Phal - issues with fertilizer, pots, and environment, mainly - just issues... - Orchid Board

D_novice · #8 03-28-2017, 02:22 PM

Quote:

Originally Posted by jkofferdahl

Humidity trays are pretty much useless. I use them to catch water run-off, but not to raise humidity.

With all due respect to Mr. Offerdahl, whose orchid-growing results speak for themselves, the topic of humidity trays has been passionately and thoroughly bandied about in other threads in this forum. Some esteemed OB participants equate them with doctors recommending smoking for its health benefits!....

This topic is of interest to me, since I grow in windows, don't have much of a greenhouse, and own several humidity trays.

For getting plants and a room from 30% humidity to 65%, there's no question a humidity tray can't do it by itself, esp. compared to a humidifier, mister, misting by hand, etc.

However, I think one of the problems with humidity trays is the lack of surface area in which the water can evaporate into the air. A flat water surface, covered with a thick plastic grate that limits air movement, and in which the water is probably covered with a thin film of who knows what that "tightens up" the surface tension, is a different animal than a dish or tray or humidity tray containing a porous mineral substrate live lava rock or other pumice, gravel, coarse sand, or even expanded leca clay in which the water can easily evaporate.

I have been playing with my humidity trays, and misting and some cheap hygrometers. The humidity is highest on top of the damp gravel, and still better than no tray + gravel at the level of the top of the plant (so the undersides of the leaves, and the lower leaves, are getting a benefit of increased humidity.) Misting is still best, but it isn't passive, and machines are a whole different order of complexity.

So - I would recommend against an absolute (hyperbolic?!) statement "humidity trays are useless and do nothing", but rather (like so many things) "it depends". And it depends on a million different things, like what plants, ambient room humidity, what else you're trying to help with humidity, etc.

And, for those who think the AOS publications department hasn't read anything or grown any orchids in 5 or 6 decades, even some - gasp! - growers with sterling reputations still recommend this outdated (

) old-fashioned trick:

Humidity: 50% to 80% relative humidity can be provided by placing the pots in the tray filled with 1" to 2" of gravel, and 3/4 inch of water. The evaporation will increase the humidity around the plants.

Fox Valley Orchids, Culture Instructions