My Phal potting mix, watering regime & method

[james mickelso]

Ray, I use medium to course bark along with sponge rock (1/2") and charcol. If I over pot I run the risk of fungus (or bacterial) rot. If I over pot it is most likely that this condition will occur. I have lost a lot of orchids from Catts to cyms every time I over potted. I now either use lava rock or my current mix and never over pot. And the rot has gone bye bye. I have a large fan on constantly too. I agree that wicking is the transpirating agent but always caution newer accolytes not to over pot because of my experiences. I think with the plant sitting on the mix, right underneath the plant interferes with this wicking process. Of course finer media developes the problem faster than a course mix like mine. Thoughts please.

[Ray]

In my opinion, and with info from a few experiments I have done, I still think it's more of a limited evaporation rate phenomenon than one of wicking, and I cannot see how roots would interfere with the process.

Bark- and CHC-based mixes simply don't wick well at all.

Put an inch of water in a glass, and fill it up with your potting medium. You'll be able to see the wicking rate pretty easily. Most LECA brands will be wet clear to the top in a matter of 15-20 minutes, while most barks I've tried never transfer the moisture upward completely - the evaporation rate is greater than the ability of the bark to absorb and become fully saturated and then transfer it to the adjacent particles.

As to roots interfering, I would think that as they absorb water themselves, the medium around them would dry faster if that was appreciable, and would be unaffected otherwise.