How much cold can warm growing orchids take?
 

Hi guys,
My greenhouse heater stopped working last week and I haven't been able to fix it. I'm ordering a new one, but it most likely won't arrive before I go out of town on the 19th. Most of the orchids I have in the greenhouse are intermediates, but I have some warmer growing orchids as well. Temps outside have been in the mid to low forties with occasional dips into the high 30s at night and 60-70 during the day. I'm not sure what the temps inside the greenhouse are, but the roof is double walled polycarbonate, which should provide some insulation. Do you guys think it'll be okay if I leave my orchids in the greenhouse for the next month?

The plants I'm most concerned about are:
Phal hybrids
Vandas (one is a coerulea which should be fine)
Paph lowii, Kolosand, and Maudiae hybrids
Rhynchostylis gigantea
Mokara Salaya Gold
Rhynchorides (Rhynchostylis x Aerides)
Angraecum x veitchii and sesquipedale
Gongora tricolor

Phals really don't like anything lower than 50-55 ish, and any lower than that they may show cold damage. I don't know about the rest, I don't grow any of those. Usually as long as it doesn't freeze, the orchids are not exposed to wind (not a problem in the GH) and you keep the plants on the dry side they should be ok. But wait for input from people who have experience with growing outdoors, I'm a windowsill grower!

The outside temps mean nothing if you are in a greenhouse. You NEED to know the temps you get inside. Consider a minimum registering thermometer - they measure the lowest temp since the last reset. I've even seen some inexpensive (under $20) digital units that will show highest and lowest temps.

My guess is that you'll be ok, but it's only a guess without actual temps. My growing area is outside, but near the house and somewhat sheltered, it runs about 8-10 degrees warmer than the National Weather Service temps these days. With the double wall polycarbonate you should get better results than me.

The other really important thing is how long the temps stay down. To hit 40 or 45 for a few minutes is different than staying there for 12 hours.

Unless your greenhouse is huge, even a couple of light bulbs in an enclosed area will warm it considerably.

Even though you live in CA, try checking the FL social group. You'll get an idea of the temps various people expose their plants to.

Keeping the warm growing plants dry while the temps are down will really help them weather the cold. My guess is that they'll be okay - most orchids are pretty resilient.

The only other tip I'd offer is when you get your new heater, if they have been really cold for a prolonged spell, don't bring them straight back up to normal temperatures too quickly. This can do quite a lot of damage, causing splitting and marking,and sometimes even death if the plant was near freezing, as I found out the hard way when my greenhouse froze last winter. I'd be particularly careful with anything with fleshy leaves

How much cold can warm growing orchids take?
 

If you are concerned with just "survival" you would be surprised how much cold even warm-growing orchids can endure. Last winter it went down to 32 in my GH twice. I don't know just how long it stayed that way but nothing, even Phals, showed any sign of distress. I keep a large fan running 24/7/365 so maybe that helped.
Beverly A.

Agree with the above thoughts - they should be OK.
The real key, as others have said, is what the INSIDE temps do throughout the day, and that is where a good Min/Max thermometer will help you out with.
Have you thought of a temp controlled "emergency" back up heater such as an electric type device (even a ceramic panel type that uses little energy) for the future?
We use two flat panel ceramic heaters (they use about 65 watts of energy) in our chicken coop to keep the girls warm throughout the New England winters. Might be a thought, esp when combined with a good circulation system, as a back up to your main heating source. Just a thought......

Sorry to tell ya, but Mokaras will not tolerate those kinds of lows, period.

If they get that cold and you have no way of providing the warmth they need, then I don't suggest even growing them.

Phal hybrids cannot tolerate those kinds of lows either.

Most of my orchids are warm to hot growing. They also grow outside, well, at least they were...

...they're all inside right now as it was 31% F this morning. Same low tomorrow as well. :((

See my thread http://www.orchidboard.com/community...side-pond.html to follow our unseasonal weather . I decided to empty my greenhouse rather than keep heating it (electrically) and now my spare room is full of things (cacti, succculents, hardy orchids in pots) that can cope with unheated room temperature, and my dining room looks like an orchid nursery :rofl: