Wintering Cymbidiums and what the heck is this?
 

Alright, first off I have to winter my cymbidiums indoors, in my house.... I have a very bright window sill that stays very cool, like 10-15 degrees cooler than the rest of the house because of the sheer curtain.... During the colder days it has stayed right in the mid to upper 50s, nights I don't know because I'm not up at 4-5 am when the nights get the coldest... So far they have faired well, but we have yet to hit the truely fridgid months.... So my question, how cold is too cold for a steady temperature? And what signs will I see if they are in fact getting too cold? Also I have been waiting over a month now, is this a new growth or a spike? It is growing painfully slow..... Could this be due to temperature?

That's a spike which means it gets the right amount of light and cool temps.
They can get temps slightly bellow freezing for a couple of hours. I think anything beyond this might damage them.
The key factor under these temps is no frost. The symptoms I can't really help you 'cause I've never damaged a Cymb.

You might consider picking up a high/low thermometer which will show you how low and how high an area has gone. I suspect one will be in your local hardware store or on Amazon.

Everything seems to be working for you now. Keep doing it. I doubt the inside of your house will get below freezing.

We're talking 140 year old windows so I don't know.... Right now I am not too concerned, but in January and February when we start getting -15 and -20°F at night I may have to watch more closely, and yes a gadget is on my list, maybe after the holidays....

Roberta has pictures of nursery cymbs covered in ice. They recovered and bloomed. Mine were under cover outside when temps dipped into the high , 20s. They had some frost damage but, are spiking. Lowe's or Home Depot has min max thermometers for $10. If it's too cold, you can always put plastic on the inside of your windows.

I have a plan b, a window sill that gets cool, but not nearly as cool as this so if I have to I can move them for a few weeks, but it is good to know they can survive 20s, I don't think it will go much lower than that for very long, and on super cold nights they may just have to deal with being in the mid to low 60s. I have also been making sure they don't touch the glass... I have had some get frostbite before from touching the window

As long as the temperataure at the location of the plants is above 32 def F (0 deg C) Cyms should be fine. That thermometer that you place next to the plants will help you to track that. If it is indoors, I don't think temps will go that low. These are tough plants.

Decorate that window with x-mass lights and leave them up and on until Easter.

Yeah that's sooo not happening!! Haha

Cymbidiums can stand about 4 hours with temperatures as low as 28F but I would not go lower than that if you wish to prevent damage to spikes, buds and foliage. Get yourself that hi-lo temperature gauge for Christmas. :D. It beats guessing.