Question
Jim.
Thank you so much for your reply. On careful inspection I see no sooty black mildew. However, on very close inspection this morning, I find that of my three remaining "healthy" leaves that one of them has a "mushy" spot about the size of a nickel next to the stem. I had not noticed this on any of the others.

I can easily move my orchid about 3feet from the window which will put it closer to a sealing fan that we never turn off. Ironically, I am traveling to San Jose on Wednesday and need to leave my husband some detailed instructions. Do you think I need to repott it before I go? Is it possible that when I put the orchid pot on the rocks over the water that it somehow got too wet?
I am using regular tap water which is harsh for many plants in our area. Should I switch to distilled water?

Thanks again for your help.

Followup To

Question -
I have phalaenopsis white orchid that I was given in December. It did beautifully for many months here in South Texas. I have had it in a southwest corner near a south facing window. The window has a lace curtain to filter the light. In the past month or so it has lost its three lower leaves. These have turned yellow and dropped off. I have also noticed that the roots on the surface seem to be drying out. I water it about every 5 days and allow it to dry out between waterings. After the first leaves began to turn yellow, I read where the orchid should have moisture. So I put gravel in a pot and would pour water so that it would not reach the orchid pot, but the air around it would be moist. I felt like that only hastened the yellowing of the leaves, so I have gone back to watering every 5 days or so. Please advise.

Answer -
Hello Kathy,

While it is not unusual for one or two bottom leaves to turn yellow and die, three is something to be concerned about. Can you see evidence of a black sooty substance at the leaf bases of the ones that turned yellow?  If there is, that could indicate the presence of a fungus growth caused by water droplets sitting overnight on the leaf.  

Exposed or aerial roots drying out is a common occurence.  You can minimize the drying by lightly misting the roots several times during the day, but do not mist within 4 hours of sunset.  Also, it would be a good idea to place the phal where it will be exposed to some gentle breezes, this will help dry off the leaves prior to nightfall.  

A humidity tray under the pot can help increase the humidity slightly as the water evaporates.  That along with misting should help a lot.  

In South Texas, the heat from the sun may be a bit too hot for the phal, even with a lace curtain filtering the sun.  Position it at least 3 feet away from the window so there is little or no sunlight upon it in the afternoon.  

Hope this helps.  Good luck and good growing.

Jim Kawasaki
San Jose, Ca.

Answer
Hi again Kathy,

Mushy spot on a leaf near the stem?  That may or may not be something to be concerned about.  My fear is that it may be caused by a bacteria infection and if it is, this can be fatal.  If you want to be careful, I would suggest removing the suspect leaf by cutting it off as close to the stem as you can with a sterile cutter.  I use industrial grade single-edge razor blades for this purpose, the are available at most paint and hardware stores as they are used with paint scrapers and some types of box cutters.  

Moving it closer to where it will get some air movement from the ceiling fan would be great!  You can repot now or later, choice is yours.  You can continue to use your hard tap water but water it twice.  By "twice", I mean water it then wait about an hour then water again.  The first watering will disolve any harsh salts in the potting mix and the second watering will flush it out.  But, if you choose to go with distilled water, be sure to get a complete fertilizer that has lots of different minerals in it.  

Coming to San Jose on Wednesday?  Hope you have a great trip.  Business or pleasure?  I'd love to meet you but unfortunately I'll be busy for most of this week working on my stepfather's farm.  I grew up on a farm, worked in the computer industry, retired and took care of grandkids for 13 years and now I'm back to being a farmer!  I've come full circle!!!  (LOL)  

Jim