Sorry, but humidty trays do very little good in an open room.

Copying from my own page on humidty:

"A general caveat about all of the humidity-enhancing methods described for
in-home growing: remember that unless your growing area is sealed off from
the rest of your home, any effort to raise the humidity level around your
plants is actually trying to raise the humidity of your entire house!
Because of that, especially if there is air circulation due to fans or
forced air heating, the less active methods like the humidity trays appear
to be of very limited value."

Copying an Orchidsource.com post by Todd Zimmerman:

"I am sorry, but "Hmidity trays add 10% to 20% humidity to your room
humidity." is just not possible unless your room is an aquarium.

I have been distressed about this bit of published folk lore ever since I
began growing.

Without going into the physics of it....

I have sat in a small, room with no ventilation, taking readings every five
minutes (trials of ten readings) from a hygrometer suspended 10" above an
open seedling tray of water (leaf height), and found no difference
(statistically significant or even imaginarily noticable) when compared to
readings taken above the same tray when it was dry. The hygrometer was
tested between trials and the room allowed to vent fully.

In addition to the vapor input to the room from the tray (surface areas
about 1.5 square feet), my lungs (surface area coparable to that of a tennis
court) were actively pumping warm air, at a humidity of 95%, into that same
room. Even that did not increase the humidity readings more than 2% from the
beginning of a trial to the end (equally for both wet and dry trays).

Pots over the tray would reduce the effective evaporative surface area of
the tray. Plants will increase humidity by transpiration and by slowing air
movement. Fans will move water vapor away from the plants.

Someone said that there was a similar study published in Orchids magazine
several years ago (with the same conclusions)."


--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies, Books, Artwork, and Lots of Free Info!

.. . . . . . . . . . .
"John M. Gamble" wrote in message
...
In article ,
Bolero wrote:
FIne for what?


Getting the air above winter-dry and making the orchid less
uncomfortable.

40% is below the ideal in any sense of the word.


Ideal, yes, "achievable by mere mortals who don't own a greenhouse", no.

Humidity trays don't work in my opinion either.


This is flatly untrue. One can reach %40 humidity given
humidity trays and some pebbles (which help with the surface
area that exposes the water).

--
-john

February 28 1997: Last day libraries could order catalogue cards
from the Library of Congress.