Daily temperature differentials

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Oct 25, 2015
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I've been finding that daily temperature differentials are almost as important in good paph growing as light and water.

I'm sure there are exceptions but in general, it seems a 10 degree difference between day and night provide better growth than a constant temperature for most paphs. For example, the recommended avg temps for sanderianums is around 27-29C, but you won't have good growth by having little temp variations between this average. Contrary, night temps of 20C and day temps of 32C would be better.

It's not something I hear people giving advice on. Usually you just see the average temp recommendations.

Do others share the same experience?
I do not agree. Plus you are making me do math and math hurts my brain! Ouch!!
32C is close to 90F. I prefer 25C, 77 to 80 degrees Fahrenheit. I feel that most of my orchids become more and more stressed when it rises above 82. Paphs. And Phrags. included.
Since I summer everything outside from May to October, I and my orchids are under Mother Natures control. Of course, the warmer it gets, I increase my waterings.

This time of year, my plant room averages around 75F. What is that? 23C? That is during the days. Nights get down closer to 72, even 70F when it is snowing, windy and down near Zero F. There is fairly little fluctuation indoors. I would prefer the mid to low 60’s, say 62. But that would be undesirable for me and my kitties.

I am just of the opinion that maybe they like it near 90 all the time but I think they look stressed at that level.. I realize that the Brachypetalums are faced with the 90’s in their native habitat, but they grow well shaded.
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I would still suggest that a 70F night and 80F day (gradual increase and decrease to these points between noon and midnight) is better than a constant 75F.

Both scenarios have a daily average of 75F but very different fluctuations in temps.

I do recognize the ideal daily average temperatures will vary from species to species. I also could expect some would prefer minimal temp variations but I think that would be the exceptions to the norm.
Interesting topic, I asked myself the same question and for Cattleyas I would agree. For paphs it might vary from species to species and there are so many variables, 30 degC in the sun will stress the plant a lot more than 30 degC in the shade. I noticed that some of my paphs were getting stressed in my greenhouse in Summer which has big temperature swings, so I moved them into the house where it is more constant and those plants are doing better there in spite of the lower humidity and much less temperature differential.

My theory is that those plants that grow in sheltered conditions on the forest floor are in a fairly stable microclimate. Species like P. phillipinense on the other hand seems to love heat and sun, so I keep that one in the greenhouse in Summer, I basically grow it like a Cattleya. I think Paphs are a bit more variable in their requirements compared to Catts.
I grow indoors where there’s barely any difference in day night temps in any season. No problem growing and blooming paphs, catts and phals
Look at where the species originate, and how temperatures fluctuate there.

The closer to the equator, the less seasonal and daily variation. The higher the altitude, the more of each.
I think you summed it up correctly. Most of the paphs I grow are found in high altitude environments, so that would explain my observations.

So I'll retract my earlier statement that most paphs prefer large temperatures differentials and accept that there are many that would prefer something more stable.

For those plants that do like large temp variation, I think this fact gets lost in growing recommendations that simply state the daily averages.
Having visited and slept in the Borneo rainforest I can say that there are definitely temperature differentials between night and day! It doesn't get cold at night but, without the sun, it is noticeably cooler and feels less humid at night. I didn't take a thermometer with me on this holiday to give you any figures though but I would say any web pages saying temperatures are the same day and night are not accurate for this area.
OH, I did not address temperature differentials.
Way back, way way back, I learned that a 15 degree difference between night and day was a good goal to strive for. I still think that today.
However, here in my little brick ranch in Michigan, that is next to impossible. Why? Under lights, indoors for the winter, I am lucky to get an 8 degree drop night after night. 10 Degrees would be exciting, 12 unheard of. I am at the mercy of indoor heating. This will make most of you shudder but my first winter here in 2018-19, I had 8 0r 9 nights below zero! Burrrrrrr❄️❄️❄️ The lowest was minus 14F. It was like my furnace was never off! So that might have been a few degrees cooler that winter but with an 8 degree range.
Summer time is a different story. Last summer, only 2 days above 90F. A load of mid 80's but very few 90 plus. Night time lows last year ranged from 46 one early June night to a few nights in the low 70's. I think that my typical night drops here during the summer are 15-18 degrees but there might be an occasional 30 degree drop. The orchids seem unaffected by a couple of crazy nights.
I just figure that it is what it is. At 74, I am not building a greenhouse. AT LEAST I DO NOT HAVE A WINTER TIME GREENHOUSE HEATING BILL.
It is important to all plants. In the wild, there naturally exists day & night temperature differences. Many orchids occur at well over sea levels and the temperature differentials between day and night are even greater.
It mainly has to do with converting and storing energy (ATP into complex sugars for later use) within them.
With proper temperature range and differentials between day and night, plants will do noticeably better for obvious reasons.
Is the day/night temperature difference something to aim for during the winter months (for those of us who bring our plants indoors)? I know some species need that drop in autumn, but that’s a tricky one to pull off in winter. I suppose if they are sitting near the window the lack of sun at night makes some difference…?
As long as you don't have a heater in the room, there would naturally be day/night temperature difference. The difference might actually be greater in the winter than any other season. Especially true for me on sunny winter days. The problem is that it gets too warm during the midday. So for those that need even cool winter, this can disrupt their cycle.

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