One thing you might want to be aware of as well is that they don't like tap water due to the chemicals in it. The best thing to use is either rain water (as long as the PH is neautral), RO or distilled water. If using distilled water be sure to add a very minimal amount of fertilizer with trace elements in it to the water when you water (doesn't have to be everytime, but should be consistent) as distilled water does not have any trace elements or nutrients in it.

I have relatively low humidity (between 40 and 50 percent during the winter) but nothing as low as yours. That being said, both of my Tolumnia's have new growths coming out of them.

You might want to consider getting or building a wardian case for your tolumnia's to help up the humidity. I have read that people who do this have had tremendous success with them.

Thanks for all the advice-- definitely some things to think about. It makes sense that it would require a high-quality water for watering since they grow in trees. I have RO water so I'll use that for sure. I fertilize all my chids at 1/4 strength the manufacturer's suggestion-- do you think that is light enough?

I water mine with tap water, and fertilize about the same as my other orchids

Good to hear. My fertilizer is weak weak... plus its non-urea, so the chances of burn is minimized greatly.

sounds good - I've only ever got sun/heat burn on mine (minimal, from getting afternoon sun on extremely hot days) - not had any problems from tap water or fertilizer - tho of course I can't say how my tap water might compare with someone else's, but it's moderately hard. I do make sure to flush the pots well once a month at least.

My response to growing Tolumnia and my low humidity
 

Ok-- so I've been warned that these guys like humidity, to get watered and then to dry out come night fall, and they light high light....

So this is my response to those demands.

https://lh6.googleusercontent.com/_-...0/IMAG0007.jpg

Goodwill is a great place to pick up weird vases! I got this one today and used the wire holder the plant came with to suspend the plant inside the vase, not touching the glass or the bottom. I placed sphag on the bottom to act as a evaporative reservoir to up the humidity. I also decided to place my vanda coerulea species into the vase as it needed a better home, too.

I spray the plants in the morning-- heavily so it drenches the sides of the vase and the plant's potting media and that's it. It keeps a noticeable humidity all day but come night, it's dry, but with the sphag in there, not bone dry like the outside air.

Your thoughts, suggestions of improvement etc?

I like the vase idea! I wish I had the space for something like that...

I was also thinking of wrapping my Tolumnia's pots in sphagnum to increase local humidity. That way the roots won't be wet, but the area around them will stay more humid. Any thoughts about this, anyone?

hmmm ... don't know what kind of humidity you have - I haven't had to do anything special - potted in very small clay pots (clay holds a bit of moisture) in fast draining, fast drying media - water them daily in warm/hot, dry weather, a bit less often in cool, damper weather (I make sure they are dry before watering)

I do have a mounted Tolu sylvestris - gets watered daily most of the year, but every two days in winter - twice a day in hot, dry weather (haven't got this one to bloom yet tho - grrr!)

the humidity here varies quite a bit - always damper at night than during the day, summer days can be quite dry (less than 30%, usually mid-low 20s), can be as low as teens, or single digits on occasion), summer nights usually have moderate humidity - winter is usually higher (moderate humidity during the day, very high at night, tho occasionally can also be quite low, but it's rare)

Here in Seattle it is always relatively humid, 50% or greater...Maybe I won't worry too much about increasing humidity.

Thus far, I have been misting heavily in the AM every day, and soaking for 15 minutes once a week. The plant looks pretty good. I even picked up a second one today (Pink Panthers)!

My only thought about wrapping sphag around the clay is that clay is extremely pourus, so I don't know how well the clay would dry out with sphag (with somewhat constant wetness) being wrapped around it. I say try it and see!