CHC Potting Medium & S/H

[scy]

I have a miltoniopsis and cymbidium potted in a terrestrial mix. I noticed that the terrestrial mix is not really drying out in the winter and would like to repot it in a different medium asap before root rot hits (if it hasn't already). Sphag does not work well in my growing conditions. It does not dry out fast enough and the temperature at night is 50 degrees F. I was thinking of using a combination of 2/3 bark mix, 1/3 medium coconut husk chips. I have no experience with coconut husk chips and welcome any advice on what would be ideal.

On a side note, I have a small phal that originally was potted in sphag. It had lots of new root growths (small nubs), so I decided to repot in semi-hydroponics. I presoaked / cleaned the medium well for a few days, soaked medium and roots in rooting hormone, and kept the phal on a heating pad to help stimulate root growth. However, the roots were still a healthy green but I noticed white fuzzy mold was growing only on the roots! I unpotted it and felt the roots to see if they were dying but they were still very firm and green. I rubbed off the mold, disinfected with physan (medium too) and tried again. Now the roots have pretty much died off except for one. I am thinking of repotting it to bark to save it unless anyone has a better suggestion on what to do. I know that semi-hydroponics is not always a sure thing and really dependent on conditions. I wanted to use this as a learning experience and figure out where I went wrong. My guess would be it was too cold even with the heating pad.

[Ray]

I have never mixed bark and CHC - they are usually a substitute for each other. I would pick one, and consider adding a bit of sphagnum (20% maybe?) for more moisture retention without suffocation.

Fungus or mold growing on roots was not because of the S/H environment, but may have been more favorable for growth on an already-contaminated plant. Without knowing more details, it's not possible to give you any decent analysis of what went wrong.

It's hard for me to understand how it could have been too cold on a heating pad, unless the room was just overall way too cold.

[scy]

I have tried a bark sphag mix. The result was the bark dried up while the sphag remained soggy wet. I never knew if I should wait for the sphag to dry before watering again. The sphag just wouldn't dry even after 14 days, so I'd like to stay away from it as it just isn't right for me. The bark tends to dry up rather quickly. They are in an eastern facing window. The cymbidium and miltoniopsis are not on a heating pad. The daytime temperature on cloudy days are about 55-65 and 70-80 on sunny days. Night temps are around 50. The air is dry but some air flow as there is a vent above the window area. The vent is angled so the air blows off to the side and not directly on them. What would you recommend I use other than sphag? Would coconut husk chips be too wet if used alone?

As for the phal on the heating pad, sorry if my I gave the wrong impression. I never meant to imply that it grew white mold as a result of semi-hydroponics. I just wanted to know what I did wrong so I could avoid it from happening again. I had a dendrobium I got from Lowes that was dying from being overwatered / root rot. I repotted it in bark and all the leaves dropped in a matter of days. It seemed to be a lost cause and I had nothing else to lose, so I repotted in semi-hydroponics and sure enough, it bounced back! It still has a long road ahead of it, but the few roots that it did have really perked up and turned green!

How can I keep the roots free of the white fuzzy mold? I've already cleaned the media once before and soaked the plant in physan in 2-5 minutes. What else can I do?

[Ray]

Physan is a topical disinfectant. If the fungus is within the plant, you'll have to use something like Cleary's 3336WP.