how cold is too cold?
 

Hi all
We have been having some crazy northern Ontario weather. I have 2 phals and 2 cymbidiums outside we went from yesterday being 25C to 6C today. I am trying to encourage spikes on these plants so don't want to bring them in prematurely and mess up that process. But I also don't want to damage them or slow them too much (one phal might not be ready to bloom again same with the cyms as I bought them out of bloom this summer at home depot so I have no idea what sort of schedule they are on) So to bring in or not to bring in? is it detrimental to bring them in and out as the weather changes? This is the first year I've put any orchids outside.

I think the Phals should not be out in +6 but my Cyms were out in around +3. I have brought them in now since it seems fall has arrived here. Cym's can take close to freezing but Phals would need a chill of around 55F or 60. Not sure what that is in Celsius, maybe 10 or 12C.

*walks out and grabs phals* One i think has the beginning of a spike I wish I hadn't noticed it so early it might be stalled...its set near a draft still but inside. I see some sort of growth on my cym but i think its just new growth to small to tell yet.

No cool growing orchids like to go lower than 45F if at all possible. Cyms will tolerate 32F for no longer than 8 hours but some damage may be done to the spikes/flowers.

For warm growers like Phals, you are safest in never letting them get below 50F. Serious damage will be done at 40F or lower for any length of time.

I doubt you did any damage to Phals at a short term exposure to 6C (~43F), but don't make a habit of it. If they were at ground level or next to a building they probably didn't even get quite that cold.

As other have said, the Cyms should have no problem with 6C.

they were on my balcony under a large potted raspberry and the cyms... they don't seem to have suffered but ill not let them out unless it warms up a bit again. there back in there inside locations for now.. the cyms ill leave unless it gets colder/windy

I would agree that with warm growers, bringing them in when it gets below 10 C (50 F) is safest. My experience is that my plants, including Phals, have unintentionally experienced temperatures that dipped to 4 C (about 39 F) during the coldest part of the morning, outdoors and unprotected. I would not advise doing this, though.

I think if you have had an average temperature drop of 5 C over the past month or two, you probably have had all the temperature change you need for your Phals.

The easy way to convert. Farenheit to C. Minus 30 and halve the resut.

50F > 20, halve it >10C

Are Catts, Phals, Dens, Vandas and oncidiums the same, more or less? Down to 50F is OK? Or is 55 right? I know they need to go cold enough....

Cymbidiums to 5C yeah?

Fwiw some of my noid Phals saw night time temps in the mid to upper 40s several times last winter, and one morning air temp was a recorded 42F in the room they were in. There was actually frost on the inside of the windows. They didn't miss a beat.

If it is just one night, for a few hours, even warm growers are usually okay, if there is no wind, in the forties. Usually. I do have some plants and orchids that just would not be able to take those temperatures. The noID phals are pretty tough, though, and I usually do not worry about them when temperatures are temporary.
If it is autumn and we begin getting cooler temperatures, I bring my plants inside. It is just not worth stressing the plants just before winter when the conditions won't be completely ideal.

I don't think I would intentionally even leave Catts, Phals and some Onc. as low as 50 but it is likely OK. I run the greenhouse in winter at 55F nighttime temp and a large variety of chids are fine with that. I do have a heat mat for several warm loving Catts and Dens tho.

When they are kept cool, remember not to over water.

going down to 0 tonight so everyone is in. My catts are so young they only went out for partial days when it was optimal, same with the oncidium and baby Vanilla but they were never out nights even in august. Ill probably set my cyms back out tomorrow for the day but going to have to watch the weather

Everything has already been said, but large standard cymbidiums can take quite a bit of cold so you can leave it outside until first frost.

How is your phal?? I hope it is fine.
6 C is way too cold for it. I would not expose them to anything under 15 C. I had a terrible experience with phals as a kid. I learned the hard way. lol

Certain cattleyas can also take quite a bit of cold, but just to be sure, keep it above 10 or 15 for good health. Most cattleyas I believe almost all, respond to day length to know when to flower, and some need "drier" period like walkeriana.

Good to know about the Catt's flowering requirements mine are all small and live on a seedling heat mat. my phals are noId and in the winter the heat is set at 15 so its never colder then that, but my place is generally on the cool side, the phals look fine they definitely didn't freeze they are probably in for the season now... hoping the one with the little nub of a spike wakes up soon and gets to flowering. The cyms are back out for the day at least not sure how tonight will be.

good that your phals are fine. If they show spikes, do not suddenly move them to a different locations where the temperature is quite different.
Since yours place is on the cooler side, I don't think it'll be a much of a problem.

If you are keeping it at around 15C day and night, then you might want to be careful with watering.

Also, if your place gets lots of light during the day, there will still be enough diurnal difference.
At 15C, I would feel quite chilly and need a warm jacket on.

Remember phals in general will spike just fine in warmer conditions. It's the general decline of the temperature that signals them to set spikes rather than a certain set temperature.
After hot summer, just a slight drop of indoor temperature is enough to help them spike.
say, night minimum 18 C give or take.