But the spike trigger for the "standard" Cyms is that big day-night differential that happens naturally the fall in coastal California - it's not just the cool nights, it's the combination of cool nights and warm days. The so-called "warmth tolerant" breeding introduces some of the more tropical species so that they are less picky about that diurnal temperature range to bloom.

[SADE2020]

Originally Posted by K-Sci

The brightest part of my greenhouse is around 2750fc at mid-day, and much less beginning mid-afternoon due to shading from the house roof. Hence, I'd like to increase the light levels. I can't go much higher than, say 3000-3500fc mid summer, but we are well past the Sun's mid-June apogee and the weather is notably cooler.


-Keith

Hi Keith

I have the opposite of you, lot of sun all day long and I've done the shading like a Onion with many layers.

Now, if you are using an APP to measure the natural lighting there is one thing your should consider; the heat & UV, that the apps don't give you. Meaning that those 2750fc now would not have the same heat and therefore the effect in the leaves now in Oct. would be less damiging in 1 month; Nov. Even with a fan blowing also the average time of exposure to the same light+heat will boile any new growth.

Adaptation is the Key. They will adapt to what you think is best, just go slowly.

Good luck with your setup!

[Ray]

I’m glad others picked up the red coloration not necessarily being due to deficiencies, but it can be. Leaves will tend to be dark, dull, and smaller in that case.

The business about phalaenopsis needing more nitrogen than other orchids is simply untrue. It is more correlated to growth rate than genus.

[Shadeflower]

I am already postivie I am seeing beneficial results after 2 days

Nah just joking but nothing has died yet so that's good.

Like ES says I just watched it recently in the motes video.

That is what my testing is for but it will take 6 months for me to have any conclusions.

I know all about the reddenning but why will some develop reddening and others not? We don't have the answer, that much I know. I can carry on assuming it is just what some do and others don't but that's not my style so just letting people know I will be testing the hypothesis to back off the light if leaves turn red or maybe investigate if it is because plants are trying to grow faster than the nutrients they are receiving.

I have been feeding most my orchids with just 10 ppm Magnesium this year, Roy Tokunaga recommends 20 ppm minimum.

So I'm in a perfect position to make these observations. I will show a picture of the red dendrobium leaf if I can.

[K-Sci]

Originally Posted by SADE2020

Hi Keith

I have the opposite of you, lot of sun all day long and I've done the shading like a Onion with many layers.

Now, if you are using an app to measure the natural lighting there is one thing your should consider; the heat & UV, that the apps don't give you. Meaning that those 2750fc now would not have the same heat and therefore the effect in the leaves now in Oct. would be less damiging in 1 month; Nov. Even with a fan blowing also the average time of exposure to the same light+heat will boile any new growth.

Adaptation is the Key. They will adapt to what you think is best, just go slowly.

Good luck with your setup!

I'm using a dedicated light meter to make measurements. I wouldn't trust a phone APP, if that's what you meant. Still, the light meters designed for photography will have the same issue - they only measure the visible spectrum.

That said, my experience is consistent with what you're describing. Last fall I had my Neofinetias in full sun all day. The steeper angle of the sun causes it to pass through more atmosphere, which reduces the heating.

This thread may be getting a bit long to read all the way through. In my earlier posts, I described how I increased light intentionally, which was rolling the shade cloth back part way, and unintentionally by cutting down a large shrub on the south end of my greenhouse that provided *a lot* more shade than I realized. The light level increased from 2575fc to around 6000fc on about 1/3 of my cattleyas. I set up a fan to blow directly across the affected orchids keeping the leaves cool. None were burned. I'm going to keep running the fan during the day for another month or so the orchids have a chance to adapt, and the sun becomes a bit less intense.

-Keith

[Shadeflower]

It's all related keith.

you say you had to add ventilation.

I am saying I have to add fetilizer due to the increased growth

Stephen is suggesting more water

[SADE2020]

Originally Posted by K-Sci

I'm using a dedicated light meter to make measurements. I wouldn't trust a phone APP, if that's what you meant. Still, the light meters designed for photography will have the same issue - they only measure the visible spectrum.

That said, my experience is consistent with what you're describing. Last fall I had my Neofinetias in full sun all day. The steeper angle of the sun causes it to pass through more atmosphere, which reduces the heating.

This thread may be getting a bit long to read all the way through. In my earlier posts, I described how I increased light intentionally, which was rolling the shade cloth back part way, and unintentionally by cutting down a large shrub on the south end of my greenhouse that provided *a lot* more shade than I realized. The light level increased from 2575fc to around 6000fc on about 1/3 of my cattleyas. I set up a fan to blow directly across the affected orchids keeping the leaves cool. None were burned. I'm going to keep running the fan during the day for another month or so the orchids have a chance to adapt, and the sun becomes a bit less intense.

-Keith

Fantastic Then!! Right, I didn't read well the Rolling the Shade back Part wey, part! Sorry.