Greenhouse shade advice needed.

[estación seca]

Alan spoke to our club Sep 16. He still sells plants. I bought some. His Web site is gone. I didn't ask him about that.

[K-Sci]

Originally Posted by isurus79

They would go yellow (too much sun) and slowly wither away and die. Moving them to shadier conditions helped with the bleaching and changing media to slightly more water retentive wood (i.e. orchiata was switched to cypress mulch) has made them perk up quite a bit. Seems like the online information about this species is not very good!

Powhatan, Virginia is certainly more moderate than nearly anywhere in Texas or Mississippi

Do you suppose that the problem you saw was the combination of high light and heat? You said C. warscewiczii grew better with less light, but have you had success flowering it in the lower light conditions? I think Chadwick was advising higher light levels to flower them well.

This summer I grew ‘Frau Melanie Beyrodt’ in my very hot greenhouse with many consecutive days of 95F highs and 75F lows. At the beginning of the summer light levels were around 3500cp (much less now). Both of my C. intermedia got slightly bleached out but the FMB stayed a nice lively light green. Were you growing the earlier flowering type or the later flowering Sanderiana type. I'm sure you know what I'm driving at.

I should add that my FMB is a very much lighter shade of green than my Lueddemannianas. This would tend to support your conclusion.

-Keith

[isurus79]

Originally Posted by K-Sci

Do you suppose that the problem you saw was the combination of high light and heat?

Yes, exactly. I think the heat can be alleviated with additional water at the roots for longer, which appears to be working.

Originally Posted by K-Sci

You said C. warscewiczii grew better with less light, but have you had success flowering it in the lower light conditions? I think Chadwick was advising higher light levels to flower them well.

This is the first summer growing in shadier conditions, so I'll have to report back when mine blooms in 2022. However, the leaves are still light green, so I'm confident that I'll have a good bloom. In any case, I'll report my findings!

Originally Posted by K-Sci

Were you growing the earlier flowering type or the later flowering Sanderiana type. I'm sure you know what I'm driving at.

My sole blooming size survivor is not a sanderiana type. I honestly don't know that the later bloomers would do well in Texas summer!

Here's the first bloom thread on my survivor: Cattleya warsecwiczii (SVO x Bedford)

I also have a nicely maturing compot of coeruleas from H&R that are growing in leaps and bounds in a shadier position than the blooming size plant.

[K-Sci]

Originally Posted by estación seca

If the air circulation is high it won't be a problem. Moving air carries the heat from leaves and allows them to stay at ambient temperatures.

High air circulation means everything is moving.

I cut down a tall shrub at the south end of my greenhouse not realizing that the sun is low enough to shine on the first 3 feet of bench. As a result, the plants there get very strong sunlight (6000fc) with daytime highs in the mid 80's. My C. tigrina, C. walkeriana, and Neofinetia falcata are receiving these high light levels for 4-5 hours/day. With strong air movement the leaves get comfortable bathwater warm. I see no burning or yellowing from the 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. The orchids only see about a 25F of the 33F swing because I button up the greenhouse at night. I don't want the phalaenopsis, in particular, to be chilled below 55-60F.

-Keith

[Shadeflower]

Interesting discussion guys. Hope to hear how these light adjutments go.

I am still forming my own clonclusions and haven't been growing catts long enough yet but my early conclusions go a long these lines.

Too much light can cause burns in the leaves
Too much heat can cause sunburns (similar to the above basically but more damage)

Too much light can also cause leaf bleaching where the ends turn too yellow and too much light can cause leaves to redden.

I am planning to perform my own experiemtns. I've got one that is developing some leaf bleaching from too much light but the leaves are actively seeking out the light and the leaves have not got any sunburn.

So I could turn down the light but based on my recent discussion on fertilizing I am planning to experiement by providing this one a bit more fertilizer. I am a bit anxious doing it, I have doubled my fertilizer strength which has doubled the Nitrogen so wish me luck. I hope it works out ok.

I also have a Vanda, a Cattleya and a Dendrobium which I moved to higher light. The change in growth in the Dendrobium was phenomental. It went from doing nothing to produing 5 new bulbs but at the same time those bulbs grew a bit stunted and had very red leaves. Too much light right? No. I really do not believe so. The change in growth the increased light triggered was amazing but at the same time producing 5 bulbs just overwhelmed this plant which had very low energy reserves (wrinkled bulbs) so all the leaves turned red.

I could move the plant to a lower light but I believe that is not the full story. So red leaves are generally caused by a phosphorous or magnesium deficiency. Like said I am fully aware that the more light you give the worse the problem gets but I don't think the plant is getting too much light as it hasn't gotten sunburns yet which even more light would cause. But trying to grow faster under higher light triggers the deficiency (if there is one) to get worse so it's time for me to test this out so I'll be giving one more phosphorous, a couple more Magnesium and the one with bleached leaves will get more Nitrogen,

Then the phalaenopsis I have with red leaves, like Tedro's, I will also be experimenting with after reading that phalaenopsis need twice the N than Cattleya's do.

Shold be interesting. Eager to hear opinions or suggestions but I have a limited number of plants to try this with so we'll see what I find.

Again one can always lower light but that at the same time would surely lower flowering.

I don't believe in the concept that lowering light improves flowering for some. I've seen it suggested. I don't believe it and think there is more to it.

So we shall see, I will make some observations and hopefully know more by next year.

[K-Sci]

Originally Posted by Shadeflower

Hope to hear how these light adjutments go...I am still forming my own clonclusions.

Discussing light levels is a bit loose-goosey when the actual light levels are not known. I use this light meter, which is very reasonably priced.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

What fertilizer brand/formulation are you using?

-Keith

[isurus79]

Originally Posted by Shadeflower

So red leaves are generally caused by a phosphorous or magnesium deficiency. Like said I am fully aware that the more light you give the worse the problem gets...

Not quite! Red leaves are the plant's natural sunscreen and are not a deficiency, nor are red leaves considered a problem.

[K-Sci]

Originally Posted by isurus79

Not quite! Red leaves are the plant's natural sunscreen and are not a deficiency, nor are red leaves considered a problem.

I've also never heard of red leaves being caused by a deficiency. Where did you hear this?


-Keith

[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.

[estación seca]

In his book that I keep telling people to read Motes mentions that magnesium deficiency can cause red spotting and streaking in Vandas during cool weather. It can take many months of supplementation to remedy the situation. I haven't read enough to know whether it occurs in other genera.