Overnight Temp for CAM Orchids

[Clawhammer]

Hello everyone.

I grow inside and control my temperature with an air conditioner, the lights take care of the heat, so I have total control over the temperature in my environment.

During the summer I have to cool the room overnight with the A/C. I set the unit's timer to make the room 67 degrees for 6 hours.

Question, what is the temperature that cattleya and other CAM orchids begin to open their stomata? Do I need to go to 67 degrees?

Also, does the length of time that the stomata are open have much of an effect on growth rate?

I am trying to balance the cost of running the AC vs maximizing growth.

[Ray]

I am by no means an expert here, but I am not aware that temperature is a trigger for opening and closing stomata in CAM plants. As it's a day/night thing, wouldn't light intensity be more of a trigger?

Having said that, I do know that the CO2-capturing chemical reactions can be affected by temperature, but that varies pretty greatly between plants.

Growth is all about carbon assimilation, so if carbon is absorbed primarily through the open stomata, certainly the amount of time they are open plays a role...BUT, there must be a balance between time to absorb and capture carbon and time to process it, so it would seem that skewing the balance too far one way or the other would be detrimental.

[WaterWitchin]

With the cost of air conditioning, I would think it's not worth it growth wise. That's just speculation, based on my air conditioning bills each year. Mine certainly aren't all grown at optimum temps... especially during the hottest and coldest part of the year. No science to back this up.

[Clawhammer]

Thank you both! Very helpful. Since the stomata are light triggered I will focus on making my dark period dark and maintain my shortened period of cooling.

One way I have reduced my AC cost is to time my lights to come on at 2am. That way the lights are off for most of the hottest part of the day so my AC unit doesn't have to battle heat from the light and heat from outside.

[rbarata]

From what I know, the main factors are HR (set it to mimic the habitat), CO2 content (the higher the better at night) and light/darkness.

[Ray]

Another factor about stomata: If there is plentiful water at the root system, a hormonal signal moves up to the leaves signalling opening. If not, they will tend to stay closed.

That is one reason that - no matter what the medium or if mounted - I try to keep my plants as moist as I can without suffocating the roots, so "drying out between waterings" doesn't become a growth-slowing factor.

[isurus79]

As anecdotal evidence, my Catts grow at breakneck speed all summer long and we don't see temps below 75-80 at night for months on end.

[WaterWitchin]

Same here

[Keysguy]

pfffffft. 75-80 is a cold snap for mine! I think Ray nailed it. It's probably way more light than temp.

[Clawhammer]

Y'all just saved me some A/C money!