Saving all of my phalaenopsis orchids from mold
 

Hello everyone! I've recently had a problem with a fuzzy, white / gray mold destroying most of my orchids' roots. I was hoping that you guys could give me some advice because I'm honestly at a loss for what to do at this point!

I've been moving all of my phals from sphagnum moss to a bark mix over the past few months because a previous orchid fell victim to over-watering and strangulation by a very compact ball of moss on its roots. Now I water less than weekly, maybe every other week or every week and a half to try to keep my orchids safe from rot. I gently mist their leaves and let the water drip onto their roots, and I'm careful to only water during the day because it's been a little chilly here at night.

I had only one orchid left in moss because I bought it around the time that I was re-potting the others a few months ago and the roots seemed perfectly fine the way they were — the moss wasn't too tight on the roots, it was drying out fine after watering, and the roots looked healthy upon examination. However, I noticed some mold on the wooden support stick today which was a huge red flag so I decided to re-pot that phal to bark so I could see what was going on in there. I had to cut about half of its roots out because they were dead or mushy.

After I finished cleaning and re-potting that orchid, I examined my other orchids just to be safe and noticed a small speck of white on another so I took it out of its pot. Sure enough, the nearly brand new bark was absolutely covered in mold and all but its single aerial root was dead and rotting. Thankfully that root is healthy, but it has some open cracks so I'm worried that it may fall victim to the mold soon as well. I currently have it sitting out potless so I can water it every few days as it dries out and monitor it for mold. I plan to re-pot it once I see some new growth.

How could something like this happen if I haven't been watering my orchids very much at all? I've been very, very careful after losing my last orchid, even to the point of underwatering at times. Have I been doing something wrong? What can I do to stop this mold? It just keeps coming back and I'm worried that I'm going to lose more orchids if this continues...

Any help at all would be greatly appreciated! Thank you so much!

Welcome, pallaleiga

Photos, we need photos 'caus an image speakes for a thousand words.

I agree photos would help.

What kind of pots are they in? What kind of bark mix are you using?

You shouldn’t need to mist the leaves. If you get water sitting in the crown for extended periods you can get rot.

Most of the fuzzy molds are not pathogenic, they’re decomposers colonizing dead tissue. You kind of have to strike a balance with watering. If you go from moss to bark weaker / unhealthy roots tend to die. These will naturally decompose/mold. If you treat roots with something like hydrogen peroxide you can also kill them: the damage won’t be immediately apparent but you’re likely to end up with most of the roots dying and rotting shortly thereafter. You can also kill the roots if watering is too infrequent with long periods where the substrate is bone dry followed by periods of saturation.

With the watering regime you describe, I’m having trouble figuring out how anything would get wet enough to mold unless you have a bark mix very high in particulates (like Miracle Gro orchid mixes) and/or a pot with insufficient ventilation and/or drainage. Pictures would really help.

I agree with the above two posts and would like to know specifically what kind of bark you are using and where you got it. Some brand name from the gardening department of a store, a special mix from an online vendor, or something else? Also, I think we need to know exactly what kind of pots your orchids are in. I agree the watering regimen you describe is in no way overwatering, under normal circumstances.