Maximum summer tempereatures

[JScott]

I'm fairly new to Texas, and I am finding that the summers are much hotter even than what we had in Oklahoma. It's barely June and we are in the 90s just about every day, with nightly lows in the mid-80s. I mostly grow Catts, Phals, and Oncidiums. A few of the intergeneric Oncids I bring inside in the summer always because they have a lot of Odontoglossum in them and can't take the heat, but I'm starting to worry about some of the others. I've had to bring a few of my Phals inside because the leaves were starting to get all wilty, even though they were watered well and had good root systems. Once they came inside, the leaves perked back up and the plants are fine now.

How much heat can Catts really tolerate long term? I know the ideal temperatures are low to mid 80s in the day and mid 60s in the night, but my temperatures never get below 80 even at night. It this going to cause problems for me? Do I need to bring some plants back inside?

I have them growing outside in an area where they get a little morning sun, then filtered light through the branches of trees for the rest of the day. There's no burn, and leaf color is good, so I don't think the light is excessive. I'm just worried about the heat. Am I worrying over nothing, or are there some plants that would do better under lights in the house when it's this hot outside? I'm particularly worried about my Cattleya skinneri 'Carpenteria'. It has good roots and multiple new growths, and they were doing just fine, but then I put it outside and it got hot, and now the new growths aren't really growing much or at all. It's like it just stalled out. Nothing is dying on it, the new growths still look healthy, but they're just sitting there. It is fairly new, and it was expensive, and I'd hate to lose it.

I have a few plants that stay inside all year. My Cattleya Canhamiana 'Azure Skies' seems to just love growing under artificial lights. It grows faster and blooms more with better color than when I put it outside. I don't know why, but some of them just seem to like to live indoors all year. Is maybe skinneri one of these? Does anybody grow that one under lights?

[estación seca]

Mid 80s F / 30s C at night is a struggle for most Catts. Your day temperatures would be tolerated with cooler nights. Many orchids do their CO2 absorption at night, and high temperatures impede this.

Take up Vanda and Bulbophyllum.

[Ray]

I am surprised to hear the phalaenopsis suffered. Of the plants you mentioned, they should be the most tolerant of heat.

One thing for certain: High heat requires deep shade.

[Keysguy]

I have a lot of Cattleya's from across the spectrum of cultural requirements and they all do extremely well for me growing outdoors in Key West under 60% shade cloth. Believe me, it gets hot during the summer. Typical is high 80's with high humidity and "feels like" temps in high 90's. I think the key for me is that when it's hot, it's also the rainy season so they are getting watered maybe not every day but close to it and when it rains....they get soaked good! Another positive factor is by being located 100 yards from the ocean, those awesome trade winds are always blowing providing great cooling and drying conditions.
Regarding Phals and heat, for whatever reason I have always struggled with them, indoors, outdoors, doesn't seem to matter. There is a wide temp tolerance range for them though, probably moreso than Catts. and I am slowly discovering that in my current growing conditions, they seem to do much better if they are mounted. I think again it plays to the cooling/drying of the wind. This is all just observed speculation on my part.

[estación seca]

I got to thinking... Laelia purpurata, and some of the bifoliate Brazilian Catt species, will easily tolerate your summers. Catasetums love hot, humid summer nights. Many tropical terrestrial orchids, too.