Cold Hardiness of orchids outside.

[BrassavolaStars]

Hello All,

I had a question about my orchids.

I am still keeping my orchids outside the greenhouse.

Is this acceptable? Right now where I live, the daytime temperature is around 77F and the night temperature is between 53-62F.
Is 52F too cold for a few hours every night? Most of my orchids are cattleyas and dendrobium but I also have a few phals, angraecums, and oncidiums.

I heard that most if not all orchids like a 15F drop in temperature at night but is low 50s at night too cold for warm growers?

[Roberta]

Getting too cold for the Phals, so those definitely need to come in . The others, it depends on which ones in each group, some are more cold-tolerant than others. The more tropical ones, like Phals, really don't need that much temperature drop - the professional growers do a precise cool-down (timing, light, and temperature closely controlled) to facilitate blooming at a specific time. For a hobbyist, it doesn't matter much whether your Phal blooms the week before or the week after Christmas. But where you live, the temperature can turn cold abruptly this time of year, and you don't want to be caught by unpleasant surprise. 62 deg. F isn't bad, but much below that may be hazardous to some of the warmer-growing ones. I suspect that they have already received all the "cold jolt" that might be of benefit, now time for protection.

[camille1585]

As already said, Phals definitely won't appreciate it much to stay outside now, they love it warm. And then there are other orchids which don't mind coolers temps as much, but it's not optimal for them. As soon as my night temps under 15C (60F?) a few days in a row I bring in all the orchids except the ones that I know enjoy cool weather (Neofinetia, and some Dens)

[Fairorchids]

Phals are borderline now. Ditto for warm growing Dendrobiums.

For Cattleyas, Oncidiums (intergeneric hybrids) and Cool to Intermediate Dendrobiums, there is no rush. I grow all of those (and some Vandas) in a greenhouse, where the thermostat is set at 55F (12.8C), and they are doing fine.

Last season I had to use a different greenhouse (Den. nobile production house, with thermostat set at 52F = 11.1C). I moved Vandas to a warmer greenhouse (with Phals), everything else stayed in the cooler house. Only 1 Cattleya (out of 200+ plants) did not like the cold.

In general, I wouldn't worry about bringing the majority of the plants inside till night time temps consistently drop down to 45F. I would bring in decidedly warm growing species, such as C. violacea, now.