What do you have? Except for a few, the low 50s is fine it the day warms up and they are getting light.

With the exception of the Phals and possibly the Dendrobiums, the rest will mostly be happy with those night temperatures. You may want to raise the day temp a bit if the sunlight/artificial light does not.

Main problem will be keeping the humidity at a reasonable level.

I agree with CJ and richard that only the phals need a warmer temperature. How many do you have?

My experience of trying to heat a basement plant room at night is that in a 12 x 16 room, a fairly large "room" heater (one that needed it's own dedicated electrical line) didn't raise the temperature of the whole room by much, tho it's warm near the heater. And it certainly cost at least as much as a large heating mat.

My room is not air-tight, tho. If your room is air tight you may have better luck with a room heater.

If you have only a few phals the heating mat may be the better and cheaper way to go. They are expensive, but probably won't cost more than a heater, and they are cheaper to run.

Thank you all! I am a beginner who is moving into his third year with this obsession. I started out with phals. I have five now and I think I have a decent handle on their care, it was the other plants I was worried about. My plants are located in a 9'x10' room in front of a sliding glass door that faces south. They are sitting in moist pebble trays. The plants get good sun during the day, but I was worried about night temps because the glass doesn't offer much in the way of insulation. Thanks again for your help.

An oil filled heater will not break the bank, is cheap to run and can raise the temps in your grow area by a few degrees. You can place the phals closest to the source to keep the temps up at night and turn it off in the day.

Brooke

Use a pivoting ceramic heater. H.D. 10$-15$. Heater will stop-start when room is at temp. Low 50s is slightly chilly. 'Specially if you have older windows. 60 is better
Mike

My "cold" indoor growing area (the kitchen windowsill) currently has a temperature of 9C at 08:36. The temperature in the warmer growing area is 16.3C.

Plants seem to tolerate cooler temperatures in winter provided you can get some direct filtered sunlight on the leaves. If you try and raise the day temperature too much, you might, as Carol says run into trouble with humidity. The room upstairs gets very warm during sunny winter days but i suspect nothing much would grow up there because of low humidity.

The only orchids i grow indoors are Phalaenopsis species and hybrids and a couple of maudiae Paphiopedilums.

My greenhouse stays completely open as long as nighttime temperatures are above 50. My challenge is when the daytime temperatures don't go above 70. I start watching the high/low thermometer and the weather report in mid-October.