bobc wrote:
Thanks Nancy and Jack.
Nancy, the plants are in clay pots on my windowsill with about 40
other plants (mostly orchids, but some Tillandsia, a couple African
violets and a couple jungle cacti).
The relative humidity isn't that great, but it's averages around 40%.
It fluctuates during spring, summer and fall with the weather outside
because the windows are open 24/7 during those seasons.

You may try plastic pots or insert your clay into a plastic container
for added moisture. Humidity trays may help locally. If you keep a
fan running that quickly disperses the moisture. They need air
movement, too. You could also add a bit of sphagnum to the top of the
mix. I've added about 15% to my bark mix for moisture retention. With
a standard mix, of 4 bark, 1 perlite, 1 charcoal, add a little less
than 1 part sphagnum, or for 6 parts combined mix add 1 part of
sphagnum. I measure the sphagnum dry, not packed, then soak it to add
to the mix. It doesn't take much.

Jack, I'm gonna try mine on cork bark with a bit of Sphagnum like the
Soph. and Den.
I only get 65 -70% RH immediately after watering or if the humidity is
that high naturally.
But first I may try watering the Ang. more often - it's in very chunky
bark.
I can't have high relative humidity around the orchids since they're in
our living room window and there's no way I'm gonna get to hang plastic
around the plant area - that just won't fly. I don't think it's
healthy to have that much water vapor in the house?

The comfort zone for humidity is between 40 and 60%, a little more
won't hurt with good air movement. You cna't let it accumulate ex. an
unvented bath or shower because of mold and condensation. Most houses
get too dry during the heating season, during the winter a humidifier
near your plants would rapidly be dispersed throughout the rest of the
house, especially with a forced air system. Because you keep windows
open during the cooling season, I wouldn't worry then.

Are your plants actually on the windowsill? If you could track down a
narrow table and keep it a couple of inches away from the wall, the
cold draft would fall to the floor and not roll across your plants and
pots. I've also used clear shower curtain in the window to help divert
the flow of cold air. A fan from the side or center of the room aimed
at the window would help push the draft away from the plants. It would
disperse the cooler air outwards along the wall.

I bought a frame to an old china buffet for $5, with the intent of
making a growing cabinet for seedlings. Nothing there except the shell
and legs, the drawers or doors were long gone. It's long enough for a
4' florescent, and big enough for about 3 flats of small plants. I
will paint the inside with white exterior paint, replace the doors with
plexiglass or framed vinyl. The fans and lights can be plugged into
GFCI outlet, and should be fine with careful watering. Because it is
on legs, there is room for a drain and a container to catch the runoff
when I water. If it doesn't work, I won't have much invested in it,
and will still have the light for another application. I really want
to convert an entertainment center. Basically the same but taller, and
with concealed storage for drainage and supplies, etc. I'll find one
at a garage sale or discarded next to a dumpster that will work for the
mods I have in mind. Then I can call it a "Wardian Case" and have a
nice display that will satisfy T's esthetics for room decor.

I didn't mention Tolumnia in my post. I really like the plants,

Aren't they cute? I have more trouble breaking the spike on the
prionochilum. I grow mine mounted. You didn't mention the orientation
of the window. South should work, East or west may work. A lot
depends on obstructions both inside and out.

Best wishes,

Nancy